ALLIED WASTE INDUSTRIES INC
8-K, 1996-10-02
REFUSE SYSTEMS
Previous: CONTINENTAL BANCORPORATION, 15-12G, 1996-10-02
Next: ALLSTATE FINANCIAL CORP /VA/, DEF 14A, 1996-10-02



<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                    FORM 8-K


                                 CURRENT REPORT



                       Pursuant to Section 13 or 15(d) of
                      the Securities Exchange Act of 1934



              Date of Report (Date of earliest event reported)
                    October 2, 1996 (September 17, 1996)
                    ------------------------------------


                        Allied Waste Industries, Inc.
- --------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)


                                  Delaware
- --------------------------------------------------------------------------------
                 (State or other jurisdiction of incorporation)



          0-19285                                            88-0228636    
- ----------------------------------             ---------------------------------
 (Commission File Number)                      (IRS Employer Identification No.)



              7201 East Camelback Road, Suite 375, Scottsdale, Arizona 85251
- --------------------------------------------------------------------------------
          (Address of principal executive offices)       (Zip Code)



Registrant's telephone number, including area code    (602) 423-2946
                                                  ------------------------------


                                  Applicable
- --------------------------------------------------------------------------------
         (Former name or former address, if changed since last report.)





<PAGE>   2
ITEM 2.   ACQUISITION OR DISPOSITION OF ASSETS

         On September 17, 1996, Allied Waste Industries, Inc. ("Allied")
entered into a Stock Purchase Agreement (the "Agreement") with Laidlaw Inc.
("Laidlaw"), among others, which provides for the sale of the solid waste
management operations of Laidlaw to Allied (the "Acquisitions").  Under the
terms of the Agreement, Laidlaw will receive consideration (the
"Consideration") consisting of: (i) $1,200,000,000 in cash (the "Cash
Consideration"), (ii) a 7% Junior Subordinated Debenture in the principal
amount of $150,000,000 (the "7% Debenture"), (iii) a Zero Coupon Junior
Subordinated Debenture in the principal amount of $168,300,000 (the "Zero
Coupon Debenture" and, together with the 7% Debenture, the "Allied
Debentures"), (iv) 14,600,000 shares of the common stock, par value $.01 per
share, of Allied (the "Common Stock"), and (v) warrants to purchase 20,400,000
shares of Common Stock (the "Warrants").  In the event the companies being
acquired have a deficit in working capital on the Closing Date, the amount of
the Cash Consideration will be reduced accordingly.  The Consideration was
determined through extensive negotiations between Allied and Laidlaw.

         The sources of the Cash Consideration will be (i) a bank credit
facility in the aggregate amount of $1,250,000,000 (the "Credit Facility")
pursuant to a financing commitment letter received by Allied from Goldman Sachs
Credit Partners L.P., Citibank, N.A., Citicorp Securities, Inc., Citicorp USA,
Inc., and Credit Suisse; and (ii) an offering of Senior Subordinated Notes due
2006 in the principal amount of $475,000,000 (the "Senior Notes") to be
underwritten by Goldman, Sachs & Co. and Citicorp Securities, Inc.

         The Acquisitions have been approved by the boards of directors of both
Allied and Laidlaw, and are expected to be consummated in the first quarter of
1997.  Laidlaw currently provides solid waste collection, transportation,
storage, recycling and disposal services in 18 states and 7 Canadian provinces.
Laidlaw's operations include 140 facilities, of which 73 provide solid waste
hauling services, 31 provide recycling services and 29 are sanitary landfills.
Following the Acquisitions, Allied is expected to become the fourth largest
solid waste management company in North America, with a market presence in 23
states and 7 Canadian provinces.  As the result, the combined company will have
49 sanitary landfills with approximately 1 billion gate yards of permitted air 
space, 29 transfer stations and 115 collection facilities.

Description of the Agreement

         The Agreement provides that the Acquisitions will be effected pursuant
to the following specific transactions:

(i)      Allied Holdings (United States), Inc. ("Allied U.S."), a Delaware
         corporation and a wholly-owned subsidiary of Allied, will acquire all
         of the issued and outstanding capital stock of Laidlaw Waste Systems,
         Inc. ("LWSI"), a Delaware corporation, from Laidlaw Transportation,
         Inc. ("LTI"), a Delaware corporation and an indirect wholly-owned
         subsidiary of Laidlaw, for the Cash Consideration and 7,225,000 shares
         of Common Stock;





                                      2
<PAGE>   3

(ii)     3294862 Canada Inc. ("Allied Canada"), a Canadian corporation
         and an indirect wholly-owned subsidiary of Allied, will acquire all of
         the issued and outstanding capital stock of Laidlaw Waste Systems
         (Canada) Ltd. ("LWSC"), a Canadian corporation and a wholly-owned
         subsidiary of Laidlaw, for consideration of the 7% Debenture, the Zero
         Coupon Debenture, the Warrants and 5,500,000 shares of Common Stock;
         and

        
(iii)    Allied Canada will acquire all of the issued and outstanding capital
         stock of Laidlaw Medical Services Ltd. ("LMS"; LWSI, LWSC and LMS are
         collectively referred to as the "Acquired Companies"), a Canadian
         corporation and a wholly-owned subsidiary of Laidlaw for 1,875,000
         shares of Common Stock.
        
         The 7% Debenture and the Zero Coupon Debenture issued by Allied Canada
will be exchanged for like Debentures issued by 3294854 Canada Inc. ("Allied
Finance"), a Canadian corporation and a wholly owned subsidiary of Allied.

         The Agreement contains representations and warranties, indemnities and
conditions to closing customary to transactions of this type.  Neither party
will have any obligation to indemnify the other for breaches of certain
covenants and representations and warranties unless the aggregate amount of
damages sustained with respect to those covenants, representations and
warranties exceed $25,000,000.

         The Agreement provides that Laidlaw will not: (i) acquire additional
securities of Allied, (ii) sell Allied Common Stock or Warrants except as
authorized by the Agreement, (iii) offer to purchase, either individually or as
a member of a group, securities of Allied, (iv) solicit proxies, either
individually or as a member of a group, related to any securities of Allied or
(v) take certain other actions with respect to Allied (the foregoing
restrictions are referred to collectively as the "Standstill Provisions").
Notwithstanding the Standstill Provisions, Laidlaw is permitted to distribute
shares of Common Stock or the Warrants under the Agreement pursuant to: (v) a
dividend of Common Stock or  Warrants pro rata among all Laidlaw stockholders,
(w) a sale in accordance with Rule 144 under the Securities Act of 1933, as
amended (the "Securities Act"), (x) a sale pursuant to the exercise of the
registration rights set forth in the Registration Agreement (defined below),
(y) a sale in a private transaction to a buyer that is not an affiliate of
Laidlaw and will hold no more than 9% of the Common Stock outstanding following
such sale or (z) a tender offer or certain other transactions proposed by a
third party.  Laidlaw will cause all of the Common Stock held by Laidlaw or any
of its affiliates to attend all stockholder meetings of Allied to ensure that a
quorum is present at any such meeting.  Laidlaw also has the right to designate
two nominees to Allied's board of directors (the "Board").  The Standstill
Provisions will terminate upon the earlier to occur of the fifth anniversary of
the Closing or such time as Laidlaw and its affiliates own less than 5% of the
outstanding voting securities of Allied.  Laidlaw's obligation to cause its
shares of Common Stock to be present at any annual or special meeting of
stockholders, and Laidlaw's right to nominate two members of the Board will
terminate upon the earlier to occur of the fifth anniversary of the Closing or
such time as Laidlaw and its affiliates own less than 10% of the outstanding
voting securities of Allied.





                                      3
<PAGE>   4
         Each party will pay its own expenses incurred pursuant to the
Acquisitions and no expenses of Laidlaw will be paid by any of the Acquired
Companies.  The Agreement may be terminated (i) by the mutual consent of Allied
and Laidlaw; (ii) by either Allied or Laidlaw if the Acquisitions have not been
consummated on or before the later of December 31, 1996 or the 61st day after
the United States Securities and Exchange Commission has approved the Notice of
Annual Meeting, Proxy Statement and Proxy regarding the special meeting of the
stockholders of Allied to be held to approve the issuance of Common Stock
pursuant to the Agreement; or (iii) by Allied or Laidlaw if the stockholders of 
Allied fail to approve the Acquisitions.
        
Description of the 7% Debenture

         The 7% Debenture will be initially issued by Allied Canada in the form
attached to the Agreement as Exhibit A-1 (the "Allied Canada 7% Debenture")
and, immediately following the Closing, the Allied Canada 7% Debenture will be
exchanged for a 7% Debenture (the "Allied Finance 7% Debenture") issued by
Allied Finance in the form of Exhibit B-1 to the Agreement pursuant to the
Debenture Exchange Agreement attached to the Agreement as Exhibit M.  The terms
of the Allied Canada 7% Debenture and the terms of the Allied Finance 7%
Debenture will be substantially the same (as used herein, the term "7%
Debenture" refers to both the Allied Canada 7% Debenture and the Allied Finance
7% Debenture).

         The 7% Debenture has a 12-year term and accrues interest on the
principal amount of $150,000,000 at a rate of 7% per annum.  Interest on the 7%
Debenture shall be deferred until the third anniversary of the Closing, at
which time the interest shall be payable semi-annually.  If interest is paid in
shares of Common Stock, the number of shares is determined by dividing the
amount of interest due by the current market price of the Common Stock
calculated using a 20 day average of the closing prices for the Common Stock on
the Nasdaq Stock Market ending three days prior to the measurement date (the
"Current Market Price").  The 7% Debenture will be subordinate to the Credit
Facility and the Senior Notes.  Allied will guaranty payment of the 7%
Debenture subject to the rights of any senior debt pursuant to the Guaranty
attached to the Agreement as Exhibit H-1.  The 7% Debenture will have customary
default provisions upon any failure to make required payments or bankruptcy on
the part of Allied or Allied Finance.  Upon maturity, the principal amount of
the 7% Debenture will be paid in cash.  The 7% Debenture may be redeemed after
the fifth anniversary of the Closing at a scheduled cash price.  Upon a change
of control of Allied, Laidlaw may force Allied to repurchase the 7% Debenture
at a scheduled price, subject to the rights of any senior debt of Allied and
Allied's option to repurchase the 7% Debenture with a number of shares of
Common Stock determined by dividing such scheduled price by the Current Market
Price.  The 7% Debenture may be transferred in whole, or in parts of not less
than $75,000,000, to any party that agrees to be bound by its terms.

Description of the Zero Coupon Debenture

         The Zero Coupon Debenture will be initially issued by Allied Canada in
the form attached to the Agreement as Exhibit A-2 (the "Allied Canada Zero
Coupon Debenture") and, immediately following the Closing, the Allied Canada
Zero Coupon Debenture will be exchanged for a Zero





                                      4
<PAGE>   5
Coupon Debenture (the "Allied Finance Zero Coupon Debenture") issued by Allied
Finance in the form of Exhibit B-2 to the Agreement pursuant to the Debenture
Exchange Agreement.  The terms of the Allied Canada Zero Coupon Debenture and
the terms of the Allied Finance Zero Coupon Debenture will be substantially the
same (as used herein, the term "Zero Coupon Debenture" refers to both the
Allied Canada Zero Coupon Debenture and the Allied Finance Zero Coupon
Debenture).

         The Zero Coupon Debenture has a 12-year term and does not accrue
interest on the principal amount of $168,300,000.  The Zero Coupon Debenture
will be subordinate to the Credit Facility and the Senior Notes.  Allied will
guaranty payment of the Zero Coupon Debenture subject to the rights of any
senior debt pursuant to the Guaranty attached to the Agreement as Exhibit H-2.
The Zero Coupon Debenture will have customary default provisions upon any
failure to make required payments or bankruptcy on the part of Allied or Allied
Finance.  Upon maturity, the principal amount of the Zero Coupon Debenture will
be paid in cash.  Upon a change of control of Allied, Laidlaw may force Allied
to repurchase the Zero Coupon Debenture at a scheduled price, subject to the
rights of any senior debt of Allied and Allied's option to repurchase the Zero
Coupon Debenture with a number of shares of Common Stock determined by dividing
such scheduled price by the Current Market Price.  The Zero Coupon Debenture
may be transferred in whole, or in parts of not less than $75,000,000, to any
party that agrees to be bound by its terms.

Description of the Warrants

         The Warrants are attached to the Agreement as Exhibit C and will be
issued by Allied at the Closing.  The Warrants are exercisable for 20,400,000
shares of Common Stock at an exercise price of $8.25 per share.  The term of
the Warrants is twelve years.  The Warrants are freely exercisable by any
holder that is not Laidlaw or an Affiliate (as defined in the Warrants) of
Laidlaw.  The Warrants may not be exercised by Laidlaw or any of its Affiliates
unless a change of control of Allied occurs.  The Warrants are transferrable to
any person or entity that is not Laidlaw or an Affiliate so long as, after such
transfer, the transferee will not own more than 9% of the Common Stock.  The
Warrants may be transferred to any Affiliate of Laidlaw if such transfer is
pursuant to a pro-rata distribution of Warrants to all stockholders of Laidlaw.
The exercise price and number of shares of Common Stock for which the Warrants
may be exercised are subject to adjustment upon the occurrence of (i) any
combination, subdivision, reorganization or reclassification of the Common
Stock (including a reorganization or reclassification pursuant to a merger) or
(ii) any dividend of assets or securities to all holders of the Common Stock.

Description of the Registration Agreement

         The Stock Registration Agreement (the "Registration Agreement") is
attached to the Agreement as Exhibit E and will be entered into by Allied,
Laidlaw and LTI at the Closing.  The Registration Agreement provides that
Laidlaw shall have certain rights (the "Registration Rights") to cause shares
of Common Stock received pursuant to the Agreement, shares of Common Stock
received for any payment of interest on or redemption of the Allied Debentures,
and the Warrants (the "Registrable Securities") to be registered under the
Securities Act.  Laidlaw has the right to cause Allied to file a Registration
Statement under the Securities Act registering those Registrable





                                      5
<PAGE>   6
Securities designated by Laidlaw (a "Demand Registration") on up to 5
occasions, provided that Laidlaw may only exercise one Demand Registration
during any twelve month period and any Demand Registration must relate to no
less than 5,000,000 Registrable Securities.  Laidlaw will receive one
additional Demand Registration if either the 7% Debenture or the Zero Coupon
Debenture are redeemed for shares of Common Stock pursuant to their terms.
Pursuant to the Registration Agreement, Laidlaw also has the right to cause
Registrable Securities to be included in any registration statement under the
Securities Act filed by Allied so long as certain restrictions on the inclusion
of such Registrable Securities are met.  The right to cause one Demand
Registration may be transferred to a purchaser of Registrable Securities that
is not an affiliate of Laidlaw.  The Registration Rights terminate six months
after the twelfth anniversary of the Closing.

Description of the Management Agreement

         The Waste Services Management Agreement (the "Management Agreement")
is attached to the Agreement as Exhibit F and will be entered into by Allied
and Laidlaw at the Closing.  The Management Agreement provides that until the
fifth anniversary of the Closing, Laidlaw will not (i) engage in the business
of residential or commercial non-hazardous solid waste collection or recycling;
(ii) own, lease or operate a landfill regulated under Subtitle D of the
Resource Conservation and Recovery Act of 1976, as amended, except those
landfills currently owned, leased or operated by Laidlaw; (iii) solicit any
managerial employee of Allied to leave Allied's employ; (iv) disclose the
customers of the Acquired Companies to any third party; or (v) promote or
assist any party to do any of the foregoing; provided that Laidlaw may continue
to operate its businesses that are not part of the Acquired Companies in the
ordinary course of those businesses as currently constituted.  If Laidlaw or
any of its subsidiaries acquires any business that engages in the collection,
transportation, storage, recycling, or disposal of non-hazardous solid waste,
it will offer to sell such business to Allied at a specified price and on
specified terms within 30 days of such acquisition.  If Allied does not
purchase such business at the specified price and on the specified terms,
Laidlaw may only sell such business at a price and upon terms greater than
those offered to Allied.

Amendment to the TPG Agreement

         On September 17, 1996, Allied entered into an Agreement (the
"Amendment") with TPG Partners, L.P. and TPG Parallel I, L.P. (collectively,
"TPG") to amend certain provisions of the Securities Purchase Agreement between
Allied and TPG dated October 27, 1994 (the "TPG Agreement") conditioned upon
the Closing.  Pursuant to the Amendment, Allied will amend its bylaws to expand
the Board to 12 persons.  TPG will be entitled to designate three directors
(the "TPG Designees") to serve on the Board, Allied will designate four
directors, Laidlaw will designate two directors, and three new outside
directors will be selected by a newly-formed nominating committee of the Board.
The initial outside directors must be acceptable to TPG, in its sole
discretion, but subsequent nominees to the Board (other than the TPG Designees)
shall not be subject to approval by TPG.  The TPG Designees will serve on the
committees of the Board commensurate with the number of Board seats held by
them, and one TPG Designee shall serve on the nominating committee of the
Board.  TPG has the right to fill any vacancy occurring in the Board due to the
failure of any duly elected TPG Designee to complete his term.  The Amendment
deleted the





                                      6
<PAGE>   7
requirement contained in the TPG Agreement that TPG vote in favor of the slate
of directors nominated by the Board and the corresponding requirement that
Allied use its best efforts to cause the persons nominated by TPG to be elected
to the Board.  TPG's right to nominate the TPG Designees to serve on the Board
shall terminate if, at any time, TPG and its affiliates own less than either
(i) 6.5% of the Common Stock (calculated on a fully diluted basis) or (ii)
5,888,637 shares of Common Stock.

         Pursuant to the Amendment, Allied will increase the number of demand
registrations that TPG is entitled to elect from one to three.  The standstill
provisions of the TPG Agreement shall terminate upon the earlier to occur of
(x) the fifth anniversary of the closing date of the TPG Agreement and (y) the
time at which TPG and its affiliates own less than either (i) 6.5% of the
Common Stock (calculated on a fully diluted basis) or (ii) 5,888,637 shares of
Common Stock.  The provision contained in the TPG Agreement that terminates the
standstill provisions if any of the TPG Designees fails to be elected to the
Board was deleted and in its place was inserted a provision that the standstill
provisions terminate if Allied fails to nominate any TPG Designee to the Board.
Finally, the Amendment deletes the requirement contained in the TPG Agreement
that 66.66% of the Board of Directors of Allied approve certain corporate
actions.

ITEM 7.   FINANCIAL STATEMENTS, PRO FORMA FINANCIAL STATEMENTS AND EXHIBITS.

         (a)  Financial Statements of Businesses Acquired.

         At the present time, it is impracticable to provide financial
statements specified in Rule 3-05(b) of Regulation S-X for the business
acquired.  Such financial statements will be filed as soon as practicable but
not later than 60 days from the date of this report.

         (b)  Pro Forma Financial Information

         At the present time, it is impracticable to provide pro forma
financial information required pursuant to Article 11 of Regulation S-X.  Such
pro forma financial information will be filed as soon as practicable but not
later than 60 days from the date of this report.

         (c)  Exhibits

         The following exhibits, from which schedules have been omitted and
will be furnished to the Commission upon its request, are filed with this
report on Form 8-K:

         2.1     Stock Purchase Agreement dated September 17, 1996 among Allied
                 Waste Industries, Inc., Allied Holdings (United States), Inc.,
                 3294862 Canada Inc., Laidlaw Inc., Laidlaw Transportation,
                 Inc., Laidlaw Waste Systems, Inc., Laidlaw Waste Systems
                 (Canada) Ltd., and Laidlaw Medical Services Ltd.
         
                 Exhibits
                 Exhibit A-1      Form of Allied Canada 7% Debenture





                                      7
<PAGE>   8

                                                                        
                                                                        
                 Exhibit A-2      Form of Allied Canada Zero Coupon Debenture
                 Exhibit B-1      Form of Allied Finance 7% Debenture 
                 Exhibit B-2      Form of Allied Finance Zero Coupon Debenture
                 Exhibit C        Form of Allied Warrant 
                 Exhibit D        Form of Laidlaw Subscription Agreement    
                 Exhibit E        Form of Stock Registration Agreement      
                 Exhibit F        Form of Waste Services Management Agreement 
                 Exhibit G        Form of Release Agreement            
                 Exhibit H-1      Form of Guaranty related to Allied Finance 7%
                                  Debenture
                 Exhibit H-2      Form of Guaranty related to Allied Finance 
                                  Zero Coupon Debenture 
                 Exhibit I        Form of Opinion of Laidlaw's U.S. Counsel
                 Exhibit J        Form of Opinion of Laidlaw's Canadian Counsel
                 Exhibit K        Form of Opinion of Allied's U.S. Counsel      
                 Exhibit L        Form of Opinion of Allied's Canadian Counsel  
                 Exhibit M        Form of Debenture Exchange Agreement          
                 Exhibit N        Form of Offset Letter Agreement               
                                                                                
                 Schedules (omitted)                                            
                 Schedule I       Acquired Subsidiaries                         
                 Schedule II      Retained Subsidiaries                         
                 Schedule III     Intercompany Waste Agreements                 
                 Schedule IV      Retained Land                                 
                 Schedule V       Leased Assets                                 
                 Allied Disclosure Schedule                                     
                 Laidlaw Disclosure Schedule                                   
 
         10.1    Agreement between Allied Waste Industries, Inc., TPG Partners,
                 L.P. and TPG Parallel I, L.P. dated September 17, 1996.





                                      8
<PAGE>   9
                                   SIGNATURE

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                       ALLIED WASTE INDUSTRIES, INC.



Date:    October 2, 1996               By: /s/ Steven M. Helm    
     ---------------------                 ------------------------------------
                                       Name:   Steven M. Helm               
                                              ---------------------------------
                                       Title:  Vice President/Legal         
                                              ---------------------------------






                                      9



<PAGE>   10

                                EXHIBIT INDEX



       EXHIBIT                                          
       NUMBER                   DESCRIPTION
       -------                  -----------

        2.1      Stock Purchase Agreement dated September 17, 1996 among Allied
                 Waste Industries, Inc., Allied Holdings (United States), Inc.,
                 3294862 Canada Inc., Laidlaw Inc., Laidlaw Transportation,
                 Inc., Laidlaw Waste Systems, Inc., Laidlaw Waste Systems
                 (Canada) Ltd., and Laidlaw Medical Services Ltd.
                  

                 Exhibits

                 Exhibit A-1      Form of Allied Canada 7% Debenture
                 Exhibit B-1      Form of Allied Finance 7% Debenture 
                 Exhibit B-2      Form of Allied Finance Zero Coupon Debenture
                 Exhibit C        Form of Allied Warrant 
                 Exhibit D        Form of Laidlaw Subscription Agreement    
                 Exhibit E        Form of Stock Registration Agreement      
                 Exhibit F        Form of Waste Services Management Agreement 
                 Exhibit G        Form of Release Agreement            
                 Exhibit H-1      Form of Guaranty related to Allied Finance 7%
                                  Debenture
                 Exhibit H-2      Form of Guaranty related to Allied Finance 
                                  Zero Coupon Debenture 
                 Exhibit I        Form of Opinion of Laidlaw's U.S. Counsel
                 Exhibit J        Form of Opinion of Laidlaw's Canadian Counsel
                 Exhibit K        Form of Opinion of Allied's U.S. Counsel
                 Exhibit L        Form of Opinion of Allied's Canadian Counsel  
                 Exhibit M        Form of Debenture Exchange Agreement          
                 Exhibit N        Form of Offset Letter Agreement               
                                                                                
                 Schedules (omitted)                                            
                 Schedule I       Acquired Subsidiaries                         
                 Schedule II      Retained Subsidiaries                         
                 Schedule III     Intercompany Waste Agreements                 
                 Schedule IV      Retained Land                                 
                 Schedule V       Leased Assets                                 
                 Allied Disclosure Schedule                                     
                 Laidlaw Disclosure Schedule                                   
 
         10.1    Agreement between Allied Waste Industries, Inc., TPG Partners,
                 L.P. and TPG Parallel I, L.P. dated September 17, 1996.



<PAGE>   1
================================================================================

                            STOCK PURCHASE AGREEMENT

                                     among

      Allied Waste Industries, Inc., Allied Holdings (United States), Inc.
                            and 3294862 Canada Inc.


                                      and


                  Laidlaw Inc., Laidlaw Transportation, Inc.,
                          Laidlaw Waste Systems, Inc.,
                    Laidlaw Waste Systems (Canada) Ltd., and
                         Laidlaw Medical Services Ltd.


                                  dated as of
                               September 17, 1996

================================================================================
<PAGE>   2
                               TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                                                         Page
<S>      <C>     <C>                                                      <C>
ARTICLE  I

                       DEFINITIONS AND INTERPRETATION . . . . . . . . .    2

         1.1     Definitions  . . . . . . . . . . . . . . . . . . . . .    2
         1.2     Interpretation . . . . . . . . . . . . . . . . . . . .   16
         1.3     Knowledge  . . . . . . . . . . . . . . . . . . . . . .   16

ARTICLE II

                              THE ACQUISITIONS  . . . . . . . . . . . .   17

         2.1     Sales and Purchases of Shares  . . . . . . . . . . . .   17
         2.2     Consideration for LWSI Shares  . . . . . . . . . . . .   17
         2.3     Consideration for LWSC and LMS Shares  . . . . . . . .   17
         2.4     Post-Closing Adjustment of Working Capital . . . . . .   18

ARTICLE III

                      THE CLOSING AND RELATED MATTERS   . . . . . . . .   19

         3.1     The Closing  . . . . . . . . . . . . . . . . . . . . .   19
         3.2     Actions in Contemplation of Closing  . . . . . . . . .   19
         3.3     Other Actions at the Closing . . . . . . . . . . . . .   21

ARTICLE IV

             REPRESENTATIONS AND WARRANTIES OF LAIDLAW SELLERS  . . . .   22

         4.1     Organization of Laidlaw Sellers  . . . . . . . . . . .   22
         4.2     Authority Relative to this Agreement . . . . . . . . .   22
         4.3     No Violations  . . . . . . . . . . . . . . . . . . . .   22
         4.4     Consents and Approvals . . . . . . . . . . . . . . . .   23
         4.5     Acquired Subsidiaries  . . . . . . . . . . . . . . . .   23
         4.6     No Other Subsidiaries  . . . . . . . . . . . . . . . .   24
         4.7     Conduct of Solid Waste Business  . . . . . . . . . . .   24
         4.8     Financial Statements . . . . . . . . . . . . . . . . .   25
</TABLE>





                                       i
<PAGE>   3
<TABLE>
<S>      <C>     <C>                                                      <C>
         4.9     Absence of Certain Changes . . . . . . . . . . . . . .   26
         4.10    No Undisclosed Liabilities . . . . . . . . . . . . . .   26
         4.11    Acquired Subsidiary Properties . . . . . . . . . . . .   26
         4.12    Landfills  . . . . . . . . . . . . . . . . . . . . . .   26
         4.13    Taxes and Tax Returns  . . . . . . . . . . . . . . . .   27
         4.14    Litigation . . . . . . . . . . . . . . . . . . . . . .   28
         4.15    Environmental Matters  . . . . . . . . . . . . . . . .   28
         4.16    Governmental Licenses and Permits; Compliance
                          with Laws . . . . . . . . . . . . . . . . . .   29
         4.17    Labor Matters  . . . . . . . . . . . . . . . . . . . .   30
         4.18    Employee Benefit Plans . . . . . . . . . . . . . . . .   30
         4.19    Material Contracts . . . . . . . . . . . . . . . . . .   32
         4.20    Bank Accounts  . . . . . . . . . . . . . . . . . . . .   34
         4.21    Officers and Directors . . . . . . . . . . . . . . . .   34
         4.22    Brokers  . . . . . . . . . . . . . . . . . . . . . . .   34

ARTICLE V

              REPRESENTATIONS AND WARRANTIES OF ALLIED PARTIES  . . . .   34

         5.1     Organization of Allied Parties . . . . . . . . . . . .   34
         5.2     Authority Relative to this Agreement . . . . . . . . .   34
         5.3     Status of Allied Common Shares . . . . . . . . . . . .   35
         5.4     No Violations  . . . . . . . . . . . . . . . . . . . .   35
         5.5     Consents and Approval  . . . . . . . . . . . . . . . .   36
         5.6     Allied Capitalization  . . . . . . . . . . . . . . . .   36
         5.7     Allied Subsidiaries  . . . . . . . . . . . . . . . . .   37
         5.8     SEC Filings  . . . . . . . . . . . . . . . . . . . . .   37
         5.9     Allied Financial Statements  . . . . . . . . . . . . .   38
         5.10    Absence of Certain Changes . . . . . . . . . . . . . .   38
         5.11    No Undisclosed Liabilities . . . . . . . . . . . . . .   38
         5.12    Allied Properties  . . . . . . . . . . . . . . . . . .   38
         5.13    Taxes and Tax Returns  . . . . . . . . . . . . . . . .   39
         5.14    Litigation . . . . . . . . . . . . . . . . . . . . . .   39
         5.15    Environmental Matters  . . . . . . . . . . . . . . . .   40
         5.16    Governmental Licenses and Permits; Compliance
                          with Laws . . . . . . . . . . . . . . . . . .   41
         5.17    Labor Matters  . . . . . . . . . . . . . . . . . . . .   41
         5.18    Opinion of Financial Advisor . . . . . . . . . . . . .   41
         5.19    Financing  . . . . . . . . . . . . . . . . . . . . . .   42
         5.20    Letter from Stockholders . . . . . . . . . . . . . . .   42
         5.21    Brokers  . . . . . . . . . . . . . . . . . . . . . . .   42
         5.22    Aggregation  . . . . . . . . . . . . . . . . . . . . .   42
</TABLE>





                                       ii
<PAGE>   4
<TABLE>
<S>      <C>     <C>                                                      <C>
ARTICLE VI

                     LAIDLAW AGREEMENTS PENDING CLOSING . . . . . . . .   42

         6.1     Conduct of Business  . . . . . . . . . . . . . . . . .   42
         6.2     Forbearance by the Acquired Subsidiaries . . . . . . .   44
         6.3     Access and Information . . . . . . . . . . . . . . . .   45
         6.4     Supplemental Information . . . . . . . . . . . . . . .   45
         6.5     Audit of Financial Statements  . . . . . . . . . . . .   46
         6.6     Access for Environmental Report  . . . . . . . . . . .   46
         6.7     Confidentiality  . . . . . . . . . . . . . . . . . . .   47
         6.8     Consummation of Acquisitions . . . . . . . . . . . . .   47

ARTICLE VII

                      ALLIED COVENANTS PENDING CLOSING  . . . . . . . .   47

         7.1     Conduct of Allied's Business . . . . . . . . . . . . .   47
         7.2     Forbearance by Allied  . . . . . . . . . . . . . . . .   48
         7.3     Access and Information . . . . . . . . . . . . . . . .   49
         7.4     Supplemental Information . . . . . . . . . . . . . . .   49
         7.5     Allied Stockholders' Meeting . . . . . . . . . . . . .   49
         7.6     Emcon Environmental Report . . . . . . . . . . . . . .   50
         7.7     Confidentiality  . . . . . . . . . . . . . . . . . . .   50
         7.8     Consummation of Acquisitions . . . . . . . . . . . . .   50

ARTICLE VIII

                             MUTUAL CONDITIONS  . . . . . . . . . . . .   50

         8.1     No Adverse Proceedings . . . . . . . . . . . . . . . .   50
         8.2     HSR Waiting Period . . . . . . . . . . . . . . . . . .   50
         8.3     Allied Stockholder Approval  . . . . . . . . . . . . .   51
         8.4     Competition Act Matters  . . . . . . . . . . . . . . .   51

ARTICLE IX

                CONDITIONS TO OBLIGATIONS OF ALLIED PARTIES   . . . . .   51

         9.1     Representations True at Closing  . . . . . . . . . . .   51
         9.2     No Adverse Changes . . . . . . . . . . . . . . . . . .   52
         9.3     Opinion of Laidlaw U.S. Counsel  . . . . . . . . . . .   52
         9.4     Opinion of Laidlaw Canadian Counsel  . . . . . . . . .   52
         9.5     Investment Canada Act  . . . . . . . . . . . . . . . .   52
         9.6     Competition Act Matters  . . . . . . . . . . . . . . .   52
</TABLE>





                                      iii
<PAGE>   5
<TABLE>
<S>      <C>     <C>                                                      <C>
         9.7     Audited Financial Statements . . . . . . . . . . . . .   53
         9.8     Emcon Environmental Report . . . . . . . . . . . . . .   53
         9.9     Acquisitions Financing . . . . . . . . . . . . . . . .   53
         9.10    Outstanding Indebtedness . . . . . . . . . . . . . . .   53

ARTICLE X

                    CONDITIONS TO LAIDLAW'S OBLIGATIONS   . . . . . . .   53

         10.1    Representations True at Closing  . . . . . . . . . . .   53
         10.2    No Adverse Changes . . . . . . . . . . . . . . . . . .   54
         10.3    Opinion of Allied's U.S. Counsel . . . . . . . . . . .   54
         10.4    Opinion of Allied's Canadian Counsel . . . . . . . . .   54

ARTICLE XI

                           ADDITIONAL AGREEMENTS  . . . . . . . . . . .   54

         11.1    HSR Act Filings  . . . . . . . . . . . . . . . . . . .   54
         11.2    Competition Act Filings  . . . . . . . . . . . . . . .   54
         11.3    Investment Canada Act Filings  . . . . . . . . . . . .   55
         11.4    Other Consents and Approvals . . . . . . . . . . . . .   55
         11.5    Publicity  . . . . . . . . . . . . . . . . . . . . . .   55
         11.6    Expenses . . . . . . . . . . . . . . . . . . . . . . .   55
         11.7    Securities Law Matters . . . . . . . . . . . . . . . .   55
         11.8    Rule 144 Reports . . . . . . . . . . . . . . . . . . .   57
         11.9    Use of Laidlaw Name  . . . . . . . . . . . . . . . . .   57
         11.10   Environmental Remediation  . . . . . . . . . . . . . .   58
         11.11   Laidlaw Guaranties . . . . . . . . . . . . . . . . . .   58
         11.12   Laidlaw Board Representation . . . . . . . . . . . . .   60
         11.13   Attendance at Stockholder Meetings . . . . . . . . . .   60
         11.14   Laidlaw Standstill . . . . . . . . . . . . . . . . . .   60
         11.15   Transition Agreement . . . . . . . . . . . . . . . . .   62

ARTICLE XII

                                TAX MATTERS   . . . . . . . . . . . . .   63

         12.1    Section 338 Election . . . . . . . . . . . . . . . . .   63
         12.2    Future Tax Returns . . . . . . . . . . . . . . . . . .   64
         12.3    Tax Covenants  . . . . . . . . . . . . . . . . . . . .   66
         12.4    Other Tax Matters, Post-Closing Cooperation  . . . . .   67
</TABLE>





                                       iv
<PAGE>   6
<TABLE>
<S>      <C>     <C>                                                      <C>
         12.5    Tax Controversies  . . . . . . . . . . . . . . . . . .   67
         12.6    Certain Pending Tax Controversies  . . . . . . . . . .   69

ARTICLE XIII

           NATURE AND SURVIVAL OF REPRESENTATIONS AND WARRANTIES  . . .   69

         13.1    Nature of Statements . . . . . . . . . . . . . . . . .   69
         13.2    Survival of Representations and Warranties . . . . . .   69

ARTICLE XIV

                              INDEMNIFICATION   . . . . . . . . . . . .   70

         14.1    Indemnification by the Laidlaw Sellers . . . . . . . .   70
         14.2    Indemnification by Allied  . . . . . . . . . . . . . .   73
         14.3    Third Party Claims . . . . . . . . . . . . . . . . . .   74

ARTICLE XV

                         AMENDMENT AND TERMINATION  . . . . . . . . . .   77

         15.1    Amendment  . . . . . . . . . . . . . . . . . . . . . .   77
         15.2    Waiver . . . . . . . . . . . . . . . . . . . . . . . .   77
         15.3    Termination  . . . . . . . . . . . . . . . . . . . . .   77
         15.4    Substitute Financing . . . . . . . . . . . . . . . . .   78
         15.5    Consequences of Termination  . . . . . . . . . . . . .   79

ARTICLE XVI

                             GENERAL PROVISIONS . . . . . . . . . . . .   79

         16.1    Non-Business Days  . . . . . . . . . . . . . . . . . .   79
         16.2    Notices  . . . . . . . . . . . . . . . . . . . . . . .   79
         16.3    Entire Agreement . . . . . . . . . . . . . . . . . . .   80
         16.4    Assignment; Binding Effect . . . . . . . . . . . . . .   80
         16.5    Counterparts.  . . . . . . . . . . . . . . . . . . . .   80
         16.6    Governing Law; Jurisdiction. . . . . . . . . . . . . .   80
         16.7    Severability of Provisions . . . . . . . . . . . . . .   81
         16.8    Specific Performance . . . . . . . . . . . . . . . . .   81
         16.9    Joint Drafting.  . . . . . . . . . . . . . . . . . . .   81
         16.10   Captions . . . . . . . . . . . . . . . . . . . . . . .   81
         16.11   No Third-Party Beneficiaries.  . . . . . . . . . . . .   81
</TABLE>





                                       v
<PAGE>   7
                              List of Exhibits

Exhibit A-1           Form of Allied Canada 7% Debenture 

Exhibit A-2           Form of Allied Canada Zero Coupon Debenture

Exhibit B-1           Form of Allied Finance 7% Debenture

Exhibit B-2           Form of Allied Finance Zero Coupon Debenture

Exhibit C             Form of Allied Warrant

Exhibit D             Form of Laidlaw Subscription Agreement

Exhibit E             Form of Stock Registration Agreement

Exhibit F             Form of Waste Services Management Agreement

Exhibit G             Form of Release Agreement

Exhibit H-1           Form of Guaranty [Allied Finance 7% Debenture]

Exhibit H-2           Form of Guaranty [Allied Finance Zero Coupon Debenture]

Exhibit I             Form of Opinion of Laidlaw's Counsel

Exhibit J             Form of Opinion of Laidlaw's Canadian Counsel

Exhibit K             Form of Opinion of Allied's Counsel

Exhibit L             Form of Opinion of Allied's Canadian Counsel

Exhibit M             Form of Debenture Exchange Agreement

Exhibit N             Form of Offset Letter Agreement





                                       vi
<PAGE>   8

                               List of Schedules


                          Acquired Subsidiaries -- Schedule I
                          Retained Subsidiaries -- Schedule II
                          Intercompany Waste Agreements -- Schedule III
                          Retained Land -- Schedule IV
                          Leased Assets  -- Schedule V

                          Allied Disclosure Schedule
                          Laidlaw Disclosure Schedule





                                      vii
<PAGE>   9
                            STOCK PURCHASE AGREEMENT


         This Stock Purchase Agreement (this "Agreement"), dated as of
September 17, 1996, among Allied Waste Industries, Inc., a Delaware corporation
("Allied"), Allied Holdings (United States), Inc., a Delaware corporation and a
wholly owned subsidiary of Allied ("Allied U.S.") and 3294862 Canada Inc., a
Canadian corporation and a wholly owned subsidiary of Allied U.S. ("Allied
Canada"), all of which are collectively referred to in this Agreement as the
"Allied Parties," and Laidlaw Inc., a Canadian corporation ("Laidlaw"), Laidlaw
Transportation, Inc., a Delaware corporation and an indirect wholly owned
subsidiary of Laidlaw ("LTI"), Laidlaw Waste Systems, Inc., a Delaware
corporation and a wholly owned subsidiary of LTI ("LWSI"), Laidlaw Waste
Systems (Canada) Ltd., a Canadian corporation and a wholly owned subsidiary of
Laidlaw ("LWSC"), and Laidlaw Medical Services Ltd., a Canadian corporation and
a wholly owned subsidiary of Laidlaw ("LMS"), all of which are collectively
referred to in this Agreement as the "Laidlaw Parties."

                              W I T N E S S E T H:

         WHEREAS, Laidlaw, exclusively through LWSI, LWSC, LMS and their
respective direct and indirect subsidiaries, is engaged in the solid waste
management business in the United States and Canada; and

         WHEREAS, Laidlaw wishes to sell all of its United States and Canadian
solid waste management operations; and

         WHEREAS, Allied, through the acquisition by Allied U.S. of all of the
issued and outstanding capital stock of LWSI and the acquisition by Allied
Canada of all of the issued and outstanding shares of the share capital of each
of LWSC and LMS, wishes to purchase, all of the United States and Canadian
solid waste management operations of Laidlaw;

         NOW, THEREFORE, the Allied Parties and the Laidlaw Parties
(collectively, the "Parties") agree as follows:
<PAGE>   10
                                   ARTICLE  I

                         DEFINITIONS AND INTERPRETATION

         1.1     Definitions.  In this Agreement:

                 "Acquired Canadian Subsidiaries" means those Acquired
         Subsidiaries which are incorporated under the laws of Canada or a
         Canadian province.

                 "Acquired Subsidiaries" means (i) LWSI, (ii) the direct and
         indirect wholly owned Subsidiaries of LWSI listed and identified on
         the attached Schedule I, (iii) LWSC, (iv) the direct and indirect
         wholly owned Subsidiaries of LWSC listed and identified on the
         attached Schedule I, (v) LMS, and (vi) the 55% owned Subsidiary of LMS
         identified on the attached Schedule I, collectively.

                 "Acquired U.S. Subsidiaries" means those Acquired Subsidiaries
         which are incorporated under the laws of a state of the United States.

                 "Acquisitions" mean the U.S. Acquisition and the Canadian
         Acquisitions, collectively.

                 "Additional Allied Common Shares" means shares of Allied
         Common Stock which may be issued after the Closing (i) in payment of
         interest on, or in redemption of, Allied Finance Debentures pursuant
         to the Laidlaw Subscription Agreement or (ii) pursuant to the Allied
         Warrant.

                 "Advance Ruling Certificate" means an advance ruling
         certificate issued by the Competition Act Director under Section 102
         of the Competition Act.

                 "Affiliate" means, with respect to any Person, another Person
         that directly, or indirectly through one or more intermediaries,
         controls, is controlled by or is under common control with such Person
         with the terms "control" and "controlled" meaning for purposes of this
         definition, the power to direct the management and policies of a
         Person, directly or indirectly, whether through the ownership of
         voting securities or partnership or other ownership interests, or by
         contract or otherwise.

                 "Allied Canada Debentures" means the Allied Canada 7%
         Debenture and the Allied Canada Zero Coupon Debenture.

                 "Allied Canada 7% Debenture" means the 7% Junior Subordinated
         Debenture Due [twelve years after the Closing Date] of Allied Canada,
         in





                                      -2-
<PAGE>   11
         substantially the form of Exhibit A-1 attached to this Agreement
         which, is to be issued by Allied Canada to Laidlaw under Section 2.3.

                 "Allied Canada Zero Coupon Debenture" means the Zero Coupon
         Junior Subordinated Debenture Due [twelve years after the Closing
         Date] of Allied Canada, in substantially the form of Exhibit A-2
         attached to this Agreement, which is to be issued by Allied Canada to
         Laidlaw under Section 2.3.

                 "Allied Common Shares" means the shares of Allied Common Stock
         issuable to Laidlaw and LTI under Sections 2.2 and 2.3 as partial
         consideration for the LWSC Shares and the LWSI Shares.

                 "Allied Common Stock" means the Common Stock, $.01 par value
         per share, of Allied.

                 "Allied Disclosure Schedule" means the Disclosure Schedule
         signed for identification purposes only by the respective Presidents,
         Chief Executive Officers or Chief Financial Officers of the respective
         Allied Parties, which the Allied Parties have delivered to the Laidlaw
         Sellers on or before the date of this Agreement, and which contains
         information relevant to the representations and warranties made by the
         Allied Parties in Article V.

                 "Allied Fairness Opinion" means the opinion of Goldman, Sachs
         & Co. referred to in Section 5.18.

                 "Allied Finance" means 3294854 Canada, Inc., a Canadian
         corporation and a wholly owned subsidiary of Allied.

                 "Allied Finance Debentures" means the Allied Finance 7%
         Debenture and the Allied Finance Zero Coupon Debenture.

                 "Allied Finance 7% Debenture" means the 7% Junior Subordinated
         Debenture Due [twelve years after the Closing Date] of Allied Finance,
         in substantially the form of Exhibit B-1 attached to this Agreement,
         which is to be issued by Allied Finance to Laidlaw pursuant to the
         Debenture Exchange Agreement.

                 "Allied Finance Zero Coupon Debenture" means the Zero Coupon
         Junior Subordinated Debenture Due [twelve years after the Closing
         Date] of Allied Finance, in substantially the form of Exhibit B-2
         attached to this Agreement, which is to be issued by Allied Finance to
         Laidlaw pursuant to the Debenture Exchange Agreement.





                                      -3-
<PAGE>   12
                 "Allied Proxy Statement" has the meaning specified in Section
         7.5.

                 "Allied Reorganization Transaction" means: (i) any merger,
         consolidation, recapitalization, liquidation or other business
         combination transaction involving Allied; (ii) any tender offer or
         exchange offer for any securities of Allied; or (iii) any sale or
         other disposition of assets of Allied or any of its Subsidiaries in a
         single transaction or in a series of related transactions.

                 "Allied Securities" means, collectively, the Allied Common
         Shares, the Allied Canada Debentures, the Allied Finance Debentures,
         the Allied Warrant, the Allied Warrant Shares and the Additional
         Allied Common Shares.

                 "Allied SEC Filings" has the meaning specified in Section 5.8.

                 "Allied Stockholders' Meeting" means the meeting of Allied's
         stockholders referred to in Section 7.5, as it may be continued
         following any temporary adjournment or adjournments thereof.

                 "Allied Warrant" means the warrant for the purchase of shares
         of Allied Common Stock, to be issued by Allied to Laidlaw under
         Section 2.3 which shall be in substantially the form of Exhibit C
         attached to this Agreement.

                 "Allied Warrant Shares" means the shares of Allied Common
         Stock which may be issued upon any exercise of the Allied Warrant.

                 "Ancillary Agreements" means, collectively, the Stock
         Registration Agreement, the Allied Canada Debentures, the Allied
         Finance Debentures, the Waste Services Management Agreement, the
         Release, the Guaranties, the Laidlaw Subscription Agreement, the
         Debenture Exchange Agreement and the Offset Letter Agreement.

                 "Antitrust Division" means the Antitrust Division of the
         United States Department of Justice.

                 "Business Day" means a day other than Saturday, Sunday or any
         day on which banks located in Toronto, Ontario or New York, New York
         are authorized or obligated to close.

                 "Canadian Acquisitions" means the respective acquisitions by
         Allied Canada of the LWSC Shares and the LMS Shares from Laidlaw as
         contemplated in Section 2.1.





                                      -4-
<PAGE>   13
                 "C$" or "Canadian dollars" refers to lawful currency of Canada.

                 "Canadian GAAP" means Canadian generally accepted accounting
         principles consistently applied throughout the specified period and,
         if applicable, the immediately preceding comparable period.

                 "Closing" has the meaning specified in Section 3.1.

                 "Closing Date" means (a) the fifth Business Day immediately
         following the earliest date upon or by which (i) the waiting period
         under the HSR Act shall have expired or otherwise been terminated,
         (ii) the Competition Act Director shall have issued and not
         subsequently withdrawn or threatened to withdraw, an Advance Ruling
         Certificate relating to the Acquisitions, (iii) the Allied Parties
         shall have received the advice from the Competition Act Director
         specified in Section 9.7, (iv) the ICA Minister shall have made the
         determination, or shall have been deemed to have made the
         determination, specified in Section 9.6, and (iv) all other conditions
         to the respective obligations of the Parties set forth in Articles
         VIII, IX and X shall have been satisfied or waived, or (b) such other
         date as Allied and Laidlaw may agree.

                 "Closing Date Working Capital" means the positive or negative
         amount obtained by subtracting (i) the amount which would be reflected
         as current liabilities on a combined balance sheet of the Acquired
         Subsidiaries dated as of the Closing Date and prepared in accordance
         with U.S. GAAP on a consistent basis with the SWM Group May 31
         Combined Financial Statement from (ii) the amount which would be
         reflected on such a balance sheet as current assets.

                 "Code" means the United States Internal Revenue Code of 1986, 
         as amended.

                 "Commitment Letter" means the letter dated September 17, 1996,
         addressed to Allied, relating to senior credit facilities in an
         aggregate principal amount of $1,225,000,000 to be provided by Goldman
         Sachs Credit Partners L.P., Citicorp USA, Inc. and Credit Suisse, as
         initial lenders, in connection with, and conditioned upon consummation
         of, the Acquisitions, subject to the satisfaction of other conditions
         and upon the terms set forth therein including attachments thereto.

                 "Competition Act" means the Canadian federal Competition Act,
         R.S.C. 1985, c. C-34, as amended.

                 "Competition Act Director"  means the Canadian Director of
         Investigation and Research appointed under the Competition Act.





                                      -5-
<PAGE>   14
                 "Confidentiality Agreement" means the confidentiality
         agreement dated as of July 3, 1996, as amended, between Allied and
         Laidlaw.

                 "Current Market Price" per share of Allied Common Stock on any
         specified date means the average daily market prices (determined as
         set forth below in this definition), of the Allied Common Stock for
         the 20 consecutive Trading Days ending on the third Trading Day before
         that date.  The market price for each such Trading Day shall be the
         average of the last sale prices on such Trading Day on all stock
         exchanges and the Nasdaq Stock Market on which the Allied Common Stock
         may then be listed or admitted for quotation, respectively; provided,
         that if no sale takes place on any such Trading Day on any such
         exchange or the Nasdaq Stock Market, the average of the closing bid
         and asked prices on such day as officially quoted thereon shall be
         used, or, if Allied Common Stock is not then listed or admitted for
         quotation on any stock exchange or the Nasdaq Stock Market, the market
         price for each Trading Day shall be the average of the reported bid
         and asked prices on such day on the over-the-counter market, or, if
         Allied Common Stock is not quoted on the over-the- counter market, the
         market price for each Trading Day shall be the average of the bid and
         asked prices furnished by any member of the National Association of
         Securities Dealers selected by Allied.

                 "Damages" means all obligations, claims, liabilities, damages,
         penalties, deficiencies, losses, investigations, proceedings,
         judgments, fines, and reasonable costs and expenses (including, but
         not limited to, reasonable costs and expenses incurred in connection
         with the performance of obligations, interest, bonding and court costs
         and attorneys', accountants', engineers', consultants' and
         investigators' fees and disbursements) and disbursements incurred in
         connection with any investigation or defense of any of the foregoing.

                 "Debenture Exchange Agreement" means the Debenture Exchange
         Agreement entered into by Laidlaw and Allied Finance in substantially
         the form of Exhibit M to this Agreement.

                 "Emcon Environmental Report" has the meaning specified in
         Section 6.6.

                 "Environmental Claim" means any claim by a Person alleging or
         imposing actual or potential liability (including potential liability
         for any investigatory cost, containment or oversight cost, control
         cost, prevention cost, remediation cost, cleanup cost, governmental
         response cost, natural resources damage, toxic tort claim, property
         damage, personal injury, or penalty) arising out of, based on,
         resulting from or relating to (i) the presence, storage, transport,
         disposal, use, discharge, release or threatened release of any
         Hazardous Substance at any location, whether or not owned by the
         Person against which





                                      -6-
<PAGE>   15
         the claim is made, or (ii) circumstances forming the basis for any
         liability under, or any violation or alleged violation of, any
         Environmental Law.

                 "Environmental Laws" means all applicable U.S. or Canadian
         federal, state, provincial, local and other foreign Laws, including
         common Laws and administrative or judicial interpretations of those
         Laws by any Governmental Entity, and published non-legally binding
         policies and guidelines of any Canadian Governmental Entity, relating
         to the preservation of natural resources, pollution or the protection
         of human health and safety from the effects of pollution or the
         environment (which includes its ambient air, surface water, ground
         water, land surface or subsurface strata), including Laws relating to
         emissions, discharges, releases or threatened releases of Hazardous
         Substances, or otherwise relating to the manufacture, processing,
         distribution, use, existence, treatment, storage, disposal, transport,
         recycling, reporting or handling of Hazardous Substances, but not
         including zoning and land use Laws.

                 "Environmental Permits" means all permits, licenses,
         registrations, certifications, exemptions, approvals and other
         authorizations of or by any Governmental Entity required under any
         Environmental Law for any Acquired Subsidiary, or Allied or any of its
         Subsidiaries, as the case may be, to conduct its or their operations
         as presently conducted.

                 "ERISA" means the Employee Retirement Income Security Act of 
         1974, as amended.

                 "ERISA Affiliate" means, with respect to any Person, any trade
         or business, whether or not incorporated, which together with that
         Person would be deemed a single employer within the meaning of Section
         4001 of ERISA or Section 414 of the Code.

                 "Exchange Act" means the Securities Exchange Act of 1934, as
         amended, and the rules and regulations of the SEC promulgated under
         such Act.

                 "FTC" means the United States Federal Trade Commission.

                 "Governmental Entity" means any U.S., Canadian, state,
         territorial, federal, provincial, local or foreign court, executive
         office, legislature, governmental agency or ministry, commission, or
         administrative, regulatory or self-regulatory authority or
         instrumentality.

                 "Guaranties" means the guaranties of the Allied Finance
         Debentures which are to be entered into by Allied in substantially the
         form of Exhibits H-1 and H-2, respectively, attached to this
         Agreement.





                                      -7-
<PAGE>   16
                 "Hazardous Substances" means chemicals, pollutants,
         contaminants, wastes (including ambient wastes, hazardous wastes and
         liquid industrial wastes), or other substances (including toxic,
         deleterious or hazardous substances), as defined, listed or regulated
         pursuant to Environmental Laws, including, asbestos or
         asbestos-containing materials, polychlorinated biphenyls, pesticides
         and oils, and petroleum and petroleum products (as those exemplary
         terms are defined in or regulated under the United States National Oil
         and Hazardous Substances Pollution Contingency Plan, 40 C.F.R.
         Sections  300.1 et seq. and other Environmental Laws).

                 "High Yield Event Notice" has the meaning specified in Section
         15.4.

                 "Highly Confident Letter" means the letter dated September 17,
         1996, from Goldman, Sachs & Co. and Citicorp Securities, Inc. to
         Allied, in which Goldman, Sachs & Co. and Citicorp Securities, Inc.
         represent that they are highly confident of their ability to complete
         the sale in a private placement or public offering of unsecured
         subordinated promissory notes of Allied U.S. in an aggregate principal
         amount of at least $475,000,000 in connection with, and conditioned
         upon consummation of, the Acquisitions, subject to the satisfaction of
         the other conditions and upon the terms set forth therein.

                 "HSR Act" means the Hart-Scott-Rodino Antitrust Improvements
         Act of 1976, as amended.

                 "ICA Minister" means the Minister responsible for
         administering the Investment Canada Act.

                 "Income Tax Act" means the Canadian federal Income Tax Act,
         R.S.C. 1985 c. 1, as amended.

                 "Indebtedness" means with respect to any Person at any date,
         (a) all indebtedness of such Person for borrowed money or for the
         deferred purchase price of property or services (other than current
         trade liabilities incurred in the ordinary course of business and
         payable in accordance with customary practices), (b) any other
         indebtedness of such Person which is evidenced by a note, bond,
         debenture, letter of credit or similar instrument, (c) all obligations
         of such Persons with respect to guarantees, (d) all obligations of
         such Person under leases of property which are required to be
         capitalized under U.S. GAAP, (e) all obligations of such Person in
         respect of acceptances issued or created for the account of such
         Person (other than endorsements in the ordinary course of business),
         (f) all obligations in respect of interest rate swaps or other
         interest rate hedging products or foreign currency exchange agreements
         or exchange rate hedging arrangements, (g) all obligations in respect
         of reimbursement obligations





                                      -8-
<PAGE>   17
         under letters of credit, and (h) all liabilities of the type referred
         to in clauses (a) through (g) above that are secured by any lien,
         charge, security interest or encumbrance on any property owned by such
         Person even though such Person has not assumed or otherwise become
         liable for the payment thereof.

                 "Intercompany Agreements" means all contracts, agreements,
         policies, practices and understandings, whether written or oral,
         between any one or more of the Acquired Subsidiaries, on the one hand,
         and any one or more members of the Laidlaw Group other than the
         Acquired Subsidiaries, on the other hand, relating to any sharing or
         allocation of expenses, personnel, services or facilities, including
         the Tax Allocation Agreements but specifically excluding the
         Intercompany Waste Agreements.

                 "Intercompany Indebtedness" means, at any date, all amounts
         owed on that date by an Acquired Subsidiary, or any obligation of an
         Acquired Subsidiary, contingent or otherwise on that date, to Laidlaw
         or any other member of the Laidlaw Group other than the Acquired
         Subsidiaries, including under any Tax Allocation Agreement or other
         Intercompany Agreement, but excluding all amounts owed by any Acquired
         Subsidiary to any member of the Laidlaw Group under any Intercompany
         Waste Agreement.

                 "Intercompany Investment" means, at any date, any equity
         interests in any Acquired Subsidiary, except the LWSI Shares, the LWSC
         Shares, the LMS Shares and the common or ordinary shares of each other
         Acquired Subsidiary.

                 "Intercompany Receivable" means, at any date, all amounts owed
         on that date to an Acquired Subsidiary by Laidlaw or any other member
         of the Laidlaw Group other than the Acquired Subsidiaries, including
         under any Tax Allocation Agreement or other Intercompany Agreement.

                 "Intercompany Waste Agreements" means those certain agreements
         relating to the handling of waste by certain of the Acquired
         Subsidiaries as described on Schedule III attached to this Agreement.

                 "Investment Canada Act" means the Investment Canada Act,
         R.S.C. 1985, c. C-28, as amended.

                 "Laidlaw Disclosure Schedule" means the Disclosure Schedule
         signed for identification purposes only by the respective Presidents,
         Chief Executive Officers or Senior Vice Presidents of each of the
         Laidlaw Sellers, which the Laidlaw Sellers have delivered to the
         Allied Parties on or before the date of this Agreement, and which
         contains information relevant to the representations and warranties
         made by the Laidlaw Sellers in Article IV.





                                      -9-
<PAGE>   18
                 "Laidlaw Group" means, at any date, Laidlaw and all of its 
         Affiliates at that date (but excluding after the Closing, the Acquired
         Subsidiaries), and "member of the Laidlaw Group" refers to Laidlaw or 
         any such Affiliates.

                 "Laidlaw Guaranty" means any guaranty, performance guaranty,
         bond, performance bond, suretyship arrangement, surety bond, credit,
         letter of credit, reimbursement agreement or other undertaking,
         deposit commitment or arrangement by which any member of the Laidlaw
         Group is or may be primarily, secondarily, contingently or
         conditionally liable for or in respect of (or which creates,
         constitutes or evidences a Lien on any of the assets or properties of
         any member of the Laidlaw Group which secures the payment or
         performance of) any present or future liability or obligation of any
         Acquired Subsidiary as set forth on in Section 4.19 (viii) of the
         Laidlaw Disclosure Schedule.

                 "Laidlaw Issuer Bank" means any bank or other financial
         institution which is the issuer of a letter of credit which is a
         Laidlaw Reclamation Guaranty.

                 "Laidlaw Sellers" means Laidlaw and LTI, together.

                 "Laidlaw Subscription Agreement" means the agreement among
         Allied, Allied Finance, Laidlaw and LTI pursuant to which LTI has
         agreed to subscribe for shares of the Allied Common Stock upon certain
         conditions therein set forth, which shall be in substantially the form
         of Exhibit D.

                 "Latest Allied Balance Sheet" has the meaning specified in
         Section 5.9.

                 "Law" means a law, statute, ordinance, rule, code or
         regulation enacted or promulgated, or order, directive, instruction or
         other legally binding guideline or policy issued or rendered by, any
         Governmental Entity.

                 "Leased Assets" means those assets described on Schedule V to
         this Agreement which are owned by Laidlaw or another member of the
         Laidlaw Group (other than the Acquired Subsidiaries) and leased to the
         Acquired Subsidiaries.

                 "LESL" means Laidlaw Environmental Services Ltd., an Ontario
         corporation, a wholly owned subsidiary of Laidlaw and a Retained
         Subsidiary.

                 "Lien" means a lien, mortgage, deed of trust, deed to secure
         debt, pledge, hypothecation, assignment, deposit arrangement,
         easement, preference, priority, assessment, security interest, lease,
         sublease, charge, claim, adverse claim, levy,





                                      -10-
<PAGE>   19
         interest of other Persons, or other encumbrance of any kind (including
         any conditional sale or other title retention agreement having the
         same economic effect as any of the foregoing).

                 "LMS Shares" means all of the common or ordinary shares in the
         issued and outstanding share capital of LMS which are 100% owned by
         Laidlaw.

                 "LMT" means Laidlaw Med Trade Medical Services Inc., a British
         Columbia corporation, an Acquired Canadian Subsidiary, and a 55% owned
         Subsidiary of LMS.

                 "LTI U.S. Consolidated Tax Group" means the affiliated group
         of corporations within the meaning of Section 1504(c) of the Code, of
         which LTI is the common parent corporation, which files a consolidated
         Tax Return for U.S. federal income Tax purposes, and which includes
         LTI, the Acquired U.S. Subsidiaries, and certain of the Retained
         Subsidiaries.

                 "LWSC Group Subsidiaries" means LWSC and all of its
         Subsidiaries which are Acquired Subsidiaries.

                 "LWSC Shares" means all of the common or other shares, C$1.00
         par value, in the issued and outstanding share capital of LWSC.

                 "LWSI Group Subsidiaries" means LWSI and all of its
         Subsidiaries which are Acquired Subsidiaries.

                 "LWSI Shares" means all of the  issued and outstanding shares
         of Common Stock, $1.00 par value per share, of LWSI, which are all
         owned by LTI.

                 "Mailing Date" has the meaning specified in Section 7.5.

                 "Material Adverse Effect" means (i) when used with reference
         to the Acquired Subsidiaries, a material adverse effect on the
         financial condition, business, assets, prospects or results of
         operations of the Acquired Subsidiaries taken as a whole, (ii) when
         used with reference to the Laidlaw Sellers, a material adverse effect
         on their ability to perform their obligations under this Agreement or
         any Ancillary Agreement to which any of them is a party, (iii) when
         used with reference to Allied and its Subsidiaries, a material adverse
         effect on the financial condition, business, assets, prospects or
         results of operations of Allied and its Subsidiaries (including from
         and after the Closing, the Acquired Subsidiaries) taken as a whole,
         and (iv) when used with reference to the Allied Parties, a material
         adverse effect on their ability to perform their obligations





                                      -11-
<PAGE>   20
         under this Agreement or any Ancillary Agreement to which any of them 
         is a party.

                 "Medical Waste"  means waste generated by health care or
         health care related facilities that is or may be contaminated with a
         potentially infectious agent or other potentially hazardous material.

                 "Offset Letter Agreement" means the letter agreement dated the
         Closing Date among Allied, Allied Finance, Laidlaw and LTI, in
         substantially the form of Exhibit N attached to this Agreement, to be
         executed and delivered pursuant to Section 3.3.

                 "Ontario Securities Act" means the Securities Act (Ontario),
         R.S.O. 1990, c.S.5, as amended.

                 "Option Assets" means those assets which are the subject of
         the letter agreement relating to the option to purchase certain assets
         granted to Allied by Laidlaw referred to in Section 16. 3 of this
         Agreement.

                 "Permitted Liens" means (i) those Liens set forth in Section
         4.11 of the Laidlaw Disclosure Schedule or Section 5.12 of the Allied
         Disclosure Schedule, as applicable, (ii) those Liens reflected in the
         Allied SEC Filings, in the case of the Allied Parties and their assets
         or properties, (iii) any Lien that is set forth in the title reports
         or title insurance binders that have been made available to the Allied
         Parties by the Laidlaw Sellers relating to any interest in real
         property owned by an Acquired Subsidiary, (iv) Liens for water and
         sewer charges and current taxes not yet due and payable or being
         contested in good faith, and (v) other Liens (including, mechanics',
         couriers', workers', repairers', materialmen's, warehousemen's and
         other similar Liens) arising in the ordinary course of business as
         would not in the aggregate materially adversely affect the value of,
         or materially adversely interfere with the use of, the property
         subject thereto.

                 "Person" means an individual, corporation, partnership,
         association, joint stock company, limited liability company,
         Governmental Entity, business trust, unincorporated organization, or
         other legal entity.

                 "Post-Closing Tax Period" means any Tax period (or portion
         thereof) beginning after the close of business on the Closing Date.

                 "Pre-Closing Laidlaw Insurance Claims" means any U.S.
         liability, personal injury, property damage, workers compensation or
         other similar claim (other than health and welfare insurance claims)
         made against any Acquired Subsidiary by any Person with respect to a
         loss, damage, claim, incident or





                                      -12-
<PAGE>   21
         occurrence which occurred before the time of Closing, including any
         such matter which was incurred but not reported on or before the time
         of Closing.

                 "Pre-Closing Tax Period" means any Tax period (or portion
         thereof) ending on or before the close of business on the Closing
         Date.

                 "Release" means the Release Agreement required to be delivered
         to the Acquired Subsidiaries as provided in Section 3.3 (iv).

                 "Remainder High Yield Securities" has the meaning specified 
         in Section 15.4.

                 "Retained Land" means the real property owned by LWSC, more
         specifically identified on Schedule IV attached to this Agreement.

                 "Retained Subsidiaries" means (i) Laidlaw Chem-Waste, Inc., a
         Delaware corporation and a wholly owned Subsidiary of LWSI, (ii) all
         of the direct and indirect Subsidiaries of Laidlaw Chem-Waste, Inc.
         (all of which are specifically listed and identified on the attached
         Schedule II), (iii) LESL, and (iv) all of the direct and indirect
         Subsidiaries of LESL (all of which are specifically listed and
         identified on the attached Schedule II).

                 "Revenue Canada" means Revenue Canada, Customs, Excise and
         Taxation, the Canadian federal Taxing Authority.

                 "SEC" means the United States Securities and Exchange
         Commission or any successor agency.

                 "Securities Act" means the United States Securities Act of
         1933, as amended, and the rules and regulations of the SEC promulgated
         thereunder.

                 "Senior Subordinated Debentures" means the senior subordinated
         debentures to be issued by Allied U.S.  in connection with the
         financing contemplated by the Highly Confident Letter.

                 "SFAS 109" means the United States standard on accounting for
         income taxes effective September 1, 1993 promulgated by the Financial
         Accounting Standards Board.

                 "Solid Waste"  means any waste which can be lawfully disposed
         of in a landfill regulated under Subtitle D of the Resource
         Conservation and Recovery Act of 1976, as amended ("RCRA").





                                      -13-
<PAGE>   22
                 "Solid Waste Business" means (i) the collection, compaction,
         transportation, resource recovery, storage, recycling or disposal of
         Solid Waste and Medical Waste, and (ii) the methane gas collection and
         electricity generation and distribution operations related to the
         disposal of Solid Waste.

                 "Stock Registration Agreement" means the Stock Registration
         Agreement to be entered into at the Closing among Allied, Laidlaw and
         LTI as provided in Section 3.3.

                 "Subsidiary" of a Party means an Affiliate of that Party more
         than 50% of the aggregate voting power (or of any other form of voting
         equity interest in the case of a Person that is not a corporation) of
         which is beneficially owned by that Party directly or indirectly
         through one or more other Persons.

                 "Substitute Financing Election" has the meaning specified in 
         Section 15.4.

                 "Substitute Financing Notice" has the meaning specified in
         Section 15.4.

                 "Substitute Financing Purchase Price" has the meaning
         specified in Section 15.4.

                 "SWM Group Financial Statements" means all financial
         statements of the Acquired Subsidiaries or specified groups of
         Acquired Subsidiaries delivered to the Allied Parties under Sections
         4.8 and 6.4, the terms "SWM Group Consolidated Financial Statements,"
         "SWM Group Combined Financial Statements," "SWM Group May 31 Combined
         Financial Statements," and "SWM Group Separate Company Financial
         Statements" have the meanings specified in Sections 4.8 and 6.4 and
         the term "SWM Group Audited Combined Financial Statements" is defined
         in Section 6.5.

                 "SWM Group Income Taxes" means all Taxes, including United
         States and Canadian federal, state, provincial and local Taxes for
         which any Acquired Subsidiary is or may be directly or indirectly
         liable (and including interest and penalties thereon), based on or
         measured by the income or profits of any Acquired Subsidiary or the
         LTI U.S. Consolidated Tax Group.

                 "SWM Group Landfill" means any landfill owned, occupied,
         leased or operated by, or under the management or control of, an
         Acquired Subsidiary as set forth in Schedule 4.12 of the Laidlaw
         Disclosure Schedule.

                 "Tax" means any tax of any kind, however denominated,
         including any interest, penalties, fines or other additions to tax
         that may become payable in





                                      -14-
<PAGE>   23
         respect thereof or in respect of a failure to comply with any
         requirement relating to any Tax Return, imposed by any United States
         or Canadian federal, territorial, state, provincial, local or
         non-United States or non- Canadian Governmental Entity, including all
         income, gross income, gross receipts, profits, goods and services,
         social security, health, old age security, Canadian Pension Plan,
         Quebec Pension Plan, sales and use, ad valorem, excise, custom,
         franchise, business license, property, occupation, real property
         gains, payroll and employee withholding, unemployment or employment
         insurance, real and personal property, stamp, environmental, transfer,
         workers' compensation, payroll, severance, alternative minimum,
         windfall, and capital taxes, premiums, surtaxes, charges, levies,
         assessments, reassessments, and other obligations of the same or a
         similar nature to any of the foregoing.

                 "Tax Allocation Agreements" means all contracts, agreements,
         policies, practices, intercompany procedures and understandings,
         whether written or oral, between any Acquired Subsidiary and any other
         Person (including another Acquired Subsidiary) by which all or any
         portion of any U.S. or Canadian federal, state, provincial or local
         income Tax is allocated to or shared or required to be paid by any
         Acquired Subsidiary.

                 "Tax Returns" means all tax returns, declarations, reports,
         estimates, information returns and statements required to be filed
         with any Taxing Authority, or provided to any partner, shareholder,
         joint venturer or member under U.S. or Canadian federal, state,
         provincial, local or foreign Laws (including reports with respect to
         backup withholding and payments to Persons other than Taxing
         Authorities), and annual tax returns or information returns on behalf
         of employee benefit plans sponsored by Laidlaw or Allied, as the case
         may be, or any of their respective ERISA Affiliates.

                 "Taxing Authority" means any Governmental Entity responsible
         for the imposition, assessment, enforcement or collection of any Tax.

                 "Trading Day" means any day during the course of which the
         principal securities exchange (or the Nasdaq Stock Market), as the
         case may be, on which the Allied Common Stock is listed or admitted
         for quotation is open for the exchange of securities.

                 "Unadjusted LMS Consideration" has the meaning specified in
         Section 2.3.

                 "Unadjusted LWSC Consideration" has the meaning specified in 
         Section 2.3.





                                      -15-
<PAGE>   24
                 "Unadjusted LWSI Consideration" has the meaning specified in 
         Section 2.2.

                 "U.S. Acquisition" means the acquisition by Allied U.S. of the
         LWSI Shares from LTI as contemplated in Section 2.1.

                 "$" or "U.S. dollars" refers to lawful currency of the United
         States.

                 "U.S. GAAP" means United States generally accepted accounting
         principles consistently applied throughout the specified period and
         the immediately preceding comparable period.

                 "Wages" has the meaning given such term by Section 3401(a) of
         the Code.

                 "WARN Act" means the United States Worker Adjustment and
         Retraining Notification Act of 1988.

                 "Waste Services Management Agreement" means the Waste Services
         Management Agreement, substantially in the form attached hereto as
         Exhibit F, to be entered into at the Closing between Laidlaw, Laidlaw
         Environmental Services, Inc., LESL and Allied as provided in Section
         3.3(iii).

         1.2     Interpretation.  Capitalized terms defined in this Agreement
are equally applicable to both their singular and plural forms.  References to
a designated "Article" or "Section" refer to an Article or Section of this
Agreement, unless otherwise specifically indicated.  In this Agreement,
"including" is used only to indicate examples, without limitation to the
indicated examples, and without limiting any generality which precedes it.

         1.3     Knowledge.  When a representation and warranty in Article IV
or Article V is made to the  "knowledge" of a Party, it means receipt of notice
by, or actual knowledge, of any of the following officers of that Party: the
Chief Executive Officer, Chief Financial Officer, and General Counsel (or
Vice-President-Legal in the case of Allied).  The "knowledge" of any Laidlaw
Party shall also be deemed to include such "knowledge" of the Chief Executive
Officer and Chief Financial Officer of each of LTI, LWSI, LWSC, LMT and LMS,
and the Chief Compliance Officer for environmental matters and the Director of
Human Resources of Laidlaw.  The "knowledge" of any Allied Party shall also be
deemed to include such "knowledge" of the Chief Compliance Officer for
environmental matters and the Director of Human Resources of Allied.  No
representation or warranty made by a Party may be qualified or limited by
reference to the "knowledge" of such Party unless due inquiry has actually been
made by the above referenced officers of such Party.





                                      -16-
<PAGE>   25
                                   ARTICLE II

                                THE ACQUISITIONS

         2.1     Sales and Purchases of Shares.  On the terms and subject to
the conditions of this Agreement:

                 (i)      LTI agrees to sell, free of all Liens, and Allied
         U.S. agrees to purchase, the LWSI Shares; and

                 (ii)     Laidlaw agrees to sell, free of all Liens, and Allied
         Canada agrees to purchase, the LWSC Shares and the LMS Shares.

         2.2     Consideration for LWSI Shares.  Subject to adjustment after
the Closing as provided in Section 2.4, the consideration payable by Allied
U.S. for the LWSI Shares (the "Unadjusted LWSI Consideration") shall be:

                 (i)      $1,200,000,000 payable in cash at the Closing; and

                 (ii)     7,225,000 shares of Allied Common Stock to be issued
         and delivered by Allied to LTI at the Closing.

         2.3     Consideration for LWSC and LMS Shares.  Subject to adjustment
after the Closing as provided in Section 2.4:

                 (i)      the consideration payable by Allied Canada for the
         LWSC Shares (the "Unadjusted LWSC Consideration") shall be (x) the
         Allied Canada Debentures, (y) the Allied Warrant, and (z) 5,500,000
         shares of Allied Common Stock; and

                 (ii)     the consideration payable by Allied Canada for the
         LMS Shares (the "Unadjusted LMS Consideration") shall be 1,875,000
         shares of Allied Common Stock.

Pursuant to the Debenture Exchange Agreement, immediately following the
delivery by Allied Canada of the Unadjusted LWSC Consideration, Allied Finance
will purchase from Laidlaw, and Laidlaw will sell and transfer to Allied
Finance, the Allied Canada Debentures in exchange for the Allied Finance
Debentures.

         2.4     Post-Closing Adjustment of Working Capital.  The consideration
payable pursuant to Sections 2.2 and 2.3 shall be subject to adjustment after
the Closing as provided in this Section 2.4.  On or before 20 Business Days
following the Closing, the





                                      -17-
<PAGE>   26
Laidlaw Parties shall calculate and deliver to the Allied Parties a written
statement (the "Laidlaw Settlement Statement") setting forth the amount of the
Closing Date Working Capital.

         The Laidlaw Settlement Statement shall be calculated by Laidlaw and
certified in writing by the Chief Financial Officer of Laidlaw.  In preparing
the Laidlaw Settlement Statement, Laidlaw shall use U.S. GAAP, consistent with
the SWM Group May 31 Combined Financial Statements and the SWM Group Audited
Combined Financial Statements in all respects.  Allied will grant to Laidlaw
reasonable access to the books and records of the Acquired Subsidiaries after
the Closing for the purpose of determining the Laidlaw Settlement Statement.

         The Laidlaw Settlement Statement shall be final and binding on the
Allied Parties unless, within 30 Business Days following the date of delivery
to them of the Laidlaw Settlement Statement, Allied notifies Laidlaw in writing
(a "Notice of Objection") that Allied does not accept as correct the amount of
any calculation reflected in the Laidlaw Settlement Statement.  If Allied
timely delivers a Notice of Objection to Laidlaw, then Allied and Laidlaw shall
respectively instruct Arthur Andersen L.L.P. and Coopers & Lybrand to attempt
to reach mutual agreement as to each disputed calculation made in the Laidlaw
Settlement Statement.  If within ten Business Days after the matter has been
referred to such accounting firms, they have not reached agreement as to all
disputed calculations, then Arthur Andersen L.L.P. and Coopers & Lybrand shall
be promptly instructed by Allied and Laidlaw, respectively, to designate a
third accounting firm of internationally recognized standing, which (acting as
experts and not as arbitrators) shall be instructed to make, as soon as
practicable after the matter is referred to such firm, all calculations which
are in dispute, and the determination of such third accounting firm in the
matter shall be final and binding on all Parties.

         Once all amounts required to be calculated under the preceding
provisions of this Section 2.4 have been finally determined under this Section
2.4, and if the Closing Date Working Capital is a deficit, then the Laidlaw
Parties shall pay to Allied in the manner described below the amount of such
deficit, which payment shall be accounted for, as a reduction of the Unadjusted
LWSI Consideration, the Unadjusted LWSC Consideration, the Unadjusted LMS
Consideration or a combination thereof, as the case may be.  The payments
required by this Section 2.4 shall be made in cash, within two Business Days
after the amount or amounts of the adjustment or adjustments have been finally
determined as provided in this Section 2.4, by wire transfers to Allied (to
accounts designated by it in writing at least one Business Day before the day
on which the transfer is required to be made), of U.S. dollar immediately
available funds.  The fees of all accounting firms engaged to make any
calculations under this Section 2.4 shall be paid by (i) Laidlaw if the effect
of all disputed calculations made by such accounting firms results in
adjustments in favor of Allied by $250,000 or more in





                                      -18-
<PAGE>   27
comparison to the adjustments which would have been made had Allied accepted
the Laidlaw Settlement Statement or (ii) Allied in all other cases.


                                  ARTICLE III

                        THE CLOSING AND RELATED MATTERS

         3.1     The Closing.  The respective sales and purchases of the LWSI
Shares, the LWSC Shares and the LMS Shares (the "Closing") shall take place
concurrently at the offices of Cravath, Swaine & Moore, 825 Eighth Avenue, New
York, New York at 10:00 a.m. local time on the Closing Date.  At the Closing:

                 (i)      LTI shall deliver to Allied U.S. the certificates
         evidencing the LWSI Shares, duly endorsed in blank or accompanied by
         duly executed stock powers, and in proper form for registration in the
         name of Allied U.S., against delivery by Allied U.S. of the Unadjusted
         LWSI Consideration;

                 (ii)     Laidlaw shall deliver to Allied Canada the
         certificates evidencing the LWSC Shares, duly endorsed in blank or
         accompanied by duly executed stock powers, and in proper form for
         registration in the name of Allied Canada, against payment by Allied
         Canada of the Unadjusted LWSC Consideration; and

                 (iii)    Laidlaw shall deliver to Allied Canada the
         certificates evidencing the LMS Shares, duly endorsed in blank or
         accompanied by duly executed stock powers, and in proper form for
         registration in the name of Allied Canada, against payment by Allied
         Canada of the LMS Consideration.

         All cash amounts payable by Allied U.S. at the Closing shall be
payable by wire transfers, to accounts designated in writing by Laidlaw at
least two Business Days before the Closing Date, of U.S. dollar funds
immediately available in Toronto.

         3.2     Actions in Contemplation of Closing.  On or before the Closing
Date, and in any event not later than immediately before the Closing:

                 (i)      LWSI shall transfer to LTI, as a dividend on the LWSI
         Shares, all of the issued and outstanding capital stock of Laidlaw
         Chem-Waste, Inc., a Retained Subsidiary;

                 (ii)     LWSC shall transfer to Laidlaw, by means of a
         purchase, all of the issued and outstanding capital stock of LESL;





                                      -19-
<PAGE>   28
                 (iii)    the Acquired Subsidiaries which own the Retained Land
         and the Option Assets shall transfer to Laidlaw, by means of a
         purchase, the Retained Land and the Option Assets;

                 (iv)     Laidlaw or LTI will contribute to the capital of each
         of the Acquired Subsidiaries any and all Intercompany Indebtedness of
         each of the Acquired Subsidiaries (net of any Intercompany Receivables
         of each of the Acquired Subsidiaries) as of the Closing Date;

                 (v)      all Tax Allocation Agreements shall be terminated as
         to all Acquired Subsidiaries without any further liability thereunder
         on the part of any Acquired Subsidiaries;

                 (vi)     all Intercompany Agreements shall be terminated as to
         all Acquired Subsidiaries without any further liability thereunder on
         the part of any Acquired Subsidiary;

                 (vii)    the Liens in favor of Laidlaw International Finance
         Corporation described in Section 4.11 of the Laidlaw Disclosure
         Schedule shall be terminated and released of record to the
         satisfaction of the Allied Parties and title to the related assets
         will be transferred to the Acquired Subsidiary which owns the
         equitable title to such assets;

                 (viii)   Laidlaw will transfer to an Acquired Canadian
         Subsidiary designated at the Closing, the Leased Assets, at no cost to
         Allied;

                 (ix)     all remaining Intercompany Investments shall be
         eliminated except as specifically agreed to by Allied; and

                 (x)      Laidlaw shall cause to be delivered to Allied the
         resignation of Kenneth L. Lyons as sole director and President of the
         Acquired Subsidiaries, and shall assume and perform in full all
         obligations, agreements and commitments of any type relating to the
         resignation or the employment of Mr. Lyons arising before the Closing.

         3.3     Other Actions at the Closing.  In addition to the consummation
of the Acquisitions, the following actions shall take place at the Closing:

                 (i)      Allied, Allied Finance, Laidlaw and LTI shall enter
         into the Laidlaw Subscription Agreement in substantially the form
         attached as Exhibit D to this Agreement;





                                      -20-
<PAGE>   29
                 (ii)     Allied, Laidlaw and LTI shall enter into a Stock
         Registration Agreement in substantially the form of Exhibit E attached
         to this Agreement, pertaining to the registration of the Allied Common
         Shares, the Additional Allied Common Shares, the Allied Warrant and
         the Allied Warrant Shares;

                 (iii)    Allied and Laidlaw shall enter into a Waste Services
         Management Agreement in substantially the form of Exhibit F attached
         to this Agreement;

                 (iv)     the Laidlaw Sellers, the Retained Subsidiaries, the
         Allied Group and the Acquired Subsidiaries shall enter into a Release
         in substantially the form of Exhibit G attached to this Agreement, by
         which the Laidlaw Sellers will release each Acquired Subsidiary from
         all claims and causes of action other than those specified in Exhibit
         G;

                 (v)      Laidlaw and Allied Finance shall enter into the
         Debenture Exchange Agreement in substantially the form of Exhibit M
         attached to this Agreement;

                 (vi)     Allied shall execute and deliver to Laidlaw the
         Guaranties, which shall be in substantially the form of Exhibits H-1
         and H-2 attached to this Agreement, by which Allied will guaranty the
         payment of the Allied Finance Debentures; and

                 (vii)    Allied, Allied Finance, Laidlaw and LTI shall execute
         and deliver the Offset Letter Agreement in substantially the form of
         Exhibit N attached to this Agreement, by which Laidlaw will agree to
         certain offsets against the Allied Finance Debentures.


                                   ARTICLE IV

                         REPRESENTATIONS AND WARRANTIES
                                       OF
                                LAIDLAW SELLERS

         The Laidlaw Sellers jointly and severally represent and warrant to the
Allied Parties that:

         4.1     Organization of Laidlaw Sellers.  Each Laidlaw Seller is a
corporation duly organized and validly existing under the Laws of Canada, in
the case of Laidlaw, or duly organized, validly existing and in good standing
under the Laws of the State of Delaware, in the case of LTI.





                                      -21-
<PAGE>   30
         4.2     Authority Relative to this Agreement.  Each Laidlaw Party has
the requisite corporate power to enter into and perform its obligations under
this Agreement and each Ancillary Agreement to which it will be a party.  The
execution and delivery of this Agreement and each Ancillary Agreement to which
the respective Laidlaw Parties will be parties, the consummation of the
Acquisitions, in the case of the Laidlaw Sellers, and the other transactions
contemplated in Articles II and III, in the case of all Laidlaw Parties, have
been duly authorized by the respective Boards of Directors of the Laidlaw
Parties, and no other corporate proceedings on the part of any Laidlaw Party,
including any approval by the stockholders of Laidlaw, are necessary to
authorize this Agreement, any Ancillary Agreement to which any Laidlaw Party
will be a party, the consummation of the Acquisitions, or the other
transactions contemplated in Articles II and III.  This Agreement has been duly
executed and delivered by each Laidlaw Party.  Each Ancillary Agreement
required to be executed and delivered by a Laidlaw Party at the Closing will
be, upon its execution and delivery as provided in Section 3.3 or elsewhere in
this Agreement, duly executed and delivered by such Laidlaw Party.  Assuming
the valid authorization, execution and delivery of this Agreement (and each
Ancillary Agreement to which an Allied Party will be a party) by each Allied
Party, this Agreement is, and each Ancillary Agreement to which a Laidlaw Party
is a party will be, upon its execution and delivery at the Closing as provided
in Section 3.3 or elsewhere in this Agreement, a valid and binding obligation
of such Laidlaw Party, enforceable in accordance with its terms, except as such
enforceability may be limited by bankruptcy, insolvency, reorganization,
moratorium or other laws relating to or affecting creditors' rights generally
or by equitable principles.

         4.3     No Violations.  The execution, delivery and performance of
this Agreement and the applicable Ancillary Agreements by the respective
Laidlaw Sellers and the consummation of the Acquisitions and the other
transactions contemplated in Articles II and III will not:

                 (i)      constitute a breach or violation of or default under
         the charter or bylaws (or similar organizational documents) or
         internal rules or regulations governing the conduct of corporate
         actions of any Laidlaw Party or any Acquired Subsidiary or any Law
         applicable to any Laidlaw Party or any Acquired Subsidiary; or

                 (ii)     except as accurately reflected in Section 4.3 of the
         Laidlaw Disclosure Schedule, violate or conflict with, or result in a
         breach of, or constitute a default (or an event which, with notice or
         lapse of time or both, would constitute a default) under, or result in
         the termination of, or accelerate the performance required by, or
         result in a right of termination under, or result in the creation of
         any Lien upon the LWSI Shares, the LWSC Shares, the LMS Shares or any
         of the assets or properties of any Acquired Subsidiary under, any
         contract, indenture, loan document, license, permit, order, decree or
         instrument





                                      -22-
<PAGE>   31
         to which any Laidlaw Seller or any Acquired Subsidiary is a party or
         by any of them or their assets or properties are bound.

         4.4     Consents and Approvals.  No consent, order, approval, waiver
or authorization of, or registration, application, declaration or filing with,
any Governmental Entity or other Person is required with respect to any Laidlaw
Party or any Acquired Subsidiary in connection with the execution and delivery
of this Agreement or any Ancillary Agreement, the consummation of the
Acquisitions, or the other transactions contemplated in Articles II and III,
except for:

                 (i)      the HSR Act, Competition Act and Investment Canada
         Act filings and approvals contemplated in this Agreement;

                 (ii)     the consents and approvals described on Schedule 4.4
         of the Laidlaw Disclosure Schedule; and

                 (iii)    other cases, considered individually and in the
         aggregate, in which any failure to make any such registration,
         application, declaration or filing or obtain any such consent, order,
         approval, waiver or other authorization could not have a Material
         Adverse Effect on the Acquired Subsidiaries or the Laidlaw Sellers.

         4.5     Acquired Subsidiaries.  Section 4.5 of the Laidlaw Disclosure
Schedule sets forth with respect to each Acquired Subsidiary (i) its
jurisdiction of incorporation, (ii) each jurisdiction in which it is qualified
to do business as a foreign corporation, (iii) its authorized, issued and
outstanding shares of capital stock, and (iv) the holder or holders of all of
its issued and outstanding shares of capital stock.  Each Acquired Subsidiary
is a corporation duly organized, validly existing and in good standing under
the laws of its jurisdiction of incorporation and has full authority and
corporate power to conduct its business as it is currently being conducted.
Each Acquired Subsidiary is duly qualified to do business, and in good
standing, in each jurisdiction where the nature of its properties or business
requires such qualification, except for failures to be so qualified which could
not, individually or in the aggregate, have a Material Adverse Effect on the
Acquired Subsidiaries.

         All of the issued and outstanding shares of capital stock of each
Acquired Subsidiary are validly issued, fully paid and nonassessable, and are
owned of record and beneficially, and free of any Liens, by Laidlaw, LTI or
another Acquired Subsidiary (as reflected in Schedule 4.5 of the Laidlaw
Disclosure Schedule), except as otherwise noted in Section 4.5 of the Laidlaw
Disclosure Schedule with respect to LMT (as to which all other stockholders,
and their percentage share of ownership, are identified in Section 4.5 of the
Laidlaw Disclosure Schedule).  There are no preemptive rights or outstanding
subscriptions, options, warrants, calls, rights, convertible securities,





                                      -23-
<PAGE>   32
obligations to make capital contributions or advances, voting trust
arrangements, shareholders' agreements (other than as noted in Section 4.5 of
the Laidlaw Disclosure Schedule with respect to LMT) or other agreements,
commitments or understandings relating to the capital stock of any Acquired
Subsidiary.

         The Laidlaw Sellers will deliver to the Allied Parties prior to
Closing true and correct copies of the charter and bylaws (or similar
organizational documents) of each Acquired Subsidiary.  Each Acquired Canadian
Subsidiary is a "private company" within the meaning of Ontario Securities Act.

         4.6     No Other Subsidiaries.  No Acquired Subsidiary has any
Subsidiary which is not another Acquired Subsidiary or a Retained Subsidiary.
Except as described in Section 4.6 of the Laidlaw Disclosure Schedule, and
except for other Acquired Subsidiaries and Retained Subsidiaries, no Acquired
Subsidiary owns or is obligated to acquire any investment in any other
corporation, partnership, joint venture or other business entity.

         4.7     Conduct of Solid Waste Business.  The Laidlaw Group is engaged
in the Solid Waste Business only through the Acquired Subsidiaries, and neither
Laidlaw, any Retained Subsidiary, nor any other member of the Laidlaw Group
conducts any operations associated with, or owns any assets or properties used
in, or holds any permits or licenses used in, the Solid Waste Business, except
for operations which after the Closing Date will be conducted only as permitted
under the Waste Management Services Agreement.  None of the Acquired
Subsidiaries is or has been engaged in any business other than the Solid Waste
Business or owns or has owned any assets or properties which are used in any
business other than the Solid Waste Business.

         4.8     Financial Statements.  The Laidlaw Sellers have delivered to
the Allied Parties:

                 (i)      unaudited consolidated balance sheets of the LWSI
         Group Subsidiaries (prepared for the LWSI Group Subsidiaries as a
         separate consolidated group of corporations for financial reporting
         purposes) at August 31, 1995 and May 31, 1996, and the related
         unaudited consolidated statements of operations, stockholder's equity
         and cash flows for the LWSI Group Subsidiaries (similarly prepared)
         for the respective years ended August 31, 1994 and 1995 and the nine
         months ended May 31, 1996;

                 (ii)     unaudited combined balance sheets of the LWSC Group
         Subsidiaries and LMS and its Subsidiary (prepared for the LWSC Group
         Subsidiaries and LMS and its Subsidiary as a separate combined group
         of corporations for financial reporting purposes) at August 31, 1995
         and May 31, 1996, and the related unaudited combined statements of
         operations, stockholder's





                                      -24-
<PAGE>   33
         equity and cash flows for the LWSC Group Subsidiaries and LMS and its
         Subsidiary (similarly prepared) for the respective years ended August
         31, 1994 and 1995 and the nine months ended May 31, 1996; and

                 (iii)    unaudited combined balance sheets of the LWSI Group
         Subsidiaries, the LWSC Subsidiaries and LMS and its Subsidiary at
         August 31, 1994, August 31, 1995 and May 31, 1996, and the related
         unaudited combined statements of operations, stockholder's equity and
         cash flows of the LWSI Group Subsidiaries, the LWSC Group Subsidiaries
         and LMS and its Subsidiary for the respective years ended August 31,
         1994 and 1995 and the nine months ended May 31, 1996, together with
         the related notes thereto.

         The SWM Group Financial Statements described in clauses (i) and (ii)
above are collectively referred to in this Agreement as the "SWM Group
Consolidated Financial Statements," the SWM Group Financial Statements
described in clause (iii) above are referred to in this Agreement as the "SWM
Group Combined Financial Statements" and the SWM Group Combined Financial
Statements at May 31, 1996 and for the nine months then ended are referred to
in this Agreement as the "SWM Group May 31 Combined Financial Statements."  All
SWM Group Financial Statements are stated in U.S. dollars.

         The SWM Group Consolidated Financial Statements have been prepared in
accordance with U.S. GAAP, except for compliance with SFAS 109 and the omission
of explanatory footnote disclosures.  The SWM Group Combined Financial
Statements and the SWM Group May 31 Combined Financial Statements have been
prepared by combining the relevant SWM Group Consolidated Financial Statements
in accordance with U.S. GAAP applicable to the preparation of combined
financial statements.

         All SWM Group Financial Statements fairly present in all material
respects the separate company, consolidated or combined, as the case may be,
financial position of the respective Acquired Subsidiaries or groups of
Acquired Subsidiaries covered thereby at the respective dates thereof, and the
results of their separate company or consolidated or combined, as the case may
be, operations, stockholder's equity and (except as to the SWM Group Separate
Company Financial Statements) cash flows for the respective Acquired
Subsidiaries or groups of Acquired Subsidiaries covered thereby for the
respective periods indicated, in accordance with U.S. GAAP except for
compliance with SFAS 109 and the omission of explanatory footnote disclosures
as noted above.

         4.9     Absence of Certain Changes.  Except as set forth in Section
4.9 of the Laidlaw Disclosure Schedule, since May 31, 1996, the Acquired
Subsidiaries have conducted their businesses only in the ordinary course,
consistent with past practice, and there has not occurred a Material Adverse
Effect with respect to the Acquired





                                      -25-
<PAGE>   34
Subsidiaries or any event that could result in a Material Adverse Effect with
respect to the Acquired Subsidiaries.

         4.10    No Undisclosed Liabilities.  Except as disclosed in the SWM
Group Financial Statements or as set forth in Sections 4.10 and 4.14 of the
Laidlaw Disclosure Schedule, no Acquired Subsidiary has any liabilities or
obligations, known or unknown, fixed or contingent, other than (i) those
liabilities and obligations (other than for borrowed money) arising since May
31, 1996 in the ordinary course of its business and consistent with its past
practice, (ii) liabilities and obligations other than for borrowed money
arising after the date of this Agreement without violation of Sections 6.1 and
6.2, or (iii) liabilities and obligations that, individually or in the
aggregate, could not result in a Material Adverse Effect on the Acquired
Subsidiaries.

         4.11    Acquired Subsidiary Properties.  The Acquired Subsidiaries
have good and marketable title to their respective properties and assets,
including those reflected in the SWM Group May 31 Combined Financial Statements
(other than properties and assets disposed of in the ordinary course of
business since May 31, 1996, which in the aggregate are not material), free of
all Liens except Permitted Liens and Liens disclosed in Section 4.11 of the
Laidlaw Disclosure Schedule.

         4.12    Landfills.  Section 4.12 of the Laidlaw Disclosure Schedule
lists each SWM Group Landfill and accurately describes each such landfill by
its city or county and state or province of location, total acreage, permitted
acreage, estimated remaining permitted capacity in tons, estimated or mandated
closure date, and estimated closure, post-closure and reclamation liability at
its projected or mandated closure date (computed at the closure date with and
without discount to present value) and any other recorded or unrecorded
accruals, contingent or otherwise, or reserves related to landfill liabilities
of any type.  Section 4.12 of the Laidlaw Disclosure Schedule also lists each
landfill not owned or operated by an Acquired Subsidiary, but to which any
Acquired Subsidiary hauls solid waste.

         4.13    Taxes and Tax Returns.  Except as described in Section 4.13 of
the Laidlaw Disclosure Schedule:

                 (i)      all Tax Returns required to be filed with any Taxing
         Authority with respect to any Pre-Closing Tax Period by or on behalf
         of the Acquired Subsidiaries (including the U.S. consolidated income
         Tax Returns of LTI) have been duly filed on a timely basis in
         accordance with all applicable Laws, or will be timely filed in
         accordance with Section 12.2;

                 (ii)     at the time of their filings all such Tax Returns
         were or will be complete and correct;





                                      -26-
<PAGE>   35
                 (iii)    there are no Liens for Taxes upon any assets of any
         Acquired Subsidiary, except Liens for Taxes not yet due for current
         Tax periods ending on or after the Closing Date;

                 (iv)     there are no outstanding deficiencies, assessments or
         written proposals for the assessment of Taxes proposed, asserted or
         assessed against any Acquired Subsidiary, or for which any Acquired
         Subsidiary could be directly or indirectly liable and there is no
         basis for any additional assessment or reassessment for any Taxes for
         which adequate provision has not been made in the books and records of
         the Acquired Subsidiaries;

                 (v)      no extension of the statute of limitations or waiver
         of normal reassessment periods on the assessment of any Taxes has been
         granted to or on behalf of any Acquired Subsidiary;

                 (vi)     no LWSC Group Subsidiary is or has ever been a
         controlled foreign corporation as defined by Code Section 957;

                 (vii)    each Acquired U.S. Subsidiary will be a member of the
         LTI U.S. Consolidated Tax Group on the Closing Date;

                 (viii)   Laidlaw and its Affiliates have never owned and do
         not now own any shares of Allied, any of its Affiliates or any
         predecessor thereof;

                 (ix)     no Acquired Canadian Subsidiary has had a permanent
         establishment or income effectively connected with the conduct of a
         trade or business in the United States, and no Acquired U.S.
         Subsidiary has had a permanent establishment or income effectively
         connected with the conduct of a trade or business in Canada; and

                 (x)      no Acquired Subsidiary is a member of any unitary or
         combined group for state or provincial tax purposes.

         4.14    Litigation.  Except as disclosed in Section 4.14 of the
Laidlaw Disclosure Schedule, there is no suit, action, investigation or
proceeding pending or, to the knowledge of the Laidlaw Sellers, threatened
against any of the Acquired Subsidiaries at law or in equity before or by any
Governmental Entity or before any arbitrator or mediator of any kind, that
could have a Material Adverse Effect on the Acquired Subsidiaries, and there is
no judgment, decree, injunction, rule or order of any Governmental Entity or
arbitrator or mediator to which any Acquired Subsidiary (or any of its assets
or properties) is subject that could have a Material Adverse Effect on the
Acquired Subsidiaries.  There is no suit, action, investigation or proceeding
pending or, to the knowledge of the Laidlaw Sellers, threatened against either
Laidlaw Seller at law





                                      -27-
<PAGE>   36
or in equity before or by any Governmental Entity or before any arbitrator or
mediator of any kind, that could have a Material Adverse Effect on the Laidlaw
Sellers, and there is no judgment, decree, injunction, rule or order of any
Governmental Entity or arbitrator or mediator to which either Laidlaw Seller is
subject that could have a Material Adverse Effect on the Laidlaw Sellers.
Neither Laidlaw Seller has knowledge of any grounds on which any suit, action,
investigation or proceeding of the nature referred to in this Section 4.14
might be commenced with any reasonable likelihood of success.

         4.15    Environmental Matters.  Except as described in Section 4.15 of
the Laidlaw Disclosure Schedule (as may be updated on or before 5 Business Days
before the Closing), and except to the extent that the inaccuracy of any of the
following, individually or in the aggregate, could not have a Material Adverse
Effect on the Acquired Subsidiaries:

                 (i)      the Acquired Subsidiaries hold, and are in compliance
         with and have been in compliance with, all Environmental Permits, and
         are otherwise in compliance and have been in compliance with, all
         applicable Environmental Laws, and there is no condition that could
         prevent or interfere with compliance by the Acquired Subsidiaries with
         all Environmental Laws;

                 (ii)     no modification, revocation, reissuance, alteration,
         transfer or amendment of any Environmental Permit, or any review by,
         or approval of, any Governmental Entity or other Person of any
         Environmental Permit is required in connection with the execution or
         delivery of this Agreement or any Ancillary Agreement, the
         consummation of the Acquisitions, or the operation of the business of
         the Acquired Subsidiaries immediately after the Closing;

                 (iii)    no Acquired Subsidiary has received any Environmental
         Claim, nor has any Environmental Claim been threatened against any
         Acquired Subsidiary;

                 (iv)     no Acquired Subsidiary has entered into, agreed to or
         is subject to any outstanding judgment, decree, order or other
         directive issued by, or consent arrangement with, any Governmental
         Entity under any Environmental Law, including any such judgment,
         decree, order or other directive relating to compliance with any
         Environmental Law or to the investigation, cleanup, remediation or
         removal of Hazardous Substances;

                 (v)      to the knowledge of the Laidlaw Sellers, there are no
         circumstances that could give rise to liability under any agreement
         with any Person or by operation of law by or under which any Acquired
         Subsidiary would be required to defend, indemnify, hold harmless, or
         otherwise be





                                      -28-
<PAGE>   37
         responsible for any violation by or other liability or expense of such
         Person, or alleged violation by or other liability or expense of such
         Person, arising under any Environmental Law;

                 (vi)     to the knowledge of the Laidlaw Sellers, there are no
         other circumstances or conditions that could give rise to liability or
         obligation of any Acquired Subsidiary under any Environmental Law; and

                 (vii)    the liabilities and reserves reflected on the SWM
         Group May 31 Combined Financial Statements adequately provide for, in
         accordance with U.S. GAAP (x) all future claims and costs for closure,
         intermediate capping, post-closure monitoring, investigation and
         maintenance, reclamation, remediation, restoration and cleanup of all
         SWM Group Landfills (or any landfill or other facility previously
         owned, occupied, leased or operated by, or previously under the
         management or control of, any Acquired Subsidiary or any landfill to
         which an Acquired Subsidiary has transported waste), and (y) all
         Environmental Claims against the respective groups of Acquired
         Subsidiaries covered by the SWM Group May 31 Combined Financial
         Statements.

         4.16    Governmental Licenses and Permits; Compliance with Laws.
Except as described in Section 4.16 of the Laidlaw Disclosure Schedule, no
Acquired Subsidiary has received any notice of any revocation or modification
or any license, certification, tariff, permit, registration, exemption,
approval or other authorization by any Governmental Entity, the revocation or
modification of which has had or is reasonably likely to have a Material
Adverse Effect on the Acquired Subsidiaries.  The business of each Acquired
Subsidiary complies and has been conducted in compliance with all applicable
Laws, except for violations or failure to comply, if any, that, individually or
in the aggregate, could not have a Material Adverse Effect on the Acquired
Subsidiaries.

         4.17    Labor Matters.  Section 4.17 of the Laidlaw Disclosure
Schedule lists and describes each collective bargaining agreement covering
employees of any Acquired Subsidiary.  Except as disclosed in Section 4.17 of
the Laidlaw Disclosure Schedule, (i) no Acquired Subsidiary is a party to or
bound by any collective bargaining or similar agreement with any labor
organization applicable to employees of any Acquired Subsidiary, (ii) there is
no labor strike, dispute, slowdown, work stoppage, unresolved material labor
union grievance or labor arbitration proceedings pending or, to the knowledge
of the Laidlaw Sellers, threatened against any Acquired Subsidiary, and (iii)
to the knowledge of the Laidlaw Sellers, there are no current union organizing
activities among employees of any Acquired Subsidiary.

         Since the enactment of the WARN Act, no Acquired Subsidiary has
effectuated (i) a "plant closing" (as defined in the WARN Act) affecting any
site of employment





                                      -29-
<PAGE>   38
or one or more facilities or operating units within any site of any employment
or facility of an Acquired Subsidiary.  No Acquired Subsidiary has been
affected by any transaction or engaged in layoffs or employment terminations
sufficient in number to trigger application of any similar Canadian federal,
state, provincial or local Law.  Except as set forth in Section 4.17 of the
Laidlaw Disclosure Schedule, no employees of any Acquired Subsidiary have
suffered an "employment loss" (as defined in the WARN Act) since December 31,
1995.

         4.18    Employee Benefit Plans.  Section 4.18 of the Laidlaw
Disclosure Schedule sets forth each retirement, pension, bonus, stock purchase,
profit sharing, stock option, deferred compensation, severance or termination
pay, insurance, medical, hospital, dental, vision care, drug, sick leave,
disability, salary continuation, legal benefits, unemployment benefits,
vacation, incentive or other compensation plan or arrangement or other employee
benefit which is maintained, or otherwise contributed to or required to be
contributed to, by any of the Acquired Subsidiaries, any member of the Laidlaw
Group or any ERISA Affiliate of Laidlaw for the benefit of employees or former
employees and directors or former directors of any of the Acquired Subsidiaries
and their spouses, dependents or beneficiaries (the "Laidlaw Employee Plans").
True and correct copies of each of the Laidlaw Employee Plans have been made
available to the Purchaser, along with the most recent annual report for the
Plan, any trust agreement relating to the Plan and the most recent summary plan
description, actuarial report and determination letter for the Plan.  Each of
the Acquired Subsidiaries has complied, and currently is in compliance, both as
to form and operation, in all material respects, with the applicable provisions
of ERISA and each other Law or regulation imposed or administered by any
Governmental Entity with respect to each of the Laidlaw Employee Plans.  Except
as set forth in Section 4.18 of the Laidlaw Disclosure Schedule, none of the
Acquired Subsidiaries has at any time maintained, adopted, established,
contributed to or been required to contribute to, otherwise participated in or
been required to participate in, or had any liability with respect to, any
"employee benefit plan" within the meaning of section 3(3) of ERISA.  All
Laidlaw Employee Plans providing pension or retirement benefits or obligations
to current or former employees or their spouses, dependents and beneficiaries
are referred to collectively as "Laidlaw Pension Plan" and identified on the
Laidlaw Disclosure Schedule.  Except as set forth in Section 4.18 of the
Laidlaw Disclosure Schedule, no provision concerning the Laidlaw Pension Plan
is contained in any collective bargaining agreement affecting any current or
former employees of any Acquired Subsidiary.  Each Laidlaw Pension Plan that is
required to be qualified under Section 401(a) and Section 501(a) of the Code
has received a determination letter to such effect and no event has occurred
which is reasonably likely to result in the disqualification of any such
Laidlaw Pension Plan.  The Laidlaw Pension Plan is registered under, and is in
material compliance with, applicable Law.  All contributions to, and payments
from, each Laidlaw Employee Plan which may have been required to be made in
accordance with the terms of any such Laidlaw Employee Plan and, where
applicable, the Laws which





                                      -30-
<PAGE>   39
govern such Laidlaw Employee Plan, have been made in a timely manner, and each
Laidlaw Employee Plan has otherwise at all times been administered in
accordance with its terms and applicable Law in all material respects.  All
material reports, Tax Returns and similar documents with respect to any Laidlaw
Employee Plan required to be filed with any Governmental Entity or distributed
to any Laidlaw Employee Plan participant have been duly filed on a timely basis
or distributed.  There are no pending investigations by any Governmental Entity
involving or relating to an Laidlaw Employee Plan, no threatened or pending
claims (except for claims for benefits payable in the normal operation of the
Laidlaw Employee Plans), suits or proceedings against any Laidlaw Employee Plan
or asserting any rights or claims to benefits under any Laidlaw Employee Plan
which could give rise to a liability nor, to the knowledge of the Laidlaw
Sellers, are there any facts that could give rise to any liability in the event
of any such investigation, claim, suit or proceeding.  No notice has been
received by either of the Laidlaw Sellers or any of the Acquired Subsidiaries
of any complaints or other proceedings of any kind involving any of the
Acquired Subsidiaries or any of the employees of any of the Acquired
Subsidiaries or other potential claimants before any Governmental Entity
relating to any Laidlaw Employee Plan or to any of the Acquired Subsidiaries
and to the knowledge of the Laidlaw Sellers, there is no basis for any such
claims.  Except as set forth in Section 4.18 of the Laidlaw Disclosure
Schedule, the assets of each Laidlaw Employee Plan are at least equal to the
liabilities, contingent or otherwise, of such Laidlaw Employee Plan on a plan
termination basis, and each Laidlaw Pension Plan is fully funded on a going
concern and solvency basis in accordance with its terms, applicable actuarial
recommendations and applicable Law.  Neither Laidlaw nor any of the Acquired
Subsidiaries contribute to or have an obligation to contribute to, and, to the
knowledge of Laidlaw, have not within 6 years prior to the date of this
Agreement contributed to or had an obligation to contribute to, a
multi-employer plan within the meaning of Section 3(37) of ERISA.  No event has
occurred and, to the knowledge of the Laidlaw Sellers, there exists no
condition or set of circumstances in connection with which Allied, any of its
affiliates or the Acquired Subsidiaries could be subject to any liability under
the terms of each Laidlaw Employee Plan or under any applicable law of any
Governmental Entity, other than any condition or set of circumstances that
could not have a Material Adverse Effect on the Acquired Subsidiaries.  In
connection with the consummation of the transactions contemplated by this
Agreement, no payments have or will be made under a Laidlaw Employee Plan
which, in the aggregate, would be nondeductible under Section 280G of the Code.

         The beneficiaries under all Laidlaw Employee Plans shall consist only
of employees or former employees and directors or former directors of any of
the acquired subsidiaries and their spouses, dependents or beneficiaries.  No
acquired subsidiary shall have any liability under the Laidlaw Employee Stock
Option Plan.  The amount to fund the Supplemental Executive Retirement Plan
shall not exceed $300,000.00





                                      -31-
<PAGE>   40
         4.19    Material Contracts.  Section 4.19 of the Laidlaw Disclosure
Schedule lists all of the following written or oral contracts, agreements and
commitments (collectively, the "SWM Group Contracts"):

                 (i)      all employment, consulting or personal services
         agreements or contracts with any present or former officer, director
         or employee of any Acquired Subsidiary who has an annual salary of
         $125,000 or more (determined by using the currency in which they are
         paid;

                 (ii)     all solid waste management agreements and contracts
         (including those relating to the receipt, transport, disposal or other
         management of waste) between any Acquired Subsidiary and any
         municipality or other Governmental Entity or Person which call for
         annual payments to or by any Acquired Subsidiary of $1,000,000 or
         more, which list includes the term of such agreements or contracts;

                 (iii)    all contracts, agreements, agreements in principle,
         letters of intent and memoranda of understanding which call for or
         contemplate the future disposition (including restrictions on transfer
         and rights of first offer or refusal) or acquisition of (or right to
         acquire) any interest in any business enterprise, and all contracts,
         agreements and commitments relating to the future disposition of a
         material portion of the assets and properties of any Acquired
         Subsidiary other than in the ordinary course of business;

                 (iv)     all contracts, agreements with, or commitments to,
         any Person containing any provision or covenant relating to the
         indemnification or holding harmless by any Acquired Subsidiary of any
         Person which could result in a liability to an Acquired Subsidiary of
         $500,000 or more;

                 (v)      all leases or subleases of real property used in the
         conduct of business of any Acquired Subsidiary providing for annual
         rental payments to be paid by or on behalf of an Acquired Subsidiary
         of more than $500,000 in each case;

                 (vi)     all contracts or agreements committing any Acquired
         Subsidiary to make a capital expenditure in excess of $500,000;

                 (vii)    all guaranties or other commitments or undertakings
         under which any Acquired Subsidiary may be primarily, secondarily,
         contingently or conditionally liable for or in respect of (or which
         creates, constitutes or evidences a Lien on any of the assets or
         properties of any Acquired Subsidiary which secures the payment or
         performance of) any present or future liability or





                                      -32-
<PAGE>   41
         obligation of or to any member of the Laidlaw Group or any officer or
         director of the Laidlaw Group;

                 (viii)   all Laidlaw Guaranties;

                 (ix)     all contracts, agreements and undertakings with any
         Governmental Entity or other Person which contain any provision or
         covenant limiting (x) the ability of any Acquired Subsidiary to engage
         in any line of business, to compete with any Person, to do business
         with any Person or in any location or to employ any Person or (y) the
         ability of any Person to compete with or obtain products or services
         from any Acquired Subsidiary;

                 (x)      all outstanding proxies, powers of attorney or
         similar delegations of authority granted by any Acquired Subsidiary to
         any member of the Laidlaw Group or any other Person; and

                 (xi)     all Intercompany Agreements.

         The Laidlaw Parties shall deliver to the Allied Parties within 15 days
of the Closing a true and correct copy of each SWM Group Contract.  Each of the
SWM Group Contracts is in full force and effect and constitutes a legal, valid
and binding obligation of the Acquired Subsidiary which is a party to it, and,
to the knowledge of the Laidlaw Sellers, of each other Person that is a party
to it.  Except as set forth in Section 4.19 of the Laidlaw Disclosure Schedule,
no Acquired Subsidiary is, and, to the knowledge of the Laidlaw Sellers, no
other party to any SWM Group Contract is, in violation, breach or default of
such SWM Group Contract or, with or without notice or lapse of time or both,
would be in violation, breach or default of any such SWM Group Contract, except
for any violation, breach or default which, individually or in the aggregate,
could not result in a Material Adverse Effect on the Acquired Subsidiaries.
Except as set forth in Section 4.19 of the Laidlaw Disclosure Schedule, no SWM
Group Contract provides that any party thereto other than an Acquired
Subsidiary may terminate such SWM Group Contract by reason of the execution of
this Agreement or the consummation of the Acquisitions.

         4.20    Bank Accounts.  Section 4.20 of the Laidlaw Disclosure
Schedule lists each bank, trust company or similar institution with which any
Acquired Subsidiary maintains an account or safe deposit box, and accurately
identifies each such account or safe deposit box by its number or other
identification and the names of all individuals authorized to draw thereon or
have access thereto.

         4.21    Officers and Directors.  Section 4.5 of the Laidlaw Disclosure
Schedule accurately lists by name and title all officers and directors of each
Acquired Subsidiary.





                                      -33-
<PAGE>   42
         4.22    Brokers.  No broker, finder or investment banker is entitled
to any brokerage, finder's or other fee or commission from any Allied Party or
any Acquired Subsidiary in connection with this Agreement or the Acquisitions
based upon arrangements made by or on behalf of any Laidlaw Party.

         4.23    Aggregation.  The imperfections, defects, orders, actions,
defaults, liabilities, inaccuracies and other items omitted from disclosure in
connection with the representations and warranties made in Sections 4.1 through
4.22 on grounds of immateriality, lack of knowledge or failure to have a
Material Adverse Effect do not and could not, taken as a whole, constitute a
Material Adverse Effect on the Laidlaw Sellers or the Acquired Subsidiaries.


                                   ARTICLE V

                         REPRESENTATIONS AND WARRANTIES
                                       OF
                                 ALLIED PARTIES

         The Allied Parties jointly and severally represent and warrant to the
Laidlaw Sellers that:

         5.1     Organization of Allied Parties.  Each Allied Party is a
corporation duly organized, validly existing and in good standing under the
Laws of the State of Delaware, or, in the case of Allied Canada, the Laws of
Canada.  Each Allied Party has full authority and corporate power to conduct
its business as it is currently being conducted and as to be conducted
following consummation of the Acquisitions.  Each Allied Party is duly
qualified to do business, and in good standing, in each jurisdiction where the
nature of its properties or business requires such qualification.

         5.2     Authority Relative to this Agreement.  Each Allied Party has
the requisite corporate power and authority to enter into and perform its
obligations under this Agreement and each Ancillary Agreement to which it will
be a party, and, in the case of Allied, the Allied Warrant, and in the case of
Allied Canada, the Allied Canada Debentures.  The execution and delivery of
this Agreement and each Ancillary Agreement to which the respective Allied
Parties will be parties, the consummation of the Acquisitions, the issuance or
delivery of Allied Securities, and the other transactions contemplated in
Articles II and  III have been duly authorized by the respective Boards of
Directors of the Allied Parties, and except for the approval by Allied's
stockholders of the issuance by Allied of the Allied Common Shares in
connection with the U.S. Acquisition, the issuance of Allied Warrant Shares
upon any exercises of Allied Warrant in accordance with its terms and the
issuance of the Additional Allied Common Shares, no other corporate proceedings
on the part of any Allied Party are necessary to





                                      -34-
<PAGE>   43
authorize this Agreement, any Ancillary Agreement to which any Allied Party
will be a party, the issuance and delivery of the Allied Securities, the
consummation of the Acquisitions, or the other transactions contemplated in
Articles II and III.  This Agreement has been duly executed and delivered by
each Allied Party.  The Allied Debentures, the Allied Warrant and each
Ancillary Agreement required to be executed and delivered by an Allied Party at
the Closing will be, upon its or their execution and delivery as provided in
Section 3.3, duly executed and delivered by such Allied Party.  Assuming the
valid authorization, execution and delivery of this Agreement (and each
Ancillary Agreement to which a Laidlaw Party will be a party) by each Laidlaw
Party, this Agreement is, and upon their issuance and delivery at the Closing,
the Allied Debentures and the Allied Warrant will be, and upon its execution
and delivery by an Allied Party, each Ancillary Agreement to which an Allied
Party is a party will be, valid and binding obligations of each Allied Party
(or Allied in the case of the Allied Warrant or Allied Canada in the case of
the Allied Canada Debentures), enforceable in accordance with their terms,
except as enforceability may be limited by bankruptcy, insolvency,
reorganization, moratorium or other law relating to or affecting creditors'
rights generally or by equitable principles.

         5.3     Status of Allied Common Shares.  Upon their issuance as
provided in Sections 2.2 and 2.3, the Allied Common Shares will be, and upon
any issuance thereof by the Company in accordance with the Allied Warrant or
the Laidlaw Subscription Agreement, the Additional Allied Common Shares will
be, duly authorized, validly issued, fully paid and nonassessable.

         5.4     No Violations.  The execution, delivery and performance of
this Agreement and the applicable Ancillary Agreements by the respective Allied
Parties, the issuance and delivery by Allied of the Allied Securities, and the
consummation of the Acquisitions and the other transactions contemplated in
Articles II and III will not:

                 (i)      constitute a breach or violation of or default under
         the charter or bylaws (or similar organizational documents) or
         internal rules or regulations governing the conduct of  corporate
         actions of any Allied Party or any of their respective Subsidiaries or
         any Law applicable to any Allied Party or any of their respective
         Subsidiaries; or

                 (ii)     except as accurately reflected in Section 5.4 of the
         Allied Disclosure Schedule, violate or conflict with or result in a
         breach of, or constitute a default (or an event which, with notice or
         lapse of time or both, would constitute a default) under or result in
         the termination of, or accelerate the performance by, or result in a
         right of termination under, or result in the creation of any Lien upon
         the assets or properties of Allied or any of its Subsidiaries under,
         any contract, indenture, loan document, license, permit, order, decree
         or





                                      -35-
<PAGE>   44
         instrument to which any Allied or any of its Subsidiaries is a party
         or by which any of them or their assets or properties are bound.

         5.5     Consents and Approval.  No consent, order, approval, waiver,
authorization of, or registration, application, declaration or filing with, any
Person is required with respect to any Allied Party or any Subsidiary of Allied
in connection with the execution and delivery of this Agreement, the issuance
of the Allied Securities, the consummation of the Acquisitions, and the other
transactions contemplated in Articles II and III, except for:

                 (i)      the HSR Act, Competition Act, and Investment Canada
         Act filings and approvals contemplated in this Agreement;

                 (ii)     the consents and approvals described on Section 5.5
         of the Allied Disclosure Schedule;

                 (iii)    the approval by Allied's stockholders, as
         contemplated in Section 7.5; and

                 (iv)     other cases, considered individually and in the
         aggregate, in which any failure to make such registration,
         application, declaration or filing or to obtain any such consent,
         order, approval, waiver or other authorization could not have a
         Material Adverse Effect on Allied and its Subsidiaries.

         5.6     Allied Capitalization.  The authorized capital stock of Allied
consists of (i) 100 million shares of Allied Common Stock, and (ii) 10 million
shares of Preferred Stock, $.10 par value, of Allied ("Allied Preferred
Stock").  At September 10, 1996, 58,859,811 shares of Allied Common Stock, and
14,943 shares of Allied Preferred Stock, were issued and outstanding, all of
which were duly and validly issued, fully paid and nonassessable.  Except as
set forth in the Allied SEC Filings or Section 5.6 of the Allied Disclosure
Schedule, no subscription, warrant, option, convertible security, stock
appreciation or other right (contingent or other) to purchase or acquire any
shares of any class of capital stock of Allied or any of its Subsidiaries is
authorized or outstanding and there is not outstanding any commitment of Allied
or any of its Subsidiaries to issue any shares, warrants, options or other such
rights or to distribute to holders of any class of its capital stock any
evidences of indebtedness or assets.  Except as set forth in the Allied SEC
Filings, neither Allied nor any of its Subsidiaries has any contingent or other
obligation to purchase, redeem or otherwise acquire any shares of its capital
stock or any interest therein or to pay any dividend or make any other
distribution in respect thereof.  Except as set forth in the Allied SEC
Filings, Allied is not a party to any voting agreement, voting trust or similar
agreement or arrangement relating to its capital stock or any agreement or
arrangement relating to or providing for registration rights with respect to
its capital stock.





                                      -36-
<PAGE>   45
         5.7     Allied Subsidiaries.  Each Subsidiary of Allied is a
corporation duly organized, validly existing and in good standing under the
laws of its jurisdiction of incorporation and has full authority and corporate
power to conduct its business as it is presently being conducted.  Each
Subsidiary of Allied is duly qualified to do business, and in good standing, in
each jurisdiction where the nature of its properties or business requires such
qualification, except for failures to be so qualified which could not,
individually or in the aggregate, have Material Adverse Effect on Allied and
its Subsidiaries.  Except as accurately disclosed in the Allied SEC Filings,
all of the outstanding shares of capital stock of each Subsidiary of Allied are
validly issued, fully paid and nonassessable and are owned of record and
beneficially by Allied or a wholly owned direct or indirect Subsidiary of
Allied.  Except as set forth in the Allied SEC Filings, there are no
outstanding subscriptions, options, warrants, calls, rights, convertible
securities, obligation to make capital contributions or advances, voting trust
arrangements, shareholder's agreements or other agreements, commitments or
understandings relating to the issued and outstanding capital stock of any
Subsidiary of Allied.  Except as described in Section 5.7 of the Allied
Disclosure Schedule, Allied does not, directly or indirectly, have any equity
investment in any corporation, partnership or joint venture or other business
entity.

         5.8     SEC Filings.  Allied has filed all forms, reports and
documents required to be filed with the SEC since May 15, 1996, the date on
which Allied's registration statement on Form S-4 (No. 333-5585) (the "Allied
Registration Statement") became effective, and Allied has made available to the
Laidlaw Sellers true and complete copies of (i) the Allied Registration
Statement, (ii) Allied's Annual Report on Form 10-K for the year ended December
31, 1995, and (iii) all other reports, statements and registration statements
(including Current Reports on Form 8-K) filed by Allied with the SEC since
December 31, 1995 (collectively, the "Allied SEC Filings").  The Allied SEC
Filings (including all financial statements or schedules included in them) (i)
were prepared in compliance in all material respects with the requirements of
the Securities Act or the Exchange Act, as the case may be, and (ii) did not at
the time of filing (or if amended, supplemented or superseded by a later
filing, on the date of the later filing) contain any untrue statement of a
material fact or omit to state a material fact required to be stated therein or
necessary in order to make the statements therein, in light of the
circumstances under which they were made, not misleading.

         5.9     Allied Financial Statements.  The consolidated balance sheets
and consolidated statements of operations, stockholder's equity and cash flows
of Allied and its Subsidiaries included in the Allied SEC Filings fairly
present in all material respects the consolidated financial position of Allied
and its Subsidiaries at their respective dates and the consolidated results of
operations of Allied and its Subsidiaries for the respective periods then
ended, in accordance with U.S. GAAP, subject, in the case of unaudited interim
financial statements, to year-end adjustments (which consist of normal
recurring accruals) and the absence of explanatory footnote disclosures
required by U.S.





                                      -37-
<PAGE>   46
GAAP.  Allied's unaudited consolidated balance sheet at June 30, 1996 included
in the Allied SEC Filings is herein called the "Latest Allied Balance Sheet."

         5.10    Absence of Certain Changes.  Except as set forth in Section
5.10 of the Allied Disclosure Schedule, since June 30, 1996, Allied and its
Subsidiaries have conducted their businesses only in the ordinary course,
consistent with past practice, and there has not occurred a Material Adverse
Effect with respect to Allied and its Subsidiaries or any event that could
result in a Material Adverse Effect on Allied and its Subsidiaries.

         5.11    No Undisclosed Liabilities.  Except as disclosed in the Latest
Allied Balance Sheet or in Sections 5.11 and 5.14 of the Allied Disclosure
Schedule, Allied and its Subsidiaries have no liabilities or obligations, known
or unknown, fixed or contingent, other than (i) those arising since June 30,
1996 in the ordinary course of business and consistent with past practice, (ii)
liabilities and obligations arising after the date of this Agreement without
violation of Sections 7.1 and 7.2, or (iii) liabilities and obligations that,
individually or in the aggregate, could not result in a Material Adverse Effect
on Allied and its Subsidiaries.

         5.12    Allied Properties.  Allied and its Subsidiaries have good and
marketable title to the properties and assets used in the conduct of their
business including those reflected in the Latest Allied Balance Sheet (other
than properties and assets disposed of in the ordinary course of business since
June 30, 1996, which, in the aggregate, are not material), free of all Liens
except Permitted Liens and Liens disclosed in Section 5.12 of the Allied
Disclosure Schedule.  Section 5.12 of the Allied Disclosure Schedule lists each
landfill owned or operated by Allied and its Subsidiaries and accurately
describes each such landfill by its city or county and state or province of
location, total acreage, permitted acreage, estimated remaining permitted
capacity in tons, estimated or mandated closure date, and estimated closure,
post-closure and reclamation liability at its projected or mandated closure
date (computed at the closure date with and without discount to present value).
Section 5.12 of the Allied Disclosure Schedule also lists each solid waste
landfill not owned or operated by Allied and its Subsidiaries, but to which
Allied and its Subsidiaries hauls solid waste.

         5.13    Taxes and Tax Returns.  Except as described in Section 5.13 of
the Allied Disclosure Schedule:

                 (i)      all Tax Returns required to be filed with any Taxing
         Authority with respect to any Pre-Closing Tax Period by or on behalf
         of Allied and its Subsidiaries have been or will be duly filed on a
         timely basis in accordance with all applicable laws;





                                      -38-
<PAGE>   47
                 (ii)     at the time of their filings all such Tax Returns
         were or will be complete and correct;

                 (iii)    the reserves for Taxes reflected in the Latest Allied
         Balance Sheet are adequate to cover all Taxes that have not been paid,
         but which under U.S. GAAP were accruable, through the date of the
         Latest Allied Balance Sheet.

                 (iv)     there are no Liens for Taxes upon any assets of
         Allied or any of its Subsidiaries, except Liens for Taxes not yet due
         for current Tax periods ending with or after the Closing Date;

                 (v)      there are no outstanding deficiencies, assessments or
         written proposals for the assessment of Taxes proposed, asserted or
         assessed against Allied or any Subsidiary of Allied and there is no
         basis for any additional assessments or reassessments for any Taxes
         for which adequate provision has not been made in the books and
         records of Allied or its Subsidiaries, as the case may be; and

                 (vi)     no extension of the statute of limitations or waiver
         of normal reassessment periods on the assessment of any Taxes has been
         granted to Allied or any Subsidiary of Allied.

         5.14    Litigation.  Except as disclosed in the Allied SEC Filings or
in Section 5.14 of the Allied Disclosure Schedule, there is no suit, action,
investigation or proceeding pending or, to the knowledge of the Allied Parties,
threatened against Allied or any of its Subsidiaries at law or in equity before
or by any Governmental Entity or before any arbitrator or mediator of any kind,
that could have a Material Adverse Effect on Allied and its Subsidiaries, and
there is no judgment, decree, injunction, rule or order of any Governmental
Entity, arbitrator or mediator to which Allied or any Allied Subsidiary is
subject that could have a Material Adverse Effect on Allied and its
Subsidiaries.  No Allied Party has knowledge of any grounds on which any suit,
action, investigation or proceeding of the nature referred to in this Section
5.14 might be commenced with any reasonable likelihood of success.

         5.15    Environmental Matters.  Except as reflected in the Allied SEC
Filings or as described in Section 5.15 of the Allied Disclosure Schedule (as
may be updated on or before 5 Business Days before the Closing), and except to
the extent that the inaccuracy of any of the following, individually or in the
aggregate, could not have a Material Adverse Effect on Allied and its
Subsidiaries:

                 (i)      Allied and its Subsidiaries hold, and are in
         compliance with and have been in compliance, all Environmental
         Permits, and are otherwise in compliance and have been in compliance
         with, all applicable Environmental





                                      -39-
<PAGE>   48
         Laws, and there is no condition that could prevent or interfere with
         compliance by the Allied or any of its Subsidiaries with any
         Environmental Law;

                 (ii)     no modification, revocation, reissuance, alteration,
         transfer or amendment of any Environmental Permit, or any review by,
         or approval of, any Governmental Entity or other third party of any
         Environmental Permit is required in connection with the execution or
         delivery of this Agreement or any Ancillary Agreement, the
         consummation of the Acquisitions or the operation of the business of
         Allied and its Subsidiaries on the Closing Date;

                 (iii)    neither Allied nor any of its Subsidiaries has
         received any Environmental Claim, nor has any Environmental Claim been
         threatened against Allied or any of its Subsidiaries;

                 (iv)     neither Allied nor any of its Subsidiaries has
         entered into, agreed to or is subject to any outstanding judgment,
         decree, order or other directive issued by, or consent arrangement
         with, any Governmental Entity under any Environmental Law, including
         any such judgment, decree, order or other directive relating to
         compliance with any Environmental Law or to the investigation,
         cleanup, remediation or removal of Hazardous Substances;

                 (v)      to the knowledge of the Allied Parties, there are no
         circumstances that could give rise to liability under any agreements
         with any Person under which Allied or any of its Subsidiaries would be
         required to defend, indemnify, hold harmless, or otherwise be
         responsible for any violation by or other liability or expense of such
         Person, or alleged violation by or other liability or expense of such
         Person, arising under any Environmental Law;

                 (vi)     to the knowledge of the Allied Parties, there are no
         other circumstances or conditions that could give rise to liability or
         obligation of Allied or any of its Subsidiaries under any
         Environmental Law; and

                 (vii)    the liabilities and reserves for closure,
         post-closure monitoring and maintenance and environmental remediation
         reflected on the Latest Allied Balance Sheet adequately provide for,
         in accordance with U.S. GAAP, all future claims and costs for closure,
         post-closure monitoring, investigation and maintenance, reclamation,
         remediation, restoration and cleanup of all landfills now or
         previously owned, occupied or leased or operated by Allied or any of
         its Subsidiaries (or now or previously under the management or control
         of Allied or any of its Subsidiaries) and all Environmental Claims
         against Allied or any of its Subsidiaries.





                                      -40-
<PAGE>   49
         5.16    Governmental Licenses and Permits; Compliance with Laws.
Except as described in the Allied SEC Filings or Section 5.16 of the Allied
Disclosure Schedule, neither Allied nor any of its Subsidiaries has received
notice of any revocation or modification of any license, certification, tariff,
permit, registration, exemption, approval or other authorization by any
Governmental Entity, the revocation or modification of which could have a
Material Adverse Effect on Allied and its Subsidiaries.  The conduct of the
business of Allied and its Subsidiaries complies and has been conducted in
compliance with all applicable Laws, except for violations or failures to
comply, if any, that, individually or aggregate, could not have a Material
Adverse Effect on Allied and its Subsidiaries.

         5.17    Labor Matters.  There is no labor strike, dispute, slowdown,
work stoppage, unresolved material labor union grievance or labor arbitration
proceedings pending or, to the knowledge of Allied, threatened against Allied
or any of its Subsidiaries, and no material current union organizing activities
among employees of Allied or its Subsidiaries.  Since the enactment of the WARN
Act, neither Allied nor any of its Subsidiaries has effectuated (i) a "plant
closing" (as defined in the WARN Act) affecting any site of employment or one
or more facilities or operating units within any site of any employment
facility or (ii) a "mass layoff" (as defined in the WARN Act) affecting any
site of employment or facility of Allied or any of its Subsidiaries.  Neither
Allied nor any of its Subsidiaries has been affected by any transaction or
engaged in any layoffs or employment terminations sufficient in number to
trigger application of any similar state, provincial or local law.  No
employees of Allied or any of its Subsidiaries have suffered an "employment
loss" (as defined in the WARN Act) since December 1, 1995.

         5.18    Opinion of Financial Advisor. On the date of this Agreement,
Allied has received the opinion of Goldman, Sachs & Co. to the effect that on
the basis of the assumptions referred to therein, the consideration payable by
the Allied Parties in connection with the Acquisitions, taken as a whole, is
fair to Allied.

         5.19    Financing.  The Allied Parties have delivered to the Laidlaw
Sellers copies of the Commitment Letter and the Highly Confident Letter.  The
Commitment Letter and the Highly Confident Letter remain in effect at the date
of this Agreement.  The funds committed to be made available to the Allied
Parties under the Commitment Letter and the funds to be sought by Allied
through the sale of the securities described in the Highly Confident Letter,
together with Allied's funds and funds otherwise available to Allied, are
sufficient to consummate the Acquisitions.

         5.20    Letter from Stockholders.  On or before the date of this
Agreement, Allied has received, and has delivered to the Laidlaw Parties copies
of, a letter from Roger A. Ramsey and Thomas H. Van Weelden, expressing their
agreement to vote all shares of Allied Common Stock held by them for approval
of the matters to be





                                      -41-
<PAGE>   50
submitted to Allied's stockholders for approval pursuant to Section 7.5 of this
Agreement.

         5.21    Brokers.  Except for Goldman, Sachs & Co., which has acted as
financial advisor to Allied in connection with the Acquisitions, no broker,
finder or investment banker is entitled to any brokerage, finder's or other fee
or commission in connection with this Agreement or the Acquisitions based upon
arrangements made by or on behalf of any Allied Party.

         5.22    Aggregation.  The imperfections, defects, orders, actions,
defaults, liabilities, inaccuracies and other items omitted from disclosure in
connection with the representations and warranties made in Sections 5.1 through
5.21 on grounds of immateriality, lack of knowledge or failure to have a
Material Adverse Effect do not and could not, taken as a whole, constitute a
Material Adverse Effect on the Allied Parties.


                                   ARTICLE VI

                       LAIDLAW AGREEMENTS PENDING CLOSING

         The Laidlaw Sellers jointly and severally agree that pending the
Closing, without the prior written consent of Allied:

         6.1     Conduct of Business.  Each Acquired Subsidiary shall conduct
its operations according to its ordinary and usual course of business, comply
with applicable Laws, comply with the terms of Laidlaw Employee Plans
(including by making all contributions required by the terms of the Laidlaw
Pension Plan, applicable actuarial recommendations and applicable Law), and use
its best efforts to preserve intact its business organization, keep available
the services of its officers and employees and maintain normal business
relationships with customers, suppliers and others having business
relationships with it.  The Laidlaw Parties shall confer on a regular and
frequent basis with one or more designated representatives of Allied to report
on operational matters of materiality and to report the general status of
on-going operations of the Acquired Subsidiaries.  The Laidlaw Parties shall
notify Allied of:

                 (i)      any unexpected material emergency or other material
         change in the normal course of business or in the operation of the
         properties of the Acquired Subsidiaries;

                 (ii)     the instigation of or any significant development in
         any regulatory proceedings, governmental complaints, investigations or
         hearings (or communications indicating that any may be contemplated)
         involving either





                                      -42-
<PAGE>   51
         Laidlaw Seller, or any Acquired Subsidiary, which instigation or
         development could have a Material Adverse Effect on the Acquired
         Subsidiaries or the Laidlaw Sellers;

                 (iii)    proposed budgets, capital expenditures, acquisitions
         and dispositions of assets and other decisions involving material
         properties of the Acquired Subsidiaries; and

                 (iv)     any matter or event which comes to the knowledge of
         the Laidlaw Sellers and which makes or could make any representation
         and warranty made by the Laidlaw Sellers in Article IV untrue or
         inaccurate.

         The Laidlaw Parties shall keep Allied fully informed of such events
and permit Allied's representatives access to all materials prepared in
connection with such events.

         The Laidlaw Sellers agree to advance to the Acquired Subsidiaries
during the period from the date of this Agreement through the Closing Date
funds sufficient to allow the Acquired Subsidiaries to maintain their working
capital at levels sufficient to support their continued operations in the
ordinary course of their business and consistent with past practices.  The
Laidlaw Sellers further agree, without limiting the generality of the preceding
sentence, to (i) maintain and continue their customer billing, receivable
collection and payables payment practices in a manner consistent with past
practices and in the ordinary course of business, and (ii) make the capital
expenditures at the times and in the amounts included in the schedule of
capital expenditures included in Section 6.2 to the Laidlaw Disclosure
Schedule.

         6.2     Forbearance by the Acquired Subsidiaries.  The Laidlaw Parties
shall not cause or permit any Acquired Subsidiary to, and no Laidlaw Party
which is an Acquired Subsidiary shall:

                 (i)      amend its charter or bylaws (or other similar
         organizational documents);

                 (ii)     issue, sell, pledge, dispose of or encumber any
         shares of its capital stock or securities convertible into any such
         shares, or enter into any agreement or commitment with respect to the
         issuance or purchase of any such shares or securities;

                 (iii)    in the case of LWSI, LWSC and LMS only, pay any
         dividend or other distribution in respect of the LWSI Shares, the LWSC
         Shares or the LMS Shares, or redeem purchase or acquire any LWSI
         Shares, the LWSC Shares or the LMS Shares, except that LWSI and LWSC
         may make the distributions required to be made by them under Section
         3.2;





                                      -43-
<PAGE>   52
                 (iv)     incur any indebtedness for borrowed money other than
         Intercompany Indebtedness;

                 (v)      make or commit to make any capital investment,
         capital expenditure, capital addition or capital improvement, except
         to the extent that any single capital expenditure made or committed to
         be made by any Acquired Subsidiary and all capital expenditures made
         or committed to be made by all Acquired Subsidiaries do not exceed the
         amounts set forth in the budget of capital expenditures included in
         Section 6.2 of the Laidlaw Disclosure Schedule.

                 (vi)     except in the ordinary course of business, and except
         for settlements made by insurers, enter into any compromise or
         settlement of any litigation, proceeding or governmental investigation
         relating to such Acquired Subsidiary or its respective properties
         which requires such Acquired Subsidiary to make a payment in excess of
         $1.5 million or which would result in the imposition of any
         restriction upon the operations of such Acquired Subsidiary, or the
         disposition of any of its properties, except for restrictions or
         dispositions which could have a Material Adverse Effect on the
         Acquired Subsidiaries;

                 (vii)    sell real property or any interest in or improvement
         upon real property (other than the real property, interests in and
         improvements upon real property described in Section 6.2 of the
         Laidlaw Disclosure Schedule) or any other capital asset the book value
         or sales price of which is more than $500,000;

                 (viii)   amend the Laidlaw Pension Plan or Laidlaw Employee
         Plans or make any statement relating to any anticipated or proposed
         increase in benefits under the Laidlaw Pension Plan or Laidlaw
         Employee Plans for current, future or former employees of any of the
         Acquired Subsidiaries other than strictly in accordance with the terms
         of the Laidlaw Pension Plan or Laidlaw Employee Plans as currently
         constituted;

                 (ix)     transfer, license, lease, sell, dispose, mortgage or
         encumber any assets or properties other than in the ordinary course of
         business; or

                 (x)      increase compensation, benefits or severance for
         employees of any Acquired Subsidiary except as required by any
         collective bargaining agreements entered into by the Acquired
         Subsidiaries as in effect on the date of this Agreement, and except as
         set forth in Section 6.2 of the Laidlaw Disclosure Schedule.

         6.3     Access and Information.  The Laidlaw Parties shall give to
Allied and its representatives (including its lenders and their
representatives) full access during normal business hours to all the
properties, books, contracts, commitments, records, Tax





                                      -44-
<PAGE>   53
Returns, personnel and advisors of Laidlaw and the Acquired Subsidiaries so
that Allied may have full opportunity to make such investigation of the
Acquired Subsidiaries as it shall reasonably request in advance.  The Laidlaw
Parties will cause Coopers & Lybrand to permit Arthur Andersen L.L.P. to review
and examine the work papers of Coopers & Lybrand relating to Laidlaw and the
Acquired Subsidiaries.  The Laidlaw Parties will promptly furnish to Allied all
information with respect to the Acquired Subsidiaries which Allied may
reasonably request.  Additionally, the Laidlaw Parties will furnish Allied all
information concerning the Acquired Subsidiaries required for inclusion in any
application, filing statement or notice to be made by any Allied Party to, or
filed or joined in by any Allied Party with, any Governmental Entity in
connection with this Agreement or the Acquisitions, including the Allied Proxy
Statement, and none of such information shall, at the date furnished, contain
any untrue statement of a material fact or omit to state any material fact
necessary in order to make the statements made therein, in light of the
circumstances under which they were made, not misleading.  The Laidlaw Parties
shall prior to the Mailing Date promptly inform Allied on becoming aware that
any information concerning any of the Acquired Subsidiaries furnished to Allied
pursuant to this Section 6.3 contains any such material misstatement or
omission.

         6.4     Supplemental Information.  (a)  As soon as practicable after
the date of this Agreement and in no event later than October 1, 1996, the
Laidlaw Sellers shall furnish to Allied an unaudited separate balance sheet
(prepared on a company only basis) of each Acquired Subsidiary at August 31,
1995, and the related unaudited separate statements of operations and
stockholder's equity (similarly prepared) for each Acquired Subsidiary for the
year then ended (the "SWM Group Separate Company Financial Statements").  The
SWM Group Separate Company Financial Statements will be prepared in accordance
with U.S. GAAP, except for compliance with SFAS 109 and the omission of
explanatory footnote disclosures.

         (b) The Laidlaw Parties shall furnish to Allied copies of interim
monthly financial statements for the Acquired Subsidiaries (prepared using the
format customarily used by Laidlaw for such internal reports and, no less
frequently than each fiscal quarter, prepared for the Acquired Subsidiaries for
such fiscal quarter on a combined basis) as soon as practicable but in any
event within 35 days after the end of each month or quarter, as the case may
be, together with any information ordinarily prepared in connection with such
financial statements.  All such interim financial statements shall fairly
present in all material respects in accordance with such accounting principles
the separate company, combined or consolidated, as the case may be, financial
position of the respective Acquired Subsidiaries or groups of Acquired
Subsidiaries covered thereby at the respective dates thereof, and the results
of their separate company or consolidated, as the case may be, operations,
stockholders' equity and cash flows for the respective Acquired Subsidiaries or
groups of Acquired Subsidiaries covered thereby for the respective periods
covered thereby, subject to year-





                                      -45-
<PAGE>   54
end adjustments (consisting of normal recurring accruals) and the omission of
explanatory footnote materials required by U.S. GAAP and Canadian GAAP.

         6.5     Audit of Financial Statements.  The Laidlaw Parties shall
cause Coopers & Lybrand to conduct an audit of the Acquired Subsidiaries on a
combined basis and to issue their unqualified report thereon, which audit will
include combined balance sheets at August 31, 1995 and August 31, 1996, and the
related combined statements of operations, stockholder's equity and cash flows
for the years ended August 31, 1994, 1995 and 1996 ("SWM Group Audited Combined
Financial Statements").  The Laidlaw Parties shall deliver the SWM Group
Audited Combined Financial Statements, together with the unqualified report
thereon by Coopers & Lybrand, to the Allied Parties as soon as practicable
after the date of this Agreement and in no event later than October 1, 1996.
The SWM Group Audited Combined Financial Statements shall be prepared in
accordance with U.S. GAAP and the rules of the SEC relating to the preparation
of financial statements.  The Laidlaw Parties shall cause Coopers & Lybrand to
consent to the inclusion of the SWM Group udited Combined Financial statements
in any proxy statement, registration statement or other SEC filings of Allied
or any subsidiary of Allied.

         6.6     Access for Environmental Report.  The Laidlaw Parties shall
cause the Acquired Subsidiaries to give to Emcon Environmental Services, Inc.
("Emcon"), independent environmental consultants engaged by and at the expense
of the Allied Parties, full access to the facilities, personnel and records of
the Acquired Subsidiaries as such consultants shall reasonably request
(including for physical inspection of sites and the drilling of wells and the
conducting of soil borings and other Phase II investigatory techniques) in
order to conduct Phase I and II environmental assessments of each parcel of
real property owned, or under the management or control of, or operated, leased
or occupied by, an Acquired Subsidiary, and to prepare a report reflecting the
findings and recommendations of such consultants concerning such Phase I and
Phase II environmental assessments (the "Emcon Environmental Report").  The
Laidlaw Parties shall use their best efforts to ensure that all information
provided to Emcon in the course of its conduct of such environmental
assessments is accurate, complete and not misleading (including by omissions).
The Laidlaw Parties will provide, and will cause the Acquired Subsidiaries to
provide, upon written request therefor, all consents, approvals and directions
(and waivers of privacy, freedom of information and similar Laws) so as to
permit such consultants to have prompt and unrestricted access to all relevant
information in the possession or under the control of Governmental Entities.

         6.7     Confidentiality.  All information and data furnished by the
Allied Parties to the Laidlaw Sellers under Section 7.3 or any other provision
of this Agreement shall be received, held, treated and, if applicable, returned
to the Allied Parties, in accordance and compliance with the Confidentiality
Agreement.





                                      -46-
<PAGE>   55
         6.8     Consummation of Acquisitions.  The Laidlaw Parties shall use
their best efforts to perform and fulfill, and shall use their best efforts to
cause the Laidlaw Sellers and the Acquired Subsidiaries to perform and fulfill,
all conditions and obligations on their part to be performed and fulfilled
under this agreement, to the end that the Acquisitions shall be consummated.


                                  ARTICLE VII

                        ALLIED COVENANTS PENDING CLOSING

         The Allied Parties agree that pending the Closing, without the prior
written consent of Laidlaw:

         7.1     Conduct of Allied's Business. Allied and its Subsidiaries
shall conduct their operations according to their ordinary and usual course of
business, and shall use their best efforts to preserve intact their business
organization, keep available the services of their officers and employees and
maintain normal business relationships with customers, suppliers and others
having business relationships with it.  The Allied Parties shall confer on a
regular and frequent basis with one or more designated representatives of
Laidlaw to report on operational matters of materiality and to report the
general status of on-going operations of Allied.  The Allied Parties shall
notify Laidlaw of:

                 (i)      any unexpected material emergency or other material
         change in the normal course of business or in the operation of the
         properties of Allied and its Subsidiaries;

                 (ii)     the instigation of or any significant development in
         any regulatory proceedings, governmental complaints, investigations or
         hearings (or communication indicating that any may be contemplated)
         involving Allied and its Subsidiaries, which instigation or
         development could have a Material Adverse Effect on Allied and its
         Subsidiaries;

                 (iii)    material acquisitions and dispositions of assets; and

                 (iv)     any matter or event which comes to the knowledge of
         the Allied Parties and which makes or could make any representation
         and warranty made by the Allied Parties in Article V untrue or
         inaccurate.

         The Allied Parties shall keep Laidlaw fully informed of such events
and permit Laidlaw's representatives access to all materials prepared in
connection with such events.





                                      -47-
<PAGE>   56
         7.2     Forbearance by Allied.  Allied shall not:

                 (i)      amend or propose to amend its Certificate of
         Incorporation (except to increase the number of shares of Allied
         Common Stock it is authorized to issue) or bylaws;

                 (ii)     issue any shares of Allied Common Stock or securities
         convertible into or exchangeable for shares of Allied Common Stock, or
         enter into any agreement or commitment with respect to the issuance or
         purchase of any such shares or securities, except that Allied may (x)
         issue shares of Allied Common Stock upon any exercise of any presently
         outstanding warrants or any conversion of any presently outstanding
         shares of convertible Allied Preferred Stock or any presently
         outstanding convertible indebtedness of Allied which are, in each such
         case, described in the Allied SEC Filings, (y) issue employee and
         director stock options under presently existing director and employee
         stock option plans and shares of Allied Common Stock issuable upon any
         exercise of any options granted under any such plan, and (z) issuances
         of not more than an aggregate of five million shares of Allied Common
         Stock in connection with future acquisitions of other business
         enterprises inclusive of those acquisitions set forth on Section 5.10
         of the Allied Disclosure Schedule;

                 (iii)    split, combine or reclassify any outstanding shares
         of Allied Common Stock; or

                 (iv)     declare, pay or set aside for payment any dividend or
         other distribution in respect of any outstanding shares of Allied
         Common Stock.

         7.3     Access and Information.  Allied shall give the Laidlaw Sellers
and their representatives full access during normal business hours to all the
properties, books, contracts, commitments and records of Allied and its
Subsidiaries so that the Laidlaw Sellers may have full opportunity to make such
investigation of Allied and its Subsidiaries as they shall reasonably request
in advance.  Allied will furnish each Laidlaw Seller all information concerning
Allied and its Subsidiaries required for inclusion in any application, filing,
statement or notice made by any Laidlaw Party to, or filed or joined in by any
Laidlaw Party with, any Governmental Entity in connection with this Agreement
or the Acquisitions, and none of such information shall, at the date furnished,
contain any untrue statement of a material fact or omit to state any material
fact necessary in order to make the statements made therein, in light of the
circumstances under which they were made, not misleading.

         7.4     Supplemental Information.  Allied shall, within five days
following each such filing, furnish Laidlaw with a copy of each Current Report
on Form 8-K, each Quarterly Report on Form 10-Q and each Annual Report on Form
10-K filed by Allied





                                      -48-
<PAGE>   57
with the SEC.  Allied shall also furnish Laidlaw copies of Allied's interim
monthly consolidated financial statements as soon as practicable but in any
event within 35 days after the end of each month, together with any information
ordinarily prepared in connection with such financial statements.  All
financial statements included in each such Quarterly Report on Form 10-Q and
Annual Report on Form 10-K shall be prepared in conformity with U.S. GAAP,
shall present fairly in all material respects, in accordance with U.S. GAAP,
the consolidated financial position of Allied and its Subsidiaries at the end
of the periods covered thereby and the results of their consolidated operations
for the periods covered thereby, subject, in the case of unaudited interim
financial statements, to year-end adjustments (consisting of normal recurring
accruals) and the omission of  explanatory footnote materials required by U.S.
GAAP.

         7.5     Allied Stockholders' Meeting. Allied shall call a special
meeting of the holders of Allied Common Stock to be held to vote to approve the
issuance of the Allied Common Shares, the Additional Allied Common Shares, the
Allied Warrant, and the Warrant Shares, and to approve the authorization of
additional shares of authorized Allied Common Stock.  Allied will use its best
efforts to hold the Allied Stockholders' Meeting no later than 40 days
following the date of mailing of the definitive proxy statement to be furnished
to its stockholders in connection with such meeting (the "Allied Proxy
Statement").  Subject to fiduciary duties under applicable Law, Allied will
recommend approval of the matters referred to above, and agrees to use its best
efforts to obtain a favorable vote thereon.  In connection with the Allied
Stockholders' Meeting, Allied shall prepare and file with the SEC, as soon as
practicable following the delivery to Allied of the SWM Group Audited
Consolidated Financial Statements, a preliminary copy of the Allied Proxy
Statement.  As soon as practicable thereafter, Allied will cause to be mailed
to each holder of Allied Common Stock a copy of the Allied Proxy Statement
complying in all material respects with the Exchange Act.  All information
concerning Allied or any of its Subsidiaries included in the Allied Proxy
Statement will be, on the date of commencement of the mailing of the Allied
Proxy Statement (the "Mailing Date"), true and correct in all material respects
without omission of any material fact required to be stated to make the
information set forth therein not misleading.

         7.6     Emcon Environmental Report.  The Allied Parties shall use
their best efforts to cause the Emcon Environmental Report to be prepared as
soon as practicable after the date of this Agreement, and the Allied Parties,
promptly upon their receipt of such Report, shall deliver a copy of the Report
to the Laidlaw Parties.

         7.7     Confidentiality.  All information and data furnished by the
Laidlaw Sellers to the Allied Parties under Section 6.3 or any other provision
of this Agreement shall be received, held, treated and, if applicable, returned
to the Laidlaw Sellers, in accordance and compliance with the Confidentiality
Agreement.





                                      -49-
<PAGE>   58
         7.8     Consummation of Acquisitions.  The Allied Parties shall use
their best efforts to perform and fulfill, and shall use its best efforts to
cause the Allied Parties to perform and fulfill, all conditions and obligations
on their part to be performed and fulfilled under this Agreement, to the end
that the Acquisitions shall be consummated.


                                  ARTICLE VIII

                               MUTUAL CONDITIONS

         The respective obligations of all Parties to consummate the
Acquisitions and to take the other actions called for under Articles II and III
are subject to the fulfillment of each of the following conditions on or before
the Closing Date:

         8.1     No Adverse Proceedings.  No order entered or Law promulgated
or enacted by any Governmental Entity shall be in effect which would prevent
consummation of the Acquisitions, and no proceeding brought by a Governmental
Entity or any other Person shall have been commenced and be pending which seeks
to restrain, enjoin, prevent or materially delay or restructure any
Acquisition.

         8.2     HSR Waiting Period.  The waiting period under the HSR Act
shall have expired or otherwise been terminated.

         8.3     Allied Stockholder Approval.  The matters to be submitted to
the stockholders as set forth in Section 7.5 of this Agreement shall have been
approved by the requisite vote of the holders of Allied Common Stock.

         8.4     Competition Act Matters.  Either (i) the Competition Act
Director shall have issued an Advance Ruling Certificate in respect of the
Acquisitions and shall not have subsequently withdrawn the Advance Ruling
Certificate or indicated that he has obtained new information as result of
which the Competition Act Director is no longer satisfied that he would not
have sufficient grounds on which to make an application under Section 92 of the
Competition Act with respect to the Acquisitions, or (ii) the applicable time
period under Section 123 of the Competition Act shall have expired.


                                   ARTICLE IX

                  CONDITIONS TO OBLIGATIONS OF ALLIED PARTIES

         The respective obligations of the Allied Parties to consummate the
Acquisitions and to take the other actions called for under Articles II and III
are subject to the fulfillment of each of the following conditions on or before
the Closing Date:





                                      -50-
<PAGE>   59
         9.1     Representations True at Closing.  (a)  The Laidlaw Parties
shall have performed and complied in all material respects with all obligations
and agreements required to be performed or complied with by them under this
Agreement at or prior to the Closing, and the representations and warranties of
the Laidlaw Sellers contained in this Agreement (other than those set forth in
Section 4.15) shall be true and correct when made and at and as of the Closing
as if made at and as of such date and time, except to the extent that any
breaches of such representations and warranties (such breaches being determined
individually or in the aggregate and as if references to "Material Adverse
Effect", "in all material respects" and "knowledge of the Laidlaw Sellers" were
deleted in their entirety and the effect of any such references were eliminated
altogether) could not result in Damages in excess of $25,000,000; and the
Allied Parties shall have received certificates, each dated the Closing Date,
of the President or a Vice President of  each of the Laidlaw Sellers, to the
effect set forth in this Section 9.1(a).

                 (b)  The representations and warranties of the Laidlaw Sellers
contained in Section 4.15 hereof shall be true and correct as of the Closing,
except to the extent that any breaches of such representations and warranties
(such breaches being determined individually or in the aggregate and as if
references to "Material Adverse Effect", "in all material respects", and
"Knowledge of the Laidlaw Sellers" were deleted in their entirety and the
effect of any such references were eliminated altogether), in the judgment of
the Allied Parties, acting reasonably in accordance with Section 11.10, could
not result in Damages (y) in the aggregate in excess of $6,000,000 or (z)
during the first two years following the Closing Date in excess of the amounts
to be expended during those years as calculated in determining the liabilities
and reserves referred to in Section 4.15(vii); and the Allied Parties shall
have received certificates, each dated the Closing Date, of the President or a
Vice President of each of the Laidlaw Sellers, to the effect of this Section
9.1(b); provided, however, that if the Laidlaw Sellers shall have timely made
the election to pay or provide an acceptable undertaking as provided for in
Section 11.10 and performed their obligations in compliance with Section 11.10,
then the condition stated in this Section 9.1(b) shall be deemed to be
satisfied.  For the purposes of this Section 9.1(b), calculation of Damages
with respect to periods after the first two years after the Closing Date shall
be made on a discounted basis calculated on the same basis as amounts are
discounted in connection with the calculation of the liabilities and reserves
referred to in Section 4.15(vii).

         9.2     No Adverse Changes.  Since the date of this Agreement, no
event or series of events taken in the aggregate shall have occurred which
could have a Material Adverse Effect on the Acquired Subsidiaries or the
Laidlaw Sellers.

         9.3     Opinion of Laidlaw U.S. Counsel.  The Allied Parties shall
have received an opinion, dated the Closing Date, of Katten Muchin & Zavis,
U.S. counsel to the Laidlaw Sellers, in the form attached as Exhibit I to this
Agreement.





                                      -51-
<PAGE>   60
         9.4     Opinion of Laidlaw Canadian Counsel.  The Allied Parties shall
have received an opinion, dated the Closing Date, of Ivan Cairns, Senior Vice
President and General Counsel of Laidlaw,  to the effect set forth in Exhibit J
attached to this Agreement.

         9.5     Investment Canada Act.  The Allied Parties shall have received
from the ICA Minister a notice, satisfactory in form and substance to the
Allied Parties, under subsection 21(1) of the Investment Canada Act, stating
that the Acquisitions are likely to be of net benefit to Canada, or the ICA
Minister shall have been deemed, under Section 21(2) of the Investment Canada
Act, to be satisfied that the Acquisitions are likely to be of net benefit to
Canada and the Allied Parties shall have received a notice from the ICA
Minister to that effect.

         9.6     Competition Act Matters.  Either (i) the Competition Act
Director shall have issued an Advance Ruling Certificate in respect of the
Acquisitions and shall not have subsequently withdrawn the Advance Ruling
Certificate or indicated that he has obtained new information as a result of
which the Competition Act Director is no longer satisfied that he would not
have sufficient grounds on which to make an application under Section 92 of the
Competition Act in respect of the Acquisitions, or (ii) the Competition Act
Director or his representative shall have advised the Allied Parties (on terms
and in form satisfactory to them) that the Competition Act Director does not
currently intend to make an application under Section 92 of the Competition Act
in respect of the Acquisitions, and such advice shall not have been amended or
rescinded.

         9.7     Audited Financial Statements.  The Allied Parties shall have
received the SWM Group Audited Combined Financial Statements (and related
footnotes) and the report thereon by Coopers & Lybrand, which report shall have
been unqualified.

         9.8     Emcon Environmental Report.  The Allied Parties shall have
received the Emcon Environmental Report.

         9.9     Acquisitions Financing.  The Allied Parties shall have
received the proceeds of the financings contemplated in the Commitment Letter
and the Highly Confident Letter, or proceeds from other financing with respect
to the Acquisitions which are satisfactory to the Allied Parties, in an
aggregate amount of at least $1,700,000,000.

         9.10    Outstanding Indebtedness.  The Indebtedness of the Acquired
Subsidiaries, in the aggregate, will not exceed $4,900,000, excluding the
Laidlaw Guaranties and guaranties of purchase money indebtedness of owner
operators not to exceed C$8,600,000.





                                      -52-
<PAGE>   61
                                   ARTICLE X

                      CONDITIONS TO LAIDLAW'S OBLIGATIONS

         The respective obligations of the Laidlaw Parties to consummate the
Acquisitions and to take the other actions called for under Articles II and III
are subject to the fulfillment of each of the following conditions on or before
the Closing Date:

         10.1    Representations True at Closing. The Allied Parties shall have
performed and complied in all material respects with all obligations and
agreements required to be performed or complied with by them under this
Agreement at or prior to the Closing and the representations and warranties of
the Allied Parties contained in this Agreement shall be true and correct when
made and at and as of the Closing as if made at and as of such date and time,
except to the extent that any breaches of such representations and warranties
(such breaches being determined individually or in the aggregate, and as if
references to "Material Adverse Effect", and "knowledge of the Allied Parties"
were deleted in their entirety and the effect of any such references were
eliminated altogether) could not result in Damages in excess of $25,000,000 and
the Laidlaw Sellers shall have received certificates, each dated the Closing
Date, of the President or Vice President of each of the Allied Parties, to the
effects set forth in this Section 10.1.

         10.2    No Adverse Changes.  Since the date of this Agreement, no
event or series of events taken in the aggregate shall have occurred which
could have a Material Adverse Effect on Allied and its Subsidiaries.

         10.3    Opinion of Allied's U.S. Counsel.  The Laidlaw Sellers shall
have received an opinion, dated the Closing Date, of Porter & Hedges, L.L.P.,
U.S. counsel to the Allied Parties, in the form attached as Exhibit K to this
Agreement.

         10.4    Opinion of Allied's Canadian Counsel.  The Laidlaw Parties
shall have received an opinion, dated the Closing Date, of Davies, Ward & Beck,
Canadian solicitors for the Allied Parties, to the effects set forth in Exhibit
L attached to this Agreement.


                                   ARTICLE XI

                             ADDITIONAL AGREEMENTS

         11.1    HSR Act Filings.  Within 10 Business Days after the date of
this Agreement, Laidlaw and Allied shall file notification and report forms
under the HSR Act with the FTC and the Antitrust Division, and shall use their
best efforts to respond





                                      -53-
<PAGE>   62
as promptly as practicable to all requests received from the FTC or the
Antitrust Division for additional information or documentation.

         11.2    Competition Act Filings.  The Allied Parties and the Laidlaw
Sellers agree to file with the Competition Act Director, within 10 Business
Days after the date of this Agreement, the information set out in Section 121
of the Competition Act, certified in accordance with Section 118 of the
Competition Act.  If the Competition Act Director, before the expiration of
seven days after the date of filing of such information, requires the
information set out in Section 122 of the Competition Act, the Allied Parties
and the Laidlaw Sellers shall file the required information with the
Competition Act Director within 10 Business Days after the date the information
is required by him.  The Allied Parties shall prepare and file with the
Competition Act Director, and the Laidlaw Sellers shall cooperate with the
Allied Parties in their preparation and filing of, an Advance Ruling
Certificate in respect to the Acquisitions, and all Parties will provide to the
Competition Act Director all information requested by him in connection with
the Advance Ruling Certificate application.

         11.3    Investment Canada Act Filings.  The Allied Parties agree to
prepare and file with the ICA Minister, within 10 Business Days after the date
of this Agreement, an application for review under the Investment Canada Act in
connection with the Acquisitions, and the Laidlaw Sellers agree to cooperate
with the Allied Parties in connection with such application.

         11.4    Other Consents and Approvals.  All Parties shall use their
best efforts to obtain before the Closing, in addition to the approvals and
consents referred to in Section 8.2, 8.3, 8.4, 9.5, and 9.6, and all other
consents and approvals listed and disclosed in Section 4.4 of the Laidlaw
Disclosure Schedule, Section 4.19 of the Laidlaw Disclosure Schedule or Section
5.5 of the Allied Disclosure Schedule; provided, however, that nothing in this
Section 11.4 or Sections 11.1, 11.2, or 11.3 shall require any Allied Party or
any Acquired Subsidiary to (i) dispose of or to hold separately all or any
material portion of the assets, properties or businesses of the Acquired
Subsidiaries or the assets, properties or business of Allied and its
Subsidiaries or agree to the imposition of any material limitation on the
ability of Allied and its Subsidiaries after the Closing (including the
Acquired Subsidiaries) to conduct their business and own their assets and
properties after the Closing in substantially the same manner as before the
Closing, or (ii) in the case of Section 11.3 and the application referred to
therein, make any undertaking relating to any Acquired Canadian Subsidiary or
its assets, properties, business, operations, employees or practices, which in
the reasonable judgment of the Allied Parties, would or could have, after the
Closing, a Material Adverse Effect on the Acquired Subsidiaries.

         11.5    Publicity.  No Party other than Allied or Laidlaw shall issue
any press release or public announcement pertaining to the Acquisitions.
Allied and Laidlaw shall





                                      -54-
<PAGE>   63
consult with each other concerning any such press release or public
announcement and shall use their best efforts to agree on its text before its
public dissemination and before making any filings with any Governmental Entity
or national securities exchange with respect to any such press release or
public announcement.  In cases where Allied and Laidlaw are unable to agree on
a press release or public announcement, the Party proposing it will not issue
or make it unless the proposing Party is required to do so by Law, in which
case the Party so obligated shall use its reasonable efforts to provide a copy
of the press release or public announcement to the other Party before its
filing or public dissemination.

         11.6    Expenses.  Except as otherwise provided in Section 2.4 or
Article XII, each Party shall pay its own costs and expenses incurred in
connection with the Acquisitions, whether or not the Acquisitions are
consummated.  No such costs or expenses shall be paid by or charged to any
Acquired Subsidiary.

         11.7    Securities Law Matters.  The Laidlaw Parties represent and
warrant to the Allied Parties that the Allied Securities to be issued to the
Laidlaw Parties under this Agreement are being acquired, and any Allied Warrant
Shares issued upon any exercise of the Allied Warrant, Allied Common Stock
issued pursuant to the Laidlaw Subscription Agreement or Additional Allied
Common Shares will be acquired, by the Laidlaw Parties for investment, for
their own account and not with a view to, or for resale in connection with, any
distribution of Allied Securities within the meaning of the Securities Act.  No
Allied Securities may be sold, transferred, or otherwise disposed of without
registration under the Securities Act and any applicable state or provincial
securities laws, rules, regulations or policies.  Notwithstanding such
representations, and subject to the provisions of this Agreement and the terms
of such securities, the Allied Parties agree to permit a sale or transfer of
such securities if Allied obtains satisfactory assurances that the sale or
transfer may be made without registration under the Securities Act and related
rules and regulations (and all applicable state or provincial securities laws,
rules, regulations or policies) including, without limitation receipt by the
Allied of an opinion to such effect from counsel reasonably satisfactory to
Allied, or compliance by the Laidlaw Parties with the requirements Rule 144(k)
or Rule 144A under the Securities Act.

         Laidlaw agrees that all Allied Canada Debentures and all Allied
Finance Debentures may be inscribed with the respective legends set forth on
the respective forms thereof attached as Exhibits to this Agreement, that the
Allied Warrant may be inscribed with the legend set forth on the form of Allied
Warrant attached as an Exhibit to this Agreement, and that all certificates
evidencing Additional Allied Common Shares, Allied Common Shares and all Allied
Warrant Shares, but only if required under the Securities Act and applicable
state or provincial securities laws at the time of their issuance, will be
inscribed with the following restrictive legend:





                                      -55-
<PAGE>   64
                            "The  shares  represented by  this  certificate
                            have not been registered  (or qualified  by
                            prospectus)  under the United States Securities Act
                            of 1933, as amended, or the securities laws of any
                            state of the United States or any province  of
                            Canada.   Such shares  may not  be offered, sold,
                            transferred,  pledged, hypothecated  or  otherwise
                            disposed  of  in  the  absence  of  such  a
                            registration thereunder other than  pursuant to an
                            exemption from such registration or  prospectus
                            requirements and delivery  to Allied  Waste
                            Industries, Inc.  of an  opinion of counsel
                            reasonably satisfactory  to it  to the  effect that
                            such transfer is exempt from registration under
                            those laws."

         11.8    Rule 144 Reports.  For as long as the Laidlaw Parties or any
Affiliate of Laidlaw owns shares of Allied Common Stock or the Allied Warrant
representing at least 10% of total number of shares of Allied Common Stock
issued and outstanding from time to time, Allied will

                 (i)      make and keep "current public information"
         "available" (as both those terms are defined in Rule 144) at all
         times;

                 (ii)     timely file with the SEC in accordance with all
         applicable rules and regulations, all reports and other documents (x)
         required of Allied for Rule 144, as it may be amended from time to
         time (or any rule, regulation, or statute replacing Rule 144) to be
         available and (y) required to be filed under Section 15d of the
         Exchange Act even if Allied's duty to file those reports or documents
         is suspended or otherwise terminated under the terms of Section 15d;
         and

                 (iii)    furnish the Laidlaw Parties a written statement by
         Allied that it has complied with the reporting requirements of the
         Exchange Act and Rule 144, together with a copy of the most recent
         annual or quarterly report of Allied and such reports and documents
         filed by Allied with the SEC as may reasonably be requested by the
         Laidlaw Parties.

         11.9    Use of Laidlaw Name.  As soon as practicable, and in any event
within 90 days after the Closing Date, the Allied Parties shall cause to be
amended the Articles or Certificate of Incorporation or Organization (or
comparable document) of each Acquired Subsidiary which has the name "Laidlaw"
in its corporate name, to remove the name "Laidlaw" from its corporate name.
As soon as practicable, and in any event within two years after the Closing
Date, the Allied Parties shall cause the name





                                      -56-
<PAGE>   65
"Laidlaw" to be removed from (i) all advertising and marketing materials used
by the Acquired Subsidiaries, (ii) all stationery, purchase orders and other
business forms used by the Acquired Subsidiaries, (iii) all motor vehicles
owned or operated by the Acquired Subsidiaries, (iv) all signs at any location
owned or operated by any Acquired Subsidiary, and (iv) all bank accounts
maintained by any Acquired Subsidiary.  From and after the second anniversary
of the Closing Date, no Allied Party will, or will cause or permit any Acquired
Subsidiary or any other Subsidiary or Affiliate of any Allied Party to, use or
employ any name, trade name, assumed name, slogan, logo, trademark or
advertising or marketing materials which contain the name "Laidlaw;" provided
however, that nothing in this Section 11.09 shall require any amendment to or
reissuance of any contract or agreement to which any Acquired Subsidiary is a
party or any permit, license, franchise or other authorization issued to any
Acquired Subsidiary, before the expiration of its current term.  For as long
during the respective 90-day and two-year periods specified above in this
Section 11.09 as the Allied Parties are diligently pursuing their obligations
under this Section 11.09, the Laidlaw Parties grant (i) to those Acquired
Subsidiaries which now have in their corporate names the "Laidlaw" the right to
continue using their corporate names, logos and trademarks, and (ii) to all
Acquired Subsidiaries the right to use the name "Laidlaw" in all of the other
applications described above in this Section 11.09.

         11.10   Environmental Remediation.  Within twenty Business Days after
their receipt of the Emcon Environmental Report, the Allied Parties shall
deliver to the Laidlaw Parties a written notice (the "Environmental Notice")
stating whether in the judgment of the Allied Parties, acting reasonably, one
or more conditions described in the Emcon Environmental Report (each an
"Environmental Defect") constitutes a breach of the representations and
warranties made by the Laidlaw Parties in Section 4.15 to the extent that the
condition to the obligations of Allied to close set forth in Section 9.1(b)
will not be met.  If the Environmental Notice states that such condition in
Section 9.1(b) will not be met, then Laidlaw may elect at the Closing pay to
Allied an amount (which is based on the Emcon Environmental Report and is
reasonably acceptable to Allied) sufficient to cure the Environmental Defect,
or provide Allied with an undertaking satisfactory to Allied that Laidlaw will
assume and pay as it becomes due all amounts relating to the Environmental
Defect, in which event the condition in Section 9.1(b) will be met.

         11.11   Laidlaw Guaranties.  The Allied Parties and those Acquired
Subsidiaries which are Laidlaw Parties agree to use all commercially reasonable
efforts, and to cause all other Acquired Subsidiaries to use all commercially
reasonable efforts, to cause each member of the Laidlaw Group to be fully and
finally released and discharged from all further liability or obligation in
respect of all Laidlaw Guaranties in respect of which such member of the
Laidlaw Group is an obligated party, within six months following the Closing
Date.  To that end, the Allied Parties and those Acquired Subsidiaries which
are Laidlaw Parties agree to use all commercially reasonable efforts to:





                                      -57-
<PAGE>   66
                 (i)      cause all liabilities and obligations of each
         Acquired Subsidiary which are guaranteed or secured by a Laidlaw
         Guaranty to be fully and faithfully performed on a timely basis and in
         accordance with their terms;

                 (ii)     secure the surrender of and the return to each
         Laidlaw Issuer Bank of each letter of credit which is a Laidlaw
         Guaranty which is outstanding at the Closing Date, without draw
         thereon by any beneficiary thereof;

                 (iii)    secure the cancellation and return to Laidlaw or to
         the issuer thereof, as appropriate, without payment thereunder, of all
         Laidlaw Guaranties which are performance, suretyship or other bonds;
         and

                 (iv)     cause to be delivered to the respective members of
         the Laidlaw Group written releases, duly executed by all necessary
         releasing parties, evidencing the full and final release of each
         member of the Laidlaw Group liable thereon or thereunder, from all
         liabilities and obligations under each Laidlaw Guaranty which is a
         guaranty or other direct undertaking or commitment on the part of such
         member of the Laidlaw Group.

         For purposes of this Section 11.12, "all commercially reasonable
efforts" on the part of any Allied Party includes:

                 (i)      the offering of a substitution of a like guaranty of
         Allied for any Laidlaw Guaranty which is a guaranty of Laidlaw; and

                 (ii)     the offering to the beneficiary or beneficiaries of
         any letter of credit which is a Laidlaw Guaranty a substitute letter
         of credit having an expiry date no earlier than the expiry date of
         such Laidlaw Guaranty and issued by a bank having credit ratings by
         each of Standard & Poors Rating Group and Moody's Investor Service,
         Inc. which are at least as high as the credit ratings given by such
         credit rating organizations for the Laidlaw Issuer Bank which is the
         issuer of such Laidlaw Guaranty.

         If at the end of six months following the Closing Date any Laidlaw
Guaranty remains outstanding, then no later than the fifth Business Day
following the expiration of such six-month period, the Allied Parties shall
cause to be delivered to Laidlaw a letter of credit which shall:

                 (i)      name Laidlaw as the beneficiary thereof;





                                      -58-
<PAGE>   67
                 (ii)     be in an amount at least equal to the aggregate
         outstanding and undrawn balances of all such outstanding Laidlaw
         Guaranties;

                 (iii)    be issued by a bank having credit ratings by each of
         Standard & Poors Rating Group and Moody's Investor Service, Inc. which
         are at least as high as the credit ratings given by such credit rating
         organizations for the Laidlaw Issuer Banks;

                 (iv)     have an expiry date no earlier than the expiry date
         of the last to expire of the Laidlaw Guaranties; provided, however,
         that if the letter of credit to be obtained by the Allied Parties for
         the benefit of Laidlaw pursuant hereto is to be issued with respect to
         more than one Laidlaw Guaranty, the amount of such letter of credit
         will reduce automatically and without any action by any party upon the
         expiring date of each Laidlaw Guaranty by the amount thereof or upon
         the acceptance by the beneficiary of such Laidlaw Guaranty of a
         substitute letter of credit provided by the Allied Parties; and

                 (v)      be payable at sight to Laidlaw upon presentation of a
         written, sworn affidavit of an officer of Laidlaw stating that the
         Laidlaw Reclamation Credit issued by such Laidlaw Issuer Bank has been
         drawn upon by the beneficiary thereof in an amount not less than the
         draw being made by Laidlaw on such letter of credit.

         11.12   Laidlaw Board Representation.  Promptly after the Closing,
Allied shall increase the size of its Board of Directors to enable James R.
Bullock and Ivan Cairns, or two other individuals who are officers of Laidlaw
designated by Laidlaw and reasonably acceptable to Allied, to be appointed to
Allied's Board of Directors.  Until the earliest to occur of (i) the fifth
anniversary of the Closing Date or (ii) the first date when the number of
Allied Common Shares held by the Laidlaw Parties and all other Affiliates of
Laidlaw represents less than ten percent of the number of shares of Allied
voting securities then issued and outstanding, Allied shall, subject to
fiduciary obligations under applicable Law, use its best efforts to cause such
two designees of Laidlaw to be nominated for election to Allied's Board of
Directors by the stockholders of Allied.  Upon the occurrence of either event
specified in clauses (i) and (ii) set forth in the preceding sentence, the
designees of Laidlaw to Allied's Board of Directors shall immediately resign
from the Board of Directors.

         11.13   Attendance at Stockholder Meetings.  Until the earlier to
occur of the fifth anniversary of the Closing Date or the date on which the
Laidlaw Sellers and all of their Affiliates collectively beneficially own a
number of shares of Allied voting securities which would represent less than
ten percent of the then issued and outstanding voting securities of Allied
voting securities, the Laidlaw Sellers agree to cause all shares of Allied
voting securities from time to time owned of record or





                                      -59-
<PAGE>   68
beneficially by either of them or any of their Affiliates to be  present at all
stockholders meetings of Allied at which the vote of Allied's stockholders is
sought so that they may be counted for the purpose of determining the presence
of a quorum at such meetings.

         11.14   Laidlaw Standstill.  Until the earlier to occur of the fifth
anniversary of the Closing Date or the date on which the Laidlaw Sellers and
all of their Affiliates collectively own a number of shares of Allied Common
Stock which would represent less than five percent of the then issued and
outstanding voting securities of Allied, neither Laidlaw Seller will, and the
Laidlaw Sellers will cause each of its Affiliates not to:

                 (i)      acquire, offer to acquire, or agree to acquire,
         directly or indirectly, by purchase or otherwise, any voting
         securities or voting rights or direct or indirect rights or options to
         acquire any voting securities of Allied or any of its Affiliates other
         than as a result of a stock split, stock dividend or similar
         recapitalization except the Allied Securities;

                 (ii)     make or cause to be made any proposal for an Allied
         Reorganization Transaction, except (x) as expressly contemplated in
         this Agreement, or (y) proposals pursuant to customary business
         transactions in the ordinary course of Allied's business;

                 (iii)    form, join or in any way participate in a "group"
         (within the meaning of Section 13(d)(3) of the Exchange Act) with
         respect to any securities of Allied or its Affiliates;

                 (iv)     make, or in any way cause or participate in, any
         "solicitation" of "proxies" to vote (as those terms are defined in
         Regulation 14A under the Exchange Act) with respect to Allied or its
         Affiliates, or communicate with, seek to advise, encourage or
         influence any Person, in any manner, with respect to the voting of,
         securities of Allied or its Affiliates, or become a "participant" in
         any "election contest" (as those terms are defined or used in Rule
         14a-11 under the Exchange Act) with respect to Allied or its
         Affiliates;

                 (v)      initiate, propose or otherwise solicit stockholders
         for the approval of one or more stockholder proposals with respect to
         Allied or its Affiliates or induce or attempt to induce any other
         Person to initiate any stockholder proposal, or seek election to or
         seek to place a representative on the Board of Directors of Allied or
         its Affiliates or seek the removal of any member of the Board of
         Directors of Allied or its Affiliates;

                 (vi)     in any manner, agree, attempt, seek or propose (or
         make any request for permission with respect thereto) to deposit any
         securities of Allied





                                      -60-
<PAGE>   69
         or its Affiliates, directly or indirectly, in any voting trust or
         similar arrangement or to subject any securities of Allied or its
         Affiliates to any other voting or proxy agreement, arrangement or
         understanding;

                 (vii)    directly or indirectly offer, sell or transfer any
         Allied Common Stock or rights to receive Allied Common Stock
         (including without limitation the Allied Common Shares, the Allied
         Warrant Shares, Additional Allied Common Shares and any Allied Common
         Stock, or rights to receive Allied Common Stock, pursuant to the
         Laidlaw Subscription Agreement) except for (v) sales made in
         compliance with the Stock Registration Agreement, (w) sales made in
         compliance with Rule 144 under the Securities Act as in effect on the
         Closing Date, (x) distributions or dividends of Allied Common Stock to
         the shareholders of Laidlaw on a pro rata basis to all shares of all
         classes of Laidlaw's then outstanding capital stock, (y) sales to a
         Person in a private transaction if, following such sale, such Person
         and its Affiliates will beneficially own (used herein as defined in
         Rule 13d-3 under the Exchange Act) 9% or less of the total number of
         shares of Allied Common Stock then outstanding, and (z) sales to a
         Person who makes an Allied Reorganization Transaction on the terms and
         conditions of such Reorganization Transaction;

                 (viii)   directly or indirectly offer, sell or transfer the
         Allied Warrant except in compliance with the terms of Section 3.1 of
         the Allied Warrant;

                 (ix)     disclose any intention, plan or arrangement, or make
         any public announcement (or request permission to make any such
         announcement), or induce any other Person to take any action,
         inconsistent with the foregoing;

                 (x)      enter into any negotiations, arrangements or
         understandings with any third party with respect to any of the
         foregoing;

                 (xi)     advise, assist or encourage or finance (or assist or
         arrange financing to or for) any other Person in connection with any
         of the foregoing; or

                 (xii)    otherwise act in concert with others, to seek to
         control or influence the management, Board of Directors or policies of
         Allied or its Affiliates;

provided, that this Section 11.14 shall not restrict or inhibit the rights of
LTI or Laidlaw to exercise its voting rights as a stockholder of Allied
(subject to Section 11.13 hereof); provided further that, the provisions of
paragraphs (i) through (xii), above, shall not apply to any Allied
Reorganization Transaction proposed by Laidlaw within 30 days





                                      -61-
<PAGE>   70
of the proposal of an Allied Reorganization Transaction by a Person that is not
cooperating or acting in collusion with or an Affiliate of Laidlaw.

         11.15   Transition Agreement.  Prior to the Closing, Laidlaw and
Allied agree to use their best efforts to enter into a transition agreement
(the "Transition Agreement") that will provide that each of them will, on
mutually agreeable terms, assist the other in providing for an orderly
transition regarding the ownership and operation of the business conducted by
the Acquired Subsidiaries at the Closing.  The Transition Agreement will
provide that each of them will make available to the other management services
including information processing, billing, payroll and payables management,
cash management and leases or subleases of office space, all of which will be
for a term of no more than one year.  The Transition Agreement will further
provide that effective on the time of the Closing, Laidlaw will terminate all
insurance coverage of any type relating to the Acquired Subsidiaries and Allied
will obtain insurance coverage regarding the Acquired Subsidiaries effective on
the time of the Closing.  Allied shall have the right to amend, modify or
terminate any and all Laidlaw Employee Plans (including the Laidlaw Pension
Plans) to the extent allowed by law and relevant collective bargaining
agreements.


                                  ARTICLE XII

                                  TAX MATTERS

         12.1    Section 338 Election.

                 (i)      Allied U.S. and LTI shall join in an election to have
         the provisions of Section 338(h)(10) of the Code and similar
         provisions of federal, state, local  or foreign law (where
         permissible) ("Section 338(h)(10)Election") apply to the acquisition
         of the stock of  each Acquired U.S. Subsidiary described herein
         whereby (i) each Acquired U.S. Subsidiary will be treated as having
         sold all of its assets in a single transaction as of the close of
         business on the Closing Date while a member of the LTI U.S.
         Consolidated Tax Group and (ii) no gain or loss will be recognized by
         LTI or any Acquired U.S. Subsidiary with respect to the sale of its
         shares of any Acquired U.S. Subsidiary.  The election will include the
         execution and subsequent filing of Internal Revenue Service Form
         8023-A pursuant to the requirements stated therein.  Allied U.S.
         shall, within 120 days of the Closing Date, provide to LTI an
         allocation of the deemed purchase price among the assets of the
         Acquired U.S. Subsidiaries in accordance with Code Sections 338 and
         1060 and any comparable provisions of state, local or foreign law, as
         appropriate (including copies of detailed workpapers and proposed
         attachments to Form 8023-A).  Such allocation shall be deemed
         acceptable to LTI unless it notifies Allied U.S.  of any objections
         within 60 days





                                      -62-
<PAGE>   71
         of receipt of such allocation.  If LTI and Allied are unable to agree
         on such allocation within 210 days of the Closing Date, then Arthur
         Andersen L.L.P. or some other independent accounting firm mutually
         acceptable to the parties hereto shall make a binding determination
         with respect to such allocation, the fees and expenses of which shall
         be paid equally by LTI and Allied U.S.

                 (ii)     The Allied Parties may, at their election, make
         elections under Section 338(g) of the Code with respect to one or more
         of the Acquired Canadian Subsidiaries.

                 (iii)    For purposes of the Section 338(h)(10) Election,
         value equal to 7,225,000 shares of Allied Common Stock shall be
         allocated to the LWSI Group Subsidiaries which are Acquired Canadian
         Subsidiaries, and the remainder to the Acquired U.S. Subsidiaries.

                 (iv)     Within 60 days of delivery to LTI of the allocation
         schedule described in Section 12.1(i) above, Laidlaw and LTI shall
         properly execute and deliver to Allied IRS Form 8023-A (together with
         attachments) and other forms that are required to be submitted to any
         federal, state, county, or local taxing authority in connection with
         the Section 338(h)(10) Election for each Acquired U.S. Subsidiary, and
         in connection with the Section 338(g) election for each Acquired
         Canadian Subsidiary.  In the event the parties have not yet agreed on
         the allocation described in Section 12.1(i), the Section 338 Forms
         shall still be delivered to Allied, and all Tax Returns filed on a
         basis consistent with the binding determination of an accounting firm
         described in Section 12.1(i).

                 (v)      After the date of this Agreement, none of the Allied
         Parties, any Acquired Subsidiary, nor the Laidlaw Sellers shall take,
         or fail to take, any action which may cause the acquisition of the
         Acquired Subsidiaries to not be eligible for the Sections 338(g) and
         338(h)(10) elections set forth herein.

         12.2    Future Tax Returns.

                 (i)      LTI shall prepare and file in a timely fashion, its
         federal, state and local corporate income Tax Returns of the Acquired
         U.S. Subsidiaries for the periods ended August 31, 1996 and August 31,
         1997 (which shall include the income of the Acquired U.S. Subsidiaries
         for the periods ended August 31, 1996 and the Closing Date).  The Tax
         Return for the period ended August 31, 1997 shall include the results
         of operations of the Acquired U.S. Subsidiaries for the Pre-Closing
         Tax Period beginning September 1, 1996, and ending on the Closing
         Date, and all income recognized as a result of all election(s) under
         Code Sections 338(h)(10) and 338(g).  LTI shall pay or discharge any
         and all U.S. Tax reflected on such Tax Returns, including the tax
         liability of any member or





                                      -63-
<PAGE>   72
         former member of the Laidlaw Sellers, however measured, for which any
         Acquired Subsidiary is or may be held liable.  Each such payment shall
         be made on or before the date any such payment is due.  LTI shall
         receive any tax refunds reflected on such returns.  The Acquired
         Subsidiaries will promptly provide the information to LTI to prepare
         such returns.

                 (ii)     Laidlaw shall prepare and file in a timely fashion,
         all corporate federal and provincial income Tax Returns of the
         Acquired Canadian Subsidiaries for the periods ended August 31, 1996
         and the day preceding the Closing Date.  Such returns shall include
         the results of operations of Acquired Canadian Subsidiaries for the
         period ending on the close of business on the day preceding the
         Closing Date.  Laidlaw shall directly pay or discharge any and all
         Taxes reflected on such Tax Returns, including the tax liability of
         each Acquired Canadian Subsidiary and any member or former member of
         the Laidlaw Sellers, however measured, for which any Acquired
         Subsidiary is or may be held liable.  Each such payment shall be made
         on or before the date any such payment is due.  Laidlaw shall receive
         any tax refunds reflected on such returns.  The Acquired Subsidiaries
         will promptly provide the information to Laidlaw to prepare such
         returns.

                 (iii)    (A)  Allied shall timely prepare and file, or cause
         the Acquired Subsidiaries to timely prepare and file, all other
         applicable Tax Returns for SWM Group Income Taxes for taxable periods
         ending subsequent to the Closing Date, including any such returns
         which relate to periods which commenced on or prior to the Closing
         Date.

                 (B)      The Acquired Subsidiaries shall pay or cause to be
         paid any and all Taxes (and applicable penalties and interest, if any)
         due as a result of the Tax Returns required to be filed pursuant to
         the preceding clause (A).

                 (C)      Prior to filing the Tax Returns referred to in
         Section 12.2(iii)(A), the Laidlaw Sellers shall reimburse the Acquired
         Subsidiaries or the Allied Parties for any SWM Group Income Taxes to
         be paid in connection with Tax Returns filed pursuant to this Section
         12.2(iii)(A) attributable to SWM Group Income Taxes accrued or
         recognized prior to or including the Closing Date, including the
         deemed sale of the assets of the Acquired Subsidiaries on the Closing
         Date pursuant to the Section 338(h)(10) Election for the Acquired U.S.
         Subsidiaries, any Section 338(g) election for the Acquired Canadian
         Subsidiaries, and any liability that arises because one or more of the
         Acquired Subsidiaries ceased on the Closing Date to be an Affiliate of
         the Laidlaw Sellers.  Allied or the Acquired Subsidiaries shall
         reimburse LTI for any payment made in excess of Laidlaw' pro rata
         share of tax computed based on the income in (iv) below.





                                      -64-
<PAGE>   73
                 (D)      Allied shall provide the Laidlaw Sellers or their
         representatives a copy of the Tax Returns prepared pursuant to this
         Section 12.2(iii), and the documentation related thereto, prior to
         filing such Tax Returns.

                 (E)      State, provincial and local Tax Returns shall be
         prepared on a basis reasonably consistent with prior Tax Returns of
         the Acquired Subsidiaries and the Code Section 338 allocations set
         forth herein.

                 (iv)     With respect to all taxable periods including any
         Pre-Closing Tax Period, the Laidlaw Sellers, Allied, and the Acquired
         U.S. Subsidiaries will make all computations, allocations,
         determinations and elections affecting the Laidlaw Sellers, the
         Acquired U.S. Subsidiaries and Acquired Canadian Subsidiaries  in
         accordance with the provisions of the Treasury regulations promulgated
         under Section 338 and 1502 of the Code, the provisions of the Income
         Tax Act and state, provincial and local income tax rules.

         12.3    Tax Covenants.

                 (i)      Without the prior written consent of Allied, neither
         of the Laidlaw Sellers nor any Affiliate of the Laidlaw Sellers shall,
         to the extent it may affect or relate to any of the Acquired
         Subsidiaries, make or change any tax election, change any annual tax
         accounting period, adopt or change any method of tax accounting, file
         any amended Tax Return, enter into any closing agreement, settle any
         Tax claim, assessment or proposed assessment, surrender any right to
         claim a Tax refund, consent to any extension or waiver of the
         limitation period applicable to any Tax claim or assessment or take or
         omit to take any other action, if any such action or omission would
         have the effect of increasing any post-closing Tax liability of any
         Acquired Subsidiary, Allied or any Affiliate of Allied.

                 (ii)     Without the prior written consent of Laidlaw, neither
         Allied nor its Affiliates shall, to the extent it may affect or relate
         to any of the Acquired Subsidiaries, make or change any tax election,
         file any amended Tax Return, enter into any Closing Agreement, settle
         any Tax claim, assessment or proposed assessment, surrender any right
         to claim a Tax refund, consent to any extension or waiver of the
         limitation period applicable to any Tax claim or assessment or take or
         omit to take any other action, if any such action or omission would
         affect a Pre-Closing Tax Period.

                 (iii)    Allied and the Laidlaw Sellers agree that so long as
         any books, records and files retained by the Laidlaw Sellers and their
         Affiliates relating to the business of the Acquired Subsidiaries, or
         the books, records and files delivered to the control of Allied
         pursuant to this Agreement to the extent they





                                      -65-
<PAGE>   74
         relate to the operations of the Acquired Subsidiaries prior to the
         Closing Date, remain in existence and available, each party (at its
         own expense) shall have the right upon prior notice to inspect and to
         make copies of the same at any time during business hours for any
         proper purpose.  Allied and the Laidlaw Sellers and their Affiliates
         shall use reasonable efforts not to destroy or allow the destruction
         of any such books, records and files without first providing 60 days'
         written notice of intention to destroy to the other, and allowing such
         other party to take possession of such records.

                 (iv)     Allied will make its personnel or that of the
         Acquired Subsidiaries available to answer requests related to Tax
         Proceedings as defined in Section 12.5(ii).  Allied will either
         provide documents needed to respond to federal, state and provincial
         information requests or queries for such proceedings within 30 days or
         allow Laidlaw to take possession of records necessary to answer such
         requests.  Unless one of the preceding provisions requires otherwise,
         the Laidlaw Seller's share of income to be reported on such Acquired
         Subsidiaries' return will be computed as of the Closing Date.

         12.4    Other Tax Matters, Post-Closing Cooperation.

                 (i)      If the Allied Parties receive any Tax Refund
         (including interest and penalties refunded) for a Pre-Closing Tax
         Period of an Acquired Subsidiary, other than any such Tax Refund
         arising from the application of a loss or Tax credit arising in a
         Post-Closing Tax Period, then such persons shall pay to the Laidlaw
         Sellers the actual amount of such Tax Refund as and when received, on
         an after-tax basis.

                 (ii)     If the Allied Parties realize any Tax Benefit in a
         Post-Closing Tax Period arising from the application of a loss
         incurred or Tax credit earned by an Acquired Subsidiary in a
         Pre-Closing Tax Period, then such persons shall pay to the Laidlaw
         Sellers the actual amount of such Tax Benefit realized 183 days
         following the end of the particular Post-Closing Tax Period during
         which such Tax Benefit was realized, on an after-tax basis.

                 (iii)    All transfer, documentary, sales, use, stamp,
         registration, goods and services, value added and other such Taxes and
         fees (including any penalties and interest) incurred in connection
         with the sale of the stock of LWSI, LMS, LWSC or any of their
         subsidiaries, or otherwise in connection with the transactions
         effected pursuant to this Agreement (collectively, the "Transfer
         Taxes") shall be borne and paid by the Laidlaw Sellers.  To the extent
         permissible under Tax law or regulations, the Laidlaw Sellers shall
         undertake all actions and file such Tax Returns or other forms or
         instruments as may be





                                      -66-
<PAGE>   75
         necessary to make payment of any Transfer Taxes due prior to or on the
         Closing Date, and present evidence of such payment at the Closing Date
         to Allied.

                 (iv)     Any payment to be made to any party under Section 12
         shall be made within 15 days of demand (or receipt in the event of a
         refund of any overpayment).  Payment after that time shall bear
         interest (y) if for the U.S. at the rate of interest prescribed by IRC
         Sec 6621(a)(1) and (z) if for Canada as prescribed by Income Tax
         Regulation 4301(b).

         12.5    Tax Controversies.

                 (i)      Allied and Laidlaw shall each use reasonable efforts
         to keep the other advised as to the status of Tax audits and
         litigation involving any direct, indirect or contingent Taxes which
         could give rise to a liability of the Laidlaw Sellers to Allied under
         this Agreement for any pre-closing period (a "Tax Liability Issue").
         Such efforts shall include attorney comfort letters provided to
         Allied's independent auditors and discussions with the Laidlaw
         attorneys representing the Allied Subsidiaries as requested by Allied.
         Laidlaw agrees to timely notify Allied regarding any proposed written
         communication (i.e., communications not relating to inquiries or
         requests for information) by Laidlaw to any such Taxing Authority with
         respect to a Tax Liability Issue to the extent that the issue would
         impact a post-closing period of Allied or the Acquired Subsidiaries.
         Allied shall have the right to consult with Laidlaw regarding any
         response to such communications.

                 (ii)     Laidlaw shall have full responsibility for and
         discretion in handling any Tax Controversy including, without
         limitation, an audit, a protest to the appeals division of the IRS, or
         similar state or local appellate division, an objection to Revenue
         Canada or any provincial tax authority and litigation in the U.S. Tax
         Court, the Tax Court of Canada or any other court of competent
         jurisdiction (a "Tax Proceeding") for any pre-closing period.  Allied
         or the Acquired Subsidiaries shall give the Laidlaw Sellers the
         ability to handle any Tax Controversy whether by power of attorney or
         as otherwise required by the Taxing Authority.  Unless the Laidlaw
         Sellers tender payment of any tax owed, with penalty and interest, to
         Allied or the Tax Authority, final settlement of any Tax Controversy
         will require Allied approval.  However, upon request by Allied and
         with the consent of Laidlaw, Allied at its own expense shall have full
         responsibility and discretion in handling any Tax Proceeding for any
         Pre-closing tax period.

                 (iii)    In the event that any one of the Acquired
         Subsidiaries is required or elects to pay any Tax, file any bond or
         deposit any amount in connection with a Tax Proceeding (or pay any
         Canadian Tax it may decide to object to or





                                      -67-
<PAGE>   76
         otherwise contest), Laidlaw shall loan to Allied no later than three
         (3) Business Days before such payment is required to be made, without
         interest and until a final determination with respect to such Tax has
         occurred, one hundred percent of the amount to be paid or deposited by
         Allied.  Within three (3) Business Days of the receipt by Allied  of a
         refund of any amount loaned to it by Laidlaw (including any interest
         received by Allied), Allied shall pay such refunded amount to Laidlaw
         net of any Tax cost incurred by Allied and its Affiliates as a result
         of such refund.

                 (iv)     If the completion or settlement of any Tax Proceeding
         relating to a Pre-Closing Tax Period, tax controversy or amended Tax
         Return gives rise to a tax benefit for any Post-Closing Tax Period to
         the Allied Parties, the Acquired Subsidiaries and any Affiliates, then
         such persons shall pay to Laidlaw the actual amount of such tax
         benefit realized by such persons as it relates to such Pre-Closing Tax
         Period as and when received on an after tax basis.  No payment will be
         made under this paragraph for less than $50,000 per period or for a
         period of more than ten years.

                 (v)      If the completion or settlement of any Tax Proceeding
         relating to a Pre-Closing Tax Period, tax controversy or amended Tax
         Return gives rise to a tax liability for any Post-Closing Tax Period
         to the Allied Parties, the Acquired Subsidiaries and any Affiliates,
         then Laidlaw shall pay to such persons the actual amount of such tax
         liability on an after-tax basis as and when paid.  No payment will be
         made under this paragraph for less than $50,000 per period or for a
         period of more than ten years.

                 (vi)     By written notice to Laidlaw, Allied shall have the
         right to instruct Laidlaw to forego proceedings with respect to one or
         more items for which Laidlaw may be liable to indemnify Allied.  Such
         notice shall constitute a waiver of the right of Allied to
         indemnification for any Taxes arising out of such item for the period
         or periods involved, but shall not otherwise waive any rights of
         Laidlaw to any refund of a deposit under Section 12.5(iii).

         12.6    Certain Pending Tax Controversies.

                 (i)      C$27,421,816 is on deposit with Revenue Canada and
         the Provincial tax authorities with respect to the Canlea controversy.
         Such deposit shall be treated as a loan from Laidlaw to PWSL made
         pursuant to Section 12.5(iii) and returned to Laidlaw in accordance
         with that provision.

                 (ii)     Allied and its Subsidiaries shall not cause the debt
         payable by PWSL to 635952 Ontario Ltd. (a wholly owned subsidiary of
         PWSL, and an Acquired Canadian Subsidiary) in the amount of
         C$37,847,056, to be settled or





                                      -68-
<PAGE>   77
         extinguished by way of payment in whole or in part, canceled, settled
         by way of corporate reorganization, converted or exchanged for some
         other property, or do any such thing (or fail to do any such thing)
         which would cause the debt to be unenforceable in law, without the
         written consent of Laidlaw.


                                  ARTICLE XIII

             NATURE AND SURVIVAL OF REPRESENTATIONS AND WARRANTIES

         13.1    Nature of Statements.  All, but only those, statements
contained in this Agreement or any Disclosure Schedule or certificate delivered
or by on behalf of a Party under this Agreement shall be deemed representations
and warranties made by that Party in connection with the transactions
contemplated by this Agreement.

         13.2    Survival of Representations and Warranties.  Regardless of any
investigation made at any time by or on behalf of any Party or of any
information any Party may have as a result of any such investigation, all
representations and warranties made in or pursuant to this Agreement (including
in any Disclosure Schedule or certificate delivered under this Agreement)
shall, except as otherwise provided in this Section 13.2, survive the Closing
and shall continue in effect indefinitely thereafter unless and until
terminated as provided in this Section 13.2.  The representations and
warranties made by the Laidlaw Sellers in Article IV (other than in Sections
4.2, 4.3, 4.4, 4.5, 4.11, 4.13 and 4.15 of Article IV) and the representations
and warranties made by the Allied Parties in Article V (other than in Sections
5.2, 5.3, 5.4, 5.5, the first sentence of Section 5.12, 5.13 and 5.15 of
Article V) shall terminate on the date which is 18 months following the Closing
Date.  The representations and warranties made by the Laidlaw Sellers in
Sections 4.2, 4.3, 4.4, 4.5 and 4.11, and the representations and warranties
made by Allied in Sections 5.2, 5.3, 5.4, 5.5 and the first sentence of Section
5.12 shall survive the Closing indefinitely.  The representations and
warranties made by the Laidlaw Sellers in Section 4.13, the representations and
warranties made by the Allied Parties in Section 5.13, and the covenants,
obligations and agreements set forth in Article XII shall terminate on the date
the statute of limitations and times for assessment (giving effect to any
waiver, mitigation or extension thereof) with respect to any Tax liability in
question has run in favor of all Acquired Subsidiaries and the LTI-US
Consolidated Tax Group, or Allied and its Subsidiaries, as the case may be,
against the U.S. federal, Canadian federal, state provincial, or local
government, as the case may be.  The representations and warranties by the
Laidlaw Sellers in Section 4.15 shall (i) terminate on the Closing Date as to
all matters that are disclosed in writing to the Allied Parties at least 5
Business Days prior to the Closing pursuant to Section 4.15 of this Agreement
or disclosed with specificity in the Emcon Environmental Report or are
otherwise disclosed by Laidlaw in writing to Allied at least 5 Business Days
before the Closing, and (ii) terminate on the third anniversary of the Closing
Date as to all





                                      -69-
<PAGE>   78
matters other than those described in the preceding clause (i) which are known
to the Laidlaw Sellers on the Closing Date.  The representations and warranties
made by the Allied Parties in Section 5.15 shall terminate on the third
anniversary of the Closing.  If a bona fide claim is asserted before the
expiration of the survival period of a representation or warranty, such
representation, warranty, covenant, obligation or agreement shall continue in
effect until the claim is settled, adjudicated or otherwise resolved.  With
respect to this Section 13.2, "known" means with respect to any matter referred
to in clause (ii) above that (x) the matter is known to any Person who is or
was an officer, director, employee or agent of, or consultant to, any member of
the Laidlaw Group (including the Acquired Subsidiaries) on or before the
Closing Date or (y) any such Person is aware of facts which would have led a
reasonable Person to have conducted an investigation or inquiry likely to have
led to discovery of such matter.


                                  ARTICLE XIV

                                INDEMNIFICATION

         The respective indemnification obligations of the Laidlaw Sellers and
Allied are as follows:

         14.1    Indemnification by the Laidlaw Sellers.  The Laidlaw Sellers
jointly and severally agree to pay and to indemnify and hold harmless each
Allied Party and each Acquired Subsidiary and their respective Affiliates (but,
in the case of the Acquired Subsidiaries, only their respective Affiliates
after the Closing), successors and assigns from and against any and all Damages
suffered by the Allied Parties or the Acquired Subsidiaries which are caused
by, arising out of or in respect of:

                 (i)      any U.S. federal income Tax liability of the LTI US
         Consolidated Tax Group for all taxable periods ending before, on or
         after the Closing Date;

                 (ii)     all other SWM Group Income Taxes attributable to any
         Pre-Closing Tax Period (including any transaction consummated in such
         Pre-Closing Tax Period);

                 (iii)    any Tax resulting from or attributable to the
         distribution of the Retained  Subsidiaries and the Retained Land;

                 (iv)     any Tax on or attributable to the elimination,
         reversal, release, satisfaction, distribution, or discharge of
         Intercompany Indebtedness and Intercompany Investments of the Acquired
         Subsidiaries (including any intercompany items solely between the
         Acquired Subsidiaries, as well as items between Laidlaw and other
         Laidlaw Affiliates), and any other reorganization





                                      -70-
<PAGE>   79
         steps or other actions taken by Laidlaw and its Affiliates in placing
         the Acquired Subsidiaries in the condition required for Closing
         (including, without limitation, the actions set forth in Section 3.2);

                 (v)      any obligation of Allied or the Acquired Subsidiaries
         to contribute to the payment of any SWM Group Income Taxes determined
         on a consolidated, combined or unitary basis allocable to any
         Pre-Closing Period with respect to a group of corporations that
         includes or included the Acquired Subsidiaries;

                 (vi)     any (x) Pre-Closing Laidlaw Insurance Claims, and (y)
         liability (including any Environmental Claim relating to any
         Environmental Law) arising out of the activities, business, assets or
         operations of any member of the Laidlaw Group other than the Acquired
         Subsidiaries (excluding the Option Assets), including their
         predecessors, affiliates, successors and assigns;

                 (vii)    any claim by any member of the Laidlaw Group against
         any Acquired Subsidiary based on any event occurring or condition
         existing on or before the Closing Date;

                 (viii)   any breach or default in the performance by either
         Laidlaw Seller of any covenant or agreement made by such Laidlaw
         Seller in this Agreement or in any Ancillary Agreement to which either
         Laidlaw Seller is a party;

                 (ix)     any breach of warranty or inaccurate or erroneous
         representation made by either Laidlaw Seller in Article IV of this
         Agreement (other than the representations and warranties set forth in
         Sections 4.2, 4.3, 4.4, 4.5, 4.11, 4.13 and 4.15 of this Agreement) or
         in the Laidlaw Disclosure Schedule or in any certificate delivered by
         or on behalf of the Laidlaw Sellers under, or concerning the
         representations and warranties made in Article IV of this Agreement
         (other than the representations and warranties set forth in Sections
         4.2, 4.3, 4.4, 4.5, 4.11, 4.13 and 4.15);

                 (x)      any breach of warranty or inaccurate or erroneous
         representation made by either Laidlaw Seller in Sections 4.2, 4.3,
         4.4, 4.5, 4.11 and 4.13 of this Agreement or the Laidlaw Disclosure
         Schedule related to such representations and warranties or the
         certificate delivered by or on behalf of the Laidlaw Sellers under, or
         concerning such representations and warranties; and

                 (xi)     any breach of warranty or inaccurate or erroneous
         representation made by either Laidlaw Seller in Section 4.15 of this
         Agreement or the Laidlaw Disclosure Schedule related to such
         representation or warranties or the certificate delivered by or on
         behalf of the Laidlaw Seller under, or concerning such





                                      -71-
<PAGE>   80
         representations and warranties, but only to the extent any such
         warranty or representation survives the Closing pursuant to Section
         13.2 of this Agreement.

provided, however, that the amount of any Damages in respect of which the
Laidlaw Parties shall be required to indemnify the Allied Parties under clauses
(viii) and (ix) above (but not under clauses (i) through (vii), clause (viii)
(to the extent such clause relates to performance by the Laidlaw Parties of the
covenants and agreements contained in clause (ii) of the final paragraph of
Section 6.1) inclusive, and clauses (x) and (xi) of this Section 14.1) shall be
limited to the amount by which the aggregate of all such Damages exceeds
$25,000,000; and provided further that no claim for Damages against either
Laidlaw Seller made under clauses (i) through (vii), inclusive, and clauses (x)
and (xi) of this Section 14.1 shall be reduced, modified or impaired by virtue
of the fact that any representation and warranty made by the Laidlaw Sellers in
Sections 4.2, 4.3, 4.4, 4.5, 4.11, 4.13 and 4.15 shall have been breached or
inaccurate or erroneous in any respect.  The amount of any Damages in respect
of which the Laidlaw Parties shall be required to indemnify the Allied Parties
under clause (xi) above will be limited to the amount by which the aggregate of
all such Damages exceeds $1,000,000.  For purposes of this Section 14.1, the
representations and warranties shall be read as if references therein to the
materiality to the Laidlaw Sellers and the Acquired Subsidiaries or any of them
of any condition, fact, statement, event or act (including all references to
"Material Adverse Effects" and "in all material respects") were deleted and the
effect of any such references were deleted altogether.  Thus, for example: (i)
any representation that a statement is true and correct in all material
respects shall be read as a representation that the statement is true and
correct; (ii) any representation that a condition exists except to the extent
that its failure to exist would not have a Material Adverse Effect on the
Laidlaw Sellers or the Acquired Subsidiaries, as the case may be, shall be read
as a representation that such condition exists; and (iii) any representation
that no incidents of a specific nature have occurred that would have a Material
Adverse Effect on the Laidlaw Sellers or the Acquired Subsidiaries, as the case
may be, shall be read as a representation that no incidents of such nature have
occurred.  For purposes of this Section 14.1, the representations and
warranties shall be read as if references therein to the "knowledge of the
Laidlaw Sellers" were deleted in their entirety.

         14.2    Indemnification by Allied.  Allied agrees to pay and to
indemnify and hold harmless and defend each Laidlaw Seller and its Affiliates
(but not any Acquired Subsidiary after the Closing), and their respective
successors and assigns from and against any and all Damages suffered by the
Laidlaw Parties which are caused by or arising out of or in respect of:

                 (i)      the Laidlaw Guaranties which are listed and
         identified in Section 4.19 of the Laidlaw Disclosure Schedule;





                                      -72-
<PAGE>   81
                 (ii)     any breach or default in the performance by any
         Allied Party of any covenant or agreement of such Allied Party
         contained in this Agreement or any Ancillary Agreement to which any
         Allied Party is a party;

                 (iii)    any breach of warranty or inaccurate or erroneous
         representation made by such Allied Party in Article V of this
         Agreement (other than the representations and warranties set forth in
         Sections 5.2, 5.3, 5.4, 5.5 and the first sentence of 5.12; and

                 (iv)     any breach of warranty or inaccurate or erroneous
         representation made by such Allied Party in Sections 5.2, 5.3, 5.4,
         5.5 and the first sentence of 5.12 of this Agreement;

provided, however, that the amount of any Damages in respect of which Allied
shall be required to indemnify the Laidlaw Sellers under clauses (ii) and (iii)
of this Section 14.2 shall (but not clauses (i) and (iv) of this Section 14.2)
be limited to the amount by which the aggregate of all such Damages exceeds
$25,000,000.  For purposes of this Section 14.2, the representations and
warranties shall be read as if references therein to materiality to the Allied
Parties or any of them of any condition, fact, statement, event or act
(including all references to "Material Adverse Effects" and "in all material
respects") were deleted and the effect of any such references were deleted
altogether.  Thus, for example: (i) any representation that a statement is true
and correct in all material respects shall be read as a representation that the
statement is true and correct; (ii) any representation that a condition exists
except to the extent that its failure to exist would not have a Material
Adverse Effect on the Allied Parties shall be read as a representation that
such condition exists; and (iii) any representation that no incidents of a
specific nature have occurred that would have a Material Adverse Effect on the
Allied Parties shall be read as a representation that no incidents of such
nature have occurred.  For purposes of this Section 14.2, the representations
and warranties shall be read as if references therein to the "knowledge of the
Allied Parties" were deleted in their entirety.

         The obligations of Allied under this Section 14.2 (other than the
obligation to indemnify and hold harmless the Laidlaw Sellers with respect to
the Laidlaw Guarantees referred to in clause (i) above) shall be subordinated
to the obligations of Allied and its subsidiaries under the Credit Facility (as
defined in the Guaranties) and the Senior Subordinated Debentures to the same
extent and with the same extent as the obligations of Allied under the
Guaranties are subordinated to Senior Indebtedness (as such term is defined in
the Guaranties).  If so requested by Allied or by any holder of any
Indebtedness incurred pursuant to the Credit Facility or by any holder of any
of the Senior Subordinated Debentures, the Laidlaw Sellers shall execute such
additional documents and agreements as may be requested from time to time to
evidence the subordination contemplated hereby.  Nothing contained in this
Section 14.2 will be





                                      -73-
<PAGE>   82
deemed to subordinate the obligation of the Allied Parties or the Acquired
Subsidiaries to pay to the Laidlaw Seller any amounts received by them as a
refund of taxes pursuant to Section 12.6.  Allied shall not make any payments
under this Section 14.2 to the Laidlaw Sellers (other than payments pursuant to
the obligation to indemnify and hold harmless the Laidlaw Sellers with respect
to the Laidlaw Guaranties referred to in clause (i) above) as long as the
Credit Facility (as defined in the Guaranties) and the Senior Subordinated
Debentures are in place and in effect, provided that any payment that would
have been required to be paid pursuant to this Section 14.2 but for this
paragraph will accrue interest at 7% from the date such amount would have been
paid, and such amount together with accrued interest shall become due 91 days
following the termination of the Credit Facility and after the Indebtedness
incurred pursuant to the Credit Facility referred to in the Commitment Letter
and the Indebtedness evidenced by the Senior Subordinated Debentures have been
indefeasibly paid in full in cash.

         14.3    Third Party Claims. If any Party (for purposes of this Section
14.3, an "Indemnified Party") becomes aware of a fact, circumstance, claim,
situation, demand or other matter for which it or any other Indemnified Party
has been indemnified under this Article XIV and which has resulted or could
result in a liability owed by the Indemnified Party to a third party or a claim
otherwise advanced by a third party against the Indemnified Party (any such
item being herein called a "Third Party Claim"), the Indemnified Party, shall
give prompt written notice of the Third Party Claim to the Party obligated to
provide indemnity with respect to such Third Party Claim (for purposes of this
Section 14.3, the "Indemnifying Party"), requesting indemnification therefor,
specifying the nature of and specific basis for the Third Party Claim and the
amount or estimated amount thereof to the extent then feasible; provided,
however, a failure to give such notice will not waive any rights of the
Indemnified Party except to the extent the rights of the Indemnifying Party are
actually materially prejudiced by such failure.  The Indemnifying Party shall
have the right to assume the defense or investigation of such Third Party Claim
and to retain counsel and other experts to represent the Indemnified Party and
shall pay the  fees and disbursements of such counsel and other experts.  If
within 30 days after receipt of the request (or five days if litigation is
pending) the Indemnifying Party fails to give notice to the Indemnified Party
that the Indemnifying Party assumes the defense or investigation of the Third
Party Claim, an Indemnified Party may retain counsel and other experts (whose
fees and disbursements shall be at the expense of the Indemnifying Party) to
file any motion, answer or other pleading and take such other action which the
Indemnified Party reasonably deems necessary to protect its interests or those
of the Indemnifying Party until the date on which the Indemnified Party
receives such notice from the Indemnifying Party.  If an Indemnifying Party
assumes the defense or investigation and retains such counsel and other
experts, any Indemnified Party shall have the right to retain its own counsel
and other experts, but the fees and expenses of such counsel and other experts
shall be at the expense of the Indemnified Party unless (i) the Indemnifying
Party and the Indemnified Party mutually agree to the retention of such





                                      -74-
<PAGE>   83
counsel and other experts or (ii) the named parties to any such proceeding
(including any impleaded parties) include both the Indemnifying Party and the
Indemnified Party and representation of both parties by the same counsel would,
in the opinion of counsel retained by the Indemnifying Party, be inappropriate
due to actual or potential differing interests between them.

         If requested by the Indemnifying Party, the Indemnified Party agrees
to cooperate with the Indemnifying Party and its counsel in contesting any
Third Party Claim which the Indemnifying Party defends, or, if appropriate and
related to the Third Party Claim in question, in making any counterclaim
against the person asserting the Third Party Claim, or any cross-complaint
against any person.  No Third Party Claim may be settled by the Indemnified
Party without the consent of the Indemnifying Party, which consent will not be
unreasonably withheld.  Unless the Indemnifying Party agrees in writing that
the Damages to the Indemnified Party resulting from such settlement are fully
covered by the indemnities provided herein and that such Damages are fully
compensable in money, no Third Party Claim may be settled without the consent
of the Indemnified Party, which consent will not be unreasonably withheld.
Except with respect to settlements entered without the Indemnified Party's
consent pursuant to the immediately preceding sentence, to the extent it is
determined that the Indemnified Party has no right under this Article XIV to be
indemnified by the Indemnifying Party, the Indemnified Party shall promptly pay
to the Indemnifying Party any amounts previously paid or advanced by the
Indemnifying Party with respect to such matters pursuant to this Article XIV.

         After the delivery of a notice of a Third Party Claim hereunder, at
the reasonable request of the Indemnifying Party the Indemnified Party shall
grant the Indemnifying Party and its representatives full and complete access
to the books, records and properties of the Indemnified Party to the extent
reasonably related to the matters to which the notice relates.  The
Indemnifying Party will not disclose to any third person (except its
representatives) any information obtained pursuant to the preceding sentence
which is designated as confidential by the Indemnified Party and which is not
otherwise generally available to the public, except as may be required by
applicable law.  The Indemnifying Party shall request its representatives not
to disclose any such information (except as may be required by applicable law).
All such access shall be subject to the normal safety regulations of the
Indemnified Party, and shall be granted under conditions which will not
unreasonably interfere with the business and operations of the Indemnified
Party.

         14.4    Claims Between the Parties.  If any Party (for purposes of
this Section 14.4, an "Indemnified Party") becomes aware of a fact,
circumstance, claim, situation, demand or other matter (other than an Third
Party Claim) for which it or any other Indemnified Party has been indemnified
under this Article XIV and which has resulted or could result in a liability
(any such items being herein called a "Claim") being owed





                                      -75-
<PAGE>   84
to the Indemnified Party by another Party (the "Indemnifying Party"), the
Indemnified Party shall give prompt written notice to the Indemnifying Party of
the Claim, stating the nature and basis of the Claim and the amount claimed
thereunder, together with supporting information to the Claim, if any.  If the
Indemnifying Party does not notify the Indemnified Party within 30 days from
the date such Claim notice is given that it disputes the Claim, the amount of
the Claim shall conclusively be deemed to be a liability of the Indemnifying
Party hereunder.

         14.5    Arbitration.  If an Indemnified Party and an Indemnifying
Party cannot reach agreement with respect to the validity or amount of any
Third Party Claim or a Claim within 60 days after notice thereof is first
given, the validity and amount thereof, as the case may be, shall be finally
settled by arbitration in Chicago, Illinois in accordance with the Commercial
Arbitration Rules of the American Arbitration Association (or any organization
successor thereto) then in effect (to the extent such rules do not conflict
with the terms hereof), by a panel consisting of three arbitrators, each being
qualified to make evaluations of the kind under dispute.  Each of the two
parties to such arbitration shall appoint one arbitrator and the two
arbitrators so appointed shall select the third neutral arbitrator within 30
days after their appointment.  If the arbitrators appointed by the parties are
unable or fail to agree upon the third arbitrator, the third arbitrator shall
be selected by the American Arbitration Association.  Each arbitrator shall be
unaffiliated with each of the parties hereto.  The parties hereto agree to be
bound by whatever procedural and evidentiary rules are established by the panel
of arbitrators.  The arbitrators shall render their written decision and award,
upon the concurrence of at least two of their members, within 90 days of the
appointment of the third arbitrator.  The decision of the arbitrators shall be
binding on the parties, final and nonappealable.  Any arbitration award may be
enforced in any court having jurisdiction over the party against which
enforcement is sought.  The party designated by the arbitrators as the
unsuccessful party shall pay the fees and expenses (including attorneys' fees)
incurred in connection with the arbitration by all parties thereto; provided
that if the arbitrators do not designate either party as the unsuccessful
party, Allied shall bear 50% and Laidlaw shall bear 50% of such fees and
expenses.

         14.6    Payment.  Payments of all amounts owing hereunder with respect
to any Third Party Claim shall be made within 30 days after (i) the settlement
of the Third Party Claim, or (ii) if arbitration has been commenced pursuant to
Section 14.5, the final resolution of such arbitration.  Payments of all
amounts owing hereunder with respect to any Claim shall be made within ten days
after (i) the expiration of the 60-day Claim notice period without delivery of
a notice of dispute, or (ii) if arbitration has been commenced pursuant to
Section 14.5, the final resolution of such arbitration.





                                      -76-
<PAGE>   85
                                   ARTICLE XV

                           AMENDMENT AND TERMINATION

         15.1    Amendment.  This Agreement may be amended by the Parties, by
or pursuant to action taken by their respective Boards of Directors, at any
time before or after approval by Allied's stockholders of the matters specified
in Section 7.5, but after such approval, no amendment shall be made which
materially increases the amount or materially alters terms of the Allied
Securities without the further approval of Allied's stockholders.  This
Agreement may be amended only by a written instrument executed by all of the
Parties.

         15.2    Waiver.  At any time on or before the Closing Date, each of
the Parties may (i) extend the time for the performance of any of the
obligations or other act of any of the other Party or Parties, (ii) waive any
inaccuracies in the representations and warranties made in this Agreement or in
a Disclosure Schedule of a Party, (iii) waive compliance with any of the
agreements or conditions of this Agreement which may be legally waived, and
(iv) grant consents under this Agreement.  Any such extension, waiver or grant
shall be valid only if evidenced by a written instrument executed by the Party
giving it.

         15.3    Termination.  This Agreement may be terminated at any time
before the Closing by:

                 (i)      the mutual consent of the Boards of Directors of
         Laidlaw and Allied;

                 (ii)     by either Allied or Laidlaw if the Acquisitions have
         not been consummated on or before the later to occur of December 31,
         1996 or the 61st day after the SEC has approved the Allied Proxy
         Statement (or any later date which may be agreed to by the mutual
         written consent of Allied and Laidlaw); provided, however, that such
         right to terminate this Agreement shall not be available to any Party
         that has breached in any material respect its obligations under this
         Agreement in any manner that has proximately contributed to the
         failure of the Acquisitions to occur on or before such date; or

                 (iii)    by either the Laidlaw Parties or the Allied Parties
         if the stockholders of Allied shall have failed to approve at the
         Allied Stockholders' Meeting the matters specified in Section 7.5.

         15.4    Substitute Financing.  Between the date hereof and the
Closing, the Allied Parties shall, from time to time, advise Laidlaw as to the
status of the private placement





                                      -77-
<PAGE>   86
or public offering of the Senior Subordinated Debentures.  In the event the
Allied Parties determine that all conditions contained in Articles VIII and IX
to the Allied Parties obligation to consummate the Acquisitions and to take the
other actions called for under Articles II and III can be satisfied at the
Closing except that some or all of the Senior Subordinated Debentures cannot be
sold on terms acceptable to Allied, the Allied Parties shall give notice to
Laidlaw thereof (the "High Yield Event Notice").  The High Yield Event Notice
shall specify the amount of such Senior Subordinated Debentures (the "Remainder
Senior Subordinated Debentures") which cannot be sold to third party purchasers
on terms acceptable to Allied.  If the aggregate principal amount of the
Remainder Senior Subordinated Debentures is $150,000,000 or less, on or before
noon on the first Business Day following Laidlaw's receipt of the High Yield
Event Notice, Laidlaw may give notice (the "Substitute Financing Notice") to
the Allied Parties of Laidlaw's election and agreement (the "Substitute
Financing Election") to purchase the Remainder Senior Subordinated Debentures
on the same price and terms as are applicable to purchases of Senior
Subordinated Debentures by third party purchasers (net of the discount
otherwise payable to Goldman, Sachs & Co.) (the price payable pursuant to
clauses (i) or (ii) above) the "Substitute Financing Purchase Price").  Upon
giving the Substitute Financing Notice, Laidlaw will be obligated to purchase
the Remainder Senior Subordinated Debentures on the Closing Date for the
Substitute Financing Purchase Price, and upon Laidlaw's payment of the
Substitute Financing Purchase Price at the Closing, the condition contained in
Section 9.9 to the effect that the Allied Parties shall have received the
proceeds of the financing contemplated by the Highly Confident Letter will be
deemed satisfied to the extent of the funding provided by Laidlaw.  Any Senior
Subordinated Debentures purchased by Laidlaw may not be sold, transferred or
assigned to any Person for a period of 180 days after the purchase, unless
waived by Goldman, Sachs & Co.  Upon the giving of the High Yield Event Notice,
the Allied Parties will be obligated to pay $10,000,000 to Laidlaw on the
Closing Date or (if the Closing does not occur because the aggregate principal
amount of the Remainder Senior Subordinated Debentures exceeds $150,000,000 or
Laidlaw decides not to make the Substitute Financing Election) within ten
Business Days after the date the High Yield Event Notice is given.  Such amount
will be payable even if the Acquisitions are consummated on the Closing Date as
a result of Laidlaw's purchase of the Remainder Senior Subordinated Debentures.

         15.5    Consequences of Termination.  If this Agreement is terminated
as provided in Section 15.3, it shall forthwith become void and, except as
otherwise provided in Sections 5.14 and 15.5, there shall be no liability or
obligation on the part of any Party or their respective officers or directors.
Notwithstanding the foregoing, the Confidentiality Agreement shall also survive
such a termination.  Nothing in this Section 15.5 shall, however, relieve any
Party from any liability for any breach of this Agreement.





                                      -78-
<PAGE>   87
         If this Agreement is terminated solely because the stockholders of
Allied fail to approve the matters referred to in Section 7.5 hereof, and the
failure to receive such stockholder approval directly results from the
existence of a third party offer to acquire at least 51% of Allied's stock or
assets (whether in the form of a tender offer, merger proposal, asset purchase
or otherwise) then Allied will pay to Laidlaw within 10 days of such
termination of this Agreement an amount equal to the product obtained by
multiplying 5,000,000 times the difference between (i) the price per share of
the third party offer (as in effect at the time of such stockholders' meeting)
and (ii) $8.25.


                                  ARTICLE XVI

                               GENERAL PROVISIONS

         16.1    Non-Business Days.  If the date on which any action (including
the delivery of notices) to be taken under this Agreement is to occur falls on
a day which is not a Business Day, such action will be deemed timely taken if
taken on the first Business Day following.

         16.2    Notices. All notices or other communications which are
required or may be given under this Agreement shall be in writing and shall be
deemed to have been duly given when delivered in person or transmitted by
telecopier (with receipt confirmed) to a Party at the address or telecopy
number, as applicable, set forth below (as any such address or telecopier
number may be changed from time to time by notice similarly given):

         (1)     if to any Laidlaw Party, to:

                          Laidlaw Inc.
                          3221 North Service Road
                          Burlington, Ontario
                          Canada L7R 3Y8
                          Attention:  Ivan R. Cairns
                          Telecopy No.: (905) 332-6550

         (2)     if to any Allied Party, to:

                          Allied Waste Industries, Inc.
                          7201 East Camelback Road, Suite 375
                          Scottsdale, Arizona 85251
                          Attention: Roger A. Ramsey
                          Telecopy No.: (602) 481-9347





                                      -79-
<PAGE>   88
                          with a copy to:

                          Porter & Hedges, L.L.P.
                          700 Louisiana Street, Suite 3500
                          Houston, Texas 77002
                          Attention: Robert G. Reedy
                          Telecopy No.: (713) 228-1331

         16.3    Entire Agreement.  This Agreement, its Exhibits, the
Disclosure Schedules, all documents delivered under this Agreement, the
Confidentiality Agreement and the letter agreement dated the date hereof
relating to the option to purchase the Option Assets of Laidlaw granted to
Allied constitute, and together with the Ancillary Agreements upon their
execution and delivery as herein provided will constitute, the entire
agreement, and supersede all of the prior agreements and undertakings, both
written and oral, among the Parties, or any of them, with respect to the
subject matter of this Agreement.

         16.4    Assignment; Binding Effect.  This Agreement may not be
assigned by any of its Parties.  Subject to the preceding sentence, this
Agreement shall be binding upon the Parties and their respective successors and
assigns.

         16.5    Counterparts.  This Agreement may be executed in counterparts
which together shall constitute a single agreement.

         16.6    Governing Law; Jurisdiction.  This Agreement and the rights
and obligations of the parties created hereby shall be governed by the internal
Laws of the State of Delaware without regard to its conflict of law rules.  The
Parties irrevocably consent to the non-exclusive jurisdiction of the courts of
the State of Delaware in connection with any dispute between or among them
arising under this Agreement or any Ancillary Agreement.

         16.7    Severability of Provisions.  If a provision of this Agreement
or its application to any Person or circumstance, is held invalid or
unenforceable in any jurisdiction, to the extent permitted by law, such
provision or the application of such provision to Persons or circumstances
other than those as to which it is held invalid or unenforceable and in other
jurisdictions, and the remaining provisions of this Agreement, shall not be
affected.

         16.8    Specific Performance.  Each Party agrees that one or more
other Parties would be irreparably damaged if any provision of this Agreement
were not performed in accordance with its  specific terms or was otherwise
breached.  Therefore, the Parties agrees that each Party shall be entitled to
an injunction or injunctions to prevent breaches of this Agreement or any of
its provisions and to specifically enforce this





                                      -80-
<PAGE>   89
Agreement its terms and provisions in any action instituted in any court of the
United States or Canada or any state or province thereof having subject matter
jurisdiction, in addition to any other remedy to which a Party may be entitled,
at law or in equity.

         16.9    Joint Drafting.  This Agreement and its Exhibits have been
jointly drafted by the Parties and their counsel.  Neither this Agreement nor
any of its Exhibits shall be construed against any Party based on its
authorship.

         16.10   Captions.  The article and section headings in this Agreement
are for convenience only, and shall not affect the meaning or interpretation of
this Agreement.

         16.11   No Third-Party Beneficiaries.  There are no third-party
beneficiaries of this Agreement, except that the respective Affiliates of the
Parties are entitled to the benefits of the respective indemnification
obligations of the Parties under Section 11.10 and Article XIV.

                            [SIGNATURE PAGE FOLLOWS]





                                      -81-
<PAGE>   90

         IN WITNESS WHEREOF, the Parties have duly executed this Agreement, all
as of the date first written above.

                                        LAIDLAW INC.



                                        By: /s/ IVAN R. CAIRNS
                                           ------------------------------------
                                        Title: Senior Vice President
                                              ---------------------------------
                                        
                                        
                                        
                                        LAIDLAW TRANSPORTATION, INC.
                                        
                                        
                                        
                                        By: IVAN R. CAIRNS
                                           ------------------------------------
                                        Title: Senior Vice President
                                              ---------------------------------
                                        
                                        
                                        
                                        LAIDLAW WASTE SYSTEMS, INC.
                                        
                                        
                                        
                                        By: IVAN R. CAIRNS
                                           ------------------------------------
                                        Title: Authorized Officer
                                              ---------------------------------
                                        
                                        
                                        
                                        LAIDLAW WASTE SYSTEMS (CANADA) LTD.
                                        
                                        
                                        
                                        By: IVAN R. CAIRNS
                                           ------------------------------------
                                        Title: Authorized Officer
                                              ---------------------------------





                                      -82-
<PAGE>   91
                                        LAIDLAW MEDICAL SERVICES LTD.



                                        By: IVAN R. CAIRNS
                                           ------------------------------------
                                        Title: Authorized Officer
                                              ---------------------------------
                                        
                                        
                                        ALLIED WASTE INDUSTRIES, INC.
                                        
                                        
                                        
                                        By: /s/ ROGER A. RAMSEY
                                           ------------------------------------
                                        Title: Chairman
                                              ---------------------------------
                                        
                                        
                                        
                                        ALLIED HOLDINGS (UNITED STATES), INC.
                                        
                                        
                                        
                                        By: /s/ ROGER A. RAMSEY
                                           ------------------------------------
                                        Title: President
                                              ---------------------------------
                                        
                                        
                                        
                                        3294862 (CANADA), INC.
                                        
                                        
                                        
                                        By: /s/ ROGER A. RAMSEY
                                           ------------------------------------
                                        Title: President
                                              ---------------------------------





                                      -83-
<PAGE>   92



                                                                    EXHIBIT  A-1


THIS DEBENTURE HAS NOT BEEN REGISTERED (OR QUALIFIED BY PROSPECTUS) UNDER THE
SECURITIES ACT (DEFINED BELOW), THE CANADIAN SECURITIES LEGISLATION (DEFINED
BELOW), OR THE LAWS OF ANY STATE OF THE UNITED STATES OF AMERICA, AND THIS
DEBENTURE MAY NOT BE OFFERED FOR SALE, SOLD, TRANSFERRED, PLEDGED, HYPOTHECATED
OR OTHERWISE DISPOSED OF EXCEPT IN ACCORDANCE WITH THE TERMS HEREOF AND THE
REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF THE SECURITIES ACT, THE
CANADIAN SECURITIES LEGISLATION AND SUCH STATE LAWS OTHER THAN PURSUANT TO AN
EXEMPTION FROM SUCH REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS AND UPON
DELIVERY TO ALLIED CANADA OF AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO
ALLIED CANADA TO THE EFFECT THAT SUCH TRANSFER IS EXEMPT FROM REGISTRATION AND
THE PROSPECTUS DELIVERY REQUIREMENTS UNDER THOSE LAWS.

THIS DEBENTURE WILL BE ISSUED WITH ORIGINAL ISSUE DISCOUNT ("OID").  THE HOLDER
OF THIS DEBENTURE SHOULD BE AWARE THAT SUCH HOLDER WILL BE REQUIRED TO INCLUDE
OID IN SUCH HOLDER'S GROSS INCOME FOR INCOME TAX PURPOSES IN ADVANCE OF THE
RECEIPT OF CASH ATTRIBUTABLE TO SUCH INCOME.  WITH RESPECT TO OID, THE ISSUE
DATE OF THIS DEBENTURE IS _________________, 199_, THE ISSUE PRICE IS
[$_________], THE AMOUNT OF OID IS [$_________], AND THE YIELD TO MATURITY IS
[______]%.

                   7% JUNIOR SUBORDINATED DEBENTURE DUE 200_(1)


$150,000,000                                             _________________, 199_
                       

       FOR VALUE RECEIVED, 3294862 CANADA INC., a Canadian corporation ("Allied
Canada"), promises to pay to Laidlaw Inc., a Canadian corporation ("Laidlaw"),
or  its registered assigns, the principal amount of $150,000,000 on the
Maturity Date, with interest on the principal balance outstanding from time to
time at the rate and payable at the times and in the manner hereinafter set
forth.




- -------------------------

     (1) The due date will be 12 years after the date of issuance.
<PAGE>   93
1.     Definitions.

       (a)    For all purposes of this Debenture:

              "Affiliate" means, with respect to any Person, another Person
       that directly, or indirectly through one or more intermediaries,
       controls, is controlled by or is under common control with such Person
       with the term "control," including the terms "controlling" and
       "controlled," meaning for purposes of this definition, the power to
       direct the management and policies of a Person, directly or indirectly,
       whether through the ownership of voting securities or partnership or
       other ownership interests, or by contract or otherwise.

              "Allied" means Allied Waste Industries, Inc., a Delaware
       corporation, and its successors and assigns.

              "Allied Canada" means 3294862 Canada Inc., a Canadian
       corporation, and its successors and assigns.

              "Allied Common Stock" means the Common Stock, $.01 par value per
       share, of Allied.

              "Allied U.S." means Allied Holdings (United States), Inc., a
       Delaware corporation, and its successors and assigns.

              "Allied Warrant" means the warrant for the purchase of shares of
       Allied Common Stock to be issued by Allied to Laidlaw under Section 2.3
       of the Stock Purchase Agreement.

              "Bankruptcy or Insolvency Proceeding" is defined in Subsection
       5(b) of this Debenture.

              "Blockage Period" means any period when a default or an event of
       default  or an event which, with the giving of notice or the lapse of
       time or both, would constitute a default or an event of default has
       occurred and is continuing under the terms of the Credit Facility or the
       Senior Subordinated Debentures or under the terms of any agreement or
       instrument pursuant to which any other Designated Senior Indebtedness is
       created, issued, evidenced, secured or guaranteed.

              "Business Day" means a day other than Saturday, Sunday or any day
       on which banks located in Toronto, Ontario or New York, New York are
       authorized or obligated to close.

              "Canadian Securities Legislation" means the Securities Act of the
       Province of Ontario (R.S.O. 1990, c.  S.5, as amended) and similar
       provincial legislation, and the regulations and rules promulgated
       thereunder.




                                      2
<PAGE>   94
              "Change of Control" means a change resulting when any Unrelated
       Person or any Unrelated Persons acting together that would constitute a
       Group together with any Affiliates thereof (in each case also
       constituting Unrelated Persons) shall at any time Beneficially Own more
       than 50% of the aggregate voting power of all classes of Voting Stock of
       Allied; provided, however, that if at the date any "Change of Control"
       would otherwise have occurred but for the fact that a Person was not an
       Unrelated Person because such Person or an Affiliate of such Person
       acquired shares of Allied Common Stock or all or any portion of the
       Allied Warrant from Laidlaw or from any Affiliate of Laidlaw within nine
       months prior to such date, such shares of Allied Common Stock acquired
       from Laidlaw or any Affiliate of Laidlaw, or any shares of Allied Common
       Stock issued upon exercise of the Allied Warrant or any portion thereof,
       shall at all times thereafter be excluded when calculating whether a
       Change of Control has occurred.  As used in this definition of Change of
       Control (a) "Beneficially Own" means "beneficially own" as defined in
       Rule 13d-3 of the Securities Exchange Act of 1934, as amended (the
       "Exchange Act"), or any successor provisions thereto; provided, however,
       that, for purposes of this definition, a Person shall not be deemed to
       Beneficially Own securities tendered pursuant to a tender or exchange
       offer made by or on behalf of such Person or any of such Person's
       Affiliates until such tendered securities are accepted for purchase or
       exchange; (b) "Group" means a "group" for purposes of Section 13(d) of
       the Exchange Act; (c) "Affiliate" means, with respect to any Person,
       another Person which would be an "affiliate" of such Person for purposes
       of Section 13(d) of the Exchange Act; (d) "Unrelated Person" means at
       any time any Person other than Laidlaw, any Person to whom Laidlaw or
       any of its Affiliates transfers, within nine months prior to such time,
       any shares of Allied Common Stock or all or any portion of the Allied
       Warrant or any Affiliate of Laidlaw or any such Person; provided,
       however, that Persons (other than Laidlaw or its Affiliates) to whom
       Laidlaw or any of its Affiliates transfers any shares of Allied Common
       Stock or all or any portion of the Allied Warrant after five years from
       the date hereof shall not be deemed Unrelated Persons; and (e) "Voting
       Stock" of any Person shall mean capital stock of such Person which
       ordinarily has voting power for the election of directors (or persons
       performing similar functions) of such Person, whether at all times or
       only so long as no senior class of securities has such voting power by
       reason of any contingency.

              "Credit Facility" means the Credit Agreement dated as of
       _____________, 199_, among Allied U.S., as borrower, Allied, Goldman
       Sachs Credit Partners L.P., as syndication agent, Citibank, N.A., as
       documentation agent, Credit Suisse, as administrative agent, Goldman
       Sachs Credit Partners L.P., Citicorp USA, Inc. and Credit Suisse, as
       initial lenders, and the other financial institutions now or hereafter
       parties thereto (as the same may be renewed, amended, modified,
       increased, extended, refinanced, or otherwise supplemented from time to
       time).

              "Debenture" means this 7% Junior Subordinated Debenture due
       200__.





                                       3
<PAGE>   95
              "Default" is defined in Section 8.

              "Default Rate" means an annual interest rate equal to 9% per
       annum.

              "Deferral Period" is defined in Subsection 3(b).

              "Designated Senior Indebtedness" means (i) the Senior
       Indebtedness incurred with respect to the Credit Facility, (ii) the
       Senior Indebtedness evidenced by the Senior Subordinated Debentures and
       (iii) any other Senior Indebtedness which is incurred pursuant to an
       agreement (or series of related agreements simultaneously entered into)
       providing for Indebtedness, or commitments to lend, of at least
       $10,000,000 at the time of determination and is specifically designated
       in the instrument evidencing such Senior Indebtedness or the agreement
       under which such Senior Indebtedness arises as "Designated Senior
       Indebtedness."

              "$" means U.S. dollars, the lawful currency of the United States
       of America.

              "Financing Lease"  means any lease of property, real or personal,
       the obligations of the lessee in respect of which are required in
       accordance with generally accepted accounting principles to be
       capitalized on a balance sheet of the lessee.

              "Governmental Entity" means any U.S. or Canadian, territorial,
       federal, state, provincial or local court, executive office,
       legislature, governmental agency, department, ministry, commission, or
       administrative, regulatory or self-regulatory authority or
       instrumentality.

              "Guarantee" means with respect to any Person any obligation,
       contingent or otherwise, of such Person guaranteeing or having the
       economic effect of guaranteeing any Indebtedness of any other Person
       (the "primary obligor") in any manner, whether directly or indirectly,
       and including any obligation of such Person, direct or indirect, (a) to
       purchase or pay (or advance or supply funds for the purchase or payment
       of ) such Indebtedness or to purchase (or to advance or supply funds for
       the purchase of) any security for the payment of such Indebtedness, (b)
       to purchase or lease property, securities or services for the purpose of
       assuring the owner of such Indebtedness of the payment of such
       Indebtedness or (c) to maintain working capital, equity capital or any
       other financial statement condition or liquidity of the primary obligor
       so as to enable the primary obligor to pay such Indebtedness; provided,
       however, that the term "Guarantee" shall not include endorsements for
       collection or deposit in the ordinary course of business.

              "Indebtedness" means with respect to any Person at any date, (a)
       all indebtedness of such Person for borrowed money or for the deferred
       purchase





                                       4
<PAGE>   96
       price of property or services (other than current trade liabilities
       incurred in the ordinary course of business and payable in accordance
       with customary practices), (b) any other indebtedness of such Person
       which is evidenced by a note, bond, debenture, letter of credit or
       similar instrument, (c) all obligations of such Persons with respect to
       Guarantees, (d) all obligations of such Person under Financing Leases,
       (e) all obligations of such Person in respect of acceptances issued or
       created for the account of such Person (other than endorsements in the
       ordinary course of business),  (f) all obligations in respect of
       interest rate swaps or other interest rate hedging products or foreign
       currency exchange agreements or exchange rate hedging arrangements, (g)
       all obligations in respect of reimbursement obligations under letters of
       credit, and (h) all liabilities of the type referred to in clauses (a)
       through (g) above that are secured by any lien, charge, security
       interest or encumbrance on any property owned by such Person even though
       such Person has not assumed or otherwise become liable for the payment
       thereof.

              "Indenture" means the Indenture dated _____________, 199_,
       between Allied U.S. and the Trustee pursuant to which the Senior
       Subordinated Debentures are issued.

              "Laidlaw" means Laidlaw Inc., a Canadian corporation.

              "LTI" means Laidlaw Transportation, Inc., a Delaware corporation.

              "Maturity Date" means _______________ ___, 200_ [12 years after
       the date hereof].

              "Offset Letter Agreement" means the letter agreement dated the
       Closing Date among Allied, 3294854 Canada Inc., Laidlaw and LTI, in
       substantially the form of Exhibit N attached to this Agreement, to be
       executed and delivered pursuant to Section 3.3.

              "Person" means an individual, corporation, partnership,
       association, joint stock company, limited liability company,
       Governmental Entity, business trust, unincorporated organization, or
       other legal entity.

              "Representative" means at any date, with respect to the Credit
       Facility, the Person or Persons then acting as the administrative agent
       under the Credit Facility, with respect to the Senior Subordinated
       Debentures, the Trustee, and with respect to any other Designated Senior
       Indebtedness, the holders of such Designated Senior Indebtedness or any
       Person acting as agent of such holders at such date.

              "Section 4(b) Prepayment Date" is defined in Subsection 4(b) of
       this Debenture.





                                       5
<PAGE>   97
              "Section 4(b) Prepayment Fraction" means, with respect to any
       prepayment pursuant to Section 4(b) of this Debenture, the fraction
       obtained by dividing the principal amount of the Debenture to be prepaid
       by $150 million.

              "Section 4(b) Prepayment Notice" is defined in Subsection 4(b) of
       this Debenture.

              "Section 4(b) Prepayment Option" is defined in Subsection 4(b) of
       this Debenture.

              "Section 4(b) Prepayment Price" means (i) at any date set forth in
       the table below (the "Section 4(b) Value Date"), the amount set forth
       opposite such Section 4(b) Value Date, and (ii) at any other date (the
       "Section 4(b) Determination Date"), the amount equal to the sum of (y)
       the Section 4(b) Prepayment Price as of the Section 4(b) Value Date
       immediately preceding such Section 4(b) Determination Date plus (z) an
       amount equal to the product of (A) the difference between the Section
       4(b) Prepayment Price as of the Section 4(b) Value Date immediately
       following such Section 4(b) Determination Date minus the Section 4(b)
       Prepayment Price as of the Section 4(b) Value Date immediately preceding
       such Section 4(b) Determination Date multiplied by (B) a fraction, the
       numerator of which is the number of days elapsed from (and including)
       such preceding Section 4(b) Value Date to (but excluding) such Section
       4(b) Determination Date and the denominator of which is the number of
       days from (and including) such preceding Section 4(b) Value Date to (but
       excluding) the immediately following Section 4(b) Value Date.

<TABLE>
<CAPTION>
                         Section 4(b)                Section 4(b)
                         Value Date (2)            Prepayment Price
                         ----------                ----------------
                     <S>                             <C>
                     ___________, ____               $126,700,000
                     ___________, ____               $130,400,000
                     ___________, ____               $134,600,000
                     ___________, ____               $139,400,000
                     ___________, ____               $144,700,000
                     ___________, ____               $150,000,000
                     ___________, ____               $150,000,000
                     ___________, ____               $150,000,000
</TABLE>


- ---------------------------

   (2) The initial Section 4(b) Value Date shall be the date five years after
       the date of the Debenture, and succeeding Section 4(b) Value Dates shall
       occur annually thereafter until the Maturity Date.




                                       6
<PAGE>   98
              "Section 9 Prepayment Date" is defined in Section 9(b) of this
       Debenture.

              "Section 9 Purchase Price" means (i) at any time prior to five
       years from the date hereof, $126,700,000, (ii) at any date set forth in
       the table below (the "Section 9 Value Date"), the amount set forth
       opposite such Section 9 Value Date, and (iii) at any other date (the
       "Section 9 Determination Date"), the amount equal to the sum of (y) the
       Section 9 Purchase Price as of the Section 9 Value Date immediately
       preceding such Section 9 Determination Date plus (z) an amount equal to
       the product of (A) the difference between the Section 9 Purchase Price
       as of the Section 9 Value Date immediately following such Section 9
       Determination Date minus the Section 9 Purchase Price as of the Section
       9 Value Date immediately preceding such Section 9 Determination Date
       multiplied by (B) a fraction, the numerator of which is the number of
       days elapsed from (and including) such preceding Section 9 Value Date to
       (but excluding) such Section 9 Determination Date and the denominator of
       which is the number of days from (and including) such preceding Section
       9 Value Date to (but excluding) the immediately following Section 9
       Value Date.

<TABLE>
<CAPTION>
                         Section 9                       Section 9
                        Value Date (3)               Prepayment Price
                        ----------                   ----------------
                      <S>                               <C>
                      ___________, ____                 $126,700,000
                      ___________, ____                 $130,400,000
                      ___________, ____                 $134,600,000
                      ___________, ____                 $139,400,000
                      ___________, ____                 $144,700,000
                      ___________, ____                 $150,000,000
                      ___________, ____                 $150,000,000
                      ___________, ____                 $150,000,000
</TABLE>

              "Securities Act" means the Securities Act of 1933, as amended.

              "Senior Indebtedness" means principal of, and premium, if any,
       and interest on (including interest that, but for the filing of a
       petition initiating any Bankruptcy or Insolvency Proceeding, would
       accrue on such obligations at the rate provided in the agreements or
       instruments creating or evidencing the respective obligations, whether
       or not such claim is allowed or allowable in such Bankruptcy or
       Insolvency Proceeding) and all other amounts of every kind or




- ----------------------------

   (3) The initial Section 9 Value Date shall be the date five years after the
       date of the Debenture, and succeeding Section 9 Value Dates shall occur
       annually thereafter until the Maturity Date.

                                       7
<PAGE>   99
       nature (including, but not limited to, fees, indemnities and expenses)
       due on or in connection with any Indebtedness of Allied Canada, whether
       outstanding on the date of this Debenture or thereafter created,
       incurred, assumed or Guaranteed by Allied Canada (including all
       renewals, extensions or refundings of, or amendments, modifications or
       supplements to, the foregoing) unless, in the case of any particular
       Indebtedness, the instrument creating or evidencing the same or pursuant
       to which the same is outstanding expressly provides that such
       Indebtedness shall not be senior in right of payment to this Debenture.
       Without limiting the generality of the foregoing, "Senior Indebtedness"
       shall include (a) all obligations and liabilities of every kind and
       nature (including, but not limited to, fees, expenses and indemnities)
       under the Credit Facility, the Senior Subordinated Debentures or the
       Indenture, (b) all obligations and liabilities of every kind and nature
       (including, but not limited to, fees, expenses and indemnities) in
       respect of any interest rate swaps or other interest rate hedging
       product entered into in connection with Indebtedness incurred or to be
       incurred pursuant to the Credit Facility, and (c) any renewal,
       extension, refinancing or rearrangement of any Indebtedness incurred or
       to be incurred pursuant to the Credit Facility, the Senior Subordinated
       Debentures or the Indenture.  Notwithstanding the foregoing, Senior
       Indebtedness shall not include (i) amounts owed (except to banks,
       insurance companies and other financing institutions and except for
       obligations under Financing Leases) for goods, materials, services or
       operating lease rental payments in the ordinary course of business or
       for compensation to employees of Allied Canada, (ii) any liability for
       federal, state, provincial, local or other taxes owed or owing by Allied
       Canada and (iii) Indebtedness with respect to Allied Canada's Zero
       Coupon Junior Subordinated Debenture due 200_ dated the date hereof.

              "Senior Subordinated Debentures" means the ___% Senior
       Subordinated Debentures due 200__(4) in the aggregate original principal
       amount of at least $475,000,000 issued by Allied U.S. pursuant to the
       Indenture.

              "Stock Purchase Agreement" means the Stock Purchase Agreement
       dated as of September 17, 1996, among Allied, Allied Canada, Laidlaw and
       certain other parties named therein.

              "Subordinated Obligations" is defined in Subsection 5(a).

              "Subsidiary" of a Person means an Affiliate of that Person more
       than 50% of the aggregate voting power (or of any other form of voting
       equity interest in the case of a Person that is not a corporation) of
       which is beneficially owned by that Person directly or indirectly
       through one or more other Subsidiaries.




- --------------------------


    (4) The due date of the Senior Subordinated Debentures will be 10 years
        after the date of issuance.

                                       8
<PAGE>   100
              "Trustee" means ________________________________, a national
       banking association, in its capacity as trustee under the Indenture, and
       its successors in such capacity.

       (b)    Capitalized terms defined in this Debenture are equally
applicable to both their singular and plural forms.   References to a
designated "Section" or "Subsections" refer to a Section or Subsection of this
Debenture, unless otherwise specifically indicated.  In this Debenture,
"including" is used only to indicate examples, without limitation to the
indicated examples, and without limiting any generality which precedes it.

       2.     Interest Rate; Default Rate.  From (and including) the date of
this Debenture through (but not including) the earlier of the Maturity Date or
the date the maturity of this Debenture is accelerated pursuant to Section
8(a), interest shall accrue on the unpaid principal balance of this Debenture
at an annual fixed rate equal to 7% per annum.  All past due principal and
interest shall accrue interest at the Default Rate from (and including) the day
after the date such principal or interest is payable hereunder through (but not
including) the date of payment.  Interest will be calculated on the basis of
the actual number of days elapsed over a year composed of 365 days (or 366
days, as the case may be).

       3.     Payment Terms.  Subject to Section 5:

              (a)    The outstanding principal balance of this Debenture and
       all accrued and unpaid interest thereon shall be due and payable on the
       Maturity Date.

              (b)    During the period beginning on the date hereof and ending
       three years thereafter (the "Deferral Period"), interest on the
       outstanding principal balance of this Debenture will accrue but will be
       deferred.  During the Deferral Period, interest will be compounded
       semi-annually.  After the Deferral Period, at the election of Allied
       Canada, the deferred interest may be paid at any time, and (i) the
       aggregate unpaid amount, if any, of interest deferred during the
       Deferral Period, together with interest thereon at the rate of 7% per
       annum, will be payable in eighteen equal (or as nearly equal as
       possible) installments on the ___ day of each _______ and _______ of
       each year (beginning __________, __), and on the Maturity Date and (ii)
       interest on the outstanding principal balance of this Debenture will be
       due and payable in arrears on the _____ day of each ___________ and
       _____________  of each year (beginning ___________, ____), and on the
       Maturity Date for the period commencing on (and including) the later of
       the date following the last day of the Deferral Period





                                       9
<PAGE>   101
       or the date to which interest hereon has been paid, as the case may be,
       and ending on (but excluding) the date of payment. (5)

              (c)    Each payment or prepayment hereunder shall be made in cash
       by wire transfer to an account located in Canada designated by Laidlaw.

              (d)    Any payment or action that is due hereunder on a day which
       is not a Business Day shall be deferred until the next succeeding
       Business Day (but interest shall continue to accrue on any applicable
       payment until such payment is made).

       4.     Optional Redemption.

              (a)    Except to the extent provided in Section 9, this Debenture
       may not be redeemed or prepaid, in whole or in part, on or before the
       date which is five years after the date hereof.

              (b)    Thereafter, except as otherwise provided in Section 5,
       Allied Canada shall have the right and option (the "Section 4(b)
       Prepayment Option") to redeem and prepay this Debenture, in whole or in
       part, at a discount, on the terms and subject to the conditions of this
       Section 4(b).  Allied Canada may exercise the Section 4(b) Prepayment
       Option at any time by giving the holder of this Debenture written notice
       (the "Section 4(b) Prepayment Notice") of its election to exercise the
       Section 4(b) Prepayment Option and by specifying in the Section 4(b)
       Prepayment Notice the date on which Allied Canada will prepay this
       Debenture pursuant to this Section 4(b) (the "Section 4(b) Prepayment
       Date") and the principal amount of this Debenture to be prepaid.  The
       Section 4(b) Prepayment Date shall be at least 10 Business Days, and not
       more than 20 Business Days, after the date of the Section 4(b)
       Prepayment Notice.  Upon the Section 4(b) Prepayment Date, Allied Canada
       shall prepay this Debenture to the extent specified in the Section 4(b)
       Prepayment Notice, by payment of an amount equal to the product obtained
       by multiplying the Section 4(b) Prepayment Price as of the Section 4(b)
       Prepayment Date times the Section 4(b) Prepayment Fraction.

       5.     Subordination.

              (a)    The indebtedness evidenced by, and all obligations in
       respect of, this Debenture (including the obligations under Section 9)
       and the payment of principal of, premium and interest, if any, on and
       all other obligations in respect of, this Debenture (collectively, the
       "Subordinated Obligations") are expressly subordinate to all Senior
       Indebtedness to the extent and in the manner set forth




- ------------------------------


   (5) Installments of interest will be payable on a semi-annual basis
       commencing six months after the last day of the Deferral Period.

                                       10
<PAGE>   102
       herein.  For purposes hereof, the term "subordinate" means that, unless
       and until the Senior Indebtedness has been indefeasibly paid in full in
       cash, Laidlaw will not have the right under any circumstances to, and
       will not, take, demand, commence any suit or any other proceeding for
       collection, pursue any other judicial or non-judicial remedy or receive
       from Allied Canada or any of its Subsidiaries or Affiliates, and Allied
       Canada will not and will  not permit any of its Subsidiaries or
       Affiliates to, make, give, or permit, directly or indirectly, by set-
       off, redemption, purchase or in any other manner, any payment of or on
       account of the Subordinated Obligations; provided, however, that at any
       time, except during a Blockage Period, Allied Canada shall make, and
       Laidlaw may receive, and Laidlaw may commence any suit or other
       proceeding for collection of, scheduled payments of principal or
       interest on this Debenture in accordance with the terms hereof and,
       provided, further, that at any time, except during a Blockage Period,
       Allied Canada may prepay this Debenture so long as such prepayment would
       not cause the occurrence of a Blockage Period.  Upon the termination of
       any Blockage Period, the right of Laidlaw to receive payments (including
       payments not made during the Blockage Period) shall be reinstated, and
       Allied Canada shall resume making such payments to Laidlaw in accordance
       with the terms hereof.  In no event shall Allied Canada be obligated to
       make, and Allied Canada shall not make, and shall not permit any of its
       Subsidiaries or Affiliates to make, directly or indirectly, by set-off,
       redemption, purchase or in any other manner, any payments or prepayments
       of, or on account of, any of the Subordinated Obligations during any
       Blockage Period or if such payment or prepayment would cause the
       occurrence of a Blockage Period.

              (b)    Upon any payment or distribution of any kind or character
       to creditors of Allied Canada (whether in cash, property or securities)
       in (x) a total or partial liquidation, winding up or dissolution of
       Allied Canada (whether voluntarily or involuntarily) or (y) in a
       bankruptcy, reorganization, insolvency, receivership or similar
       proceeding (including a proceeding under the Canadian Companies'
       Creditors Arrangement Act) relating to Allied Canada or its property, or
       in an assignment for the benefit of creditors or any marshaling of
       Allied Canada's assets and liabilities (any of the foregoing in clauses
       (x) and (y) being referred to herein as a "Bankruptcy or Insolvency
       Proceeding"), the holders of Senior Indebtedness will be entitled to
       receive payment in full in cash of all the principal of and interest on
       and other amounts payable in respect of such Senior Indebtedness
       (including interest accruing after the commencement of any such
       proceeding at the rate specified in the agreements or instruments
       creating or evidencing the  applicable Senior Indebtedness and whether
       or not such interest is an allowed or allowable claim under applicable
       law) before Laidlaw will be entitled to receive any payment with respect
       to this Debenture (whether in cash, property or securities); and until
       all obligations with respect to Senior Indebtedness are indefeasibly
       paid in full in cash, any distribution received by Laidlaw or to which
       Laidlaw would be entitled shall be paid over or made to the holders of
       Senior Indebtedness.  Upon the occurrence of any Bankruptcy or
       Insolvency Proceeding relating to Allied Canada, the holders of





                                       11
<PAGE>   103
       the Senior Indebtedness are authorized and empowered to (i) demand, sue
       for, collect and receive every payment or distribution on account of the
       Subordinated Obligations payable or deliverable in connection with such
       event or proceeding and give acquittance therefor, and (ii) file claims
       and proofs of claim in any statutory or non- statutory proceeding and
       take such other actions as may be necessary or desirable for the
       enforcement of the subordination provisions of this Debenture.  Promptly
       after taking any action provided in clauses (i) or (ii) above, Allied
       Canada shall give written notice thereof to the holder of this
       Debenture; provided, however, that failure to give such notice shall in
       no event affect the validity of any action so taken.

              (c)    In the event that, notwithstanding the occurrence of any
       of the events described in Subsections 5(a) and (b), any such payment or
       distribution of assets of Allied Canada of any kind or character,
       whether in cash, property or securities, shall be received by the holder
       of this Debenture which is not permitted hereby such payment or
       distribution shall be held in trust for the ratable benefit of, and
       shall be paid over or delivered to, the holders of the Senior
       Indebtedness.

              (d)    The holders of the Senior Indebtedness shall have no duty
       or obligation to the holder of this Debenture in any manner whatsoever
       and may, at any time and from time to time, in their sole discretion,
       without the consent of or notice to the holder of this Debenture and
       without impairing or releasing any rights of the holders of the Senior
       Indebtedness or any of the obligations of the holder of this Debenture
       hereunder, take any or all of the following actions:

                     (i)    change the amount, manner, place, terms of payment
              or interest rate, change or extend the time of payment of, or
              renew or alter, any of the Senior Indebtedness, or amend or
              supplement or waive any of the terms of any instrument or
              agreement now or hereafter executed pursuant to which any of the
              Senior Indebtedness is issued or incurred;

                     (ii)   sell, exchange, release, surrender, relend, realize
              upon or otherwise deal with in any manner and in any order, any
              property (or the income, revenues, profits or proceeds therefrom)
              by whomsoever at any time pledged or mortgaged to secure, or
              howsoever securing, any Senior Indebtedness;

                     (iii)  release any person liable in any manner for the
              payment or collection of the Senior Indebtedness;

                     (iv)   exercise or refrain from exercising any rights and
              remedies against Allied Canada or others, or otherwise act or
              refrain from acting or, for any reason, fail to file, record or
              otherwise perfect any security interest in or lien on any
              property of Allied Canada or any other Person; and





                                       12
<PAGE>   104
                     (v)    apply any sums received by the holders of the
              Senior Indebtedness, by whomsoever paid and however realized, to
              payment of the Senior Indebtedness in such manner as the holders
              of the Senior Indebtedness, in their sole discretion, may deem
              appropriate.

              (e)    Laidlaw and any future holder of this Debenture, by
       acceptance of this Debenture, agree to provide to any holder of Senior
       Indebtedness, at any time and from time to time, upon the written
       request of Allied Canada or such holder of Senior Indebtedness an
       agreement signed by Laidlaw or such future holder of this Debenture
       addressed to the holder of such Senior Indebtedness in substantially the
       form of, and on substantially the terms set out in, Exhibit A attached
       hereto to the effect that such holder is a holder of Senior
       Indebtedness, that the holder or holders of such Senior Indebtedness are
       entitled to the benefits of Sections 5, 6 and 13 of this Debenture and
       that the holder or holders of such Senior Indebtedness may enforce the
       terms and provisions thereof to the same extent Allied Canada would be
       able to do so, provided, however, that prior to furnishing such
       agreement, Laidlaw has received from Allied Canada or such holder such
       information as Laidlaw may reasonably request demonstrating to Laidlaw's
       reasonable satisfaction that such holder is a holder of Senior
       Indebtedness.  Laidlaw, and each subsequent holder of this Debenture, by
       acceptance of this Debenture, irrevocably appoint Allied Canada (with
       full power of substitution) as its agent and attorney in fact (which
       appointment is coupled with an interest and shall be irrevocable so long
       as any Senior Indebtedness is outstanding) to execute and deliver on
       behalf and in the name of Laidlaw or such holder, as the case may be, an
       agreement in substantially the form of, and on substantially the terms
       set out in, Exhibit A hereto in favor of each such holder of Senior
       Indebtedness and to take such further action as may be necessary or
       appropriate to effectuate the subordination as provided herein.
       Promptly after exercise of any such power, Allied Canada will give
       written notice thereof to the holder of the Debenture; provided,
       however, that failure to give such notice shall in no event affect the
       validity of any power so exercised.

              (f)    If a Default shall have occurred and be continuing (other
       than a Default pursuant to Subsection 7(b) or (c)) and the holder of
       this Debenture elects to accelerate this Debenture pursuant to Section
       8, Laidlaw shall give the Representative under the Credit Facility 30
       days' prior written notice before accelerating this Debenture, which
       notice shall state that it is a "Notice of Intent to Accelerate";
       provided, however, that Laidlaw shall not be required to give such
       notice if at such time payment of any Indebtedness incurred pursuant to
       the Credit Facility shall have been accelerated.  If payment of this
       Debenture is accelerated because of a Default, the holder shall promptly
       notify the Representatives under the Designated Senior Indebtedness and
       the holders of all other Senior Indebtedness of the acceleration.

              (g)    Until all Senior Indebtedness has been indefeasibly paid
       in full in cash, the holders of this Debenture shall not be entitled to
       assert, enforce or





                                       13
<PAGE>   105
       otherwise exercise any right of subrogation against Allied Canada or any
       other Person obligated on the Subordinated Obligations.  After all
       Senior Indebtedness has been indefeasibly paid in full in cash, and
       until the Subordinated Obligations have been so paid in full, the holder
       of this Debenture shall be subrogated to the rights of holders of Senior
       Indebtedness to receive distributions applicable to Senior Indebtedness.
       A distribution made under this Section 5 to holders of Senior
       Indebtedness which otherwise would have been made to the holder of this
       Debenture is not, as between Allied Canada and the holder of this
       Debenture, a payment by Allied Canada on Senior Indebtedness.

              (h)    This Section 5 defines the relative rights of the holder
       of this Debenture and holders of Senior Indebtedness.  Nothing in this
       Debenture shall:

                     (i)    impair, as between Allied Canada and such holder,
              the obligation of Allied Canada, which is absolute and
              unconditional, to pay principal of and, premium and interest, if
              any, on this Debenture in accordance with its terms; or

                     (ii)   except as otherwise set forth in this Section 5,
              prevent the holder of this Debenture from exercising its
              available remedies upon a Default, subject to the rights of
              holders of Senior Indebtedness to receive distributions otherwise
              payable to such holder.

       6.     No Impairment.  Section 5, this Section 6, the proviso to
Subsection 8(a), and Section 13 (and all defined terms used in such sections)
shall constitute a continuing offer to all Persons who become holders of, or
continue to hold, Senior Indebtedness, and such provisions are made for the
benefit of the holders from time to time of Senior Indebtedness, and such
Persons are conclusively presumed to have relied upon such provisions; and such
holders are made obligees hereunder, and they or each of them may enforce such
provisions.  No right of any present or future holder of any Senior
Indebtedness to enforce the subordination or other provisions referred to in
this Section 6 shall at any time in any way be prejudiced or impaired by any
act or failure to act on the part of Allied Canada or Laidlaw, or by any
non-compliance by Allied Canada or Laidlaw with the terms, provisions and
covenants of this Debenture, regardless of any knowledge thereof any such
holder may have or otherwise be charged with.  Section 5, this Section 6 and
the subordination and other provisions referred to in this Section 6 may not be
amended or modified in any manner which might terminate or impair the
subordination or such other provisions except with the prior written consent of
the Representatives of all the Designated Senior Indebtedness.

       7.     Events of Default.  "Default" means the occurrence of one or more
              of the following:

              (a)    Payment.  Allied Canada fails to pay the outstanding
       principal amount of this Debenture on the Maturity Date.





                                       14
<PAGE>   106
              (b)    Voluntary Bankruptcy.  Allied Canada (i) files a petition
       initiating a voluntary Bankruptcy or Insolvency Proceeding, (ii) seeks,
       consents to, or does not contest the appointment of a receiver or
       trustee for itself or for all or any substantial part of its property,
       (iii) is voluntarily adjudicated a bankrupt or insolvent, (iv) makes a
       general assignment for the benefit of its creditors, or (v) admits in
       writing its inability to pay its debts as they mature.

              (c)    Involuntary Bankruptcy.  A petition is filed against
       Allied Canada seeking to initiate a Bankruptcy or Insolvency Proceeding
       and such petition is not dismissed within 180 days after being filed, or
       a court of competent jurisdiction enters an order, judgment or decree
       appointing a receiver or trustee for Allied Canada, or for all or
       substantially all of its property, and such order, judgment or decree is
       not discharged or stayed within 180 days after its entry.

              (d)    Acceleration of Other Indebtedness.  An event of default
       occurs and is continuing under the Credit Facility and, as a result
       thereof, the Indebtedness outstanding pursuant to the Credit Facility is
       accelerated; provided, however, that in the event the holders of such
       Indebtedness elect to waive such event of default or to otherwise
       de-accelerate such Indebtedness, no Default shall subsist hereunder.

       8.     Remedies of Laidlaw.  Upon the occurrence and during the
continuance of a Default, Laidlaw shall have the following rights:

              (a)    Acceleration.  Subject to the provisions of Section 5
       hereof, Laidlaw may, at its option, declare the entire principal balance
       of this Debenture, together with the accrued and unpaid interest
       thereon, immediately due and payable without notice of Default, notice
       of intent to accelerate, notice of acceleration, or any other notice,
       presentment, protest, demand or action of any kind or nature whatsoever
       (each of which is hereby expressly waived by Allied Canada), whereupon
       the entire Indebtedness under this Debenture shall become immediately
       due and payable; provided, however, that no such acceleration (except
       for an acceleration upon the occurrence of a Default specified in
       Subsection 7(d)) shall be effective or of any force whatsoever and the
       holder of this Debenture may not take any action against Allied Canada
       with respect to a Default hereunder if made during a Blockage Period, or
       if such acceleration would result in a Blockage Period; provided,
       further, that in the event the Indebtedness under this Debenture is
       accelerated upon the occurrence of a Default specified in Subsection
       7(d) and the holders of the Indebtedness outstanding pursuant to the
       Credit Facility elect to waive the event of default giving rise to the
       acceleration thereunder or otherwise elect to de-accelerate such
       Indebtedness, Laidlaw shall de-accelerate the obligations hereunder.

              (b)    Other Rights.  Except as otherwise modified hereby,
       Laidlaw shall have all rights and remedies available at law or equity
       and the same (i) shall be cumulative and concurrent, (ii) may be pursued
       separately, successively, or





                                       15
<PAGE>   107
       concurrently against Allied Canada, (iii) may be exercised as often as
       occasion therefor shall arise, it being agreed by Allied Canada that the
       exercise or failure to exercise any of the same shall in no event be
       construed as a waiver or release thereof or of any other right or
       remedy, and (iv) are intended to be, and shall be, nonexclusive.

       9.     Offer of Prepayment upon Change of Control.

              (a)    Allied Canada will, within thirty business days after any
       executive officer of Allied Canada has knowledge of the occurrence of a
       Change of Control, give written notice of such Change of Control to the
       holder of this Debenture.  Subject to the provisions of Section 5, such
       notice shall contain and constitute an offer to prepay this Debenture as
       described in Subsection 9(b).

              (b)    The offer to prepay this Debenture contemplated by
       Subsection 9(a) shall be an offer to prepay, in accordance with and
       subject to this Section 9, all, but not less than all, of this Debenture
       at the Section 9 Purchase Price, together with all interest accrued and
       unpaid hereon, on a date specified in such offer (the "Section 9
       Prepayment Date") which date shall be not less than 45 days and not more
       than 60 days after the date of such offer (if the Section 9 Prepayment
       Date shall not be specified in such offer, the Section 9 Prepayment Date
       shall be the first business day after the 45th day after the date of
       such offer).

              (c)    The holder of this Debenture may accept the offer to
       prepay made pursuant to this Section 9 in whole but not in part by
       causing a notice of such acceptance to be delivered to Allied Canada
       within ten business days after receipt of the written notice to be given
       pursuant to Subsection 9(a).  A failure by a holder of this Debenture to
       respond within such time period to an offer to prepay made pursuant to
       this Section 9 shall be deemed to constitute a rejection of such offer.

              (d)    Prepayment of this Debenture pursuant to this Section 9
       shall be at the Section 9 Purchase Price.  The prepayment shall be made
       on the Section 9 Prepayment Date.

              (e)    Notwithstanding any provision hereof to the contrary, in
       no event shall Allied Canada prepay (or be obligated to prepay)  this
       Debenture pursuant to this Section 9 until 91 days after Allied Canada
       shall have prepaid the Senior Indebtedness incurred pursuant to the
       Credit Facility and the Senior Subordinated Debentures, and all other
       Senior Indebtedness which is entitled to be prepaid upon the occurrence
       of a Change of Control, unless the holder or holders of such Senior
       Indebtedness have waived or otherwise failed to enforce their rights to
       receive a prepayment of the Senior Indebtedness held by them to which
       they are entitled in connection with such Change of Control.





                                       16
<PAGE>   108
       10.    Captions.  The captions, headings, and arrangements used in this
Debenture are for convenience only and do not affect or modify the terms of
this Debenture.

       11.    Notices.  All notices or other communications which are required
or may be given under this Debenture shall be in writing and shall be deemed to
have been duly given when delivered in person or transmitted by telecopier
(with receipt confirmed) at the address or telecopy number set forth below (as
any such address or telecopier number may be changed from time to time by
notice similarly given):



       (1)    if to Laidlaw, to:

                     Laidlaw Inc.
                     3221 North Service Road
                     Burlington, Ontario
                     Canada L7R 3Y8
                     Attention:  Ivan R. Cairns
                     Telecopy No.: (905) 332-6550

       (2)    if to Allied Canada, to:

                     3294862 CANADA INC.
                     c/o Allied Waste Industries, Inc.
                     7201 East Camelback Road, Suite 375
                     Scottsdale, Arizona 85251
                     Attention: Roger A. Ramsey
                     Telecopy No.: (602) 481-9347

                     with a copy to:

                     Porter & Hedges, L.L.P.
                     700 Louisiana Street, Suite 3500
                     Houston, Texas 77002
                     Attention: Robert G. Reedy
                     Telecopy No.: (713) 228-1331


       12.    Applicable Law.  This Debenture shall be governed by and
construed in accordance with the laws of the State of Delaware and the laws of
the United States of America applicable therein (without reference to the
conflicts of law principles thereof).

       13.    Transfer Restriction.  This Debenture may not be sold, assigned,
transferred, pledged or hypothecated in any manner, directly or indirectly, by
Laidlaw or any other holder, unless the assignee, transferee, pledgee or
hypothecate has agreed in writing to be bound by the provisions of this
Debenture applicable to Laidlaw, including but not limited to the provisions of
Section 5(e) and Section 14 hereof.  Any transfer of this Debenture shall be of
the entire Debenture and not of any part of the





                                       17
<PAGE>   109
indebtedness evidenced hereby or of at least $75,000,000 of the principal
amount thereof.

       NOTICE:  THE RIGHTS AND OBLIGATIONS OF ALLIED CANADA AND LAIDLAW SHALL
BE DETERMINED SOLELY FROM WRITTEN AGREEMENTS, DOCUMENTS, AND INSTRUMENTS, AND
ANY PRIOR ORAL AGREEMENTS BETWEEN ALLIED CANADA AND LAIDLAW ARE SUPERSEDED BY
AND MERGED INTO SUCH WRITINGS.  THIS DEBENTURE (AS AMENDED IN WRITING FROM TIME
TO TIME) REPRESENTS THE FINAL AGREEMENT BETWEEN ALLIED CANADA AND LAIDLAW AND
MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR OR CONTEMPORANEOUS ORAL AGREEMENTS
BY ALLIED CANADA AND LAIDLAW. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN
ALLIED CANADA AND LAIDLAW.



                                   3294862 CANADA INC.
                                   a Canadian corporation


                                   By:                                         
                                      -----------------------------------------
                                   Name:                                       
                                        ---------------------------------------
                                   Title:                                      
                                         --------------------------------------

Agreed and Accepted:

LAIDLAW INC.
a Canadian corporation


By:                                                
   -------------------------------------
Name:                                             
     -----------------------------------
Title:                                              
      ----------------------------------





                                       19
<PAGE>   110
                                                                       EXHIBIT A
                                                   to the 7% Junior Subordinated
                                                   Debenture Due 200__ Issued by
                                                             3294862 Canada Inc.
                                                        in favor of Laidlaw Inc.


                                     [Date]


- --------------------

- --------------------

- --------------------



Gentlemen:

       Reference is made to the 7% Junior Subordinated Debenture Due 200__
dated __________, 199_ (the "Subordinated Debenture"), in the original
principal amount of $150 million issued by 3294862 CANADA INC., a Canadian
corporation ("Allied Canada"), in favor of Laidlaw Inc., a Canadian
corporation, and the [describe Senior Indebtedness] (the "Subject
Indebtedness"), being issued contemporaneously herewith by Allied Canada in
favor of [identity of holder or holders of Subject Indebtedness] (whether one
or more, the "Senior Creditor").  Hereinafter, capitalized words and phrases
used herein which are defined in the Subordinated Debenture are used herein as
therein defined.

       The undersigned (the "Subordinated Creditor") hereby represents and
warrants to the Senior Creditor that the Subordinated Creditor is the owner and
holder of the Subordinated Debenture and that the Subordinated Creditor is
entitled to make the agreements herein contained.  The Subordinated Creditor
hereby acknowledges and agrees that the principal of, and premium, if any, and
interest on (including interest that, but for the filing of a petition
initiating any Bankruptcy or Insolvency Proceeding would accrue on such
obligations at the time provided in the agreements or instruments creating or
evidencing the respective obligations, whether or not such claim is allowed in
such Bankruptcy or Insolvency Proceeding) and all other amounts of every kind
or nature (including, but not limited to, fees, indemnities and expenses and
any interest rate swaps or other interest rate hedging products entered into in
connection with the Subject Indebtedness) due on or in connection with the
Subject Indebtedness, whether outstanding on the date hereof or hereafter
created, incurred or assumed, guaranteed or in effect guaranteed by Allied
Canada (including all renewals, extensions or refundings of, or amendments,
modifications or supplements to, the foregoing) are in all respects Senior
Indebtedness, that the Senior Creditor (and any other Person who from time to
time is a holder of the Subject Indebtedness) is entitled to the benefits of
Sections 5, 6 and 13 of the Subordinated Debenture and that the Senior Creditor
(and any other Person who from time to time is a holder of the Subject
Indebtedness) may enforce the





                                      A-1
<PAGE>   111
terms and provisions of the Subordinated Debenture to the same extent that
Allied Canada or any other holder of Senior Indebtedness would be able to do
so.

       The Subordinated Creditor hereby agrees that the Subordinated Debenture
will not be sold, assigned, transferred, pledged or hypothecated in any manner,
directly or indirectly, by the Subordinated Creditor, unless the assignee,
transferee, pledgee or hypothecate has agreed in writing to be bound by the
provisions of this agreement.

       The Subordinated Creditor has executed this agreement in the space
provided below in order to induce the Senior Creditor to advance funds or
extend credit to Allied Canada, and this agreement is intended by the
Subordinated Creditor to be a binding and enforceable undertaking by the
Subordinated Creditor in favor of the Senior Creditor.

       The rights credited hereby of the Senior Creditor and of any subsequent
holder of the Senior Indebtedness will be assigned automatically, and without
any further act, by the Senior Creditor or such holder upon any sale,
assignment, conveyance or other transfer of all or any part of the Senior
Indebtedness to the extent of the interest sold, assigned, conveyed or
otherwise transferred, unless and to the extent the Senior Creditor or such
holder expressly provides otherwise in the instrument pursuant to which such
interest is conveyed.




                                           Very truly yours,

                                           [NAME OF SUBORDINATED CREDITOR]


                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------



Accepted and agreed to as of
the date first above written:

[NAME OF SENIOR CREDITOR]


By:                                 
   ---------------------------------
Name:                               
     -------------------------------
Title:                              
      ------------------------------





                                      A-2
<PAGE>   112






                                                                     EXHIBIT A-2

THIS DEBENTURE HAS NOT BEEN REGISTERED (OR QUALIFIED BY PROSPECTUS) UNDER THE
SECURITIES ACT (DEFINED BELOW), THE CANADIAN SECURITIES LEGISLATION (DEFINED
BELOW), OR THE LAWS OF ANY STATE OF THE UNITED STATES OF AMERICA, AND THIS
DEBENTURE MAY NOT BE OFFERED FOR SALE, SOLD, TRANSFERRED, PLEDGED, HYPOTHECATED
OR OTHERWISE DISPOSED OF EXCEPT IN ACCORDANCE WITH THE TERMS HEREOF AND THE
REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF THE SECURITIES ACT, THE
CANADIAN SECURITIES LEGISLATION AND SUCH STATE LAWS OTHER THAN PURSUANT TO AN
EXEMPTION FROM SUCH REGISTRATION AND PROSPECTUS REQUIREMENTS AND UPON DELIVERY
TO ALLIED CANADA OF AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO ALLIED
CANADA TO THE EFFECT THAT SUCH TRANSFER IS EXEMPT FROM REGISTRATION AND THE
PROSPECTUS DELIVERY REQUIREMENTS UNDER THOSE LAWS.

THIS DEBENTURE WILL BE ISSUED WITH ORIGINAL ISSUE DISCOUNT ("OID").  THE HOLDER
OF THIS DEBENTURE SHOULD BE AWARE THAT SUCH HOLDER WILL BE REQUIRED TO INCLUDE
OID IN SUCH HOLDER'S GROSS INCOME FOR INCOME TAX PURPOSES IN ADVANCE OF THE
RECEIPT OF CASH ATTRIBUTABLE TO SUCH INCOME.  WITH RESPECT TO OID, THE ISSUE
DATE OF THIS DEBENTURE IS _________________, 199__, THE ISSUE PRICE IS
[$_________], THE AMOUNT OF OID IS [$_________], AND THE YIELD TO MATURITY IS
[______]%.

              ZERO COUPON JUNIOR SUBORDINATED DEBENTURE DUE 200__(1)


$168,300,000                                            _________________, 199__



       FOR VALUE RECEIVED, 3294862 CANADA INC., a Canadian corporation ("Allied
Canada"), promises to pay to Laidlaw Inc., a Canadian corporation ("Laidlaw"),
or its registered assigns, the amount of $168,300,000 on the Maturity Date.






- ----------------------------------

   (1) The due date will be 12 years after the date of issuance.
<PAGE>   113
              1.     Definitions.

              (a)    For all purposes of this Debenture:

              "Accreted Value" means (i) at any date set forth in the table
       below (the "Value Date"), the amount set forth opposite such Value Date,
       and (ii) at any other date (the "Determination Date"), the amount equal
       to the sum of (y) the Accreted Value as of the Value Date immediately
       preceding such Determination Date plus (z) an amount equal to the
       product of (A) the difference between the Accreted Value as of the Value
       Date immediately following such Determination Date minus the Accreted
       Value as of the Value Date immediately preceding such Determination Date
       multiplied by (B) a fraction, the numerator of which is the number of
       days elapsed from (and including) such preceding Value Date to (but
       excluding) such Determination Date and the denominator of which is the
       number of days from (and including) such preceding Value Date to (but
       excluding) the immediately following Value Date.

<TABLE>
<CAPTION>
                                          Value Date(2)             Accreted Value
                                          ----------                --------------
                                   <S>         <C>                     <C>
                                   ___________, ____                   $ 33,200,000

                                   ___________, ____                   $ 38,000,000

                                   ___________, ____                   $ 43,500,000
                                   ___________, ____                   $ 49,800,000

                                   ___________, ____                   $ 57,000,000
                                   ___________, ____                   $ 65,300,000

                                   ___________, ____                   $ 74,700,000
                                   ___________, ____                   $ 85,500,000

                                   ___________, ____                   $ 98,000,000
                                   ___________, ____                   $112,100,000

                                   ___________, ____                   $128,400,000
                                   ___________, ____                   $147,000,000

                                   ___________, ____                   $168,300,000
</TABLE>


              "Affiliate" means, with respect to any Person, another Person
       that directly, or indirectly through one or more intermediaries,
       controls, is controlled by or is under common control with such Person,
       with the term "control," including the terms "controlling" and
       "controlled," meaning for purposes of this definition, the power to






- ----------------------------------

   (2) The initial Value Date shall be the date of the Debenture, and
       succeeding Value Dates shall occur each year thereafter until the
       Maturity Date.
<PAGE>   114
       direct the management and policies of a Person, directly or indirectly,
       whether through the ownership of voting securities or partnership or
       other ownership interests, or by contract or otherwise.

              "Allied" means Allied Waste Industries, Inc., a Delaware
       corporation, and its successors and assigns.

              "Allied Canada" means 3294862 Canada Inc. a Canadian corporation,
       and its successors and assigns.

              "Allied Common Stock" means the Common Stock, $.01 par value per
       share, of Allied.

              "Allied U.S." means Allied Holdings (United States), Inc., a
       Delaware corporation, and its successors and assigns.

              "Allied Warrant" means the warrant for the purchase of shares of
       Allied Common Stock to be issued by Allied to Laidlaw under Section 2.3
       of the Stock Purchase Agreement.

              "Bankruptcy or Insolvency Proceeding" is defined in Subsection
       4(b) of this Debenture.

              "Blockage Period" means any period when a default or an event of
       default  or an event which, with the giving of notice or the lapse of
       time or both, would constitute a default or an event of default has
       occurred and is continuing under the terms of the Credit Facility or the
       Senior Subordinated Debentures or under the terms of any agreement or
       instrument pursuant to which any other Designated Senior Indebtedness is
       created, issued, evidenced, secured or guaranteed.

              "Business Day" means a day other than Saturday, Sunday or any day
       on which banks located in Toronto, Ontario or New York, New York are
       authorized or obligated to close.

              "Canadian Securities Legislation" means the Securities Act of the
       Province of Ontario (R.S.O. 1990, c.  S.5, as amended) and similar
       provincial legislation, and the regulations and rules promulgated
       thereunder.

              "Change of Control" means a change resulting when any Unrelated
       Person or any Unrelated Persons acting together that would constitute a
       Group together with any Affiliates thereof (in each case also
       constituting Unrelated Persons) shall at any time Beneficially Own more
       than 50% of the aggregate voting power of all classes of Voting Stock of
       Allied; provided, however, that if at the date any "Change of Control"
       would otherwise have occurred but for the fact that a Person was not an
       Unrelated Person because such Person or an Affiliate of such Person
       acquired shares of Allied Common Stock or all or any portion of the
       Allied Warrant from Laidlaw or from any Affiliate





 
<PAGE>   115
       of Laidlaw within nine months prior to such date, such shares of Allied
       Common Stock acquired from Laidlaw or any Affiliate of Laidlaw, or any
       shares of Allied Common Stock issued upon exercise of the Allied Warrant
       or any portion thereof, shall at all times thereafter be excluded when
       calculating whether a Change of Control has occurred.  As used in this
       definition of Change of Control (a) "Beneficially Own" means
       "beneficially own" as defined in Rule 13d-3 of the Securities Exchange
       Act of 1934, as amended (the "Exchange Act"), or any successor
       provisions thereto; provided, however, that, for purposes of this
       definition, a Person shall not be deemed to Beneficially Own securities
       tendered pursuant to a tender or exchange offer made by or on behalf of
       such Person or any of such Person's Affiliates until such tendered
       securities are accepted for purchase or exchange; (b) "Group" means a
       "group" for purposes of Section 13(d) of the Exchange Act; (c)
       "Affiliate" means, with respect to any Person, another Person which
       would be an "affiliate" of such Person for purposes of Section 13(d) of
       the Exchange Act; (d) "Unrelated Person" means at any time any Person
       other than Laidlaw, any Person to whom Laidlaw or any of its Affiliates
       transfers, within nine months prior to such time, any shares of Allied
       Common Stock or all or any portion of the Allied Warrant or any
       Affiliate of Polaris or any such Person; provided, however, that Persons
       (other than Polaris or its Affiliates) to whom Laidlaw or any of its
       Affiliates transfers any shares of Allied Common Stock or all or any
       portion of the Allied Warrant after five years from the date hereof
       shall not be deemed Unrelated Persons; and (e) "Voting Stock" of any
       Person shall mean capital stock of such Person which ordinarily has
       voting power for the election of directors (or persons performing
       similar functions) of such Person, whether at all times or only so long
       as no senior class of securities has such voting power by reason of any
       contingency.

              "Credit Facility" means the Credit Agreement dated as of
       ___________, 199_ among Allied U.S., as borrower, Allied, Goldman Sachs
       Credit Partners L.P., as syndication agent, Citibank, N.A., as
       documentation agent, Credit Suisse, as administrative agent, Goldman
       Sachs Credit Partners L.P., Citicorp USA, Inc. and Credit Suisse, as
       initial lenders, and the other financial institutions now or hereafter
       parties thereto (as the same may be renewed, amended, modified,
       increased, extended, refinanced, or otherwise supplemented from time to
       time).

              "Debenture" means this Zero Coupon Junior Subordinated Debenture
       due 200__.

              "Default" is defined in Section 6.

              "Default Rate" means an annual interest rate equal to 9% per 
       annum.

              "Designated Senior Indebtedness" means (i) the Senior
       Indebtedness incurred with respect to the Credit Facility, (ii) the
       Senior Indebtedness evidenced by the Senior Subordinated Debentures and
       (iii) any other Senior Indebtedness which is incurred pursuant to an
       agreement (or series of related agreements simultaneously entered into)
       providing for Indebtedness, or commitments to lend, of at least
       $10,000,000 at the time





 
<PAGE>   116
       of determination and is specifically designated in the instrument
       evidencing such Senior Indebtedness or the agreement under which such
       Senior Indebtedness arises as "Designated Senior Indebtedness."

              "$" means U.S. dollars, the lawful currency of the United States
       of America.

              "Financing Lease"  means any lease of property, real or personal,
       the obligations of the lessee in respect of which are required in
       accordance with generally accepted accounting principles to be
       capitalized on a balance sheet of the lessee.

              "Governmental Entity" means any U.S. or Canadian, territorial,
       federal, state, provincial or local court, executive office,
       legislature, governmental agency, department, ministry, commission, or
       administrative, regulatory or self-regulatory authority or
       instrumentality.

              "Guarantee" means with respect to any Person any obligation,
       contingent or otherwise, of such Person guaranteeing or having the
       economic effect of guaranteeing any Indebtedness of any other Person
       (the "primary obligor") in any manner, whether directly or indirectly,
       and including any obligation of such Person, direct or indirect, (a) to
       purchase or pay (or advance or supply funds for the purchase or payment
       of ) such Indebtedness or to purchase (or to advance or supply funds for
       the purchase of) any security for the payment of such Indebtedness, (b)
       to purchase or lease property, securities or services for the purpose of
       assuring the owner of such Indebtedness of the payment of such
       Indebtedness or (c) to maintain working capital, equity capital or any
       other financial statement condition or liquidity of the primary obligor
       so as to enable the primary obligor to pay such Indebtedness; provided,
       however, that the term "Guarantee" shall not include endorsements for
       collection or deposit in the ordinary course of business.

              "Indebtedness" means with respect to any Person at any date, (a)
       all indebtedness of such Person for borrowed money or for the deferred
       purchase price of property or services (other than current trade
       liabilities incurred in the ordinary course of business and payable in
       accordance with customary practices), (b) any other indebtedness of such
       Person which is evidenced by a note, bond, debenture, letter of credit
       or similar instrument, (c) all obligations of such Persons with respect
       to Guarantees, (d) all obligations of such Person under Financing
       Leases, (e) all obligations of such Person in respect of acceptances
       issued or created for the account of such Person (other than
       endorsements in the ordinary course of business),  (f) all obligations
       in respect of interest rate swaps or other interest rate hedging
       products or foreign currency exchange agreements or exchange rate
       hedging arrangements, (g) all obligations in respect of reimbursement
       obligations under letters of credit, and (h) all liabilities of the type
       referred to in clauses (a) through (g) above that are secured by any
       lien, charge, security interest or encumbrance on any property owned by
       such Person even though such Person has not assumed or otherwise become
       liable for the payment thereof.





 
<PAGE>   117
              "Indenture" means the Indenture dated _____________, 199__,
       between Allied U.S. and the Trustee pursuant to which the Senior
       Subordinated Debentures are issued.

              "Laidlaw" means Laidlaw Inc., a Canadian corporation.

              "LTI" means Laidlaw Transportation, Inc., a Delaware corporation.

              "Maturity Date" _________________, 200__ [12 years after the date
hereof].

              "Offset Letter Agreement" means the letter agreement dated the
       date hereof among Allied, 3294862 Canada Inc., Laidlaw and LTI, in
       substantially the form of Exhibit N to the Stock Purchase Agreement.

              "Person" means an individual, corporation, partnership,
       association, joint stock company, limited liability company,
       Governmental Entity, business trust, unincorporated organization, or
       other legal entity.

              "Representative" means at any date, with respect to the Credit
       Facility, the Person or Persons then acting as the administrative agent
       under the Credit Facility, with respect to the Senior Subordinated
       Debentures, the Trustee, and with respect to any other Designated Senior
       Indebtedness, the holders of such Designated Senior Indebtedness or any
       Person acting as agent of such holders at such date.

              "Section 8 Prepayment Date" is defined in Section 8(b) of this 
       Debenture.

              "Securities Act" means the Securities Act of 1933, as amended.

              "Senior Indebtedness" means principal of, and premium, if any,
       and interest on (including interest that, but for the filing of a
       petition initiating any proceeding pursuant to any Bankruptcy or
       Insolvency Proceeding, would accrue on such obligations at the rate
       provided in the agreements or instruments creating or evidencing the
       respective obligations, whether or not such claim is allowed or
       allowable in such Bankruptcy or Insolvency Proceeding) and all other
       amounts of every kind or nature (including, but not limited to, fees,
       indemnities and expenses) due on or in connection with, any Indebtedness
       of Allied Canada, whether outstanding on the date of this Debenture or
       thereafter created, incurred, assumed or Guaranteed by Allied Canada
       (including all  renewals, extensions or refundings of, or amendments,
       modifications or supplements to, the foregoing) unless, in the case of
       any particular Indebtedness, the instrument creating or evidencing the
       same or pursuant to which the same is outstanding expressly provides
       that such Indebtedness shall not be senior in right of payment to this
       Debenture.  Without limiting the generality of the foregoing, "Senior
       Indebtedness" shall include (a) all obligations and liabilities of every
       kind and nature (including, but not limited to, fees, expenses and
       indemnities) under the Credit Facility or the Senior Subordinated
       Indebtedness, (b) all obligations and liabilities of every kind and
       nature (including, but not limited to, fees, expenses and indemnities)
       in respect of any interest rate swaps or other interest rate hedging
       product entered into in connection with Indebtedness incurred





 
<PAGE>   118
       or to be incurred pursuant to the Credit Facility, and (c) any renewal,
       extension, refinancing or rearrangement of any indebtedness incurred or
       to be incurred pursuant to the Credit Facility or the Senior
       Subordinated Indebtedness. Notwithstanding the foregoing, Senior
       Indebtedness shall not include (i) amounts owed (except to banks,
       insurance companies and other financing institutions and except for
       obligations under Financing Leases) for goods, materials, services or
       operating lease rental payments in the ordinary course of business or
       for compensation to employees of Allied Canada, (ii) any liability for
       federal, state, provincial, local or other taxes owed or owing by Allied
       Canada and (iii) Indebtedness with respect to Allied Canada's 7% Junior
       Subordinated Debentures due 200_ dated the date hereof and the Guaranty
       thereof by the Guarantor.

              "Senior Subordinated Debentures" means the ___% Senior
       Subordinated Debentures due 200_(3) in the aggregate original principal
       amount of at least $475,000,000 issued by Allied U.S. pursuant to the
       Indenture.

              "Stock Purchase Agreement" means the Stock Purchase Agreement
       dated as of September 17, 1996, among Allied, Allied Canada, Laidlaw and
       certain other parties named therein.

              "Subordinated Obligations" is defined in Subsection 4(a).

              "Subsidiary" of a Person means an Affiliate of that Person more
       than 50% of the aggregate voting power (or of any other form of voting
       equity interest in the case of a Person that is not a corporation) of
       which is beneficially owned by that Person directly or indirectly
       through one or more other Subsidiaries.

              "Trustee" means ________________________________, a national
       banking association, in its capacity as trustee under the Indenture, and
       its successors in such capacity.

       (b)    Capitalized terms defined in this Debenture are equally
applicable to both their singular and plural forms.   References to a
designated "Section" or "Subsections" refer to a Section or Subsection of this
Debenture, unless otherwise specifically indicated.  In this Debenture,
"including" is used only to indicate examples, without limitation to the
indicated examples, and without limiting any generality which precedes it.

       2.     Interest; Default Rate.  From (and including) the date of this
Debenture through (and including) the Maturity Date, no interest shall accrue
or be payable with respect to this Debenture.  All past due principal of this
Debenture shall accrue interest at the Default Rate from (but not including)
the Maturity Date through (but not including) the date of payment.  From and
after the Maturity Date, interest will be calculated on the basis of the actual
number of days elapsed over a year composed of 365 days (or 366 days, as the
case may be).






- ----------------------------------

    (3) The due date of the Senior Subordinated Debentures will be 10 years
        after the date of issuance.

 
<PAGE>   119
       3.     Payment Terms.  Subject to Section 4:

              (a)    The outstanding principal balance of this Debenture and
       all accrued and unpaid interest thereon shall be due and payable on the
       Maturity Date.

              (b)    No interest is payable with respect to the principal
       amount of this Debenture prior to the Maturity Date.   After the
       Maturity Date, interest will be payable in arrears on the ________ day
       of each ___________ and ____________ of each year on the principal
       balance of this Debenture outstanding from time to time.(4)

              (c)    Each payment or prepayment hereunder shall be made by wire
       transfer to an account located in Canada designated by Laidlaw.

              (d)    Any payment or action that is due hereunder on a day which
       is not a Business Day shall be deferred until the next succeeding
       Business Day (but interest shall continue to accrue on any applicable
       payment until such payment is made).

       4.     Subordination.

              (a)    The indebtedness evidenced by, and all obligations in
       respect of, this Debenture (including the obligations under Section 8)
       and the payment of principal of, premium and interest, if any, on and
       all other obligations in respect of, this Debenture (collectively, the
       "Subordinated Obligations") are expressly subordinate to all Senior
       Indebtedness to the extent and in the manner set forth herein.  For
       purposes hereof, the term "subordinate" means that, unless and until the
       Senior Indebtedness has been indefeasibly paid in full in cash, Laidlaw
       will not have the right under any circumstances to, and will not, take,
       demand, commence any suit or any other proceeding for collection, pursue
       any other judicial or non-judicial remedy or receive from Allied Canada
       or any of its Subsidiaries or Affiliates, and Allied Canada will not and
       will  not permit any of its Subsidiaries or Affiliates to, make, give,
       or permit, directly or indirectly, by set-off, redemption, purchase or
       in any other manner, any payment of or on account of the Subordinated
       Obligations; provided, however, that at any time, except during a
       Blockage Period, Allied Canada shall make, and Laidlaw may receive, and
       Laidlaw may commence any suit or other proceeding for collection of,
       scheduled payments of principal or interest on this Debenture in
       accordance with the terms hereof and, provided, further, that at any
       time, except during a Blockage Period, Allied Canada may prepay this
       Debenture so long as such prepayment would not cause the occurrence of a
       Blockage Period.  Upon the termination of any Blockage Period, the right
       of Laidlaw to receive payments shall be reinstated, and Allied Canada
       shall resume making such payments to Laidlaw in accordance with the
       terms hereof.  In no event shall Allied Canada be obligated to make, and
       Allied Canada shall not make, and shall not permit any of its
       Subsidiaries or Affiliates to make, directly or indirectly, by set-off,
       redemption, purchase or in any other manner, any payments or prepayments
       of,





- ----------------------------------

   (4) Interest will be payable each six months after the Maturity Date.

 
<PAGE>   120
       or on account of, any of the Subordinated Obligations during any
       Blockage Period or if such payment or prepayment would cause the
       occurrence of a Blockage Period.

              (b)    Upon any payment or distribution of any kind or character
       to creditors of Allied Canada (whether in cash, property or securities)
       in (x) a total or partial liquidation, winding up or dissolution of
       Allied Canada (whether voluntarily or involuntarily) or (y) in a
       bankruptcy, reorganization, insolvency, receivership or similar
       proceeding (including a proceeding under the Canadian Companies'
       Creditors Arrangement Act) relating to Allied Canada or its property, or
       in an assignment for the benefit of creditors or any marshaling of
       Allied Canada's assets and liabilities (any of the foregoing in clauses
       (x) and (y) being referred to herein as a "Bankruptcy or Insolvency
       Proceeding"), the holders of Senior Indebtedness will be entitled to
       receive payment in full in cash of all the principal of and interest on
       and other amounts payable in respect of such Senior Indebtedness
       (including interest accruing after the commencement of any such
       proceeding at the rate specified in the agreements or instruments
       creating or evidencing the  applicable Senior Indebtedness and whether
       or not such interest is an allowed or allowable claim under applicable
       law) before Laidlaw will be entitled to receive any payment with respect
       to this Debenture (whether in cash, property or securities); and until
       all obligations with respect to Senior Indebtedness are paid in full in
       cash, any distribution received by Laidlaw or to which Laidlaw would be
       entitled shall be paid over or made to the holders of Senior
       Indebtedness.  Upon the occurrence of any Bankruptcy or Insolvency
       Proceeding relating to Allied Canada, the holders of the Senior
       Indebtedness are authorized and empowered to (i) demand, sue for,
       collect and receive every payment or distribution on account of the
       Subordinated Obligations payable or deliverable in connection with such
       event or proceeding and give acquittance therefor, and (ii) file claims
       and proofs of claim in any statutory or non-statutory proceeding and
       take such other actions as may be necessary or desirable for the
       enforcement of the subordination provisions of this Debenture.  Promptly
       after taking any action provided in clauses (i) or (ii) above, Allied
       Canada shall give written notice thereof to the holder of this
       Debenture; provided, however that failure to give such notice shall in
       no event affect the validity of any action so taken.

              (c)    In the event that, notwithstanding the occurrence of any
       of the events described in Subsections 4(a) and (b), any such payment or
       distribution of assets of Allied Canada of any kind or character,
       whether in cash, property or securities, shall be received by the holder
       of this Debenture which is not permitted hereby such payment or
       distribution shall be held in trust for the ratable benefit of, and
       shall be paid over or delivered to, the holders of the Senior
       Indebtedness.

              (d)    The holders of the Senior Indebtedness shall have no duty
       or obligation to the holder of this Debenture in any manner whatsoever
       and may, at any time and from time to time, in their sole discretion,
       without the consent of or notice to the holder of this Debenture and
       without impairing or releasing any rights of the holders of the Senior
       Indebtedness or any of the obligations of the holder of this Debenture
       hereunder, take any or all of the following actions:





 
<PAGE>   121
                     (i)    change the amount, manner, place, terms of payment
              or interest rate, change or extend the time of payment of, or
              renew or alter, any of the Senior Indebtedness, or amend or
              supplement or waive any of the terms of any instrument or
              agreement now or hereafter executed pursuant to which any of the
              Senior Indebtedness is issued or incurred;

                     (ii)   sell, exchange, release, surrender, relend, realize
              upon or otherwise deal with in any manner and in any order, any
              property (or the income, revenues, profits or proceeds therefrom)
              by whomsoever at any time pledged or mortgaged to secure, or
              howsoever securing, any Senior Indebtedness;

                     (iii)  release any person liable in any manner for the
              payment or collection of the Senior Indebtedness;

                     (iv)   exercise or refrain from exercising any rights and
              remedies against Allied Canada or others, or otherwise act or
              refrain from acting or, for any reason, fail to file, record or
              otherwise perfect any security interest in or lien on any
              property of Allied Canada or any other Person; and

                     (v)    apply any sums received by the holders of the
              Senior Indebtedness, by whomsoever paid and however realized, to
              payment of the Senior Indebtedness in such manner as the holders
              of the Senior Indebtedness, in their sole discretion, may deem
              appropriate.

              (e)    Laidlaw and any future holder of this Debenture, by
       acceptance of this Debenture, agree to provide to any holder of Senior
       Indebtedness, at any time and from time to time, upon the written
       request of Allied Canada or such holder of Senior Indebtedness, an
       agreement signed by Laidlaw or such future holder of this Debenture
       addressed to the holder of such Senior Indebtedness in substantially the
       form of, and on substantially the terms set out in, Exhibit A attached
       hereto to the effect that such Person is a holder of Senior
       Indebtedness, that the holder or holders of such Senior Indebtedness are
       entitled to the benefits of Sections 4, 5 and 12 of this Debenture and
       that the holder or holders of such Senior Indebtedness may enforce the
       terms and provisions thereof to the same extent Allied Canada would be
       able to do so, provided, however, that prior to furnishing such
       agreement, Laidlaw has received from Allied Canada or such holder such
       information as Laidlaw may reasonably request demonstrating to Laidlaw'
       reasonable satisfaction that such Person is a holder of Senior
       Indebtedness.  Laidlaw, and each subsequent holder of this Debenture, by
       acceptance of this Debenture, irrevocably appoint Allied Canada (with
       full power of substitution) as its agent and attorney in fact (which
       appointment is coupled with an interest and shall be irrevocable so long
       as any Senior Indebtedness is outstanding) to execute and deliver on
       behalf and in the name of Laidlaw or such holder, as the case may be, an
       agreement in substantially the form of, and on substantially the terms
       set out in, Exhibit A hereto in favor of each such holder of Senior
       Indebtedness and to take such further action as may be necessary or
       appropriate to effectuate the subordination as provided herein.
       Promptly after exercise of any such power, Allied Canada will give
       written





<PAGE>   122
       notice thereof to the holders of the Debenture; provided, however, that
       failure to give such notice shall in no event affect the validity of any
       power so exercised.

              (f)    If a Default shall have occurred and be continuing (other
       than a Default pursuant to Section 6(b) or (c)) and the holder of this
       Debenture elects to accelerate this Debenture pursuant to Section 7,
       Laidlaw shall give the Representative under the Credit Facility 30 days'
       prior written notice before accelerating this Debenture, which notice
       shall state that it is a "Notice of Intent to Accelerate;" provided,
       however, that Laidlaw shall not be required to give such notice if at
       such time payment of any Indebtedness incurred pursuant to the Credit
       Facility shall have been accelerated.  If payment of this Debenture is
       accelerated because of a Default, the holder shall promptly notify the
       Representatives under the Designated Senior Indebtedness and the holders
       of all other Senior Indebtedness of the acceleration.

              (g)    Until all Senior Indebtedness has been indefeasibly paid
       in full in cash, the holders of this Debenture shall not be entitled to
       assert, enforce or otherwise exercise any right of subrogation against
       Allied Canada or any other Person obligated on the Subordinated
       Obligations.  After all Senior Indebtedness has been indefeasibly paid
       in full in cash, and until the Subordinated Obligations have been so
       paid in full, the holder of this Debenture shall be subrogated to the
       rights of holders of Senior Indebtedness to receive distributions
       applicable to Senior Indebtedness.  A distribution made under this
       Section 4 to holders of Senior Indebtedness which otherwise would have
       been made to the holder of this Debenture is not, as between Allied
       Canada and the holder of this Debenture, a payment by Allied Canada on
       Senior Indebtedness.

              (h)    This Section 4 defines the relative rights of the holder
       of this Debenture and holders of Senior Indebtedness.  Nothing in this
       Debenture shall:

                     (i)    impair, as between Allied Canada and the holder of
              this Debenture, the obligation of Allied Canada, which is
              absolute and unconditional, to pay principal of and premium and
              interest, if any, on this Debenture in accordance with its terms;
              or

                     (ii)   except as otherwise set forth in this Section 4,
              prevent the holder of this Debenture from exercising its
              available remedies upon a Default, subject to the rights of
              holders of Senior Indebtedness to receive distributions otherwise
              payable to such holder.

       5.     No Impairment.  Section 4, this Section 5, the proviso to Section
7(a), and Section 12 (and all defined terms used in such sections) shall
constitute a continuing offer to all Persons who become holders of, or continue
to hold, Senior Indebtedness, and such provisions are made for the benefit of
the holders from time to time of Senior Indebtedness, and such Persons are
conclusively presumed to have relied upon such provisions; and such holders are
made obligees hereunder, and they or each of them may enforce such provisions.
No right of any present or future holder of any Senior Indebtedness to enforce
the subordination or other provisions referred to in this Section 5 shall at
any time in any way be





                                      
<PAGE>   123
prejudiced or impaired by any act or failure to act on the part of Allied
Canada or Laidlaw, or by any non-compliance by Allied Canada or Laidlaw with
the terms, provisions and covenants of this Debenture, regardless of any
knowledge thereof any such holder may have or otherwise be charged with.
Section 4, this Section 5 and the subordination and other provisions referred
to in this Section 5 may not be amended or modified in any manner which might
terminate or impair the subordination or such other provisions except with the
prior written consent of the Representatives of all the Designated Senior
Indebtedness.

       6.     Events of Default.  "Default" means the occurrence of one or more
of the following:

              (a)    Payment.  Allied Canada fails to pay the outstanding
       principal amount of this Debenture on the Maturity Date.

              (b)    Voluntary Bankruptcy.  Allied Canada (i) files a petition
       initiating a voluntary Bankruptcy or Insolvency Proceeding, (ii) seeks,
       consents to, or does not contest the appointment of a receiver or
       trustee for itself or for all or any substantial part of its property,
       (iii) is voluntarily adjudicated a bankrupt or insolvent, (iv) makes a
       general assignment for the benefit of its creditors, or (v) admits in
       writing its inability to pay its debts as they mature.

              (c)    Involuntary Bankruptcy.  A petition is filed against
       Allied Canada seeking to initiate a Bankruptcy or Insolvency Proceeding
       and such petition is not dismissed within 180 days after being filed, or
       a court of competent jurisdiction enters an order, judgment or decree
       appointing a receiver or trustee for Allied Canada, or for all or
       substantially all of its property, and such order, judgment or decree is
       not discharged or stayed within 180 days after its entry.

              (d)    Acceleration of Other Indebtedness.  An event of default
       occurs and is continuing under the Credit Facility and, as a result
       thereof, the Indebtedness outstanding pursuant to the Credit Facility is
       accelerated; provided, however, that in the event the holders of such
       Indebtedness elect to waive such event of default or to otherwise
       de-accelerate such Indebtedness, no Default shall subsist hereunder.

       7.     Remedies of Laidlaw.  Upon the occurrence and during the
continuance of a Default, Laidlaw shall have the following rights:

              (a)    Acceleration.  Subject to the provisions of Section 4
       hereof, Laidlaw may, at its option, declare the entire principal balance
       of this Debenture, together with the accrued and unpaid interest
       thereon, immediately due and payable without notice of Default, notice
       of intent to accelerate, notice of acceleration, or any other notice,
       presentment, protest, demand or action of any kind or nature whatsoever
       (each of which is hereby expressly waived by Allied Canada), whereupon
       the entire Indebtedness under this Debenture shall become immediately
       due and payable; provided, however, that no such acceleration (except
       for an acceleration upon the occurrence of a Default specified in
       Subsection 7(d)) shall be effective or of any force whatsoever and the
       holder of this





                                      
<PAGE>   124
       Debenture may not take any action against Allied Canada with respect to
       a Default hereunder if made during a Blockage Period, or if such
       acceleration would result in a Blockage Period; provided, further, that
       in the event the Indebtedness under this Debenture is accelerated upon
       the occurrence of a Default specified in Subsection 7(d) and the holders
       of the Indebtedness outstanding pursuant to the Credit Facility elect to
       waive the event of default giving rise to the acceleration thereunder or
       otherwise elect to de-accelerate such Indebtedness, Laidlaw shall
       de-accelerate the obligations hereunder.

              (b)    Other Rights.  Except as otherwise modified hereby,
       Laidlaw shall have all rights and remedies available at law or equity
       and the same (i) shall be cumulative and concurrent, (ii) may be pursued
       separately, successively, or concurrently against Allied Canada, (iii)
       may be exercised as often as occasion therefor shall arise, it being
       agreed by Allied Canada that the exercise or failure to exercise any of
       the same shall in no event be construed as a waiver or release thereof
       or of any other right or remedy, and (iv) are intended to be, and shall
       be, nonexclusive.

       8.     Offer of Prepayment upon Change of Control.

              (a)    Allied Canada will, within thirty business days after any
       executive officer of Allied Canada has knowledge of the occurrence of a
       Change of Control, give written notice of such Change of Control to the
       holder of this Debenture.  Subject to the provisions of Section 5, such
       notice shall contain and constitute an offer to prepay this Debenture as
       described in subsection (b) of this Section 8.

              (b)    The offer to prepay this Debenture contemplated by
       subsection (a) of this Section 8 shall be an offer to prepay, in
       accordance with and subject to this Section 8, all, but not less than
       all, of this Debenture on a date specified in such offer (the "Section 8
       Prepayment Date") which date shall be not less than 45 days and not more
       than 60 days after the date of such offer (if the Section 8 Prepayment
       Date shall not be specified in such offer, the Section 8 Prepayment Date
       shall be the first business day after the 45th day after the date of
       such offer).

              (c)    The holder of this Debenture may accept the offer to
       prepay made pursuant to this Section 8 in whole but not in part by
       causing a notice of such acceptance to be delivered to Allied Canada
       within ten business days after receipt of the written notice to be given
       pursuant to subsection (a) of this Section 8.  A failure by a holder of
       this Debenture to respond within such time period to an offer to prepay
       made pursuant to this Section 8 shall be deemed to constitute a
       rejection of such offer.

              (d)    Prepayment of this Debenture pursuant to this Section 8
       shall be at the Accreted Value of the Debenture at the Section 8
       Prepayment Date.  The prepayment shall be made on the Section 8
       Prepayment Date.

              (e)    Notwithstanding any provision hereof to the contrary, in
       no event shall Allied Canada prepay (or be obligated to prepay)  this
       Debenture pursuant to this





                                      
<PAGE>   125
       Section 8 until 91 days after Allied Canada shall have prepaid the
       Senior Indebtedness incurred pursuant to the Credit Facility and the
       Senior Subordinated Debentures, and all other Senior Indebtedness which
       is entitled to be prepaid upon the occurrence of a Change of Control,
       unless the holder or holders of such Senior Indebtedness have waived or
       otherwise failed to enforce their rights to receive a prepayment of the
       Senior Indebtedness held by them to which they are entitled in
       connection with such Change of Control.

       9.     Captions.  The captions, headings, and arrangements used in this
Debenture are for convenience only and do not affect or modify the terms of
this Debenture.

       10.    Notices. All notices or other communications which are required
or may be given under this Debenture shall be in writing and shall be deemed to
have been duly given when delivered in person or transmitted by telecopier
(with receipt confirmed) at the address or telecopy number set forth below (as
any such address or telecopier number may be changed from time to time by
notice similarly given):

       (1)    if to Laidlaw, to:

                     Laidlaw Inc.
                     3221 North Service Road
                     Burlington, Ontario
                     Canada L7R 3Y8
                     Attention:  Ivan R. Cairns
                     Telecopy No.: (905) 332-6550

       (2)    if to Allied Canada, to:

                     3294862 Canada Inc.
                     c/o Allied Waste Industries, Inc.
                     7201 East Camelback Road, Suite 375
                     Scottsdale, Arizona 85251
                     Attention: Roger A. Ramsey
                     Telecopy No.: (602) 481-9347

                     with a copy to:

                     Porter & Hedges, L.L.P.
                     700 Louisiana Street, Suite 3500
                     Houston, Texas 77002
                     Attention: Robert G. Reedy
                     Telecopy No.: (713) 228-1331

       11.    Applicable Law. This Debenture shall be governed by and construed
in accordance with the laws of the State of Delaware and the laws of the United
States of America applicable therein (without reference to the conflicts of law
principles thereof).





                                      
<PAGE>   126
       12.    Transfer Restriction. This Debenture may not be sold, assigned,
transferred, pledged or hypothecated in any manner, directly or indirectly, by
Laidlaw or any other holder, unless the assignee, transferee, pledgee or
hypothecate has agreed in writing to be bound by the provisions of this
Debenture applicable to Laidlaw, including but not limited to the provisions of
Section 4(e) and Section 13 hereof.  Any transfer of this Debenture shall be of
the entire Debenture and not of any part of the indebtedness evidenced hereby
or of at least $75,000,000 of the principal amount thereof.

       NOTICE:  THE RIGHTS AND OBLIGATIONS OF ALLIED CANADA AND LAIDLAW SHALL
BE DETERMINED SOLELY FROM WRITTEN AGREEMENTS, DOCUMENTS, AND INSTRUMENTS, AND
ANY PRIOR ORAL AGREEMENTS BETWEEN ALLIED CANADA AND LAIDLAW ARE SUPERSEDED BY
AND MERGED INTO SUCH WRITINGS.  THIS DEBENTURE (AS AMENDED IN WRITING FROM TIME
TO TIME) REPRESENTS THE FINAL AGREEMENT BETWEEN ALLIED CANADA AND LAIDLAW AND
MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR OR CONTEMPORANEOUS ORAL AGREEMENTS
BY ALLIED CANADA AND LAIDLAW.  THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN
ALLIED CANADA AND LAIDLAW.



                                          3294862 CANADA INC.
                                          a Canadian corporation


                                          By:
                                             ----------------------------------
                                             Name:                             
                                                  -----------------------------
                                             Title:                            
                                                   ----------------------------


Agreed and Accepted:

LAIDLAW INC.
a Canadian corporation


By:
   -------------------------------------------
Name:
     -----------------------------------------
Title:
      ----------------------------------------





<PAGE>   127

                                                                       EXHIBIT A
                                          to the Zero Coupon Junior Subordinated
                                                   Debenture Due 200__ Issued by
                                                             3294862 Canada Inc.
                                                        in favor of Laidlaw Inc.


                                     [Date]


- ---------------
- ---------------
- ---------------


Gentlemen:

         Reference is made to the Zero Coupon Junior Subordinated Debenture Due
200__ dated __________, 199__ (the "Subordinated Debenture"), in the original
principal amount of $________________ issued by 3294862 Canada Inc., a Canadian
corporation ("Allied Canada"), in favor of Laidlaw Inc., a Canadian
corporation, and the [describe Senior Indebtedness] (the "Subject
Indebtedness"), being issued contemporaneously herewith by Allied Canada in
favor of [identity of holder or holders of Subject Indebtedness] (whether one
or more, the "Senior Creditor").  Hereinafter, capitalized words and phrases
used herein which are defined in the Subordinated Debenture are used herein as
therein defined.

         The undersigned (the "Subordinated Creditor") hereby represents and
warrants to the Senior Creditor that (a) the Subordinated Creditor is the owner
and holder of the Subordinated Debenture and that the Subordinated Creditor is
entitled to make the agreements herein contained.  The Subordinated Creditor
hereby acknowledges and agrees that the principal of, and premium, if any, and
interest on (including interest that, but for the filing of a petition
initiating any Bankruptcy or Insolvency Proceeding would accrue on such
obligations at the rate provided in the agreements or instruments creating or
evidencing the respective obligations, whether or not such Bankruptcy or
Insolvency Proceeding and all other amounts of every kind or nature (including,
but not limited to, fees, indemnities and expenses and any interest rate swaps
or other interest rate hedging products entered into in connection with the
Subject Indebtedness) due on or in connection with, the Subject Indebtedness,
whether outstanding on the date hereof or hereafter created, incurred or
assumed, guaranteed or in effect guaranteed by Allied Canada (including all
renewals, extensions or refundings of, or amendments, modifications or
supplements to, the foregoing) are in all respects Senior Indebtedness, (b) the
Senior Creditor (and any other Person who from time to time is a holder of the
Subject Indebtedness) is entitled to the benefits of Sections 4, 5 and 12 of
the Subordinated Debenture, and (c) the Senior Creditor (and any other Person
who from time to time is a holder of the Subject Indebtedness) may enforce the
terms and provisions of the Subordinated Debenture to the same extent that
Allied Canada or any other holder of Senior Indebtedness would be able to do
so.


<PAGE>   128

         The Subordinated Creditor hereby agrees that the Subordinated
Debenture will not be sold, assigned, transferred, pledged or hypothecated in
any manner, directly or indirectly, by the Subordinated Creditor, unless the
assignee, transferee, pledgee or hypothecate has agreed in writing to be bound
by the provisions of this agreement.

         The Subordinated Creditor has executed this agreement in the space
provided below in order to induce the Senior Creditor to advance funds or
extend credit to Allied Canada, and this agreement is intended by the
Subordinated Creditor to be a binding and enforceable undertaking by the
Subordinated Creditor in favor of the Senior Creditor.

         The rights created hereby of the Senior Creditor and of any subsequent
holder of the Senior Indebtedness will be assigned automatically, and without
any further act, by the Senior Creditor or such holder upon any sale,
assignment, conveyance or other transfer of all or any part of the Senior
Indebtedness to the extent of the interest sold, assigned, conveyed or
otherwise transferred, unless and to the extent the Senior Creditor or such
holder expressly provides otherwise in the instrument pursuant to which such
interest is conveyed.



                                     Very truly yours,

                                     [NAME OF SUBORDINATED CREDITOR]


                                     By: 
                                        ---------------------------------------
                                        Name:                                  
                                             ----------------------------------
                                        Title:                                 
                                              ---------------------------------


Accepted and agreed to as of
the date first above written:

[NAME OF SENIOR CREDITOR]


By: 
   ---------------------------------------
Name:
     -------------------------------------
Title: 
      ------------------------------------




                                      
<PAGE>   129


                                                                    EXHIBIT  B-1


THIS DEBENTURE HAS NOT BEEN REGISTERED (OR QUALIFIED BY PROSPECTUS) UNDER THE
SECURITIES ACT (DEFINED BELOW), THE CANADIAN SECURITIES LEGISLATION (DEFINED
BELOW), OR THE LAWS OF ANY STATE OF THE UNITED STATES OF AMERICA, AND THIS
DEBENTURE MAY NOT BE OFFERED FOR SALE, SOLD, TRANSFERRED, PLEDGED, HYPOTHECATED
OR OTHERWISE DISPOSED OF EXCEPT IN ACCORDANCE WITH THE TERMS HEREOF AND THE
REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF THE SECURITIES ACT, THE
CANADIAN SECURITIES LEGISLATION AND SUCH STATE LAWS OTHER THAN PURSUANT TO AN
EXEMPTION FROM SUCH REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS AND UPON
DELIVERY TO ALLIED FINANCE OF AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO
ALLIED FINANCE TO THE EFFECT THAT SUCH TRANSFER IS EXEMPT FROM REGISTRATION AND
THE PROSPECTUS DELIVERY REQUIREMENTS UNDER THOSE LAWS.

THIS DEBENTURE WILL BE ISSUED WITH ORIGINAL ISSUE DISCOUNT ("OID").  THE HOLDER
OF THIS DEBENTURE SHOULD BE AWARE THAT SUCH HOLDER WILL BE REQUIRED TO INCLUDE
OID IN SUCH HOLDER'S GROSS INCOME FOR INCOME TAX PURPOSES IN ADVANCE OF THE
RECEIPT OF CASH ATTRIBUTABLE TO SUCH INCOME.  WITH RESPECT TO OID, THE ISSUE
DATE OF THIS DEBENTURE IS _________________, 199_, THE ISSUE PRICE IS
[$_________], THE AMOUNT OF OID IS [$_________], AND THE YIELD TO MATURITY IS
[______]%.

                  7% JUNIOR SUBORDINATED DEBENTURE DUE 200_(1)


$150,000,000                                             _________________, 199_


       FOR VALUE RECEIVED, 3294854 CANADA INC., a Canadian corporation ("Allied
Finance"), promises to pay to Laidlaw Inc., a Canadian corporation ("Laidlaw"),
or  its registered assigns, the principal amount of $150,000,000 on the
Maturity Date, with interest on the principal balance outstanding from time to
time at the rate and payable at the times and in the manner hereinafter set
forth.




- -------------------------------

(1)    The due date will be 12 years after the date of issuance.
<PAGE>   130
       1.     Definitions.

       (a)    For all purposes of this Debenture:

              "Affiliate" means, with respect to any Person, another Person
       that directly, or indirectly through one or more intermediaries,
       controls, is controlled by or is under common control with such Person
       with the term "control," including the terms "controlling" and
       "controlled," meaning for purposes of this definition, the power to
       direct the management and policies of a Person, directly or indirectly,
       whether through the ownership of voting securities or partnership or
       other ownership interests, or by contract or otherwise.

              "Allied" means Allied Waste Industries, Inc., a Delaware
       corporation, and its successors and assigns.

              "Allied Common Stock" means the Common Stock, $.01 par value per
       share, of Allied.

              "Allied Finance" means 3294854 Canada Inc., a Canadian
       corporation, and its successors and assigns.

              "Allied U.S." means Allied Holdings (United States), Inc., a
       Delaware corporation, and its successors and assigns.

              "Allied Warrant" means the warrant for the purchase of shares of
       Allied Common Stock to be issued by Allied to Laidlaw under Section 2.3
       of the Stock Purchase Agreement.

              "Bankruptcy or Insolvency Proceeding" is defined in Subsection
       5(b) of this Debenture.

              "Blockage Period" means any period when a default or an event of
       default  or an event which, with the giving of notice or the lapse of
       time or both, would constitute a default or an event of default has
       occurred and is continuing under the terms of the Credit Facility or the
       Senior Subordinated Debentures or under the terms of any agreement or
       instrument pursuant to which any other Designated Senior Indebtedness is
       created, issued, evidenced, secured or guaranteed.

              "Business Day" means a day other than Saturday, Sunday or any day
       on which banks located in Toronto, Ontario or New York, New York are
       authorized or obligated to close.

              "Canadian Securities Legislation" means the Securities Act of the
       Province of Ontario (R.S.O. 1990, c.  S.5, as amended) and similar
       provincial legislation, and the regulations and rules promulgated
       thereunder.




                                      2
<PAGE>   131
              "Change of Control" means a change resulting when any Unrelated
       Person or any Unrelated Persons acting together that would constitute a
       Group together with any Affiliates thereof (in each case also
       constituting Unrelated Persons) shall at any time Beneficially Own more
       than 50% of the aggregate voting power of all classes of Voting Stock of
       Allied; provided, however, that if at the date any "Change of Control"
       would otherwise have occurred but for the fact that a Person was not an
       Unrelated Person because such Person or an Affiliate of such Person
       acquired shares of Allied Common Stock or all or any portion of the
       Allied Warrant from Laidlaw or from any Affiliate of Laidlaw within nine
       months prior to such date, such shares of Allied Common Stock acquired
       from Laidlaw or any Affiliate of Laidlaw, or any shares of Allied Common
       Stock issued upon exercise of the Allied Warrant or any portion thereof,
       shall at all times thereafter be excluded when calculating whether a
       Change of Control has occurred.  As used in this definition of Change of
       Control (a) "Beneficially Own" means "beneficially own" as defined in
       Rule 13d-3 of the Securities Exchange Act of 1934, as amended (the
       "Exchange Act"), or any successor provisions thereto; provided, however,
       that, for purposes of this definition, a Person shall not be deemed to
       Beneficially Own securities tendered pursuant to a tender or exchange
       offer made by or on behalf of such Person or any of such Person's
       Affiliates until such tendered securities are accepted for purchase or
       exchange; (b) "Group" means a "group" for purposes of Section 13(d) of
       the Exchange Act; (c) "Affiliate" means, with respect to any Person,
       another Person which would be an "affiliate" of such Person for purposes
       of Section 13(d) of the Exchange Act; (d) "Unrelated Person" means at
       any time any Person other than Laidlaw, any Person to whom Laidlaw or
       any of its Affiliates transfers, within nine months prior to such time,
       any shares of Allied Common Stock or all or any portion of the Allied
       Warrant or any Affiliate of Laidlaw or any such Person; provided,
       however, that Persons (other than Laidlaw or its Affiliates) to whom
       Laidlaw or any of its Affiliates transfers any shares of Allied Common
       Stock or all or any portion of the Allied Warrant after five years from
       the date hereof shall not be deemed Unrelated Persons; and (e) "Voting
       Stock" of any Person shall mean capital stock of such Person which
       ordinarily has voting power for the election of directors (or persons
       performing similar functions) of such Person, whether at all times or
       only so long as no senior class of securities has such voting power by
       reason of any contingency.

              "Credit Facility" means the Credit Agreement dated as of
       _____________, 199_, among Allied U.S., as borrower, Allied, Goldman
       Sachs Credit Partners L.P., as syndication agent, Citibank, N.A., as
       documentation agent, Credit Suisse, as administrative agent, Goldman
       Sachs Credit Partners L.P., Citicorp USA, Inc. and Credit Suisse, as
       initial lenders, and the other financial institutions now or hereafter
       parties thereto (as the same may be renewed, amended, modified,
       increased, extended, refinanced, or otherwise supplemented from time to
       time).

              "Debenture" means this 7% Junior Subordinated Debenture due
       200__.





                                       3
<PAGE>   132
              "Default" is defined in Section 8.

              "Default Rate" means an annual interest rate equal to 9% per 
       annum.

              "Deferral Period" is defined in Subsection 3(b).

              "Designated Senior Indebtedness" means (i) the Senior
       Indebtedness incurred with respect to the Credit Facility, (ii) the
       Senior Indebtedness evidenced by the Senior Subordinated Debentures and
       (iii) any other Senior Indebtedness which is incurred pursuant to an
       agreement (or series of related agreements simultaneously entered into)
       providing for Indebtedness, or commitments to lend, of at least
       $10,000,000 at the time of determination and is specifically designated
       in the instrument evidencing such Senior Indebtedness or the agreement
       under which such Senior Indebtedness arises as "Designated Senior
       Indebtedness."

              "$" means U.S. dollars, the lawful currency of the United States
       of America.

              "Financing Lease"  means any lease of property, real or personal,
       the obligations of the lessee in respect of which are required in
       accordance with generally accepted accounting principles to be
       capitalized on a balance sheet of the lessee.

              "Governmental Entity" means any U.S. or Canadian, territorial,
       federal, state, provincial or local court, executive office,
       legislature, governmental agency, department, ministry, commission, or
       administrative, regulatory or self-regulatory authority or
       instrumentality.

              "Guarantee" means with respect to any Person any obligation,
       contingent or otherwise, of such Person guaranteeing or having the
       economic effect of guaranteeing any Indebtedness of any other Person
       (the "primary obligor") in any manner, whether directly or indirectly,
       and including any obligation of such Person, direct or indirect, (a) to
       purchase or pay (or advance or supply funds for the purchase or payment
       of ) such Indebtedness or to purchase (or to advance or supply funds for
       the purchase of) any security for the payment of such Indebtedness, (b)
       to purchase or lease property, securities or services for the purpose of
       assuring the owner of such Indebtedness of the payment of such
       Indebtedness or (c) to maintain working capital, equity capital or any
       other financial statement condition or liquidity of the primary obligor
       so as to enable the primary obligor to pay such Indebtedness; provided,
       however, that the term "Guarantee" shall not include endorsements for
       collection or deposit in the ordinary course of business.

              "Indebtedness" means with respect to any Person at any date, (a)
       all indebtedness of such Person for borrowed money or for the deferred
       purchase





                                       4
<PAGE>   133
       price of property or services (other than current trade liabilities
       incurred in the ordinary course of business and payable in accordance
       with customary practices), (b) any other indebtedness of such Person
       which is evidenced by a note, bond, debenture, letter of credit or
       similar instrument, (c) all obligations of such Persons with respect to
       Guarantees, (d) all obligations of such Person under Financing Leases,
       (e) all obligations of such Person in respect of acceptances issued or
       created for the account of such Person (other than endorsements in the
       ordinary course of business),  (f) all obligations in respect of
       interest rate swaps or other interest rate hedging products or foreign
       currency exchange agreements or exchange rate hedging arrangements, (g)
       all obligations in respect of reimbursement obligations under letters of
       credit, and (h) all liabilities of the type referred to in clauses (a)
       through (g) above that are secured by any lien, charge, security
       interest or encumbrance on any property owned by such Person even though
       such Person has not assumed or otherwise become liable for the payment
       thereof.

              "Indenture" means the Indenture dated _____________, 199_,
       between Allied U.S. and the Trustee pursuant to which the Senior
       Subordinated Debentures are issued.

              "Laidlaw" means Laidlaw Inc., a Canadian corporation.

              "LTI" means Laidlaw Transportation, Inc., a Delaware corporation.

              "Maturity Date" means _______________ ___, 200_ [12 years after
       the date hereof].

              "Offset Letter Agreement" means the letter agreement dated the
       Closing Date among Allied, Allied Finance, Laidlaw and LTI, in
       substantially the form of Exhibit N attached to this Agreement, to be
       executed and delivered pursuant to Section 3.3.

              "Person" means an individual, corporation, partnership,
       association, joint stock company, limited liability company,
       Governmental Entity, business trust, unincorporated organization, or
       other legal entity.

              "Representative" means at any date, with respect to the Credit
       Facility, the Person or Persons then acting as the administrative agent
       under the Credit Facility, with respect to the Senior Subordinated
       Debentures, the Trustee, and with respect to any other Designated Senior
       Indebtedness, the holders of such Designated Senior Indebtedness or any
       Person acting as agent of such holders at such date.

              "Section 4(b) Prepayment Date" is defined in Subsection 4(b) of 
       this Debenture.





                                       5
<PAGE>   134
              "Section 4(b) Prepayment Fraction" means, with respect to any
       prepayment pursuant to Section 4(b) of this Debenture, the fraction
       obtained by dividing the principal amount of the Debenture to be prepaid
       by $150 million.

              "Section 4(b) Prepayment Notice" is defined in Subsection 4(b) of
       this Debenture.

              "Section 4(b) Prepayment Option" is defined in Subsection 4(b) of
       this Debenture.

              "Section 4(b) Prepayment Price" means (i) at any date set forth
       in the table below (the "Section 4(b) Value Date"), the amount set forth
       opposite such Section 4(b) Value Date, and (ii) at any other date (the
       "Section 4(b) Determination Date"), the amount equal to the sum of (y)
       the Section 4(b) Prepayment Price as of the Section 4(b) Value Date
       immediately preceding such Section 4(b) Determination Date plus (z) an
       amount equal to the product of (A) the difference between the Section
       4(b) Prepayment Price as of the Section 4(b) Value Date immediately
       following such Section 4(b) Determination Date minus the Section 4(b)
       Prepayment Price as of the Section 4(b) Value Date immediately preceding
       such Section 4(b) Determination Date multiplied by (B) a fraction, the
       numerator of which is the number of days elapsed from (and including)
       such preceding Section 4(b) Value Date to (but excluding) such Section
       4(b) Determination Date and the denominator of which is the number of
       days from (and including) such preceding Section 4(b)Value Date to (but
       excluding) the immediately following Section 4(b)Value Date.

<TABLE>
<CAPTION>
       Section 4(b)            Section 4(b)         Section 4(b)        Section 4(b)
       Value Date (2)         Prepayment Price      Value Date       Prepayment Price
       ----------             ----------------      ----------       ----------------
       <S>         <C>         <C>               <C>         <C>             <C>
       ___________, ____       $126,700,000      ___________, ____           $144,700,000
       ___________, ____       $130,400,000      ___________, ____           $150,000,000
       ___________, ____       $134,600,000      ___________, ____           $150,000,000
       ___________, ____       $139,400,000      ___________, ____           $150,000,000
</TABLE>

              "Section 9 Prepayment Date" is defined in Section 9(b) of this 
       Debenture.

              "Section 9 Purchase Price" means (i) at any time prior to five
       years from the date hereof, $126,700,000, (ii) at any date set forth in
       the table below (the "Section 9 Value Date"), the amount set forth
       opposite such Section 9




- ----------------------------

(2)    The initial Section 4(b) Value Date shall be the  date five years after
       the date of the Debenture,  and succeeding Section 4(b) Value Dates
       shall occur annually thereafter until the Maturity Date.

                                       6
<PAGE>   135
       Value Date, and (iii) at any other date (the "Section 9 Determination
       Date"), the amount equal to the sum of (y) the Section 9 Purchase Price
       as of the Section 9 Value Date immediately preceding such Section 9
       Determination Date plus (z) an amount equal to the product of (A) the
       difference between the Section 9 Purchase Price as of the Section 9
       Value Date immediately following such Section 9 Determination Date minus
       the Section 9 Purchase Price as of the Section 9 Value Date immediately
       preceding such Section 9 Determination Date multiplied by (B) a
       fraction, the numerator of which is the number of days elapsed from (and
       including) such preceding Section 9 Value Date to (but excluding) such
       Section 9 Determination Date and the denominator of which is the number
       of days from (and including) such preceding Section 9 Value Date to (but
       excluding) the immediately following Section 9 Value Date.

<TABLE>
<CAPTION>
        Section 9                     Section 9       Section 9                 Section 9
       Value Date (3)             Prepayment Price    Value Date             Prepayment Price
       ----------                 ----------------    ----------             ----------------
        <S>         <C>            <C>               <C>         <C>           <C>
        ___________, ____          $126,700,000      ___________, ____         $144,700,000
        ___________, ____          $130,400,000      ___________, ____         $150,000,000
        ___________, ____          $134,600,000      ___________, ____         $150,000,000
        ___________, ____          $139,400,000      ___________, ____         $150,000,000
</TABLE>

              "Securities Act" means the Securities Act of 1933, as amended.

              "Senior Indebtedness" means principal of, and premium, if any,
       and interest on (including interest that, but for the filing of a
       petition initiating any Bankruptcy or Insolvency Proceeding, would
       accrue on such obligations at the rate provided in the agreements or
       instruments creating or evidencing the respective obligations, whether
       or not such claim is allowed or allowable in such Bankruptcy or
       Insolvency Proceeding) and all other amounts of every kind or nature
       (including, but not limited to, fees, indemnities and expenses) due on
       or in connection with any Indebtedness of Allied Finance, whether
       outstanding on the date of this Debenture or thereafter created,
       incurred, assumed or Guaranteed by Allied Finance (including all
       renewals, extensions or refundings of, or amendments, modifications or
       supplements to, the foregoing) unless, in the case of any particular
       Indebtedness, the instrument creating or evidencing the same or pursuant
       to which the same is outstanding expressly provides that such
       Indebtedness shall not be senior in right of payment to this Debenture.
       Without limiting the generality of the foregoing, "Senior Indebtedness"
       shall include (a) all obligations and liabilities of every kind and
       nature (including, but not limited to, fees, expenses and indemnities)
       under the Credit Facility, the Senior




- ---------------------------

(3)    The initial Section 9  Value Date shall be  the date five  years after
       the date  of the Debenture,  and succeeding Section 9 Value Dates shall
       occur annually thereafter until the Maturity Date.

                                       7
<PAGE>   136
       Subordinated Debentures or the Indenture, (b) all obligations and
       liabilities of every kind and nature (including, but not limited to,
       fees, expenses and indemnities) in respect of any interest rate swaps or
       other interest rate hedging product entered into in connection with
       Indebtedness incurred or to be incurred pursuant to the Credit Facility,
       and (c) any renewal, extension, refinancing or rearrangement of any
       Indebtedness incurred or to be incurred pursuant to the Credit Facility,
       the Senior Subordinated Debentures or the Indenture.  Notwithstanding
       the foregoing, Senior Indebtedness shall not include (i) amounts owed
       (except to banks, insurance companies and other financing institutions
       and except for obligations under Financing Leases) for goods, materials,
       services or operating lease rental payments in the ordinary course of
       business or for compensation to employees of Allied Finance, (ii) any
       liability for federal, state, provincial, local or other taxes owed or
       owing by Allied Finance and (iii) Indebtedness with respect to Allied
       Finance's Zero Coupon Junior Subordinated Debenture due 200_ dated the
       date hereof.

              "Senior Subordinated Debentures" means the ___% Senior
       Subordinated Debentures due 200__(4) in the aggregate original principal
       amount of at least $475,000,000 issued by Allied U.S. pursuant to the
       Indenture.

              "Stock Purchase Agreement" means the Stock Purchase Agreement
       dated as of September 17, 1996, among Allied, Allied Finance, Laidlaw
       and certain other parties named therein.

              "Subordinated Obligations" is defined in Subsection 5(a).

              "Subscription Agreement" means the Subscription Agreement dated
       the date hereof among Allied, Allied Finance, Laidlaw and LTI.

              "Subsidiary" of a Person means an Affiliate of that Person more
       than 50% of the aggregate voting power (or of any other form of voting
       equity interest in the case of a Person that is not a corporation) of
       which is beneficially owned by that Person directly or indirectly
       through one or more other Subsidiaries.

              "Trustee" means ________________________________, a national
       banking association, in its capacity as trustee under the Indenture, and
       its successors in such capacity.

       (b)    Capitalized terms defined in this Debenture are equally
applicable to both their singular and plural forms.   References to a
designated "Section" or "Subsections" refer to a Section or Subsection of this
Debenture, unless otherwise specifically




- ---------------------------

(4)    The due date of the Senior Subordinated Debentures will be 10 years
       after the date of issuance.

                                       8
<PAGE>   137
indicated.  In this Debenture, "including" is used only to indicate examples,
without limitation to the indicated examples, and without limiting any
generality which precedes it.

       2.     Interest Rate; Default Rate.  From (and including) the date of
this Debenture through (but not including) the earlier of the Maturity Date or
the date the maturity of this Debenture is accelerated pursuant to Section
8(a), interest shall accrue on the unpaid principal balance of this Debenture
at an annual fixed rate equal to 7% per annum.  All past due principal and
interest shall accrue interest at the Default Rate from (and including) the day
after the date such principal or interest is payable hereunder through (but not
including) the date of payment.  Interest will be calculated on the basis of
the actual number of days elapsed over a year composed of 365 days (or 366
days, as the case may be).

       3.     Payment Terms.  Subject to Section 5:

              (a)    The outstanding principal balance of this Debenture and
       all accrued and unpaid interest thereon shall be due and payable on the
       Maturity Date.

              (b)    During the period beginning on the date hereof and ending
       three years thereafter (the "Deferral Period"), interest on the
       outstanding principal balance of this Debenture will accrue but will be
       deferred.  During the Deferral Period, interest will be compounded
       semi-annually.  After the Deferral Period, at the election of Allied
       Finance, the deferred interest may be paid at any time, and (i) the
       aggregate unpaid amount, if any, of interest deferred during the
       Deferral Period, together with interest thereon at the rate of 7% per
       annum, will be payable in eighteen equal (or as nearly equal as
       possible) installments on the ___ day of each _______ and _______ of
       each year (beginning __________, __), and on the Maturity Date and (ii)
       interest on the outstanding principal balance of this Debenture will be
       due and payable in arrears on the _____ day of each ___________ and
       _____________  of each year (beginning ___________, ____), and on the
       Maturity Date for the period commencing on (and including) the later of
       the date following the last day of the Deferral Period or the date to
       which interest hereon has been paid, as the case may be, and ending on
       (but excluding) the date of payment.(5)

              (c)    Each payment or prepayment hereunder shall be made in cash
       by wire transfer to an account located in Canada designated by Laidlaw.

              (d)    Any payment or action that is due hereunder on a day which
       is not a Business Day shall be deferred until the next succeeding
       Business Day




- ---------------------------

(5)    Installments of interest will be  payable on a semi-annual basis
       commencing  six months after the last day  of the Deferral Period.

                                       9
<PAGE>   138
       (but interest shall continue to accrue on any applicable payment until
       such payment is made).

              (e)    Pursuant to Article II of the Subscription Agreement, LTI
       has agreed to subscribe for shares of Allied Common Stock from time to
       time.  Reference is made to the Subscription Agreement for a complete
       statement of the terms and conditions pursuant to which such shares are
       to be issued.

       4.     Optional Redemption.

              (a)    Except to the extent provided in Section 9, this Debenture
       may not be redeemed or prepaid, in whole or in part, on or before the
       date which is five years after the date hereof.

              (b)    Thereafter, except as otherwise provided in Section 5,
       Allied Finance shall have the right and option (the "Section 4(b)
       Prepayment Option") to redeem and prepay this Debenture, in whole or in
       part, at a discount, on the terms and subject to the conditions of this
       Section 4(b).  Allied Finance may exercise the Section 4(b) Prepayment
       Option at any time by giving the holder of this Debenture written notice
       (the "Section 4(b) Prepayment Notice") of its election to exercise the
       Section 4(b) Prepayment Option and by specifying in the Section 4(b)
       Prepayment Notice the date on which Allied Finance will prepay this
       Debenture pursuant to this Section 4(b) (the "Section 4(b) Prepayment
       Date") and the principal amount of this Debenture to be prepaid.  The
       Section 4(b) Prepayment Date shall be at least 10 Business Days, and not
       more than 20 Business Days, after the date of the Section 4(b)
       Prepayment Notice.  Upon the Section 4(b) Prepayment Date, Allied
       Finance shall prepay this Debenture to the extent specified in the
       Section 4(b) Prepayment Notice, by payment of an amount equal to the
       product obtained by multiplying the Section 4(b) Prepayment Price as of
       the Section 4(b) Prepayment Date times the Section 4(b) Prepayment
       Fraction.

       5.     Subordination.

              (a)    The indebtedness evidenced by, and all obligations in
       respect of, this Debenture (including the obligations under Section 9)
       and the payment of principal of, premium and interest, if any, on and
       all other obligations in respect of, this Debenture (collectively, the
       "Subordinated Obligations") are expressly subordinate to all Senior
       Indebtedness to the extent and in the manner set forth herein.  For
       purposes hereof, the term "subordinate" means that, unless and until the
       Senior Indebtedness has been indefeasibly paid in full in cash, Laidlaw
       will not have the right under any circumstances to, and will not, take,
       demand, commence any suit or any other proceeding for collection, pursue
       any other judicial or non-judicial remedy or receive from Allied Finance
       or any of its Subsidiaries or Affiliates, and Allied Finance will not
       and will  not permit any of its Subsidiaries or Affiliates to, make,
       give, or permit, directly or indirectly,





                                       10
<PAGE>   139
       by set-off, redemption, purchase or in any other manner, any payment of
       or on account of the Subordinated Obligations; provided, however, that
       at any time, except during a Blockage Period, Allied Finance shall make,
       and Laidlaw may receive, and Laidlaw may commence any suit or other
       proceeding for collection of, scheduled payments of principal or
       interest on this Debenture in accordance with the terms hereof and,
       provided, further, that at any time, except during a Blockage Period,
       Allied Finance may prepay this Debenture so long as such prepayment
       would not cause the occurrence of a Blockage Period.  Upon the
       termination of any Blockage Period, the right of Laidlaw to receive
       payments (including payments not made during the Blockage Period) shall
       be reinstated, and Allied Finance shall resume making such payments to
       Laidlaw in accordance with the terms hereof.  In no event shall Allied
       Finance be obligated to make, and Allied Finance shall not make, and
       shall not permit any of its Subsidiaries or Affiliates to make, directly
       or indirectly, by set-off, redemption, purchase or in any other manner,
       any payments or prepayments of, or on account of, any of the
       Subordinated Obligations during any Blockage Period or if such payment
       or prepayment would cause the occurrence of a Blockage Period.

              (b)    Upon any payment or distribution of any kind or character
       to creditors of Allied Finance (whether in cash, property or securities)
       in (x) a total or partial liquidation, winding up or dissolution of
       Allied Finance (whether voluntarily or involuntarily) or (y) in a
       bankruptcy, reorganization, insolvency, receivership or similar
       proceeding (including a proceeding under the Canadian Companies'
       Creditors Arrangement Act) relating to Allied Finance or its property,
       or in an assignment for the benefit of creditors or any marshaling of
       Allied Finance's assets and liabilities (any of the foregoing in clauses
       (x) and (y) being referred to herein as a "Bankruptcy or Insolvency
       Proceeding"), the holders of Senior Indebtedness will be entitled to
       receive payment in full in cash of all the principal of and interest on
       and other amounts payable in respect of such Senior Indebtedness
       (including interest accruing after the commencement of any such
       proceeding at the rate specified in the agreements or instruments
       creating or evidencing the  applicable Senior Indebtedness and whether
       or not such interest is an allowed or allowable claim under applicable
       law) before Laidlaw will be entitled to receive any payment with respect
       to this Debenture (whether in cash, property or securities); and until
       all obligations with respect to Senior Indebtedness are indefeasibly
       paid in full in cash, any distribution received by Laidlaw or to which
       Laidlaw would be entitled shall be paid over or made to the holders of
       Senior Indebtedness.  Upon the occurrence of any Bankruptcy or
       Insolvency Proceeding relating to Allied Finance, the holders of the
       Senior Indebtedness are authorized and empowered to (i) demand, sue for,
       collect and receive every payment or distribution on account of the
       Subordinated Obligations payable or deliverable in connection with such
       event or proceeding and give acquittance therefor, and (ii) file claims
       and proofs of claim in any statutory or non- statutory proceeding and
       take such other actions as may be necessary or desirable for the
       enforcement of the subordination provisions of this





                                       11
<PAGE>   140
       Debenture.  Promptly after taking any action provided in clauses (i) or
       (ii) above, Allied Finance shall give written notice thereof to the
       holder of this Debenture; provided, however, that failure to give such
       notice shall in no event affect the validity of any action so taken.

              (c)    In the event that, notwithstanding the occurrence of any
       of the events described in Subsections 5(a) and (b), any such payment or
       distribution of assets of Allied Finance of any kind or character,
       whether in cash, property or securities, shall be received by the holder
       of this Debenture which is not permitted hereby such payment or
       distribution shall be held in trust for the ratable benefit of, and
       shall be paid over or delivered to, the holders of the Senior
       Indebtedness.

              (d)    The holders of the Senior Indebtedness shall have no duty
       or obligation to the holder of this Debenture in any manner whatsoever
       and may, at any time and from time to time, in their sole discretion,
       without the consent of or notice to the holder of this Debenture and
       without impairing or releasing any rights of the holders of the Senior
       Indebtedness or any of the obligations of the holder of this Debenture
       hereunder, take any or all of the following actions:

                     (i)    change the amount, manner, place, terms of payment
              or interest rate, change or extend the time of payment of, or
              renew or alter, any of the Senior Indebtedness, or amend or
              supplement or waive any of the terms of any instrument or
              agreement now or hereafter executed pursuant to which any of the
              Senior Indebtedness is issued or incurred;

                     (ii)   sell, exchange, release, surrender, relend, realize
              upon or otherwise deal with in any manner and in any order, any
              property (or the income, revenues, profits or proceeds therefrom)
              by whomsoever at any time pledged or mortgaged to secure, or
              howsoever securing, any Senior Indebtedness;

                     (iii)  release any person liable in any manner for the
              payment or collection of the Senior Indebtedness;

                     (iv)   exercise or refrain from exercising any rights and
              remedies against Allied Finance or others, or otherwise act or
              refrain from acting or, for any reason, fail to file, record or
              otherwise perfect any security interest in or lien on any
              property of Allied Finance or any other Person; and

                     (v)    apply any sums received by the holders of the
              Senior Indebtedness, by whomsoever paid and however realized, to
              payment of the Senior Indebtedness in such manner as the holders
              of the Senior Indebtedness, in their sole discretion, may deem
              appropriate.





                                       12
<PAGE>   141
              (e)    Laidlaw and any future holder of this Debenture, by
       acceptance of this Debenture, agree to provide to any holder of Senior
       Indebtedness, at any time and from time to time, upon the written
       request of Allied Finance or such holder of Senior Indebtedness an
       agreement signed by Laidlaw or such future holder of this Debenture
       addressed to the holder of such Senior Indebtedness in substantially the
       form of, and on substantially the terms set out in, Exhibit A attached
       hereto to the effect that such holder is a holder of Senior
       Indebtedness, that the holder or holders of such Senior Indebtedness are
       entitled to the benefits of Sections 5, 6 and 13 of this Debenture and
       that the holder or holders of such Senior Indebtedness may enforce the
       terms and provisions thereof to the same extent Allied Finance would be
       able to do so, provided, however, that prior to furnishing such
       agreement, Laidlaw has received from Allied Finance or such holder such
       information as Laidlaw may reasonably request demonstrating to Laidlaw's
       reasonable satisfaction that such holder is a holder of Senior
       Indebtedness.  Laidlaw, and each subsequent holder of this Debenture, by
       acceptance of this Debenture, irrevocably appoint Allied Finance (with
       full power of substitution) as its agent and attorney in fact (which
       appointment is coupled with an interest and shall be irrevocable so long
       as any Senior Indebtedness is outstanding) to execute and deliver on
       behalf and in the name of Laidlaw or such holder, as the case may be, an
       agreement in substantially the form of, and on substantially the terms
       set out in, Exhibit A hereto in favor of each such holder of Senior
       Indebtedness and to take such further action as may be necessary or
       appropriate to effectuate the subordination as provided herein.
       Promptly after exercise of any such power, Allied Finance will give
       written notice thereof to the holder of the Debenture; provided,
       however, that failure to give such notice shall in no event affect the
       validity of any power so exercised.

              (f)    If a Default shall have occurred and be continuing (other
       than a Default pursuant to Subsection 7(b) or (c)) and the holder of
       this Debenture elects to accelerate this Debenture pursuant to Section
       8, Laidlaw shall give the Representative under the Credit Facility 30
       days' prior written notice before accelerating this Debenture, which
       notice shall state that it is a "Notice of Intent to Accelerate";
       provided, however, that Laidlaw shall not be required to give such
       notice if at such time payment of any Indebtedness incurred pursuant to
       the Credit Facility shall have been accelerated.  If payment of this
       Debenture is accelerated because of a Default, the holder shall promptly
       notify the Representatives under the Designated Senior Indebtedness and
       the holders of all other Senior Indebtedness of the acceleration.

              (g)    Until all Senior Indebtedness has been indefeasibly paid
       in full in cash, the holders of this Debenture shall not be entitled to
       assert, enforce or otherwise exercise any right of subrogation against
       Allied Finance or any other Person obligated on the Subordinated
       Obligations.  After all Senior Indebtedness has been indefeasibly paid
       in full in cash, and until the Subordinated Obligations have been so
       paid in full, the holder of this Debenture shall be subrogated to the
       rights of holders of Senior Indebtedness to receive distributions
       applicable to





                                       13
<PAGE>   142
       Senior Indebtedness.  A distribution made under this Section 5 to
       holders of Senior Indebtedness which otherwise would have been made to
       the holder of this Debenture is not, as between Allied Finance and the
       holder of this Debenture, a payment by Allied Finance on Senior
       Indebtedness.

              (h)    This Section 5 defines the relative rights of the holder
       of this Debenture and holders of Senior Indebtedness.  Nothing in this
       Debenture shall:

                     (i)    impair, as between Allied Finance and such holder,
              the obligation of Allied Finance, which is absolute and
              unconditional, to pay principal of and, premium and interest, if
              any, on this Debenture in accordance with its terms; or

                     (ii)   except as otherwise set forth in this Section 5,
              prevent the holder of this Debenture from exercising its
              available remedies upon a Default, subject to the rights of
              holders of Senior Indebtedness to receive distributions otherwise
              payable to such holder.

       6.     No Impairment.  Section 5, this Section 6, the proviso to
Subsection 8(a), and Section 13 (and all defined terms used in such sections)
shall constitute a continuing offer to all Persons who become holders of, or
continue to hold, Senior Indebtedness, and such provisions are made for the
benefit of the holders from time to time of Senior Indebtedness, and such
Persons are conclusively presumed to have relied upon such provisions; and such
holders are made obligees hereunder, and they or each of them may enforce such
provisions.  No right of any present or future holder of any Senior
Indebtedness to enforce the subordination or other provisions referred to in
this Section 6 shall at any time in any way be prejudiced or impaired by any
act or failure to act on the part of Allied Finance or Laidlaw, or by any
non-compliance by Allied Finance or Laidlaw with the terms, provisions and
covenants of this Debenture, regardless of any knowledge thereof any such
holder may have or otherwise be charged with.  Section 5, this Section 6 and
the subordination and other provisions referred to in this Section 6 may not be
amended or modified in any manner which might terminate or impair the
subordination or such other provisions except with the prior written consent of
the Representatives of all the Designated Senior Indebtedness.

       7.     Events of Default.  "Default" means the occurrence of one or more
of the following:

              (a)    Payment.  Allied Finance fails to pay the outstanding
       principal amount of this Debenture on the Maturity Date.

              (b)    Voluntary Bankruptcy.  Allied Finance (i) files a petition
       initiating a voluntary Bankruptcy or Insolvency Proceeding, (ii) seeks,
       consents to, or does not contest the appointment of a receiver or
       trustee for itself or for all or any substantial part of its property,
       (iii) is voluntarily adjudicated a bankrupt or





                                       14
<PAGE>   143
       insolvent, (iv) makes a general assignment for the benefit of its
       creditors, or (v) admits in writing its inability to pay its debts as
       they mature.

              (c)    Involuntary Bankruptcy.  A petition is filed against
       Allied Finance seeking to initiate a Bankruptcy or Insolvency Proceeding
       and such petition is not dismissed within 180 days after being filed, or
       a court of competent jurisdiction enters an order, judgment or decree
       appointing a receiver or trustee for Allied Finance, or for all or
       substantially all of its property, and such order, judgment or decree is
       not discharged or stayed within 180 days after its entry.

              (d)    Acceleration of Other Indebtedness.  An event of default
       occurs and is continuing under the Credit Facility and, as a result
       thereof, the Indebtedness outstanding pursuant to the Credit Facility is
       accelerated; provided, however, that in the event the holders of such
       Indebtedness elect to waive such event of default or to otherwise
       de-accelerate such Indebtedness, no Default shall subsist hereunder.

       8.     Remedies of Laidlaw.  Upon the occurrence and during the
continuance of a Default, Laidlaw shall have the following rights:

              (a)    Acceleration.  Subject to the provisions of Section 5
       hereof, Laidlaw may, at its option, declare the entire principal balance
       of this Debenture, together with the accrued and unpaid interest
       thereon, immediately due and payable without notice of Default, notice
       of intent to accelerate, notice of acceleration, or any other notice,
       presentment, protest, demand or action of any kind or nature whatsoever
       (each of which is hereby expressly waived by Allied Finance), whereupon
       the entire Indebtedness under this Debenture shall become immediately
       due and payable; provided, however, that no such acceleration (except
       for an acceleration upon the occurrence of a Default specified in
       Subsection 7(d)) shall be effective or of any force whatsoever and the
       holder of this Debenture may not take any action against Allied Finance
       with respect to a Default hereunder if made during a Blockage Period, or
       if such acceleration would result in a Blockage Period; provided,
       further, that in the event the Indebtedness under this Debenture is
       accelerated upon the occurrence of a Default specified in Subsection
       7(d) and the holders of the Indebtedness outstanding pursuant to the
       Credit Facility elect to waive the event of default giving rise to the
       acceleration thereunder or otherwise elect to de-accelerate such
       Indebtedness, Laidlaw shall de-accelerate the obligations hereunder.

              (b)    Other Rights.  Except as otherwise modified hereby,
       Laidlaw shall have all rights and remedies available at law or equity
       and the same (i) shall be cumulative and concurrent, (ii) may be pursued
       separately, successively, or concurrently against Allied Finance, (iii)
       may be exercised as often as occasion therefor shall arise, it being
       agreed by Allied Finance that the exercise or failure to exercise any of
       the same shall in no event be construed as a waiver or release





                                       15
<PAGE>   144
       thereof or of any other right or remedy, and (iv) are intended to be,
       and shall be, nonexclusive.

       9.     Offer of Prepayment upon Change of Control.

              (a)    Allied Finance will, within thirty business days after any
       executive officer of Allied Finance has knowledge of the occurrence of a
       Change of Control, give written notice of such Change of Control to the
       holder of this Debenture.  Subject to the provisions of Section 5, such
       notice shall contain and constitute an offer to prepay this Debenture as
       described in Subsection 9(b).

              (b)    The offer to prepay this Debenture contemplated by
       Subsection 9(a) shall be an offer to prepay, in accordance with and
       subject to this Section 9, all, but not less than all, of this Debenture
       at the Section 9 Purchase Price, together with all interest accrued and
       unpaid hereon, on a date specified in such offer (the "Section 9
       Prepayment Date") which date shall be not less than 45 days and not more
       than 60 days after the date of such offer (if the Section 9 Prepayment
       Date shall not be specified in such offer, the Section 9 Prepayment Date
       shall be the first business day after the 45th day after the date of
       such offer).

              (c)    The holder of this Debenture may accept the offer to
       prepay made pursuant to this Section 9 in whole but not in part by
       causing a notice of such acceptance to be delivered to Allied Finance
       within ten business days after receipt of the written notice to be given
       pursuant to Subsection 9(a).  A failure by a holder of this Debenture to
       respond within such time period to an offer to prepay made pursuant to
       this Section 9 shall be deemed to constitute a rejection of such offer.

              (d)    Prepayment of this Debenture pursuant to this Section 9
       shall be at the Section 9 Purchase Price.  The prepayment shall be made
       on the Section 9 Prepayment Date.

              (e)    Notwithstanding any provision hereof to the contrary, in
       no event shall Allied Finance prepay (or be obligated to prepay)  this
       Debenture pursuant to this Section 9 until 91 days after Allied Finance
       shall have prepaid the Senior Indebtedness incurred pursuant to the
       Credit Facility and the Senior Subordinated Debentures, and all other
       Senior Indebtedness which is entitled to be prepaid upon the occurrence
       of a Change of Control, unless the holder or holders of such Senior
       Indebtedness have waived or otherwise failed to enforce their rights to
       receive a prepayment of the Senior Indebtedness held by them to which
       they are entitled in connection with such Change of Control.

       10.    Captions.  The captions, headings, and arrangements used in this
Debenture are for convenience only and do not affect or modify the terms of
this Debenture.





                                       16
<PAGE>   145
       11.    Notices.  All notices or other communications which are required
or may be given under this Debenture shall be in writing and shall be deemed to
have been duly given when delivered in person or transmitted by telecopier
(with receipt confirmed) at the address or telecopy number set forth below (as
any such address or telecopier number may be changed from time to time by
notice similarly given):



       (1)    if to Laidlaw, to:

                     Laidlaw Inc.
                     3221 North Service Road
                     Burlington, Ontario
                     Canada L7R 3Y8
                     Attention:  Ivan R. Cairns
                     Telecopy No.: (905) 332-6550

       (2)    if to Allied Finance, to:

                     3294854 CANADA INC.
                     c/o Allied Waste Industries, Inc.
                     7201 East Camelback Road, Suite 375
                     Scottsdale, Arizona 85251
                     Attention: Roger A. Ramsey
                     Telecopy No.: (602) 481-9347

                     with a copy to:

                     Porter & Hedges, L.L.P.
                     700 Louisiana Street, Suite 3500
                     Houston, Texas 77002
                     Attention: Robert G. Reedy
                     Telecopy No.: (713) 228-1331


       12.    Applicable Law.  This Debenture shall be governed by and
construed in accordance with the laws of the State of Delaware and the laws of
the United States of America applicable therein (without reference to the
conflicts of law principles thereof).

       13.    Transfer Restriction.  This Debenture may not be sold, assigned,
transferred, pledged or hypothecated in any manner, directly or indirectly, by
Laidlaw or any other holder, unless the assignee, transferee, pledgee or
hypothecate has agreed in writing to be bound by the provisions of this
Debenture applicable to Laidlaw, including but not limited to the provisions of
Section 5(e) and Section 14 hereof.  Any transfer of this Debenture shall be of
the entire Debenture and not of any part of the indebtedness evidenced hereby
or of at least $75,000,000 of the principal amount thereof.





                                       17
<PAGE>   146
       14.    OFFSET.  THE OBLIGATIONS OF ALLIED FINANCE HEREUNDER ARE, IN ALL
RESPECTS, SUBJECT TO OFFSET AS MORE FULLY SET FORTH IN THE OFFSET LETTER
AGREEMENT.  THE OFFSET RIGHTS SET FORTH IN THE OFFSET LETTER AGREEMENT SHALL BE
EFFECTIVE NOTWITHSTANDING THE ASSIGNMENT OR TRANSFER OF THIS DEBENTURE BY
LAIDLAW AND ANY TRANSFEREE SHALL TAKE THIS DEBENTURE SUBJECT TO THE TERMS
THEREOF.

       NOTICE:  THE RIGHTS AND OBLIGATIONS OF ALLIED FINANCE AND LAIDLAW SHALL
BE DETERMINED SOLELY FROM WRITTEN AGREEMENTS, DOCUMENTS, AND INSTRUMENTS, AND
ANY PRIOR ORAL AGREEMENTS BETWEEN ALLIED FINANCE AND LAIDLAW ARE SUPERSEDED BY
AND MERGED INTO SUCH WRITINGS.  THIS DEBENTURE (AS AMENDED IN WRITING FROM TIME
TO TIME) REPRESENTS THE FINAL AGREEMENT BETWEEN ALLIED FINANCE AND LAIDLAW AND
MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR OR CONTEMPORANEOUS ORAL AGREEMENTS
BY ALLIED FINANCE AND LAIDLAW. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN
ALLIED FINANCE AND LAIDLAW.



                                   3294854 CANADA, LTD.
                                   a Canadian corporation


                                   By:                                         
                                      -----------------------------------------
                                   Name:                                       
                                        ---------------------------------------
                                   Title:                                      
                                         --------------------------------------


Agreed and Accepted:

LAIDLAW INC.
a Canadian corporation


By:                                         
   -----------------------------------------
Name:                                       
     ---------------------------------------
Title:                                      
      --------------------------------------





                                       18
<PAGE>   147
                                                                       EXHIBIT A
                                                   to the 7% Junior Subordinated
                                                   Debenture Due 200__ Issued by
                                                            3294854 Canada, Ltd.
                                                        in favor of Laidlaw Inc.


                                     [Date]


- --------------------

- --------------------

- --------------------


Gentlemen:

       Reference is made to the 7% Junior Subordinated Debenture Due 200__
dated __________, 199_ (the "Subordinated Debenture"), in the original
principal amount of $150 million issued by 3294854 CANADA INC., a Canadian
corporation ("Allied Finance"), in favor of Laidlaw Inc., a Canadian
corporation, and the [describe Senior Indebtedness] (the "Subject
Indebtedness"), being issued contemporaneously herewith by Allied Finance in
favor of [identity of holder or holders of Subject Indebtedness] (whether one
or more, the "Senior Creditor").  Hereinafter, capitalized words and phrases
used herein which are defined in the Subordinated Debenture are used herein as
therein defined.

       The undersigned (the "Subordinated Creditor") hereby represents and
warrants to the Senior Creditor that the Subordinated Creditor is the owner and
holder of the Subordinated Debenture and that the Subordinated Creditor is
entitled to make the agreements herein contained.  The Subordinated Creditor
hereby acknowledges and agrees that the principal of, and premium, if any, and
interest on (including interest that, but for the filing of a petition
initiating any Bankruptcy or Insolvency Proceeding would accrue on such
obligations at the time provided in the agreements or instruments creating or
evidencing the respective obligations, whether or not such claim is allowed in
such Bankruptcy or Insolvency Proceeding) and all other amounts of every kind
or nature (including, but not limited to, fees, indemnities and expenses and
any interest rate swaps or other interest rate hedging products entered into in
connection with the Subject Indebtedness) due on or in connection with the
Subject Indebtedness, whether outstanding on the date hereof or hereafter
created, incurred or assumed, guaranteed or in effect guaranteed by Allied
Finance (including all renewals, extensions or refundings of, or amendments,
modifications or supplements to, the foregoing) are in all respects Senior
Indebtedness, that the Senior Creditor (and any other Person who from time to
time is a holder of the Subject Indebtedness) is entitled to the benefits of
Sections 5, 6 and 13 of the Subordinated Debenture and that the Senior Creditor
(and any other Person who from time to time is a holder of the Subject
Indebtedness) may enforce the





                                      A-1
<PAGE>   148
terms and provisions of the Subordinated Debenture to the same extent that
Allied Finance or any other holder of Senior Indebtedness would be able to do
so.

       The Subordinated Creditor hereby agrees that the Subordinated Debenture
will not be sold, assigned, transferred, pledged or hypothecated in any manner,
directly or indirectly, by the Subordinated Creditor, unless the assignee,
transferee, pledgee or hypothecate has agreed in writing to be bound by the
provisions of this agreement.

       The Subordinated Creditor has executed this agreement in the space
provided below in order to induce the Senior Creditor to advance funds or
extend credit to Allied Finance, and this agreement is intended by the
Subordinated Creditor to be a binding and enforceable undertaking by the
Subordinated Creditor in favor of the Senior Creditor.

       The rights credited hereby of the Senior Creditor and of any subsequent
holder of the Senior Indebtedness will be assigned automatically, and without
any further act, by the Senior Creditor or such holder upon any sale,
assignment, conveyance or other transfer of all or any part of the Senior
Indebtedness to the extent of the interest sold, assigned, conveyed or
otherwise transferred, unless and to the extent the Senior Creditor or such
holder expressly provides otherwise in the instrument pursuant to which such
interest is conveyed.



                                           Very truly yours,

                                           [NAME OF SUBORDINATED CREDITOR]


                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------



Accepted and agreed to as of
the date first above written:

[NAME OF SENIOR CREDITOR]


By:                                 
   ---------------------------------
Name:                               
     -------------------------------
Title:                              
      ------------------------------





                                      A-2
<PAGE>   149






                                                                     EXHIBIT B-2

THIS DEBENTURE HAS NOT BEEN REGISTERED (OR QUALIFIED BY PROSPECTUS) UNDER THE
SECURITIES ACT (DEFINED BELOW), THE CANADIAN SECURITIES LEGISLATION (DEFINED
BELOW), OR THE LAWS OF ANY STATE OF THE UNITED STATES OF AMERICA, AND THIS
DEBENTURE MAY NOT BE OFFERED FOR SALE, SOLD, TRANSFERRED, PLEDGED, HYPOTHECATED
OR OTHERWISE DISPOSED OF EXCEPT IN ACCORDANCE WITH THE TERMS HEREOF AND THE
REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF THE SECURITIES ACT, THE
CANADIAN SECURITIES LEGISLATION AND SUCH STATE LAWS OTHER THAN PURSUANT TO AN
EXEMPTION FROM SUCH REGISTRATION AND PROSPECTUS REQUIREMENTS AND UPON DELIVERY
TO ALLIED FINANCE OF AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO ALLIED
FINANCE TO THE EFFECT THAT SUCH TRANSFER IS EXEMPT FROM REGISTRATION AND THE
PROSPECTUS DELIVERY REQUIREMENTS UNDER THOSE LAWS.

THIS DEBENTURE WILL BE ISSUED WITH ORIGINAL ISSUE DISCOUNT ("OID").  THE HOLDER
OF THIS DEBENTURE SHOULD BE AWARE THAT SUCH HOLDER WILL BE REQUIRED TO INCLUDE
OID IN SUCH HOLDER'S GROSS INCOME FOR INCOME TAX PURPOSES IN ADVANCE OF THE
RECEIPT OF CASH ATTRIBUTABLE TO SUCH INCOME.  WITH RESPECT TO OID, THE ISSUE
DATE OF THIS DEBENTURE IS _________________, 199__, THE ISSUE PRICE IS
[$_________], THE AMOUNT OF OID IS [$_________], AND THE YIELD TO MATURITY IS
[______]%.

             ZERO COUPON JUNIOR SUBORDINATED DEBENTURE DUE 200__(1)


$168,300,000                                            _________________, 199__


         FOR VALUE RECEIVED, 3294854 CANADA INC., a Canadian corporation
("Allied Finance"), promises to pay to Laidlaw Inc., a Canadian corporation
("Laidlaw"), or its registered assigns, the amount of $168,300,000 on the
Maturity Date.





- ----------------------------------

     (1)  The due date will be 12 years after the date of issuance.

<PAGE>   150

         1.      Definitions.

         (a)     For all purposes of this Debenture:

                 "Accreted Value" means (i) at any date set forth in the table
         below (the "Value Date"), the amount set forth opposite such Value
         Date, and (ii) at any other date (the "Determination Date"), the
         amount equal to the sum of (y) the Accreted Value as of the Value Date
         immediately preceding such Determination Date plus (z) an amount equal
         to the product of (A) the difference between the Accreted Value as of
         the Value Date immediately following such Determination Date minus the
         Accreted Value as of the Value Date immediately preceding such
         Determination Date multiplied by (B) a fraction, the numerator of
         which is the number of days elapsed from (and including) such
         preceding Value Date to (but excluding) such Determination Date and
         the denominator of which is the number of days from (and including)
         such preceding Value Date to (but excluding) the immediately following
         Value Date.

<TABLE>
<CAPTION>
               Value Date (2)             Accreted Value              Value Date              Accreted Value
               ----------                 --------------              ----------              --------------
         <S>         <C>                     <C>               <C>         <C>                   <C>
         ___________, ____                   $ 33,200,000      ___________, ____                 $ 85,500,000

         ___________, ____                   $ 38,000,000      ___________, ____                 $ 98,500,000

         ___________, ____                   $ 43,500,000      ___________, ____                 $112,100,000
         ___________, ____                   $ 49,800,000      ___________, ____                 $128,400,000

         ___________, ____                   $ 57,000,000      ___________, ____                 $147,000,000
         ___________, ____                   $ 65,300,000      ___________, ____                 $168,300,000

         ___________, ____                   $ 74,700,000      ___________, ____
</TABLE>

                 "Affiliate" means, with respect to any Person, another Person
         that directly, or indirectly through one or more intermediaries,
         controls, is controlled by or is under common control with such
         Person, with the term "control," including the terms "controlling" and
         "controlled," meaning for purposes of this definition, the power to
         direct the management and policies of a Person, directly or
         indirectly, whether through the ownership of voting securities or
         partnership or other ownership interests, or by contract or otherwise.

                 "Allied" means Allied Waste Industries, Inc., a Delaware
         corporation, and its successors and assigns.

                 "Allied Common Stock" means the Common Stock, $.01 par value
         per share, of Allied.





- ----------------------------------

   (2)   The initial Value Date shall be the date of the Debenture, and
         succeeding Value Dates shall occur each year thereafter until the
         Maturity Date.


<PAGE>   151

                 "Allied Finance" means 3294854 Canada Inc. a Canadian
         corporation, and its successors and assigns.

                 "Allied U.S." means Allied Holdings (United States), Inc., a
         Delaware corporation, and its successors and assigns.

                 "Allied Warrant" means the warrant for the purchase of shares
         of Allied Common Stock to be issued by Allied to Laidlaw under Section
         2.3 of the Stock Purchase Agreement.

                 "Bankruptcy or Insolvency Proceeding" is defined in Subsection
         4(b) of this Debenture.

                 "Blockage Period" means any period when a default or an event
         of default  or an event which, with the giving of notice or the lapse
         of time or both, would constitute a default or an event of default has
         occurred and is continuing under the terms of the Credit Facility or
         the Senior Subordinated Debentures or under the terms of any agreement
         or instrument pursuant to which any other Designated Senior
         Indebtedness is created, issued, evidenced, secured or guaranteed.

                 "Business Day" means a day other than Saturday, Sunday or any
         day on which banks located in Toronto, Ontario or New York, New York
         are authorized or obligated to close.

                 "Canadian Securities Legislation" means the Securities Act of
         the Province of Ontario (R.S.O. 1990, c.  S.5, as amended) and similar
         provincial legislation, and the regulations and rules promulgated
         thereunder.

                 "Change of Control" means a change resulting when any
         Unrelated Person or any Unrelated Persons acting together that would
         constitute a Group together with any Affiliates thereof (in each case
         also constituting Unrelated Persons) shall at any time Beneficially
         Own more than 50% of the aggregate voting power of all classes of
         Voting Stock of Allied; provided, however, that if at the date any
         "Change of Control" would otherwise have occurred but for the fact
         that a Person was not an Unrelated Person because such Person or an
         Affiliate of such Person acquired shares of Allied Common Stock or all
         or any portion of the Allied Warrant from Laidlaw or from any
         Affiliate of Laidlaw within nine months prior to such date, such
         shares of Allied Common Stock acquired from Laidlaw or any Affiliate
         of Laidlaw, or any shares of Allied Common Stock issued upon exercise
         of the Allied Warrant or any portion thereof, shall at all times
         thereafter be excluded when calculating whether a Change of Control
         has occurred.  As used in this definition of Change of Control (a)
         "Beneficially Own" means "beneficially own" as defined in Rule 13d-3
         of the Securities Exchange Act of 1934, as amended (the "Exchange
         Act"), or any successor provisions thereto; provided, however, that,
         for purposes of this definition, a Person shall not be deemed to
         Beneficially Own securities tendered pursuant to a tender or exchange
         offer made by or on behalf of such Person or any of such Person's
         Affiliates until such tendered





<PAGE>   152

         securities are accepted for purchase or exchange; (b) "Group" means a
         "group" for purposes of Section 13(d) of the Exchange Act; (c)
         "Affiliate" means, with respect to any Person, another Person which
         would be an "affiliate" of such Person for purposes of Section 13(d)
         of the Exchange Act; (d) "Unrelated Person" means at any time any
         Person other than Laidlaw, any Person to whom Laidlaw or any of its
         Affiliates transfers, within nine months prior to such time, any
         shares of Allied Common Stock or all or any portion of the Allied
         Warrant or any Affiliate of Polaris or any such Person; provided,
         however, that Persons (other than Polaris or its Affiliates) to whom
         Laidlaw or any of its Affiliates transfers any shares of Allied Common
         Stock or all or any portion of the Allied Warrant after five years
         from the date hereof shall not be deemed Unrelated Persons; and (e)
         "Voting Stock" of any Person shall mean capital stock of such Person
         which ordinarily has voting power for the election of directors (or
         persons performing similar functions) of such Person, whether at all
         times or only so long as no senior class of securities has such voting
         power by reason of any contingency.

                 "Credit Facility" means the Credit Agreement dated as of
         ___________, 199_ among Allied U.S., as borrower, Allied, Goldman
         Sachs Credit Partners L.P., as syndication agent, Citibank, N.A., as
         documentation agent, Credit Suisse, as administrative agent, Goldman
         Sachs Credit Partners L.P., Citicorp USA, Inc. and Credit Suisse, as
         initial lenders, and the other financial institutions now or hereafter
         parties thereto (as the same may be renewed, amended, modified,
         increased, extended, refinanced, or otherwise supplemented from time
         to time).

                 "Debenture" means this Zero Coupon Junior Subordinated 
         Debenture due 200_.

                 "Default" is defined in Section 6.

                 "Default Rate" means an annual interest rate equal to 9% per 
         annum.

                 "Designated Senior Indebtedness" means (i) the Senior
         Indebtedness incurred with respect to the Credit Facility, (ii) the
         Senior Indebtedness evidenced by the Senior Subordinated Debentures
         and (iii) any other Senior Indebtedness which is incurred pursuant to
         an agreement (or series of related agreements simultaneously entered
         into) providing for Indebtedness, or commitments to lend, of at least
         $10,000,000 at the time of determination and is specifically
         designated in the instrument evidencing such Senior Indebtedness or
         the agreement under which such Senior Indebtedness arises as
         "Designated Senior Indebtedness."

                 "$" means U.S. dollars, the lawful currency of the United
         States of America.

                 "Financing Lease"  means any lease of property, real or
         personal, the obligations of the lessee in respect of which are
         required in accordance with generally accepted accounting principles
         to be capitalized on a balance sheet of the lessee.





<PAGE>   153

                 "Governmental Entity" means any U.S. or Canadian, territorial,
         federal, state, provincial or local court, executive office,
         legislature, governmental agency, department, ministry, commission, or
         administrative, regulatory or self-regulatory authority or
         instrumentality.

                 "Guarantee" means with respect to any Person any obligation,
         contingent or otherwise, of such Person guaranteeing or having the
         economic effect of guaranteeing any Indebtedness of any other Person
         (the "primary obligor") in any manner, whether directly or indirectly,
         and including any obligation of such Person, direct or indirect, (a)
         to purchase or pay (or advance or supply funds for the purchase or
         payment of ) such Indebtedness or to purchase (or to advance or supply
         funds for the purchase of) any security for the payment of such
         Indebtedness, (b) to purchase or lease property, securities or
         services for the purpose of assuring the owner of such Indebtedness of
         the payment of such Indebtedness or (c) to maintain working capital,
         equity capital or any other financial statement condition or liquidity
         of the primary obligor so as to enable the primary obligor to pay such
         Indebtedness; provided, however, that the term "Guarantee" shall not
         include endorsements for collection or deposit in the ordinary course
         of business.

                 "Indebtedness" means with respect to any Person at any date,
         (a) all indebtedness of such Person for borrowed money or for the
         deferred purchase price of property or services (other than current
         trade liabilities incurred in the ordinary course of business and
         payable in accordance with customary practices), (b) any other
         indebtedness of such Person which is evidenced by a note, bond,
         debenture, letter of credit or similar instrument, (c) all obligations
         of such Persons with respect to Guarantees, (d) all obligations of
         such Person under Financing Leases, (e) all obligations of such Person
         in respect of acceptances issued or created for the account of such
         Person (other than endorsements in the ordinary course of business),
         (f) all obligations in respect of interest rate swaps or other
         interest rate hedging products or foreign currency exchange agreements
         or exchange rate hedging arrangements, (g) all obligations in respect
         of reimbursement obligations under letters of credit, and (h) all
         liabilities of the type referred to in clauses (a) through (g) above
         that are secured by any lien, charge, security interest or encumbrance
         on any property owned by such Person even though such Person has not
         assumed or otherwise become liable for the payment thereof.

                 "Indenture" means the Indenture dated _____________, 199__,
         between Allied U.S. and the Trustee pursuant to which the Senior
         Subordinated Debentures are issued.

                 "Laidlaw" means Laidlaw Inc., a Canadian corporation.

                 "LTI" means Laidlaw Transportation, Inc., a Delaware
         corporation.

                 "Maturity Date" _________________, 200__ [12 years after the 
         date hereof].





<PAGE>   154

                 "Offset Letter Agreement" means the letter agreement dated the
         date hereof among Allied, Allied Finance, Laidlaw and LTI, in
         substantially the form of Exhibit N to the Stock Purchase Agreement.

                 "Person" means an individual, corporation, partnership,
         association, joint stock company, limited liability company,
         Governmental Entity, business trust, unincorporated organization, or
         other legal entity.

                 "Representative" means at any date, with respect to the Credit
         Facility, the Person or Persons then acting as the administrative
         agent under the Credit Facility, with respect to the Senior
         Subordinated Debentures, the Trustee, and with respect to any other
         Designated Senior Indebtedness, the holders of such Designated Senior
         Indebtedness or any Person acting as agent of such holders at such
         date.

                 "Section 8 Prepayment Date" is defined in Section 8(b) of this
         Debenture.

                 "Securities Act" means the Securities Act of 1933, as amended.

                 "Senior Indebtedness" means principal of, and premium, if any,
         and interest on (including interest that, but for the filing of a
         petition initiating any proceeding pursuant to any Bankruptcy or
         Insolvency Proceeding, would accrue on such obligations at the rate
         provided in the agreements or instruments creating or evidencing the
         respective obligations, whether or not such claim is allowed or
         allowable in such Bankruptcy or Insolvency Proceeding) and all other
         amounts of every kind or nature (including, but not limited to, fees,
         indemnities and expenses) due on or in connection with, any
         Indebtedness of Allied Finance, whether outstanding on the date of
         this Debenture or thereafter created, incurred, assumed or Guaranteed
         by Allied Finance (including all  renewals, extensions or refundings
         of, or amendments, modifications or supplements to, the foregoing)
         unless, in the case of any particular Indebtedness, the instrument
         creating or evidencing the same or pursuant to which the same is
         outstanding expressly provides that such Indebtedness shall not be
         senior in right of payment to this Debenture.  Without limiting the
         generality of the foregoing, "Senior Indebtedness" shall include (a)
         all obligations and liabilities of every kind and nature (including,
         but not limited to, fees, expenses and indemnities) under the Credit
         Facility or the Senior Subordinated Indebtedness, (b) all obligations
         and liabilities of every kind and nature (including, but not limited
         to, fees, expenses and indemnities) in respect of any interest rate
         swaps or other interest rate hedging product entered into in
         connection with Indebtedness incurred or to be incurred pursuant to
         the Credit Facility, and (c) any renewal, extension, refinancing or
         rearrangement of any indebtedness incurred or to be incurred pursuant
         to the Credit Facility or the Senior Subordinated Indebtedness.
         Notwithstanding the foregoing, Senior Indebtedness shall not include
         (i) amounts owed (except to banks, insurance companies and other
         financing institutions and except for obligations under Financing
         Leases) for goods, materials, services or operating lease rental
         payments in the ordinary course of business or for compensation to
         employees of Allied Finance, (ii) any liability for federal, state,
         provincial, local or other taxes owed or owing by Allied Finance and
         (iii) Indebtedness with respect to Allied Finance's 7% Junior





<PAGE>   155

         Subordinated Debentures due 200_ dated the date hereof and the
         Guaranty thereof by the Guarantor.

                 "Senior Subordinated Debentures" means the ___% Senior
         Subordinated Debentures due 200__(3) in the aggregate original
         principal amount of at least $475,000,000 issued by Allied U.S.
         pursuant to the Indenture.

                 "Stock Purchase Agreement" means the Stock Purchase Agreement
         dated as of September 17, 1996, among Allied, Allied Finance, Laidlaw
         and certain other parties named therein.

                 "Subordinated Obligations" is defined in Subsection 4(a).

                 "Subscription Agreement" means the Subscription Agreement,
         dated the date hereof among Allied, Allied Finance, Laidlaw and LTI.

                 "Subsidiary" of a Person means an Affiliate of that Person
         more than 50% of the aggregate voting power (or of any other form of
         voting equity interest in the case of a Person that is not a
         corporation) of which is beneficially owned by that Person directly or
         indirectly through one or more other Subsidiaries.

                 "Trustee" means ________________________________, a national
         banking association, in its capacity as trustee under the Indenture,
         and its successors in such capacity.

         (b)     Capitalized terms defined in this Debenture are equally
applicable to both their singular and plural forms.   References to a
designated "Section" or "Subsections" refer to a Section or Subsection of this
Debenture, unless otherwise specifically indicated.  In this Debenture,
"including" is used only to indicate examples, without limitation to the
indicated examples, and without limiting any generality which precedes it.

         2.      Interest; Default Rate.  From (and including) the date of this
Debenture through (and including) the Maturity Date, no interest shall accrue
or be payable with respect to this Debenture.  All past due principal of this
Debenture shall accrue interest at the Default Rate from (but not including)
the Maturity Date through (but not including) the date of payment.  From and
after the Maturity Date, interest will be calculated on the basis of the actual
number of days elapsed over a year composed of 365 days (or 366 days, as the
case may be).

         3.      Payment Terms.  Subject to Section 4:

                 (a)      The outstanding principal balance of this Debenture
         and all accrued and unpaid interest thereon shall be due and payable
         on the Maturity Date.





- ----------------------------------

    (3)  The due date of the Senior Subordinated Debentures will be 10 years
         after the date of issuance.


<PAGE>   156

                 (b)      No interest is payable with respect to the principal
         amount of this Debenture prior to the Maturity Date.   After the
         Maturity Date, interest will be payable in arrears on the ________ day
         of each ___________ and ____________ of each year on the principal
         balance of this Debenture outstanding from time to time.(4)

                 (c)      Each payment or prepayment hereunder shall be made by
         wire transfer to an account located in Canada designated by Laidlaw.

                 (d)      Any payment or action that is due hereunder on a day
         which is not a Business Day shall be deferred until the next
         succeeding Business Day (but interest shall continue to accrue on any
         applicable payment until such payment is made).

                 (e)  Pursuant to Article II of the Subscription Agreement, LTI
         has agreed to subscribe for shares of Allied Common Stock from time to
         time.  Reference is made to the Subscription Agreement for a complete
         statement of the terms and conditions pursuant to which such shares
         are to be issued.

         4.      Subordination.

                 (a)      The indebtedness evidenced by, and all obligations in
         respect of, this Debenture (including the obligations under Section 8)
         and the payment of principal of, premium and interest, if any, on and
         all other obligations in respect of, this Debenture (collectively, the
         "Subordinated Obligations") are expressly subordinate to all Senior
         Indebtedness to the extent and in the manner set forth herein.  For
         purposes hereof, the term "subordinate" means that, unless and until
         the Senior Indebtedness has been indefeasibly paid in full in cash,
         Laidlaw will not have the right under any circumstances to, and will
         not, take, demand, commence any suit or any other proceeding for
         collection, pursue any other judicial or non-judicial remedy or
         receive from Allied Finance or any of its Subsidiaries or Affiliates,
         and Allied Finance will not and will  not permit any of its
         Subsidiaries or Affiliates to, make, give, or permit, directly or
         indirectly, by set-off, redemption, purchase or in any other manner,
         any payment of or on account of the Subordinated Obligations;
         provided, however, that at any time, except during a Blockage Period,
         Allied Finance shall make, and Laidlaw may receive, and Laidlaw may
         commence any suit or other proceeding for collection of, scheduled
         payments of principal or interest on this Debenture in accordance with
         the terms hereof and, provided, further, that at any time, except
         during a Blockage Period, Allied Finance may prepay this Debenture so
         long as such prepayment would not cause the occurrence of a Blockage
         Period.  Upon the termination of any Blockage Period, the right of
         Laidlaw to receive payments shall be reinstated, and Allied Finance
         shall resume making such payments to Laidlaw in accordance with the
         terms hereof.  In no event shall Allied Finance be obligated to make,
         and Allied Finance shall not make, and shall not permit any of its
         Subsidiaries or Affiliates to make, directly or indirectly, by
         set-off, redemption, purchase or in any other manner, any payments or
         prepayments of,






- ----------------------------------

    (4)  Interest will be payable each six months after the Maturity Date.


<PAGE>   157

         or on account of, any of the Subordinated Obligations during any
         Blockage Period or if such payment or prepayment would cause the
         occurrence of a Blockage Period.

                 (b)      Upon any payment or distribution of any kind or
         character to creditors of Allied Finance (whether in cash, property or
         securities) in (x) a total or partial liquidation, winding up or
         dissolution of Allied Finance (whether voluntarily or involuntarily)
         or (y) in a bankruptcy, reorganization, insolvency, receivership or
         similar proceeding (including a proceeding under the Canadian
         Companies' Creditors Arrangement Act) relating to Allied Finance or
         its property, or in an assignment for the benefit of creditors or any
         marshaling of Allied Finance's assets and liabilities (any of the
         foregoing in clauses (x) and (y) being referred to herein as a
         "Bankruptcy or Insolvency Proceeding"), the holders of Senior
         Indebtedness will be entitled to receive payment in full in cash of
         all the principal of and interest on and other amounts payable in
         respect of such Senior Indebtedness (including interest accruing after
         the commencement of any such proceeding at the rate specified in the
         agreements or instruments creating or evidencing the  applicable
         Senior Indebtedness and whether or not such interest is an allowed or
         allowable claim under applicable law) before Laidlaw will be entitled
         to receive any payment with respect to this Debenture (whether in
         cash, property or securities); and until all obligations with respect
         to Senior Indebtedness are paid in full in cash, any distribution
         received by Laidlaw or to which Laidlaw would be entitled shall be
         paid over or made to the holders of Senior Indebtedness.  Upon the
         occurrence of any Bankruptcy or Insolvency Proceeding relating to
         Allied Finance, the holders of the Senior Indebtedness are authorized
         and empowered to (i) demand, sue for, collect and receive every
         payment or distribution on account of the Subordinated Obligations
         payable or deliverable in connection with such event or proceeding and
         give acquittance therefor, and (ii) file claims and proofs of claim in
         any statutory or non-statutory proceeding and take such other actions
         as may be necessary or desirable for the enforcement of the
         subordination provisions of this Debenture.  Promptly after taking any
         action provided in clauses (i) or (ii) above, Allied Finance shall
         give written notice thereof to the holder of this Debenture; provided,
         however that failure to give such notice shall in no event affect the
         validity of any action so taken.

                 (c)      In the event that, notwithstanding the occurrence of
         any of the events described in Subsections 4(a) and (b), any such
         payment or distribution of assets of Allied Finance of any kind or
         character, whether in cash, property or securities, shall be received
         by the holder of this Debenture which is not permitted hereby such
         payment or distribution shall be held in trust for the ratable benefit
         of, and shall be paid over or delivered to, the holders of the Senior
         Indebtedness.

                 (d)      The holders of the Senior Indebtedness shall have no
         duty or obligation to the holder of this Debenture in any manner
         whatsoever and may, at any time and from time to time, in their sole
         discretion, without the consent of or notice to the holder of this
         Debenture and without impairing or releasing any rights of the holders
         of the Senior Indebtedness or any of the obligations of the holder of
         this Debenture hereunder, take any or all of the following actions:





<PAGE>   158

                          (i)     change the amount, manner, place, terms of
                 payment or interest rate, change or extend the time of payment
                 of, or renew or alter, any of the Senior Indebtedness, or
                 amend or supplement or waive any of the terms of any
                 instrument or agreement now or hereafter executed pursuant to
                 which any of the Senior Indebtedness is issued or incurred;

                          (ii)    sell, exchange, release, surrender, relend,
                 realize upon or otherwise deal with in any manner and in any
                 order, any property (or the income, revenues, profits or
                 proceeds therefrom) by whomsoever at any time pledged or
                 mortgaged to secure, or howsoever securing, any Senior
                 Indebtedness;

                          (iii)   release any person liable in any manner for
                 the payment or collection of the Senior Indebtedness;

                          (iv)    exercise or refrain from exercising any
                 rights and remedies against Allied Finance or others, or
                 otherwise act or refrain from acting or, for any reason, fail
                 to file, record or otherwise perfect any security interest in
                 or lien on any property of Allied Finance or any other Person;
                 and

                          (v)     apply any sums received by the holders of the
                 Senior Indebtedness, by whomsoever paid and however realized,
                 to payment of the Senior Indebtedness in such manner as the
                 holders of the Senior Indebtedness, in their sole discretion,
                 may deem appropriate.

                 (e)      Laidlaw and any future holder of this Debenture, by
         acceptance of this Debenture, agree to provide to any holder of Senior
         Indebtedness, at any time and from time to time, upon the written
         request of Allied Finance or such holder of Senior Indebtedness, an
         agreement signed by Laidlaw or such future holder of this Debenture
         addressed to the holder of such Senior Indebtedness in substantially
         the form of, and on substantially the terms set out in, Exhibit A
         attached hereto to the effect that such Person is a holder of Senior
         Indebtedness, that the holder or holders of such Senior Indebtedness
         are entitled to the benefits of Sections 4, 5 and 12 of this Debenture
         and that the holder or holders of such Senior Indebtedness may enforce
         the terms and provisions thereof to the same extent Allied Finance
         would be able to do so, provided, however, that prior to furnishing
         such agreement, Laidlaw has received from Allied Finance or such
         holder such information as Laidlaw may reasonably request
         demonstrating to Laidlaw' reasonable satisfaction that such Person is
         a holder of Senior Indebtedness.  Laidlaw, and each subsequent holder
         of this Debenture, by acceptance of this Debenture, irrevocably
         appoint Allied Finance (with full power of substitution) as its agent
         and attorney in fact (which appointment is coupled with an interest
         and shall be irrevocable so long as any Senior Indebtedness is
         outstanding) to execute and deliver on behalf and in the name of
         Laidlaw or such holder, as the case may be, an agreement in
         substantially the form of, and on substantially the terms set out in,
         Exhibit A hereto in favor of each such holder of Senior Indebtedness
         and to take such further action as may be necessary or appropriate to
         effectuate the subordination as provided herein.  Promptly after
         exercise of any such power, Allied Finance will give written





<PAGE>   159

         notice thereof to the holders of the Debenture; provided, however,
         that failure to give such notice shall in no event affect the validity
         of any power so exercised.

                 (f)      If a Default shall have occurred and be continuing
         (other than a Default pursuant to Section 6(b) or (c)) and the holder
         of this Debenture elects to accelerate this Debenture pursuant to
         Section 7, Laidlaw shall give the Representative under the Credit
         Facility 30 days' prior written notice before accelerating this
         Debenture, which notice shall state that it is a "Notice of Intent to
         Accelerate;" provided, however, that Laidlaw shall not be required to
         give such notice if at such time payment of any Indebtedness incurred
         pursuant to the Credit Facility shall have been accelerated.  If
         payment of this Debenture is accelerated because of a Default, the
         holder shall promptly notify the Representatives under the Designated
         Senior Indebtedness and the holders of all other Senior Indebtedness
         of the acceleration.

                 (g)      Until all Senior Indebtedness has been indefeasibly
         paid in full in cash, the holders of this Debenture shall not be
         entitled to assert, enforce or otherwise exercise any right of
         subrogation against Allied Finance or any other Person obligated on
         the Subordinated Obligations.  After all Senior Indebtedness has been
         indefeasibly paid in full in cash, and until the Subordinated
         Obligations have been so paid in full, the holder of this Debenture
         shall be subrogated to the rights of holders of Senior Indebtedness to
         receive distributions applicable to Senior Indebtedness.  A
         distribution made under this Section 4 to holders of Senior
         Indebtedness which otherwise would have been made to the holder of
         this Debenture is not, as between Allied Finance and the holder of
         this Debenture, a payment by Allied Finance on Senior Indebtedness.

                 (h)      This Section 4 defines the relative rights of the
         holder of this Debenture and holders of Senior Indebtedness.  Nothing
         in this Debenture shall:

                          (i)     impair, as between Allied Finance and the
                 holder of this Debenture, the obligation of Allied Finance,
                 which is absolute and unconditional, to pay principal of and
                 premium and interest, if any, on this Debenture in accordance
                 with its terms; or

                          (ii)    except as otherwise set forth in this Section
                 4, prevent the holder of this Debenture from exercising its
                 available remedies upon a Default, subject to the rights of
                 holders of Senior Indebtedness to receive distributions
                 otherwise payable to such holder.

         5.      No Impairment.  Section 4, this Section 5, the proviso to
Section 7(a), and Section 12 (and all defined terms used in such sections)
shall constitute a continuing offer to all Persons who become holders of, or
continue to hold, Senior Indebtedness, and such provisions are made for the
benefit of the holders from time to time of Senior Indebtedness, and such
Persons are conclusively presumed to have relied upon such provisions; and such
holders are made obligees hereunder, and they or each of them may enforce such
provisions.  No right of any present or future holder of any Senior
Indebtedness to enforce the subordination or other provisions referred to in
this Section 5 shall at any time in any way be





<PAGE>   160

prejudiced or impaired by any act or failure to act on the part of Allied
Finance or Laidlaw, or by any non-compliance by Allied Finance or Laidlaw with
the terms, provisions and covenants of this Debenture, regardless of any
knowledge thereof any such holder may have or otherwise be charged with.
Section 4, this Section 5 and the subordination and other provisions referred
to in this Section 5 may not be amended or modified in any manner which might
terminate or impair the subordination or such other provisions except with the
prior written consent of the Representatives of all the Designated Senior
Indebtedness.

         6.      Events of Default.  "Default" means the occurrence of one or
more of the following:

                 (a)      Payment.  Allied Finance fails to pay the outstanding
         principal amount of this Debenture on the Maturity Date.

                 (b)      Voluntary Bankruptcy.  Allied Finance (i) files a
         petition initiating a voluntary Bankruptcy or Insolvency Proceeding,
         (ii) seeks, consents to, or does not contest the appointment of a
         receiver or trustee for itself or for all or any substantial part of
         its property, (iii) is voluntarily adjudicated a bankrupt or
         insolvent, (iv) makes a general assignment for the benefit of its
         creditors, or (v) admits in writing its inability to pay its debts as
         they mature.

                 (c)      Involuntary Bankruptcy.  A petition is filed against
         Allied Finance seeking to initiate a Bankruptcy or Insolvency
         Proceeding and such petition is not dismissed within 180 days after
         being filed, or a court of competent jurisdiction enters an order,
         judgment or decree appointing a receiver or trustee for Allied
         Finance, or for all or substantially all of its property, and such
         order, judgment or decree is not discharged or stayed within 180 days
         after its entry.

                 (d)      Acceleration of Other Indebtedness.  An event of
         default occurs and is continuing under the Credit Facility and, as a
         result thereof, the Indebtedness outstanding pursuant to the Credit
         Facility is accelerated; provided, however, that in the event the
         holders of such Indebtedness elect to waive such event of default or
         to otherwise de-accelerate such Indebtedness, no Default shall subsist
         hereunder.

         7.      Remedies of Laidlaw.  Upon the occurrence and during the
continuance of a Default, Laidlaw shall have the following rights:

                 (a)      Acceleration.  Subject to the provisions of Section 4
         hereof, Laidlaw may, at its option, declare the entire principal
         balance of this Debenture, together with the accrued and unpaid
         interest thereon, immediately due and payable without notice of
         Default, notice of intent to accelerate, notice of acceleration, or
         any other notice, presentment, protest, demand or action of any kind
         or nature whatsoever (each of which is hereby expressly waived by
         Allied Finance), whereupon the entire Indebtedness under this
         Debenture shall become immediately due and payable; provided, however,
         that no such acceleration (except for an acceleration upon the
         occurrence of a Default specified in Subsection 7(d)) shall be
         effective or of any force whatsoever and the holder of this





<PAGE>   161

         Debenture may not take any action against Allied Finance with respect
         to a Default hereunder if made during a Blockage Period, or if such
         acceleration would result in a Blockage Period; provided, further,
         that in the event the Indebtedness under this Debenture is accelerated
         upon the occurrence of a Default specified in Subsection 7(d) and the
         holders of the Indebtedness outstanding pursuant to the Credit
         Facility elect to waive the event of default giving rise to the
         acceleration thereunder or otherwise elect to de-accelerate such
         Indebtedness, Laidlaw shall de-accelerate the obligations hereunder.

                 (b)      Other Rights.  Except as otherwise modified hereby,
         Laidlaw shall have all rights and remedies available at law or equity
         and the same (i) shall be cumulative and concurrent, (ii) may be
         pursued separately, successively, or concurrently against Allied
         Finance, (iii) may be exercised as often as occasion therefor shall
         arise, it being agreed by Allied Finance that the exercise or failure
         to exercise any of the same shall in no event be construed as a waiver
         or release thereof or of any other right or remedy, and (iv) are
         intended to be, and shall be, nonexclusive.

         8.      Offer of Prepayment upon Change of Control.

                 (a)      Allied Finance will, within thirty business days
         after any executive officer of Allied Finance has knowledge of the
         occurrence of a Change of Control, give written notice of such Change
         of Control to the holder of this Debenture.  Subject to the provisions
         of Section 5, such notice shall contain and constitute an offer to
         prepay this Debenture as described in subsection (b) of this Section
         8.

                 (b)      The offer to prepay this Debenture contemplated by
         subsection (a) of this Section 8 shall be an offer to prepay, in
         accordance with and subject to this Section 8, all, but not less than
         all, of this Debenture on a date specified in such offer (the "Section
         8 Prepayment Date") which date shall be not less than 45 days and not
         more than 60 days after the date of such offer (if the Section 8
         Prepayment Date shall not be specified in such offer, the Section 8
         Prepayment Date shall be the first business day after the 45th day
         after the date of such offer).

                 (c)      The holder of this Debenture may accept the offer to
         prepay made pursuant to this Section 8 in whole but not in part by
         causing a notice of such acceptance to be delivered to Allied Finance
         within ten business days after receipt of the written notice to be
         given pursuant to subsection (a) of this Section 8.  A failure by a
         holder of this Debenture to respond within such time period to an
         offer to prepay made pursuant to this Section 8 shall be deemed to
         constitute a rejection of such offer.

                 (d)      Prepayment of this Debenture pursuant to this Section
         8 shall be at the Accreted Value of the Debenture at the Section 8
         Prepayment Date.  The prepayment shall be made on the Section 8
         Prepayment Date.

                 (e)      Notwithstanding any provision hereof to the contrary,
         in no event shall Allied Finance prepay (or be obligated to prepay)
         this Debenture pursuant to this





<PAGE>   162

         Section 8 until 91 days after Allied Finance shall have prepaid the
         Senior Indebtedness incurred pursuant to the Credit Facility and the
         Senior Subordinated Debentures, and all other Senior Indebtedness
         which is entitled to be prepaid upon the occurrence of a Change of
         Control, unless the holder or holders of such Senior Indebtedness have
         waived or otherwise failed to enforce their rights to receive a
         prepayment of the Senior Indebtedness held by them to which they are
         entitled in connection with such Change of Control.

         9.      Captions.  The captions, headings, and arrangements used in
this Debenture are for convenience only and do not affect or modify the terms
of this Debenture.

         10.     Notices. All notices or other communications which are
required or may be given under this Debenture shall be in writing and shall be
deemed to have been duly given when delivered in person or transmitted by
telecopier (with receipt confirmed) at the address or telecopy number set forth
below (as any such address or telecopier number may be changed from time to
time by notice similarly given):

         (1)     if to Laidlaw, to:

                          Laidlaw Inc.
                          3221 North Service Road
                          Burlington, Ontario
                          Canada L7R 3Y8
                          Attention:  Ivan R. Cairns
                          Telecopy No.: (905) 332-6550

         (2)     if to Allied Finance, to:

                          3294854 Canada Inc.
                          c/o Allied Finance, Inc.
                          7201 East Camelback Road, Suite 375
                          Scottsdale, Arizona 85251
                          Attention: Roger A. Ramsey
                          Telecopy No.: (602) 481-9347

                          with a copy to:

                          Porter & Hedges, L.L.P.
                          700 Louisiana Street, Suite 3500
                          Houston, Texas 77002
                          Attention: Robert G. Reedy
                          Telecopy No.: (713) 228-1331

         11.     Applicable Law. This Debenture shall be governed by and
construed in accordance with the laws of the State of Delaware and the laws of
the United States of America applicable therein (without reference to the
conflicts of law principles thereof).





<PAGE>   163

         12.     Transfer Restriction. This Debenture may not be sold,
assigned, transferred, pledged or hypothecated in any manner, directly or
indirectly, by Laidlaw or any other holder, unless the assignee, transferee,
pledgee or hypothecate has agreed in writing to be bound by the provisions of
this Debenture applicable to Laidlaw, including but not limited to the
provisions of Section 4(e) and Section 13 hereof.  Any transfer of this
Debenture shall be of the entire Debenture and not of any part of the
indebtedness evidenced hereby or of at least $75,000,000 of the principal
amount thereof.

         13.     OFFSET.  THE OBLIGATIONS OF ALLIED FINANCE HEREUNDER ARE, IN
ALL RESPECTS, SUBJECT TO OFFSET AS MORE FULLY SET FORTH IN THE OFFSET LETTER
AGREEMENT.  THE OFFSET RIGHTS SET FORTH IN THE OFFSET LETTER AGREEMENT SHALL BE
EFFECTIVE NOTWITHSTANDING THE ASSIGNMENT OR TRANSFER OF THIS DEBENTURE BY
LAIDLAW AND ANY TRANSFEREE SHALL TAKE THIS DEBENTURE SUBJECT TO THE TERMS
THEREOF.

         NOTICE:  THE RIGHTS AND OBLIGATIONS OF ALLIED FINANCE AND LAIDLAW
SHALL BE DETERMINED SOLELY FROM WRITTEN AGREEMENTS, DOCUMENTS, AND INSTRUMENTS,
AND ANY PRIOR ORAL AGREEMENTS BETWEEN ALLIED FINANCE AND LAIDLAW ARE SUPERSEDED
BY AND MERGED INTO SUCH WRITINGS.  THIS DEBENTURE (AS AMENDED IN WRITING FROM
TIME TO TIME) REPRESENTS THE FINAL AGREEMENT BETWEEN ALLIED FINANCE AND LAIDLAW
AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR OR CONTEMPORANEOUS ORAL
AGREEMENTS BY ALLIED FINANCE AND LAIDLAW.  THERE ARE NO UNWRITTEN ORAL
AGREEMENTS BETWEEN ALLIED FINANCE AND LAIDLAW.




                                   3294854 CANADA INC.
                                   a Canadian corporation
                                

                                   By:
                                      -----------------------------------------
                                   Name:
                                        ---------------------------------------
                                   Title:
                                         --------------------------------------


Agreed and Accepted:

LAIDLAW INC.
a Canadian corporation


By:
   ----------------------------------------------
Name:
     --------------------------------------------
Title:
      -------------------------------------------




<PAGE>   164

                                                                       EXHIBIT A
                                          to the Zero Coupon Junior Subordinated
                                                   Debenture Due 200__ Issued by
                                                             3294854 Canada Inc.
                                                        in favor of Laidlaw Inc.


                                     [Date]


- ----------------
- ----------------
- ----------------


Gentlemen:

         Reference is made to the Zero Coupon Junior Subordinated Debenture Due
200__ dated __________, 199__ (the "Subordinated Debenture"), in the original
principal amount of $________________ issued by 3294862 Canada Inc., a Canadian
corporation ("Allied Finance"), in favor of Laidlaw Inc., a Canadian
corporation, and the [describe Senior Indebtedness] (the "Subject
Indebtedness"), being issued contemporaneously herewith by Allied Finance in
favor of [identity of holder or holders of Subject Indebtedness] (whether one
or more, the "Senior Creditor").  Hereinafter, capitalized words and phrases
used herein which are defined in the Subordinated Debenture are used herein as
therein defined.

         The undersigned (the "Subordinated Creditor") hereby represents and
warrants to the Senior Creditor that (a) the Subordinated Creditor is the owner
and holder of the Subordinated Debenture and that the Subordinated Creditor is
entitled to make the agreements herein contained.  The Subordinated Creditor
hereby acknowledges and agrees that the principal of, and premium, if any, and
interest on (including interest that, but for the filing of a petition
initiating any Bankruptcy or Insolvency Proceeding would accrue on such
obligations at the rate provided in the agreements or instruments creating or
evidencing the respective obligations, whether or not such Bankruptcy or
Insolvency Proceeding and all other amounts of every kind or nature (including,
but not limited to, fees, indemnities and expenses and any interest rate swaps
or other interest rate hedging products entered into in connection with the
Subject Indebtedness) due on or in connection with, the Subject Indebtedness,
whether outstanding on the date hereof or hereafter created, incurred or
assumed, guaranteed or in effect guaranteed by Allied Finance (including all
renewals, extensions or refundings of, or amendments, modifications or
supplements to, the foregoing) are in all respects Senior Indebtedness, (b) the
Senior Creditor (and any other Person who from time to time is a holder of the
Subject Indebtedness) is entitled to the benefits of Sections 4, 5 and 12 of
the Subordinated Debenture, and (c) the Senior Creditor (and any other Person
who from time to time is a holder of the Subject Indebtedness) may enforce the
terms and provisions of the Subordinated Debenture to the same extent that
Allied Finance or any other holder of Senior Indebtedness would be able to do
so.





<PAGE>   165

         The Subordinated Creditor hereby agrees that the Subordinated
Debenture will not be sold, assigned, transferred, pledged or hypothecated in
any manner, directly or indirectly, by the Subordinated Creditor, unless the
assignee, transferee, pledgee or hypothecate has agreed in writing to be bound
by the provisions of this agreement.

         The Subordinated Creditor has executed this agreement in the space
provided below in order to induce the Senior Creditor to advance funds or
extend credit to Allied Finance, and this agreement is intended by the
Subordinated Creditor to be a binding and enforceable undertaking by the
Subordinated Creditor in favor of the Senior Creditor.

         The rights created hereby of the Senior Creditor and of any subsequent
holder of the Senior Indebtedness will be assigned automatically, and without
any further act, by the Senior Creditor or such holder upon any sale,
assignment, conveyance or other transfer of all or any part of the Senior
Indebtedness to the extent of the interest sold, assigned, conveyed or
otherwise transferred, unless and to the extent the Senior Creditor or such
holder expressly provides otherwise in the instrument pursuant to which such
interest is conveyed.


                                         Very truly yours,

                                         [NAME OF SUBORDINATED CREDITOR]


                                         By:                                   
                                            -----------------------------------
                                         Name:                              
                                              ---------------------------------
                                         Title:                             
                                               --------------------------------


Accepted and agreed to as of
the date first above written:

[NAME OF SENIOR CREDITOR]


By: 
   ----------------------------------------
Name:
     --------------------------------------
Title: 
      -------------------------------------




<PAGE>   166


                                                                       EXHIBIT C


THE SECURITIES REPRESENTED BY THIS WARRANT AND THE COMMON STOCK ISSUABLE UPON
EXERCISE OF THIS WARRANT HAVE NOT BEEN REGISTERED (OR QUALIFIED BY PROSPECTUS)
UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES
LAWS OF ANY STATE OF THE UNITED STATES OR ANY PROVINCE OF CANADA.  THIS WARRANT
AND THE SHARES OF COMMON STOCK ISSUABLE ON EXERCISE OF THIS WARRANT MAY NOT BE
OFFERED, SOLD, TRANSFERRED, PLEDGED, HYPOTHECATED OR OTHERWISE DISPOSED OF IN
THE ABSENCE OF REGISTRATION (OR QUALIFICATION BY PROSPECTUS) THEREUNDER OTHER
THAN PURSUANT TO AN EXEMPTION FROM SUCH REGISTRATION AND PROSPECTUS
REQUIREMENTS AND DELIVERY TO ALLIED WASTE INDUSTRIES, INC. OF AN OPINION OF
COUNSEL REASONABLY SATISFACTORY TO IT TO THE EFFECT THAT SUCH TRANSFER IS
EXEMPT FROM SUCH REGISTRATION AND PROSPECTUS REQUIREMENTS UNDER THOSE LAWS.


No. ___________                                         __________________, 1996
                                      
                                    WARRANT

                          to Purchase Common Stock of

                         ALLIED WASTE INDUSTRIES, INC.

                        Expiring on _____________, 2008


         This Common Stock Purchase Warrant (the "Warrant") certifies that for
value received and subject to the terms hereof, Laidlaw (as hereinafter
defined) is entitled to subscribe for and purchase from Allied (as hereinafter
defined), in whole or in part, 20,400,000 shares of Common Stock (as
hereinafter defined) at the Exercise Price (as hereinafter defined), subject to
and upon the terms and conditions hereinafter set forth.  The number of shares
of Common Stock purchasable hereunder, and the Exercise Price therefor are
subject to adjustment as hereinafter set forth.  This Warrant and all rights
hereunder shall expire at 5:00 p.m., Scottsdale, Arizona time, on __________,
2008 (the "Expiration Date").





<PAGE>   167
                                   ARTICLE I

                                  Definitions

         As used herein, the following terms shall have the meanings set forth
below:

         1.1     "Affiliate"means, with respect to any Person, another Person
which would be an "affiliate" of such Person for purposes of Section 13(d) of
the Exchange Act or Section 197(f)(9)(c) of the United States Internal Revenue
Code of 1986, as amended, respectively.

         1.2     "Allied" shall mean Allied Waste Industries, Inc., a Delaware
corporation, and any successor by merger, consolidation or otherwise.

         1.3     "Change of Control" means a change resulting when any
Unrelated Person or any Unrelated Persons acting together that would constitute
a Group together with any Affiliates thereof (in each case also constituting
Unrelated Persons) shall at any time beneficially own more than 50% of the
aggregate voting power of all classes of Voting Stock of Allied; provided,
however, that if at the date any "Change of Control" would otherwise have
occurred but for the fact that a Person was not an Unrelated Person because
such Person or an Affiliate of such Person acquired shares of Allied Common
Stock or all or any portion of the Allied Warrant from Laidlaw or from any
Affiliate of Laidlaw within nine months prior to such date, such shares of
Allied Common Stock acquired from Laidlaw or any Affiliate of Laidlaw, or any
shares of Allied Common Stock issued upon exercise of the Allied Warrant or any
portion thereof, shall at all times thereafter be excluded when calculating
whether a Change of Control has occurred.  As used in this definition of Change
of Control (a) "Group" means a "group" for purposes of Section 13(d) of the
Exchange Act; (b) "Unrelated Person" means at any time any Person other than
Laidlaw, any Person to whom Laidlaw or any of its Affiliates transfers, within
nine months prior to such time, any shares of Allied Common Stock or all or any
portion of the Allied Warrant or any Affiliate of Laidlaw or any such Person;
provided, however, that Persons (other than Laidlaw or its Affiliates) to whom
Laidlaw or any of its Affiliates transfers any shares of Allied Common Stock or
all or any portion of the Allied Warrant after five years from the date hereof
shall not be deemed Unrelated Persons; and (c) "Voting Stock" of any Person
shall mean capital stock of such Person which ordinarily has voting power for
the election of directors (or persons performing similar functions) of such
Person, whether at all times or only so long as no senior class of securities
has such voting power by reason of any contingency.

         1.4     As used herein, "beneficially own" shall have the meaning set
forth in Rule 13d-3 under the Exchange Act, provided that, for purposes of this
definition, a Person shall not be deemed to beneficially own securities
tendered pursuant to a tender or exchange offer made by or on behalf of such
Person or any of such Person's Affiliates until such tendered securities are
accepted for purchase or exchange.





                                      2
<PAGE>   168
         1.5     "Common Stock" shall mean and include the Common Stock of
Allied, par value $.01 per share, authorized on the date of the original issue
of this Warrant and shall also include (i) in case of any reorganization,
reclassification, consolidation, merger, share exchange or sale, transfer or
other disposition of assets, the stock or other securities provided for herein,
and (ii) any other shares of common stock of Allied into which such shares of
Common Stock may be converted.

         1.6     "Current Market Price" per share of Common Stock on any
specified date means the average daily market prices (determined as set forth
below in this definition), of the Common Stock for the 20 consecutive Trading
Days ending on the third Trading Day before that date.  The market price for
each such Trading Day shall be the average of the last sale prices on such
Trading Day on all stock exchanges and the Nasdaq Stock Market on which the
Common Stock may then be listed or admitted for quotation, respectively;
provided, that if no sale takes place on any such Trading Day on any such
exchange or the Nasdaq Stock Market, the average of the closing bid and asked
prices on such day as officially quoted thereon shall be used, or, if Common
Stock is not then listed or admitted for quotation on any stock exchange or the
Nasdaq Stock Market, the market price for each Trading Day shall be the average
of the reported bid and asked prices on such day on the over-the-counter
market, or, if Common Stock is not quoted on the over-the-counter market, the
market price for each Trading Day shall be the average of the bid and asked
prices furnished by any member of the National Association of Securities
Dealers selected by Allied.

         1.7     "Exchange Act" shall mean the Securities Exchange Act of 1934, 
as amended.

         1.8     "Exercise Price" shall mean $8.25, as adjusted from time to
time pursuant to the provisions hereof.

         1.9     "Outstanding," when used with reference to Common Stock, shall
mean (except as otherwise expressly provided herein) at any date as of which
the number of shares thereof is to be determined, all issued and outstanding
shares of Common Stock, except shares then beneficially owned or held by or for
the account of Allied and its direct or indirect wholly-owned subsidiaries.

         1.10    "Person" means an individual, corporation, partnership,
association, joint stock company, limited liability company, governmental
entity, business trust, unincorporated organization, or other legal entity.

         1.11    "Laidlaw" shall mean Laidlaw Inc., a Canadian corporation.

         1.12    "Securities Act" means the United States Securities Act of 
1933, as amended.





                                      3
<PAGE>   169
         1.13    "Trading Day" shall mean any days during the course of which
the principal securities exchange or the Nasdaq National Market, as the case
may be, on which the Common Stock is listed or admitted to trading is open for
the exchange of securities.

         1.14    "Warrant Shares" shall mean the shares of Common Stock
purchased or purchasable  upon the exercise of the Warrant by the holder
entitled to exercise the Warrant.

                                   ARTICLE II

                              Exercise of Warrant

         2.1     Method of Exercise.  The Warrant may be exercised in whole or
in part by (i) Laidlaw and its Affiliates only after the occurrence of a Change
of Control of Allied, or (ii) by any holder hereof other than Laidlaw and its
Affiliates, at any time and from time to time on or after the date hereof,
until 5:00 p.m., Scottsdale, Arizona time on the Expiration Date.  To exercise
the Warrant, the holder hereof shall deliver to Allied, at the Warrant Office
designated herein, (i) a written notice substantially in the form of the
Subscription Notice attached as an exhibit hereto, stating therein the election
of the holder hereof to exercise the Warrant in the manner provided in the
Subscription Notice; (ii) payment in full of the Exercise Price, by certified
check or by wire transfer of immediately available funds for all Warrant Shares
purchased hereunder; and (iii) the Warrant. The Warrant shall be deemed to be
exercised on the date of receipt by Allied of the Subscription Notice,
accompanied by payment for the Warrant Shares and surrender of the Warrant (the
"Exercise Date").  Upon such exercise, Allied shall, as promptly as practicable
and in any event within five business days, issue and deliver to the holder
hereof a certificate or certificates for the full number of the Warrant Shares
purchased by the holder hereof, and shall, unless the Warrant has expired,
deliver to the holder hereof a new Warrant representing the portion of the
Warrant, if any, that shall not have been exercised, in all other respects
identical to the Warrant.  The holder hereof shall be deemed to have become a
holder of record of such Common Stock on the Exercise Date and shall be
entitled to all of the benefits of such holder on the Exercise Date, including
without limitation the right to receive dividends and other distributions for
which the record date falls on or after the Exercise Date and to exercise
voting rights.

         2.2     Expenses and Taxes.  Allied shall pay all expenses and taxes
(including, without limitation, all documentary, stamp, transfer or other
transactional taxes) other than income taxes attributable to the issuance or
exercise of the Warrant and to the issuance, possession or disposition of the
Warrant Shares.

         2.3     Reservation of Shares.  Allied shall reserve at all times so
long as the Warrant remains outstanding, free from preemptive rights, out of
its authorized but unissued shares of Common Stock, solely for the purpose of
effecting the exercise of the Warrant, a sufficient number of shares of Common
Stock to provide for the exercise of the Warrant, as adjusted pursuant to
Article IV hereof.





                                      4
<PAGE>   170
         2.4     Valid Issuance.  All Warrant Shares will, upon issuance by
Allied, be duly and validly issued, fully paid and nonassessable.

         2.5     Other Agreements.   Laidlaw, Allied and certain other parties
have entered into a Stock Purchase Agreement (the "Purchase Agreement") dated
September __, 1996.  Laidlaw, Allied and certain parties named therein have
also entered into a Stock Registration Agreement (the "Registration Agreement")
dated September __, 1996.  The Warrant is the warrant to purchase Common Stock
issued to Laidlaw pursuant to the Purchase Agreement.  Laidlaw, or any
transferee of rights to registration under the Registration Agreement, shall be
entitled to the rights to registration under the Securities Act and any
applicable state securities or blue sky laws to the extent set forth in the
Registration Agreement.  The terms of the Purchase Agreement and Registration
Agreement are incorporated herein for all purposes and shall be considered a
part of the Warrant as if they had been fully set forth herein; provided, that
the rights to registration in the Registration Agreement shall be transferable
only as provided for therein.  Notwithstanding the previous sentence, in the
event of any conflict between the provisions of the Purchase Agreement or the
Registration Agreement and of the Warrant, the provisions of the Warrant shall
control.

         2.6     No Fractional Shares.  Allied shall not be required to issue
fractional shares of Common Stock on the exercise of the Warrant.  If a portion
of the Warrant shall be presented for exercise, the number of full shares of
Common Stock which shall be issuable upon such exercise shall be computed on
the basis of the aggregate number of whole shares of Common Stock purchasable
on exercise of the portion of the Warrant so presented.  If any fraction of a
share of Common Stock would, except for the provisions of this Section, be
issuable on the exercise of the Warrant, Allied shall pay an amount in cash
calculated by it to be equal to the Current Market Price of one share of Common
Stock at the time of such exercise multiplied by such fraction computed to the
nearest whole cent.

                                  ARTICLE III

                                    Transfer

         3.1     Restrictions on Transfer of the Warrant.  The Warrant may be
sold, assigned or transferred to any Person other than Laidlaw and its
Affiliates (except that this Warrant may be transferred to a wholly owned
subsidiary of Laidlaw) and may also be sold, assigned or transferred pursuant
to the exercise by the holder hereof of rights, if any, to register and sell
the Warrant pursuant to the Registration Agreement; provided, that no sale,
assignment or transfer of this Warrant will be permitted if the transferee of
this Warrant and its Affiliates, collectively, shall beneficially own after
said sale, assignment or transfer, more than 9% of the total number of shares
of Common Stock then outstanding, unless such transferee receives such Warrants
pursuant to a pro-rata distribution of Warrants to all stockholders of all
classes of Laidlaw's outstanding capital stock.





                                      5
<PAGE>   171
         3.2     Warrant Office.  Allied shall maintain an office for certain
purposes specified herein (the "Warrant Office"), which office shall initially
be the Company's offices at 7201 East Camelback Road, Suite 375, Scottsdale,
Arizona 85251 and may subsequently be such other office of Allied or of any
transfer agent retained by Allied in the continental United States as to which
written notice has previously been given to the holders hereof Allied shall
maintain, at the Warrant Office, a register for the Warrant in which Allied
shall record the name and address of  the holders hereof.  Upon any public
distribution of the Warrants, Allied shall retain a transfer agent for the
Warrants and the business address of such transfer agent shall be the Warrant
Office from the date of such public distribution.

         3.3     Split Up, Combination, Exchange and Transfer of Warrants.
Subject to the provisions of Section 3.1, the Warrants may be split up,
combined or exchanged for other Warrants representing a like aggregate number
of Warrants.  Any holder desiring to split up, combine or exchange shall make
such request in writing delivered to the Warrant Office and shall surrender the
Warrants to be so split up, combined or exchanged.  Subject to (i) any
applicable laws, rules or regulations of the United States or Canada
restricting transferability, (ii) any restriction on transferability that may
appear on a Warrant in accordance with the terms hereof, or (iii) any
"stop-transfer" instructions Allied may give to the Warrant Office to implement
any such restrictions (which instructions Allied is expressly authorized to
give), transfer of outstanding Warrants may be effected by the Warrant Office
from time to time upon the books of Allied to be maintained by the Warrant
Office for that purpose, upon a surrender of the Warrants to the Warrant Office
with the assignment form set forth in the Warrants duly executed and with
Signatures Guaranteed.  Upon any such surrender for split up, combination,
exchange or transfer, the Warrant Office shall execute and deliver to the
person entitled thereto Warrants as so requested.  the Warrant Office may
require the holder to pay a sum sufficient to cover any tax or governmental
charge that may be imposed in connection with any split up, combination,
exchange or transfer of Warrants prior to the issuance of any new Warrants.

         3.4     Cancellation of Warrants.  Any Warrants surrendered upon the
exercise of Warrants or for split up, combination, exchange or transfer, or
purchased or otherwise acquired by Allied, shall be cancelled and shall not be
reissued by Allied; and, except as provided (i) in Section 2.1, in case of the
exercise of less than all of the Warrants, or (ii) in Section 3.3, in case of a
split up, combination, exchange or transfer of the Warrants, no Warrants shall
be issued hereunder in lieu of such cancelled Warrants.  Any Warrants so
cancelled shall be destroyed by the Warrant Office unless otherwise directed by
Allied.

         3.5     Compliance with Securities Laws.  Subject to the terms of the
Registration Agreement and notwithstanding any other provisions contained in
the Warrant, the holders hereof understand and agree that the following
restrictions and limitations shall be applicable to all Warrant Shares and to
all resales or other transfers thereof pursuant to the Securities Act or
applicable securities legislation, regulations and rules of the provinces and
territories of Canada:





                                      6

<PAGE>   172


                 3.5.1    The Warrant Shares may not be sold or otherwise
transferred unless the Warrant Shares are registered (or qualified by
prospectus) under the Securities Act and applicable state or provincial or
territorial securities or blue sky laws or are exempt from such requirements.

                 3.5.2    A legend in substantially the following form will be
placed on the certificate(s) evidencing the Warrant Shares:

         "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
         OR QUALIFIED BY PROSPECTUS UNDER THE UNITED STATES SECURITIES ACT OF
         1933, AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE OF THE UNITED
         STATES OR ANY PROVINCE OR TERRITORY OF CANADA.  SUCH SHARES MAY NOT BE
         OFFERED, SOLD, TRANSFERRED, PLEDGED, HYPOTHECATED OR OTHERWISE
         DISPOSED OF IN THE ABSENCE OF SUCH A REGISTRATION (OR QUALIFICATION)
         THEREUNDER OTHER THAN PURSUANT TO AN EXEMPTION FROM SUCH REGISTRATION
         AND QUALIFICATION REQUIREMENTS AND DELIVERY TO ALLIED WASTE
         INDUSTRIES, INC. OF AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO
         IT TO THE EFFECT THAT TRANSFER IS EXEMPT FROM REGISTRATION AND
         QUALIFICATION REQUIREMENTS UNDER THOSE LAWS."

                 3.5.3    Stop transfer instructions will be imposed with
respect to the Warrant Shares so as to restrict resale or other transfer
thereof.

                                   ARTICLE IV

                                   Adjustment

         4.1     Adjustment.  The Exercise Price shall be subject to adjustment
from time to time as provided herein.  Upon each adjustment of the Exercise
Price, the holder hereof shall thereafter be entitled to purchase, at the
Exercise Price resulting from such adjustment, the number of shares of Common
Stock obtained by multiplying the Exercise Price in effect immediately prior to
such adjustment by the number of shares purchasable pursuant hereto immediately
prior to such adjustment and dividing the product thereof by the Exercise Price
resulting from such adjustment.

         4.2     Adjustment of Exercise Price

                 4.2.1    In case at any time after the date hereof Allied
shall distribute to all holders of Common Stock any rights to subscribe for or
to purchase Common Stock or any options for the purchase of Common Stock or any
stock or securities convertible into or





                                      7
<PAGE>   173
exchangeable for Common Stock (such convertible or exchangeable stock or
securities being herein called "Convertible Securities"), whether or not such
rights or options or the right to convert or exchange any such Convertible
Securities are immediately exercisable, and the price per share for which
shares of Common Stock are issuable upon the exercise of such rights or options
or upon conversion or exchange of such Convertible Securities (determined by
dividing (i) the total amount, if any, received or receivable by Allied as
consideration for the granting of such rights or options, plus the minimum
aggregate amount of additional consideration, if any, payable to Allied upon
the exercise of such rights or options, or plus, in the case of such rights or
options that relate to Convertible Securities, the minimum aggregate amount of
additional consideration, if any, payable upon the issue or sale of such
Convertible Securities and upon the conversion or exchange thereof, by (ii) the
total maximum number of shares of Common Stock issuable upon the exercise of
such rights or options or upon the conversion or exchange of all such
Convertible Securities issuable upon the exercise of such rights or options)
shall be less than the Current Market Price in effect as of the date of
granting such rights or options, then the total maximum number of shares of
Common Stock issuable upon the exercise of such rights or options or upon
conversion or exchange of all such Convertible Securities issuable upon the
exercise of such rights or options shall be deemed to be outstanding as of the
date of the granting of such rights or options and to have been issued for such
price per share, and the Exercise Price shall be reduced (but not increased,
except as otherwise specifically provided herein) to the price (calculated to
the nearest one-tenth of a cent) determined by dividing (x) an amount equal to
the sum of (1) the aggregate number of shares of Common Stock outstanding
immediately prior to such issue or sale multiplied by then existing Exercise
Price plus (2) the consideration received by Allied upon such issue or sale by
(y) the aggregate number of shares of Common Stock outstanding immediately
after such issue or sale.  Except as provided herein, no further adjustment of
the Exercise Price shall be made upon the actual issuance of such Common Stock
or of such Convertible Securities upon exercise of such rights or options or
upon the actual issuance of such Common Stock upon conversion or exchange of
such Convertible Securities.

                 4.2.2    If:  (i) the purchase price provided for in any right
or option distributed to all holders of Common Stock, (ii) the additional
consideration, if any, payable upon the conversion or exchange of any
Convertible Securities distributed to all holders of Common Stock or (iii) the
rate at which any Convertible Securities distributed to all holders of Common
Stock are convertible into or exchangeable for Common Stock shall be decreased
(other than under or by reason of provisions designed to protect against
dilution), the Exercise Price then in effect shall be decreased to the Exercise
Price that would have been in effect had such rights, options or Convertible
Securities provided for such changed purchase price, additional consideration
or conversion rate at the time initially issued.

                 4.2.3    In case at any time Common Stock or Convertible
Securities or any rights or options to purchase Common Stock or Convertible
Securities shall be issued or sold to all holders of Common Stock for cash, the
total amount of cash consideration shall be deemed to be the amount received by
Allied.  If at any time any Common Stock, Convertible Securities





                                      8
<PAGE>   174
or any rights or options to purchase any such Common Stock or Convertible
Securities shall be issued or sold to all holders of Common Stock for
consideration other than cash, the amount of the consideration other than cash
received by Allied shall be deemed to be the fair market value of such
consideration, as determined reasonably and in good faith by the Board of
Directors of Allied.  If at any time any Common Stock, Convertible Securities
or any rights or options to purchase any Common Stock or Convertible Securities
shall be issued to all holders of Common Stock in connection with any merger or
consolidation, the amount of consideration received therefor shall be deemed to
be the fair market value, as determined reasonably and in good faith by the
Board of Directors of Allied, of such portion of the assets and business of the
nonsurviving corporation as such Board of Directors may determine to be
attributable to such Common Stock, Convertible Securities, rights or options as
the case may be.  In case at any time any rights or options to purchase any
shares of Common Stock or Convertible Securities shall be issued to all holders
of Common Stock in connection with any issuance and sale of other securities of
Allied, together consisting of one integral transaction in which no
consideration is allocated to such rights or options by the parties, such
rights or options shall be deemed to have been issued without consideration.

                 4.2.4    In case Allied shall take a record of the holders of
its Common Stock for the purpose of entitling them to subscribe for or purchase
Common Stock or Convertible Securities, then such record date shall be deemed
to be the date of the issuance or sale of the Common Stock or Convertible
Securities deemed to have been issued or sold as a result of the date of the
granting of such right of subscription or purchase, as the case may be.

                 4.2.5    The number of shares of Common Stock outstanding at
any given time shall not include shares owned directly by Allied in treasury,
and the disposition of any such shares shall be considered an issuance or sale
of Common Stock.

                 4.2.6    In case Allied shall at any time after the date
hereof (i) declare a dividend on all the outstanding shares of Common Stock
payable in shares of its capital stock, (ii) subdivide the outstanding Common
Stock, (iii) combine the outstanding Common Stock into a smaller number of
shares, or (iv) issue any shares of capital stock by reclassification or
reorganization of the Common Stock (including any such reclassification in
connection with a consolidation or merger), then, in each case, the Exercise
Price in effect, and the number of shares of Common Stock issuable upon
exercise of the Warrants outstanding, at the time of the record date for such
dividend or of the effective date of such subdivision, combination,
reclassification or reorganization, shall be proportionately adjusted so that
the holders of the Warrants after such time shall be entitled to receive the
aggregate number and kind of shares which, if such Warrants had been exercised
immediately prior to such time, such holders would have owned upon such
exercise and been entitled to receive by virtue of such dividend, subdivision,
combination, reclassification or reorganization.  Such adjustment shall be made
successively whenever any event listed above shall occur.





                                      9
<PAGE>   175
                 4.2.7    In case Allied shall distribute to all holders of
Common Stock (including any such distribution made to the shareholders of
Allied in connection with a consolidation or merger) evidences of its
indebtedness or assets (other than distributions and dividends payable in
shares of Common Stock) then, in such case, the Exercise Price shall be
adjusted by multiplying the Exercise Price in effect immediately prior to the
record date for the determination of shareholders entitled to receive such
distribution by a fraction, the numerator of which shall be the Current Market
Price per share of Common Stock on such record date, less the fair market value
(as determined in good faith by the Board of Directors of Allied, in its sole
discretion) of the portion of the evidences of indebtedness or assets so to be
distributed, applicable to one share, and the denominator of which shall be
such Current Market Price per share of Common Stock on such record date.  Such
adjustment shall become effective at the close of business on such record date.

         4.3     Tender Offer.  If a purchase, tender or exchange offer (a
"Tender Offer") is made to and accepted by holders of 51 percent or more of the
outstanding shares of Common Stock, Allied shall not effect any consolidation,
merger, share exchange or sale, transfer or other disposition of all or
substantially all of Allied's assets (an "Extraordinary Transaction") with the
Person having made such Tender Offer or with any Affiliate of such Person,
unless prior to the consummation of such Extraordinary Transaction the holder
hereof shall have been given a reasonable opportunity to elect to receive, upon
the exercise of the Warrant, either: (i) the capital stock, securities, assets
or cash then issuable with respect to the Common Stock upon consummation of the
Extraordinary Transaction; or (ii) the capital stock, securities, assets or
cash issued to previous holders of the Common Stock upon acceptance of such
Tender Offer.

         4.4     De Minimis Adjustments.  No adjustment in the number of shares
of Common Stock purchasable hereunder shall be required unless such adjustment
would require an increase or decrease of at least one share of Common Stock
purchasable upon an exercise of the Warrant and no adjustment in the Exercise
Price shall be required unless such adjustment would require an increase or
decrease of at least $0.10 in the Exercise Price; provided, however, that any
adjustments that are not required to be made shall be carried forward and taken
into account in any subsequent adjustment.  All calculations shall be made to
the nearest full share or nearest one hundredth of a dollar, as applicable.

         4.5     Notifications to Holders.  In case at any time Allied
proposes:

               (i)        to declare any dividend upon its Common Stock payable
         in capital stock or make any special dividend or other distribution
         (other than cash dividends) to the holders of its Common Stock;

              (ii)        to offer for subscription pro rata to all of the
         holders of its Common Stock any additional shares of capital stock of
         any class or other rights;





                                     10

<PAGE>   176


             (iii)        to effect any capital reorganization, or
         reclassification of the capital stock of Allied, or consolidation,
         merger or share exchange of Allied with another Person, or sale,
         transfer or other disposition of all or substantially all of its
         assets; or

              (iv)        to effect a voluntary or involuntary dissolution,
         liquidation or winding up of Allied,

then, in any one or more of such cases, Allied shall give the holder hereof (a)
at least 10 days (but not more than 90 days) prior written notice of the date
on which the books of Allied shall close or a record shall be taken for such
dividend, distribution or subscription rights or for determining rights to vote
in respect of any such issuance, reorganization, reclassification,
consolidation, merger, share exchange, sale, transfer, disposition,
dissolution, liquidation or winding up, and (b) in the case of any such
issuance, reorganization, reclassification, consolidation, merger, share
exchange, sale, transfer, disposition, dissolution, liquidation or winding up,
at least 10 days (but not more than 90 days) prior written notice of the date
when the same shall take place.  Such notice in accordance with the foregoing
clause (a) shall also specify, in the case of any such dividend, distribution
or subscription rights, the date on which the date on which the holders of
Common Stock shall be entitled thereto, and such notice in accordance with the
foregoing clause (b) shall also specify the date on which the holders of Common
Stock shall be entitled to exchange their Common Stock, as the case may be, for
securities or other property deliverable upon such reorganization,
reclassification, consolidation, merger, share exchange, sale, transfer,
disposition, dissolution, liquidation or winding up,  as the case may be.

         4.6     Notice of Adjustment.  Whenever the Exercise Price or the
number of Warrant Shares issuable upon the exercise of the Warrant shall be
adjusted as herein provided, or the rights of the holder hereof shall change by
reason of other events specified herein, Allied shall compute the adjusted
Exercise Price and the adjusted number of Warrant Shares in accordance with the
provisions hereof and shall prepare and mail to the holder hereof a certificate
setting forth the adjusted Exercise Price as of the date of such event and the
adjusted number of Warrant Shares issuable upon the exercise of the Warrant or
specifying the other shares of stock, securities, assets or cash receivable as
a result of such change in rights, and showing in reasonable detail the facts
and calculations upon which such adjustments or other changes are based.

                                   ARTICLE V

                                 Miscellaneous

         5.1     Entire Agreement.  The Warrant, together with the Purchase
Agreement and the Registration Agreement, contain the entire agreement between
the holder hereof and Allied with respect to the Warrant and the Warrant Shares
purchasable upon exercise hereof and the





                                     11
<PAGE>   177
related transactions and supersedes all prior arrangements or understandings
with respect thereto.

         5.2     Governing Law. This Warrant shall be governed by and construed
in accordance with the laws of the State of Delaware.

         5.3     Waiver and Amendment.  Any term or provision of the Warrant
may be waived at any time by the party which is entitled to the benefits
thereof and any term or provision of the
Warrant may be amended or supplemented at any time by agreement of the holder
hereof and Allied, except that any waiver of any term or condition, or any
amendment or supplementation, of the Warrant shall be in writing.  A waiver of
any breach or failure to enforce any of the terms or conditions of the Warrant
shall not in any way effect, limit or waive a party's rights hereunder at any
time to enforce strict compliance thereafter with every term or condition of
the Warrant.

         5.4     Severability.  In the event that any one or more of the
provisions contained in this Warrant shall be determined to be invalid, illegal
or unenforceable in any respect for any reason, the validity, legality and
enforceability of any such provision in any other respect and the remaining
provisions of the Warrant shall not, at the election of the party for whom the
benefit or the provision exists, be in any way impaired.

         5.5     Notice.  Any notice or other document required or permitted to
be given or delivered to the holder hereof shall be in writing and delivered
at, or sent by certified or registered mail to the holder hereof at, the last
address shown on the books of Allied maintained at the Warrant Office for the
registration of the Warrant or at any more recent address of which the holder
hereof shall have notified Allied in writing.  Any notice or other document
required or permitted to be given or delivered to Allied, other than such
notice or documents required to be delivered to the Warrant Office, shall be
delivered at, or sent by certified or registered mail to, the offices of Allied
at 7201 East Camelback Road, Suite 375, Scottsdale, Arizona 85251 or such other
address within the continental United States of America as shall have been
furnished by Allied to the holder hereof.

         5.6     Limitation of Liability; Not Stockholders.  No provision of
the Warrant shall be construed as conferring upon the holder hereof the right
to vote, consent, receive dividends or receive notices (other than as herein
expressly provided) in respect of meetings of stockholders for the election of
directors of Allied or any other matter whatsoever as a stockholder of Allied
prior to exercise of the Warrant.  No provision hereof, in the absence of
affirmative action by the holder hereof to purchase shares of Common Stock, and
no mere enumeration herein of the rights or privileges of the holder hereof,
shall give rise to any liability of the holder hereof for the purchase price of
any shares of Common Stock or as a stockholder of Allied, whether such
liability is asserted by Allied or by creditors of Allied.





                                     12
<PAGE>   178
         5.7     Exchange, Loss, Destruction, etc. of Warrant. Upon receipt of
evidence reasonably satisfactory to Allied of the loss, theft, mutilation or
destruction of the Warrant, and in the case of any such loss, theft or
destruction upon delivery of an appropriate affidavit in such form as shall be
reasonably satisfactory to Allied and include reasonable indemnification of
Allied, or in the event of such mutilation upon surrender and cancellation of
the Warrant, Allied will make and deliver a new Warrant of like tenor, in lieu
of such lost, stolen, destroyed or mutilated Warrant.  A Warrant issued under
the provisions of this Section in lieu of a Warrant alleged to be lost,
destroyed or stolen, or in lieu of a mutilated Warrant, shall constitute an
original contractual obligation on the part of Allied.  The Warrant shall be
promptly canceled by Allied upon the surrender hereof in connection with any
exchange or replacement.  Allied shall pay all taxes (other than securities
transfer taxes or capital gains or income taxes) and all other expenses and
charges payable in connection with the preparation, execution and delivery of a
Warrant pursuant to this Section.

         5.8     Specific Performance.  Each party hereto agrees that one or
more other parties would be irreparably damaged if any provision of the Warrant
was not performed in accordance with its specific terms or was otherwise
breached.  Therefore, the parties hereto agree that each party shall be
entitled to an injunction or injunctions to prevent breaches of the Warrant or
any of their provisions and to specifically enforce the Warrant, its terms and
provisions in any action instituted in any court of the United States or Canada
or any state or province thereof having subject matter jurisdiction, in
addition to any other remedy to which a party may be entitled, at law or in
equity.

         5.9     Headings.  The Article and Section and other headings herein
are for convenience only and are not a part of this Warrant and shall not
affect the interpretation thereof.

IN WITNESS WHEREOF, Allied has caused this Warrant to be signed in its name.

Dated: _______________, 1996




                                 ALLIED WASTE INDUSTRIES, INC.


                                                                              
                                 ------------------------------------
                                 By:                                 
                                    ---------------------------------
                                 Title:                              
                                       ------------------------------




RECEIVED AND ACKNOWLEDGED





                                     13
<PAGE>   179
LAIDLAW TRANSPORTATION, INC.

- ---------------------------------------------------
By:
   ------------------------------------------------
Title:
      ---------------------------------------------





                                     14
<PAGE>   180
                          FORM OF SUBSCRIPTION NOTICE


          The undersigned hereby elects to exercise purchase rights represented
thereby for, and to purchase thereunder, ____________ shares of the Common
Stock covered by Warrants to purchase Common Stock, and herewith makes payment
in full for such shares, and requests (a) that certificates for such shares
(and any other securities or other property issuable upon such exercise) be
issued in the name of, and delivered to, ____________________  and (b), such
shares shall not include all of the shares issuable as provided in such
Warrant, that a new Warrant of like tenor and date for the balance of the
shares issuable thereunder be delivered to the undersigned.



                                       
                                      -----------------------------------------
                                      By:   
                                         --------------------------------------
                                      Title:       
                                            -----------------------------------




Date:
     --------------------------------------




                                     15
<PAGE>   181
                                                                       EXHIBIT D


                             SUBSCRIPTION AGREEMENT

       This Subscription Agreement dated _____________, 199_ (this
"Agreement"), is among Allied Waste Industries, Inc., a Delaware corporation
("Allied"), 3294854 Canada, Inc., a Canadian corporation ("Allied Finance"),
Laidlaw Inc., a Canadian corporation ("Laidlaw"), and Laidlaw Transportation,
Inc., a Delaware corporation ("LTI").

                              W I T N E S S E T H:

       WHEREAS, pursuant to the Stock Purchase Agreement dated as of September
17, 1996 (the "Stock Purchase Agreement"), among Allied, Allied Holdings
(United States), Inc., a Delaware corporation and a wholly owned subsidiary of
Allied ("Allied U.S."), and 3294854 Canada, Inc., a Canadian corporation and a
wholly-owned subsidiary of Allied U.S.  ("Allied Canada"), all of which are
collectively referred to in this Agreement as the "Allied Parties," and
Laidlaw, LTI, Laidlaw Waste Systems, Inc., a Delaware corporation and a wholly
owned subsidiary of LTI ("LWSI"), Laidlaw Waste Systems (Canada), Ltd., a
Canadian corporation and a wholly owned subsidiary of Laidlaw ("LWSC"), and
Laidlaw Medical Services Ltd., a Canadian corporation and a wholly owned
subsidiary of Laidlaw ("LMS"), Allied, through the acquisition by Allied U.S.
of all of the issued and outstanding capital stock of LWSI and the acquisition
by Allied Canada of all of the issued and outstanding shares in the share
capital of each of LWSC and LMS, has acquired, on the date hereof, all of the
United States and Canadian solid waste management operations of Laidlaw;

       WHEREAS, as a portion of the consideration for the purchase by Allied
Canada of the LWSC Shares (as such term is defined in the Stock Purchase
Agreement), Allied Canada has issued to Laidlaw its 7% Junior Subordinated
Debenture due 200__ dated the date hereof (the "Allied Canada 7% Debenture"),
in the original principal amount of $150,000,000 and its Zero Coupon Junior
Subordinated Debenture due 200__ dated the date hereof (the "Allied Finance
Zero Coupon Debenture" and, together with the Allied Finance 7% Debenture, the
"Allied Canada Debentures"), in the original principal amount of $168,300,000;

       WHEREAS, pursuant to the Debenture Exchange Agreement dated the date
hereof between Allied Finance and Laidlaw, Allied Finance has issued its 7%
Junior Subordinated Debenture due 200_ dated the date hereof (the "Allied
Finance 7% Debenture"), payable to Laidlaw in the original principal amount of
$150,000,000 and its Zero Coupon Junior Subordinated Debenture due 200_ dated
the date hereof (the "Allied Finance Zero Coupon Debenture" and, together with
the Allied Finance 7% Debenture, the "Debentures"), payable to Laidlaw in the
original principal amount of $168,300,000, in exchange for the Allied Canada
Debentures;

       WHEREAS, pursuant to Section 3(b) of the Allied Finance 7% Debenture,
interest on the outstanding principal balance of the Allied Finance 7%
Debenture will accrue but will be deferred during the Deferral Period (as such
term is defined in the Allied Finance 7% Debenture), and thereafter (i) the
interest deferred during the Deferral Period may, at the option of Allied
Finance, be paid at any time and, if not so paid, such deferred interest,
together with interest thereon atl 7% per annum, will be payable in eighteen
equal (or as nearly equal as possible) installments on the _____ day of each
________ and ________ of each year
<PAGE>   182
(beginning ______________, _____), and on the Maturity Date and (ii) interest
accrued after the Deferral Period will be due and payable in arrears on the
last day of each ___________ and ___________ of each year (beginning
_____________, ____), and on the Maturity Date for the period commencing on
(and including) the later of date following the last day of the Deferral Period
or the date to which interest thereon has been paid, as the case may be, and
ending on (but excluding) the date of such  payment (each installment of
interest payable as provided in either clause (i) or clause (ii) above being
hereinafter referred to as an "Interest Installment");

       WHEREAS, with respect to each Interest Installment, Allied desires to
be able to require LTI to subscribe for shares of Allied Common Stock with a
purchase price equal to the amount of such Interest Installment;

       WHEREAS, in the event a Change of Control (as hereinafter defined)
occurs and Laidlaw elects to require prepayment of the Allied Finance 7%
Debenture pursuant to Section 9 thereof or of the Allied Finance Zero Coupon
Debenture pursuant to Section 8 thereof (a "Change of Control Payment Event"),
Allied desires to be able to require LTI to subscribe for shares of Allied
Common Stock with a purchase price equal to the amount payable to Laidlaw (the
"Change of Control Proceeds") as a result of the Change of Control Payment
Event;

       NOW, THEREFORE, Allied, Allied Finance, Laidlaw and LTI (collectively,
the "Parties") agree that:

                                   ARTICLE I

                                  DEFINITIONS

       1.1    Definitions.  The terms defined in the preamble and the recitals
of this Agreement are used herein as therein defined.  The following terms have
the meaning indicated below:

              "Allied Common Stock" means the Common Stock, $.01 par value per
       share, of Allied.

              "Change of Control" means a change resulting when any Unrelated
       Person or any Unrelated Persons acting together that would constitute a
       Group together with any Affiliates thereof (in each case also
       constituting Unrelated Persons) shall at any time Beneficially Own more
       than 50% of the aggregate voting power of all classes of Voting Stock of
       Allied; provided, however, that if at the date any "Change of Control"
       would otherwise have occurred but for the fact that a Person was not an
       Unrelated Person because such Person or an Affiliate of such Person
       acquired shares of Allied Common Stock or all or any portion of the
       Allied Warrant from Laidlaw or from any Affiliate of Laidlaw within nine
       months prior to such date, such shares of Allied Common Stock acquired
       from Laidlaw or any Affiliate of Laidlaw, or any shares of Allied Common
       Stock issued upon exercise of the Allied Warrant or any portion thereof,
       shall at all times thereafter be excluded when calculating whether a
       Change of Control has occurred.  As used in this definition of Change in
       Control (a) "Beneficially Own" means "beneficially own" as defined in
       Rule 13d-3 of the Securities Exchange Act of 1934,




                                     -2-
<PAGE>   183
       as amended (the "Exchange Act"), or any successor provisions thereto;
       provided, however, that, for purposes of this definition, a Person shall
       not be deemed to Beneficially Own securities tendered pursuant to a
       tender or exchange offer made by or on behalf of such Person or any of
       such Person's Affiliates until such tendered securities are accepted for
       purchase or exchange; (b) "Group" means a "group" for purposes of
       Section 13(d) of the Exchange Act; (c) "Affiliate" means, with respect
       to any Person, another Person which would be an "affiliate" of such
       Person for purposes of Section 13(d) of the Exchange Act; (d) "Unrelated
       Person" means at any time any Person other than Laidlaw, any Person to
       whom Laidlaw or any of its Affiliates transfers, within nine months
       prior to such time, any shares of Allied Common Stock or all or any
       portion of the Allied Warrant or any Affiliate of Laidlaw or any such
       Person; provided, however, that Persons (other than Affiliates of
       Laidlaw) to whom Laidlaw or any of its Affiliates transfers any shares
       of Allied Common Stock or all or any portion of the Allied Warrant after
       five years from the date hereof shall not be deemed Unrelated Persons;
       and (e) "Voting Stock" of any Person shall mean capital stock of such
       Person which ordinarily has voting power for the election of directors
       (or persons performing similar functions) of such Person, whether at all
       times or only so long as no senior class of securities has such voting
       power by reason of any contingency.

              "Change of Control Payment Date" means (i) with respect to a
       Change of Control Payment Event with respect to the Allied Finance 7%
       Debenture, the Section 9 Prepayment Date (as such term is defined in
       Subsection 9(b) of the Allied Finance 7% Debenture) and (ii) with
       respect to a Change of Control Payment Event with respect to the Allied
       Finance Zero Coupon Debenture, the Section 8 Prepayment Date (as such
       term is defined in Subsection 8(b) of the Allied Finance Zero Coupon
       Debenture).

              "Current Market Price" per share of Allied Common Stock on any
       specified date means the average daily market prices (determined as set
       forth below in this definition), of the Allied Common Stock for the 20
       consecutive Trading Days ending on the third Trading Day before that
       date.  The market price for each such Trading Day shall be the average
       of the last sale prices on such Trading Day on all stock exchanges and
       the Nasdaq Stock Market on which the Allied Common Stock may then be
       listed or admitted for quotation, respectively; provided, that if no
       sale takes place on any such Trading Day on any such exchange or the
       Nasdaq Stock Market, the average of the closing bid and asked prices on
       such day as officially quoted thereon shall be used, or, if Allied
       Common Stock is not then listed or admitted for quotation on any stock
       exchange or the Nasdaq Stock Market, the market price for each Trading
       Day shall be the average of the reported bid and asked prices on such
       day on the over-the-counter market, or, if Allied Common Stock is not
       quoted on the over-the-counter market, the market price for each Trading
       Day shall be the average of the bid and asked prices furnished by any
       member of the National Association of Securities Dealers selected by
       Allied.

              "Interest Due Date" is defined in Section 2.1.

              "Interest Installment" is defined in the premises of this
       Agreement.





                                      -3-
<PAGE>   184
              "Maturity Date" means ____________________ __, 200_ [12 years
       after the date hereof].

              "Section 2.1 Subscription Obligation" is defined in Section 2.1.

              "Section 2.1 Subscription Shares" is defined in Section 2.1.

              "Section 2.2 Subscription Obligation" is defined in Section 2.2.

              "Section 2.2 Subscription Shares" is defined in Section 2.2.

              "Subscription Notice" means the written notice in substantially
       the form of Exhibit A attached hereto to be given pursuant to Section
       2.3.

              "Subscription Shares" means, collectively, the Section 2.1
       Subscription Shares and the Section 2.2 Subscription Shares.

                                   ARTICLE II

                            SUBSCRIPTION FOR SHARES

       2.1    Interest Payment Subscriptions.  At the date (the "Interest Due
Date") each Interest  Installment is due and payable pursuant to the Allied
Finance 7% Debenture, LTI agrees, upon  receipt of a Subscription Notice and
upon the other terms and subject to the conditions herein contained, to
subscribe (the "Section 2.1 Subscription Obligation") for a number of shares
(the "Section 2.1 Subscription Shares"), rounded up to the nearest whole
number, of the Allied Common Stock equal to the product obtained by dividing
the amount of such Interest Installment by the Current Market Price of the
Allied Common Stock as of such Interest Due Date for an aggregate purchase
price equal to the amount of such Interest Installment.

       2.2    Change of Control Subscription.  If a Change of Control Payment
Event occurs, LTI hereby agrees, upon receipt of a Subscription Notice and upon
the other terms and subject to the conditions herein contained, to subscribe
(the "Section 2.2 Subscription Obligation") for a number of shares  (the
"Section 2.2 Subscription Shares"), rounded up to the nearest whole number, of
Allied Common Stock equal to the product obtained by dividing the amount of the
Change of Control Proceeds applicable to such Change of Control Event by the
Current Market Price of the Allied Common Stock as of the Change of Control
Payment Date for an aggregate purchase price equal to the amount of the Change
of Control Proceeds.

       2.3    Method of Subscription.  If Allied elects at any time to cause
LTI to subscribe for Section 2.1 Subscription Shares or Section 2.2
Subscription Shares pursuant to this Agreement, Allied shall deliver to LTI, at
the office designated in Section 3.1(a), a written notice signed by Allied in
substantially the form of the Subscription Notice attached hereto as Exhibit A.
Upon receipt by LTI of each duly executed Subscription Notice, LTI will be
deemed to have subscribed for the number of Subscription Shares covered by the
Subscription Notice.  Upon each such subscription for Section 2.1 Subscription
Shares, Allied shall issue





                                      -4-
<PAGE>   185
and deliver to LTI, at the address set forth in Section 3.1(a), on the relevant
Interest Due Date a certificate for said Section 2.1 Subscription Shares.  Upon
delivery of such certificate, the obligation of Allied Finance to pay the
Interest Installment due on such Interest Due Date to Laidlaw shall be
automatically in all respects satisfied and discharged as provided in Section
2.5.  Upon each subscription for Section 2.2 Subscription Shares, Allied shall
issue and deliver to LTI, at the address set forth in Section 3.1(a), on the
Change of Control Payment Date a certificate for said Section 2.2 Subscription
Shares, and Laidlaw and LTI shall deliver to Allied the Debenture or Debentures
as to which a Change of Control Event has occurred marked "Cancelled."  Upon
delivery of such certificate, the obligation of Allied Finance to pay the
Change of Control Proceeds to Laidlaw shall be in all respects satisfied and
discharged.  If, as a result of any merger, consolidation, reclassification or
reorganization, the shares of Allied Common Stock have been converted into
another security, shares of such other security may be delivered hereunder in
lieu of shares of Allied Common Stock.  If shares of the Allied Common Stock
have not been converted into another security and such shares have no value or
if no shares of Allied Common Stock are available for issuance, nothing herein
contained will relieve Allied Finance of its obligation to pay Interest
Installments and amounts payable upon a change of Control, to the extent and in
the manner set forth in the Debentures.

       2.4    Rights in Subscription Shares.  LTI shall be deemed to have
become a holder of record of the Subscription Shares, and shall be entitled to
all of the benefits thereof, on the relevant Interest Due Date or Change of
Control Payment Date, as the case may be, including without limitation the
right to receive dividends and other distributions for which the record date
falls on or after such date and to exercise voting rights with respect to
Subscription Shares as of such date.

       2.5    Acknowledgments by Laidlaw.  Laidlaw hereby irrevocably
authorizes and directs Allied Finance to apply and pay to Allied all Interest
Installments and the Change of Control Proceeds in respect of which a
Subscription Notice has been given in satisfaction of LTI's obligations
hereunder to pay the purchase price for the Subscription Shares to be issued by
Allied to LTI in accordance herewith.  Laidlaw hereby further acknowledges and
agrees to the provisions herein contained, and agrees that the application and
payment of funds by Allied Finance as herein set forth on account of the
issuance of Subscription Shares to LTI as described in Section 2.3 will satisfy
and discharge the obligation of Allied Finance to pay Interest Installments
otherwise due under the Allied Finance 7% Debenture or to pay the Change of
Control Proceeds to Laidlaw upon the occurrence of a Change of Control Event.

                                  ARTICLE III

                                 MISCELLANEOUS

       3.1    Notices.  All notices or other communications which are required
or may be given under this Agreement shall be in writing and shall be deemed to
have been duly given when delivered in person or transmitted by telecopier
(with receipt confirmed) to a party at the address or telecopy number, as
applicable, set forth below (as any such address or telecopier number may be
changed from time to time by notice similarly given):


              (a)    if to Laidlaw or LTI to:






                                      -5-
<PAGE>   186


                            Laidlaw Inc.
                            3221 North Service Road
                            Burlington, Ontario
                            Canada L7R 3Y8
                            Attention: Ivan R. Cairns
                            Telecopy No.: (905) 332-6550

              (b)    if to Allied or Allied Finance, to:

                            Allied Waste Industries, Inc.
                            7201 East Camelback Road, Suite 375
                            Scottsdale, Arizona 85251
                            Attention: Roger A. Ramsey
                            Telecopy No.: (602) 481-9347

                            with a copy to:

                            Porter & Hedges, L.L.P.
                            700 Louisiana Street, Suite 3500
                            Houston, Texas 77002
                            Attention: Robert G. Reedy
                            Telecopy No.: (713) 228-1331

       3.2    Section Headings.  The article and section headings in this
Agreement are for reference purposes only and shall not affect the meaning or
interpretation of this Agreement.  References in this Agreement to a designated
"Article" or "Section" refer to an Article or Section of this Agreement unless
otherwise specifically indicated.

       3.3    Governing Law.  This Agreement shall be construed and enforced in
accordance with and governed by the law of Delaware.

       3.4    Amendments.  This Agreement may be amended only by an instrument
in writing executed by all of the Parties.

       3.5    Entire Agreement.  This Agreement constitutes the entire
agreement among the Parties concerning its subject matter.

       3.6    Assignment.  The rights and obligations hereunder of any Party
may not be assigned without written consent of each of the other Parties;
provided, however, that in the event of a permitted assignment of either of the
Debentures, the rights and obligations of Laidlaw and LTI hereunder shall be
assigned to the assignee of such Debentures to the extent of such assignment.

       3.7    Severability.  The invalidity or unenforceability of any specific
provision of this Agreement shall not invalidate or render unenforceable any of
its other provisions.  Any provision of this Agreement held invalid or
unenforceable shall be deemed reformed, if practicable, to the extent necessary
to render it valid and enforceable and to the extent permitted by law and
consistent with the intent of the parties to this Agreement.

       3.8    Counterparts.  This Agreement may be executed in multiple
counterparts, each of which shall be deemed an original, but all of which
together shall constitute the same instrument.





                                      -6-
<PAGE>   187
       IN WITNESS WHEREOF, the Parties have executed this Agreement as of the
date first above written.



                                           ALLIED WASTE INDUSTRIES, INC.



                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------

                                           3294854 CANADA, INC.


                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------

                                           LAIDLAW INC.


                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------

                                           LAIDLAW TRANSPORTATION, INC.



                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------





                                      -7-
<PAGE>   188
                                                                       EXHIBIT A
                                                       to Subscription Agreement


                          FORM OF SUBSCRIPTION NOTICE


Laidlaw Transportation, Inc.
c/o Laidlaw Inc.
3221 North Service Road
Burlington, Ontario
Canada L7R 3Y8

Attention: Ivan R. Cairns

Gentlemen:

       The undersigned hereby elects to exercise its option to require you,
pursuant to Article II of the Subscription Agreement dated __________, 199_
(the "Subscription Agreement"), among Allied Waste Industries, Inc., 3294854
Canada, Inc., Laidlaw Inc. and Laidlaw Transportation, Inc., to subscribe for
the number of shares of Allied Common Stock (the "Subscription Shares")
determined pursuant to Section [2.1] [2.2] of the Subscription Agreement for an
aggregate purchase price equal to the amount of the [Interest Installment due
on _____________, ______, pursuant to the Allied Finance 7% Debenture] [Change
of Control Proceeds] (as defined in the Subscription Agreement).

       Upon your receipt of this notice, you will be deemed to have subscribed
to the Subscription Shares and the undersigned shall issue and deliver to you a
certificate or certificates for the Subscription Shares as more fully set forth
in Section 2.3 of the Subscription Agreement.



                                            Allied Waste Industries, Inc.
                                            
                                            
                                            
Date:                                       By:                                
      ----------------------                    -------------------------------
                                            Title:                             
                                                   ----------------------------





                                      -1-
<PAGE>   189
                                                                       EXHIBIT E



                          STOCK REGISTRATION AGREEMENT

       This Stock Registration Agreement dated _____________, 199__ (this
"Registration Agreement"), is among Allied Waste Industries, Inc., a Delaware
corporation ("Allied"), Laidlaw Inc., a Canadian corporation ("Laidlaw"), and
Laidlaw Transportation, Inc., a Delaware corporation ("LTI"), both of which are
together referred to in this Registration Agreement as the "Laidlaw Parties."

                              W I T N E S S E T H:

       WHEREAS, under a Stock Purchase Agreement dated as of September 17, 1996
(the "Stock Purchase Agreement"), among Allied, the Laidlaw Parties and others,
Allied is this date issuing to the Laidlaw Parties (i) 14,600,000 shares (the
"Initial Common Shares") of Common Stock, $.01 par value per share ("Common
Stock"), of Allied, (ii) the Warrants (the "Warrants") for the purchase of
20,400,000 shares of Common Stock (subject to adjustment as provided in the
Warrants), a Zero Coupon Subordinated Debenture which may be redeemed using
Common Stock in certain events (the "Zero Coupon Debenture"), and a 7%
Subordinated Debenture which provides for the payment of interest at Allied's
option using shares of Common Stock and may be redeemed using Common Stock in
certain events (the "7% Debenture"); and

       WHEREAS, the Stock Purchase Agreement requires that this Registration
Agreement be entered into among Allied and the Laidlaw Parties upon the
issuance to the Laidlaw Parties of such securities of Allied.

       NOW, THEREFORE, Allied and the Laidlaw Parties (collectively, the
"Parties") agree that:


                                   ARTICLE I

                                  DEFINITIONS

       1.1.   Definitions.  In this Registration Agreement:

       "Canadian Securities Acts" means the applicable securities legislation
of each of the provinces and territories of Canada, and the regulations, rules
and policies made thereunder or issued by the Commissions administering such
legislation, as the same may hereafter be amended or replaced.
<PAGE>   190
       "Commissions" means the securities commissions or similar regulatory
authorities of each of the provinces and territories of Canada and any
successor regulatory authorities having similar powers.

       "Exchange Act" means the United States Securities Exchange Act of 1934,
as amended, and the rules and regulations of the SEC promulgated under such
Act.

       "Offering Expenses" means all expenses incidental to Allied's
performance of or compliance with its obligations under Section 2.2 in
connection with the qualification by prospectus of Registrable Securities under
any of the Canadian Securities Acts, including, without limitation, all filing
fees, all fees and expenses of complying with the applicable Canadian
Securities Acts, all printing and translation expenses, all fees and
disbursements of counsel to any Laidlaw Party and all fees and disbursements of
counsel to Allied and its auditors, including the expenses of any special
audits required by or incidental to such performance and compliance, and any
underwriting fees and commissions and applicable transfer taxes, if any,
relating to the distribution of the Registrable Securities.

       "Registrable Securities" means (i) the Initial Common Shares, (ii) the
Warrant to purchase 20,400,000 shares of Common Stock issued by Allied to
Laidlaw (the "Allied Warrant") and any shares of Common Stock issued upon any
exercise or exercises of the Allied Warrant (the "Allied Warrant Shares"),
(iii) any shares of Common Stock issued pursuant to the Laidlaw Subscription
Agreement entered into by Allied and the Laidlaw Parties of even date herewith,
and (iv) any shares of Common Stock issued in connection with any stock
dividend on, or any stock split, reclassification or reorganization of, shares
of Common Stock referenced in subparagraphs (i), (ii) and (iii) above.

       "SEC" means the United States Securities and Exchange Commission or any
successor agency.

       "Securities Act" means the United States Securities Act of 1933, as
amended, and the rules and regulations of the SEC promulgated under such Act.


                                   ARTICLE II

                              REGISTRATION RIGHTS

       2.1.   Incidental Rights.  If at any time or from time to time Allied
proposes to file (i) with the SEC a registration statement (whether on Form
S-1, S-2, or S-3, or any equivalent form then in effect) for the registration
under the Securities Act of any shares of Common Stock for sale, or (ii) file a
prospectus under any of the




                                      2
<PAGE>   191
Canadian Securities Acts in order to qualify a distribution under any of the
Canadian Securities Acts of any securities, for cash consideration, to the
public by Allied or on behalf of one or more shareholders of Allied (excluding
any sale of securities convertible into or exercisable for Common Stock, and
any shares of Common Stock issuable by Allied upon the exercise of employee
stock options, or to any employee stock ownership plan, or in connection with
any acquisition made by Allied, any securities exchange offer, dividend
reinvestment plan, employee benefit plan, corporate reorganization, or in
connection with any amalgamation, the merger or consolidation of Allied with
one or more other corporations if Allied is the surviving corporation), Allied
shall give the Laidlaw Parties at least 20 days' prior written notice of the
proposed filing (or if 20 days' notice is not practicable, a reasonable shorter
period to be not less than 7 days), which notice shall outline the nature of
the proposed distribution and the U.S. and Canadian jurisdictions in which
Allied proposes to qualify and offer such securities (the "Elected
Jurisdictions").  On the written request of a Laidlaw Party received by Allied
within 15 days after the date of Allied's delivery to the Laidlaw Parties of
the notice of intended registration (which request shall specify the
Registrable Securities sought to be disposed of by each Laidlaw Party and the
intended method or methods by which dispositions are intended to be made),
Allied shall, under the terms and subject to the conditions of this Article II,
(i) at its own expense as provided in Section 4.1, include in the coverage of
such U.S. registration statement (or in a separate U.S. registration statement
concurrently filed) and qualify for sale under the blue sky or securities laws
of the various states, and (ii) at the expense of the requesting Laidlaw
Parties as provided in section 4.2, use its best efforts to effect the
qualification of under the Canadian Securities Acts, in the Elected
Jurisdictions the number of Registrable Securities (herein called the
"Specified Securities") held by such Laidlaw Party, or which such Laidlaw Party
is entitled to purchase upon exercise of Warrant, and which such Laidlaw Party
has so requested to be registered or qualified for distribution, to the extent
requisite to permit the distribution (in accordance with the intended method or
methods thereof as aforesaid) in the Elected Jurisdictions requested by such
Laidlaw Party of such Registrable Securities.

       If the distribution proposed to be effected by Allied involves an
underwritten offering of the securities being so distributed by or through one
or more underwriters, and if the managing underwriter of such underwritten
offering indicates in writing its reasonable belief that including all or part
of the Specified Securities in the coverage of such registration statement or
in the distribution to be effected by such prospectus will materially and
adversely affect the sale of securities proposed to be sold (which statement of
the managing underwriter shall also state the maximum number of shares, if any,
which can be sold by the Laidlaw Party requesting registration under this
Section 2.1 without materially adversely affecting the sale of the shares
proposed to be sold), then the number of Specified Securities which the
requesting Laidlaw Party shall have the right to include in such





                                       3
<PAGE>   192
registration statement or to have qualified by such prospectus shall be reduced
to the maximum number of shares specified by the managing underwriter.  In all
cases, priority shall be afforded to securities covered by a registration
statement and/or qualified for distribution by a prospectus filed in response
to the exercise of a demand registration or qualification right by another
holder of Common Stock and no securities proposed to be sold by such other
holder shall be so reduced until all securities proposed to be sold by all
other parties have been entirely eliminated.  As to all other proposed selling
shareholders of Common Stock, including the Laidlaw Party requesting to include
Registrable Securities in the coverage of such a registration statement or
prospectus, any such reduction in the number of shares of Common Stock proposed
to be sold by the selling shareholders shall be effected on a pro rata basis in
accordance with the relationship which the number of shares of Common Stock
proposed to be sold by each selling shareholder bears to the number of shares
of Common Stock proposed to be sold by all selling shareholders.  Until the
first anniversary of the date of this Registration Agreement, the Laidlaw
Parties agree that they will not exercise registration rights under this
Section 2.1 regarding any registration statement filed on behalf of TPG
Partners, L.P. or TPG Parallel I, L.P. by Allied pursuant to the Securities
Purchase Agreement by and between Allied and TPG dated October 27, 1994.

       Allied shall have the sole right to select any underwriters, including
the managing underwriter, of any public offering of shares of Common Stock
subject to this Section 2.1.  Nothing in this Section 2.1 shall create any
liability on the part of Allied to a Laidlaw Party if Allied for any reason
decides not to file or to delay or withdraw a registration statement or
preliminary prospectus or (final) prospectus (which Allied may do in its sole
discretion).

       Each Laidlaw Party may request to have Common Stock included in an
unlimited number of registrations, and qualified by an unlimited number of
prospectuses, under this Section 2.1.

       2.2.   Mandatory Rights.  Upon written request of a Laidlaw Party made
at any time after six months following the date of this Registration Agreement,
Allied shall, under the terms and subject to the conditions set forth in this
Section 2.2 and Sections 2.4 and 2.5, (i) file (and use its reasonable efforts
to cause to become effective) a U.S.  registration statement covering, and use
its reasonable efforts to qualify for sale under the blue sky or securities
laws of the various U.S. states as may be requested by such Laidlaw Party
(except any such state in which, in the opinion of the managing underwriter of
the offering, the failure to so qualify would not materially and adversely
affect the proposed offering), and (ii) use its reasonable efforts to effect
the qualification for distribution under the Canadian Securities Acts, in
accordance with the intended method or methods of disposition set forth in that
notice, of such number of Registrable Securities, but not less than five
million





                                       4
<PAGE>   193
shares, as may be designated by such Laidlaw Party in its request, or that
portion thereof designated in said request for registration or qualification in
each of the Designated Jurisdictions (as defined below).  A request for
registration under this Section 2.2 shall specify the number of shares to be
registered, the United States and Canadian jurisdiction in which such
registration or qualification is to be effected (the "Designated
Jurisdictions") and the proposed manner of sale, including the name and address
of any proposed underwriter; provided, that all offerings contemplated by a
request for registration under this Section 2.2 shall be underwritten offerings
involving either a distribution of Registrable Shares to the public where no
single buyer, acting individually or with others, acquires more than 10% of
such offering, or a distribution by way of dividend or other distribution to
holders of Common Stock in the capital of Laidlaw where such dividend or other
distribution is made pro rata between the holders of all such classes of shares
according to the number of shares of either class held by each of them.  The
principal underwriter or underwriters for any such offering shall be selected
by the Laidlaw Party requiring registration, subject to Allied's approval,
which may not be unreasonably withheld.

       If the distribution proposed to be effected pursuant to this Section 2.2
involves an underwritten offering of the securities being so distributed by or
through one or more underwriters, and if the managing underwriter of such
underwritten offering indicates in writing its reasonable belief that including
all or part of the Registrable Securities in the coverage of such registration
statement or in the distribution to be effected by such prospectus will
materially and adversely affect the sale of the securities proposed to be sold,
then the number of securities proposed to be sold shall be reduced to the
maximum number of securities specified by the managing underwriter.  In such a
case, priority shall be afforded to Registrable Securities and the securities
that are not Registrable Securities shall be completely eliminated before the
number of Registrable Securities is reduced.

       Allied may delay the filing of any registration statement, or any
preliminary prospectus or (final) prospectus required to effect a qualification
for distribution, requested under this Section 2.2, or delay its effectiveness,
for a reasonable period (but not longer than 120 days) if, in the sole judgment
of Allied's Board of Directors, (i) a delay is necessary in light of pending
financing transactions, corporate reorganizations, or other major events
involving Allied, or (ii) filing at the time requested would materially and
adversely affect the business or prospects of Allied in view of disclosures
that may be thereby required.  Once the cause of the delay is eliminated,
Allied shall promptly notify the Laidlaw Parties requiring registration or
qualification, and promptly after a Laidlaw Party notifies Allied to proceed,
Allied shall, as required in connection with the Designated Jurisdictions
selected by the relevant Laidlaw Parties, file a registration statement or a
preliminary prospectus and/or (final) prospectus and begin performance of its
other obligations under this Section 2.2.





                                       5
<PAGE>   194
       The Laidlaw Parties shall be entitled to request not more than five
registrations or qualifications under this Section 2.2 (provided that the
filing of a registration statement and a preliminary prospectus or (final)
prospectus in more than one Designated Jurisdictions in connection with a
concurrent or substantially concurrent distribution shall be deemed for the
purposes hereof to be a single registration and qualification); provided that
the Laidlaw Parties will be entitled to one more request under this Section 2.2
if they receive shares of Common Stock in payment of the principal amount of
the Allied Zero Coupon Junior Subordinated Debenture due 200__ and the Allied
7% Junior Subordinated Debenture due 200__; and provided further that only
three of such distributions may be used to register or qualify distributions of
the Warrants.  However, if a Laidlaw Party requests a registration under this
Section 2.2, but no registration statement or (final) prospectus becomes
effective with respect to the Registrable Securities covered by such request,
then such request shall not count as a request for purposes of determining the
number of requests for registration or qualification the Laidlaw Parties may
make under this Section 2.2.

       2.3.   Registration Conditions.  Notwithstanding any other provision of
this Registration Agreement, Allied shall not be required to effect a
registration or qualification of any securities under this Article II, or file
any post-effective amendment to such a registration or a prospectus relating to
such a qualification:

              (a)    unless the requesting Laidlaw Party agrees to (x) sell and
       distribute a portion or all of its Registrable Securities in accordance
       with the plan or plans of distribution adopted by and through
       underwriters, if any, acting for Allied, and (y) bear a pro rata share
       of underwriter's discounts and commissions;

              (b)    if a registration or qualification requested under Section
       2.2, or any post-effective amendment to the registration statement
       and/or prospectus filed in connection therewith, requires, under
       applicable statutes and rules, a special audit (other than a normal
       fiscal year-end audit) of any financial statements, unless the
       requesting Laidlaw Party agrees to pay its proportionate share
       (determined by the number of shares to be sold by such Laidlaw Party in
       the offering in proportion to the total number of shares to be sold by
       Allied and all other participants in such offering) of the reasonable
       fees and expenses of accountants incurred in connection with the special
       audit and which would otherwise not be incurred;

              (c)    if, in the case of a request for registration or
       qualification under Section 2.1 or 2.2, in the opinion of counsel for
       Allied and counsel for the Laidlaw Party requesting the registration or
       qualification, as applicable, (i) the Registrable Securities for which
       registration under the Securities Act has been





                                       6
<PAGE>   195
       requested may be disposed of without adversely affecting the market
       price of such Registrable Securities within a comparable time frame
       without registration under the Securities Act and (ii) upon such
       disposition all legends on certificates representing such shares which
       restrict their transfer under the Securities Act and applicable state
       securities laws may be removed, and the sale by the applicable Laidlaw
       Party of any Registrable Securities for which qualification for
       distribution under any Canadian Securities Acts has been requested (i)
       will not constitute a "distribution" (or the corresponding term) under
       the applicable Canadian Securities Acts, or (ii) may be effected in the
       method requested (or in a method having a substantially similar economic
       effect, as to which such counsel may make any reasonable assumption for
       the purposes of such opinion) without qualification by prospectus,
       provided that the first trade of such Registrable Securities by the
       purchaser thereof from the Laidlaw Party in such sale would not
       constitute a "distribution" (or the corresponding term) under the
       applicable Canadian Securities Acts (but for (A) any unusual effort made
       to prepare the market or to create a demand for such securities made by
       or on behalf of such purchaser, (B) any extraordinary commission or
       consideration paid or to be paid in respect of such first trade, or (C)
       such purchaser being a person described in clause (C) of the definition
       of "distribution" set forth in section l(1) of the Securities Act
       (Ontario) in relation to Allied (or any corresponding provision of any
       other applicable Canadian Securities Act);

              (d)    if, in the case of a request for registration under
       Section 2.2, (x) any registration statement or prospectus covering
       securities regarding which a Laidlaw Party could have exercised
       registration rights under Section 2.1 of this Registration Agreement has
       become effective under the Securities Act or, with respect to a (final)
       prospectus, a receipt has been issued therefor under the applicable
       Canadian Securities Acts within six months preceding the date of such
       request, (y) a registration statement or prospectus requested by a
       Laidlaw Party pursuant to Section 2.2 has become effective under the
       Securities Act or, with respect to a (final) prospectus, a receipt has
       been issued therefor under the applicable Canadian Securities Acts
       within twelve months preceding the date of such request, or (z) Allied
       has given notice under Section 2.1 of its intention to file a
       registration statement under the Securities Act or a prospectus under
       any Canadian Securities Acts and has not completed or abandoned the
       proposed offering; and

              (e)    unless Allied has received from the Laidlaw Party
       requesting registration or qualification all information Allied has
       reasonably requested concerning such Laidlaw Party and its method of
       distribution of its Registrable Securities, so as to enable Allied to
       include in the registration statement or prospectus all facts required
       to be disclosed in it.





                                       7
<PAGE>   196
       2.4.   Covenants and Procedures.  If Allied becomes obligated under this
Article II to effect a registration or qualification of Registrable Securities
on behalf of a Laidlaw Party requesting registration or qualification under
this Article II (hereinafter called a "Selling Laidlaw Party"), then (as
applicable to the jurisdictions for which such registration or qualification is
to be made):

              (a)    Allied, (i) at its expense as provided in Section 4.1,
       shall prepare and file with the SEC a registration statement covering
       and, as applicable, (ii) at the expense of the requesting Laidlaw
       Parties as provided in section 4.2, prepare and file with the applicable
       Commissions (in the English and French languages, as applicable) a
       preliminary prospectus qualifying, such securities and such other
       related documents as may be necessary or appropriate relating to the
       proposed distribution, and shall use reasonable efforts to cause the
       registration statement to become effective and (with respect to Canadian
       jurisdictions) to, after any comments of the Commissions have been
       satisfied with respect thereto, prepare and file in accordance with the
       relevant Canadian Securities Acts, a (final) prospectus in the English
       and French languages, as appropriate, and receive receipts therefor and
       shall take all other steps and proceedings that may be necessary in
       order to qualify the applicable Registrable Securities for distribution
       under such Canadian Securities Acts by registrants who comply with the
       relevant provisions of such Canadian Securities Acts.  Allied will also
       (i) with respect to any U.S.  registration statement, file such
       post-effective amendments to the registration statement (and use
       reasonable efforts to cause them to become effective) and such
       supplements as are necessary so that current prospectuses are at all
       times available for a period of at least 90 days after the effective
       date of the registration statement or for such longer period, not to
       exceed 180 days, as may be required under the plan or plans of
       distribution set forth in the registration statement, and (ii) with
       respect to any Canadian prospectus, file with the Commissions such
       amendments and supplements to such preliminary prospectus and (final)
       prospectus as may be necessary to comply with the provisions of the
       Canadian Securities Acts applicable to the proposed distribution until
       the earlier of (A) such time as all of Registrable Securities proposed
       to be sold thereunder have been disposed of in accordance with the
       intended method or methods of disposition by the seller or sellers
       thereof, and (B) the expiration of a period of at least 90 days after
       the issuance by the Commissions in all applicable Canadian jurisdictions
       for the (final) prospectus or such longer period, not to exceed 180
       days, as may be required under the plan or plans of distribution set
       forth in such (final) prospectus.  Each Selling Laidlaw Party shall
       promptly provide Allied with such information with respect to such
       Selling Laidlaw Party's Registrable Securities to be so registered and
       qualified and, if applicable, the proposed terms of their offering, as
       is required for the registration or qualification.  If





                                       8
<PAGE>   197
       the Registrable Securities to be covered by the registration statement
       and/or prospectus are not to be sold to or through underwriters acting
       for Allied, Allied shall:

                     (x)    deliver to each Selling Laidlaw Party, as promptly
              as practicable, as many copies of preliminary prospectuses as
              each Selling Laidlaw Party may reasonably request (in which case
              each Selling Laidlaw Party shall keep a written record of the
              distribution of the preliminary prospectuses and shall refrain
              from delivery of the preliminary prospectuses in any manner or
              under any circumstances which would violate the Securities Act,
              the applicable Canadian Securities Acts or the securities laws of
              any other jurisdiction, including the various states of the
              United States);

                     (y)    deliver to each Selling Laidlaw Party, as soon as
              practicable after the effective date of the U.S. registration
              statement, or, as applicable, the date on which all applicable
              Commissions shall have issued a receipt for the Canadian (final)
              prospectus, and from time to time thereafter during the
              applicable period described in paragraph 2.4(a)(i) or (ii), as
              many copies of the relevant prospectuses (including any (final)
              prospectus as such Selling Laidlaw Party may reasonably request;
              and

                     (z)    in case of the happening, after the effective date
              of the registration statement and during the applicable 90 or 180
              day period described in the second sentence of paragraph 2.4(a),
              of any event or occurrence as a result of which the prospectus
              (including any preliminary prospectus or (final) prospectus), as
              then in effect, would include an untrue statement of a material
              fact or omit to state any material fact required to be stated
              therein or necessary to make any statement therein not misleading
              in the light of the circumstances in which it was made, give each
              Selling Laidlaw Party written notice of the event or occurrence
              and prepare and furnish to each Selling Laidlaw Party, in such
              quantities as it may reasonably request, copies of an amendment
              of or a supplement to such prospectus as may be necessary so that
              the prospectus, as so amended or supplemented and thereafter
              delivered to purchasers of the securities, will not contain any
              untrue statement of a material fact or omit to state any material
              fact required to be stated therein or necessary to make the
              statements therein, in the light of the circumstances under which
              it was made, not misleading.





                                       9
<PAGE>   198
              (b)    Allied will notify the Laidlaw Parties of any action by
       the SEC or any Commission to suspend the effectiveness of any
       registration statement or prospectus filed pursuant hereto or the
       initiation or threatened initiation of any proceeding for such purpose
       or the receipt by Allied of any notification with respect to the
       suspension of the qualification of the securities for sale in any
       jurisdiction.  Immediately upon receipt of any such notice, the Laidlaw
       Parties shall cease to offer or sell any Registrable Securities pursuant
       to the registration statement or prospectus in the jurisdiction to which
       such order or suspension relates.  Allied will also notify the Laidlaw
       Parties promptly of the occurrence of any event or the existence of any
       state of facts that, in the judgment of Allied, should be set forth in
       such registration statement or prospectus.  Immediately upon receipt of
       such notice, the Laidlaw Parties shall cease to offer or sell any
       Registrable Securities pursuant to such registration statement or
       prospectus, cease to deliver or use such registration statement or
       prospectus and, if so requested by Allied, return to Allied at Allied's
       expense all copies of such registration statement or prospectus.  Allied
       will as promptly as practicable take such action as may be necessary to
       amend or supplement such registration statement or prospectus in order
       to set forth or reflect such event or state of facts and provide copies
       of such proposed amendment or supplement to the Laidlaw Parties.

              (c)    On or before the date on which the registration statement
       is declared effective, or a receipt is issued by all Commissions for the
       (final) prospectus, Allied shall use its reasonable efforts to:

                     (i)    register or qualify (and cooperate with each
              Selling Laidlaw Party, the underwriter or underwriters, if any,
              and their counsel, in connection with the registration or
              qualification of) the securities covered by the registration
              statement for offer and sale under the securities or blue sky
              laws of each state and other U.S. or Canadian jurisdiction as any
              Selling Laidlaw Party or underwriter reasonably requests;

                     (ii)   use its reasonable efforts to keep each such
              registration or qualification effective, including through new
              filings, or amendments or renewals, during the period the
              registration statement or prospectus is required to be kept
              effective; and

                     (iii)  do any and all other acts or things necessary or
              advisable to enable the disposition in all such jurisdictions of
              the Common Stock covered by the applicable registration statement
              or prospectus, provided that Allied will not be required to
              qualify





                                       10
<PAGE>   199
              generally to do business in any jurisdiction where it is not then
              so qualified.

              (d)    Allied shall use its reasonable efforts to cause all
       Registrable Securities of a Selling Laidlaw Party included in the
       registration statement or qualified by prospectus to be listed, by the
       date of the first sale of such shares pursuant to such registration
       statement or prospectus, on each securities exchange on which the
       securities is then listed or proposed to be listed, if any.

              (e)    Allied shall make generally available to each Selling
       Laidlaw Party and any underwriter participating in the offering
       conducted pursuant to the registration statement an earnings statement
       satisfying Section 11(a) of the Securities Act no later than 45 days
       after the end of the 12-month period beginning with the first day of
       Allied's first fiscal quarter commencing after the effective date of the
       registration statement.  The earnings statement shall cover such
       12-month period.  This requirement will be deemed to be satisfied if
       Allied timely files complete and accurate information on Forms 10-Q,
       10-K, and 8-K under the Exchange Act, and otherwise complies with Rule
       158 under the Securities Act as soon as feasible.  In addition, in the
       event that Allied shall have become a reporting issuer (or have the
       corresponding status) under any of the Canadian Securities Acts, Allied
       shall comply with the continuous disclosure obligations of a reporting
       issuer (or the obligations attendant upon such corresponding status)
       prescribed by each Canadian Securities Act under which it has such
       status.

              (f)    Allied shall cooperate with each Selling Laidlaw Party and
       the managing underwriter or underwriters, if any, to facilitate the
       timely preparation and delivery of certificates (not bearing any
       restrictive legends) representing Registrable Securities to be sold
       under the registration statement or prospectus, and to enable such
       securities to be in such denominations and registered in such names as
       the managing underwriter or underwriters, if any, or the Selling Laidlaw
       Party, may request, subject to the underwriters' obligation to return
       any certificates representing unsold securities.

              (g)    Allied shall use its reasonable efforts to cause
       Registrable Securities covered by the registration statement or
       prospectus to be registered with or approved by such other governmental
       agencies or authorities in the U.S. or Canada (including the
       registration of Registrable Securities under the Exchange Act) as may be
       necessary to enable the Selling Laidlaw Parties or the underwriter or
       underwriters, if any, to consummate the disposition of such securities.





                                       11
<PAGE>   200
              (h)    Allied shall, during normal business hours and upon
       reasonable notice, make available for inspection by each Selling Laidlaw
       Party, any underwriter participating in any offering pursuant to the
       registration statement or prospectus, and any attorney, accountant or
       other agent retained by a Selling Laidlaw Party or any such underwriter
       (collectively, the "Inspectors"), all nonconfidential financial and
       other records, pertinent corporate documents, and properties of Allied,
       as shall be reasonably necessary to enable the Inspectors to exercise
       their due diligence responsibilities and as they may reasonably consider
       to be necessary for the purpose of establishing their due diligence
       defense (as applicable) as contemplated by the Canadian Securities Acts
       and in order to enable any such underwriters to execute the certificate
       on any prospectus required pursuant to any Canadian Securities Acts to
       be executed by them.  Allied shall also cause its officers, directors,
       and employees to supply all nonconfidential information reasonably
       requested by any Inspector in connection with the registration
       statement.

              (i)    Allied shall use its reasonable efforts to obtain a "cold
       comfort" letter and, as applicable, a "long-form comfort letter" from
       Allied's independent public accountants, and an opinion of counsel for
       Allied, each in customary form and covering such matters of the type
       customarily covered by cold comfort letters and long form comfort
       letters and legal opinions in connection with public offerings of
       securities, as the Selling Laidlaw Party reasonably requests, and
       consents from all parties from whom such consents would be required
       under the applicable Canadian Securities Acts.

              (j)    Upon any public distribution of Allied Warrants (as
       defined in the Purchase Agreement), Allied (i) shall make such changes
       to the Allied Warrants as are reasonably necessary to effect such public
       distribution and (ii) shall file a U.S. registration statement covering
       the continuous offering of the Allied Warrant Shares pursuant to the
       Allied Warrants.


                                  ARTICLE III

                                INDEMNIFICATION

       3.1.   Indemnification by Allied.  In the event of any registration or
qualification under the Securities Act or any Canadian Securities Act by any
registration agreement or prospectus pursuant to rights herein granted of
Registrable Securities held by a Laidlaw Party who becomes a Selling Laidlaw
Party, Allied will hold harmless such Selling Laidlaw Party and each
underwriter of such securities and each other person, if any, who controls such
Selling Laidlaw Party or such underwriter within the meaning of the Securities
Act, against any losses, claims,





                                       12
<PAGE>   201
damages, or liabilities (including legal fees and costs of court), joint or
several, to which such Selling Laidlaw Party or such underwriter or controlling
person may become subject under the Securities Act, the applicable Canadian
Securities Acts or otherwise, insofar as such losses, claims, damages, or
liabilities (or any actions in respect thereof) arise out of or are based upon
any untrue statement or alleged untrue statement of any material fact
contained, on its effective date, in any registration statement under which
such securities were registered under the Securities Act, or in any related
preliminary or (final) prospectus, or in any preliminary prospectus or (final)
prospectus under which such securities were qualified for distribution under
any Canadian Securities Act, or any amendment or supplement to any of the
foregoing, or which arise out of or are based upon the omission or alleged
omission to state a material fact required to be stated therein or necessary to
make the statements therein not misleading; and will reimburse such Selling
Laidlaw Party and each such underwriter and each such controlling person for
any legal or any other expenses reasonably incurred by them in connection with
investigating or defending any such loss, claim, damage, or liability;
provided, however, that Allied shall not be liable to such Selling Laidlaw
Party or its underwriters or controlling persons in any such case to the extent
that any such loss, claim, damage, or liability arises out of or is based upon
an untrue statement or alleged untrue statement or omission or alleged omission
made in such registration statement, preliminary or (final) prospectus, or such
amendment or supplement, in reliance upon and in conformity with information
furnished to Allied through a written instrument duly executed by such Selling
Laidlaw Party or such underwriter specifically for use in the preparation
thereof or results from any improper conduct of such Selling Laidlaw Party or
any such underwriter or controlling person.

       3.2.   Indemnification by Selling Laidlaw Parties.  It shall be a
condition precedent to the obligation of Allied to include in any registration
statement or to qualify by prospectus any Registrable Securities of a Selling
Laidlaw Party that Allied shall have received from such Selling Laidlaw Party
an undertaking, reasonably satisfactory to Allied and its counsel, to indemnify
and hold harmless (in the same manner and to the same extent as set forth in
Section 3.1) Allied, each director of Allied, each officer of Allied who shall
sign the registration statement or prospectus, and any person who controls
Allied within the meaning of the Securities Act, (i) with respect to any
statement or omission from such registration statement, any related preliminary
or (final) prospectus, or any amendment or supplement to it, if such statement
or omission was made in reliance upon and in conformity with information
furnished to Allied through a written instrument duly executed by such Selling
Laidlaw Party specifically for use in the preparation of such registration
statement, preliminary or (final) prospectus, or amendment or supplement, and
(ii) with respect to compliance by such Selling Laidlaw Party with applicable
laws in effecting the sale or other disposition of the securities covered by
such registration statement.





                                       13
<PAGE>   202
       3.3.   Indemnification Procedures.  Promptly after receipt by an
indemnified party of notice of the commencement of any action involving a claim
referred to in the preceding Sections of this Article III, the indemnified
party will, if a resulting claim is to be made or may be made against an
indemnifying party, give written notice to the indemnifying party of the
commencement of the action.  If any such action is brought against an
indemnified party, the indemnifying party will be entitled to participate in
and to assume the defense of the action with counsel reasonably satisfactory to
the indemnified party, and after notice from the indemnifying party to such
indemnified party of its election to assume defense of the action, the
indemnifying party will not be liable to such indemnified party for any legal
or other expenses incurred by the latter in connection with the action's
defense. An indemnified party shall have the right to employ separate counsel
in any action or proceeding and participate in the defense thereof, but the
fees and expenses of such counsel shall be at such indemnified party's expense
unless (a) the employment of such counsel has been specifically authorized in
writing by the indemnifying party, which authorization shall not be
unreasonably withheld, (ii) the indemnifying party has not assumed the defense
and employed counsel reasonably satisfactory to the indemnified party within 30
days after notice of any such action or proceeding, or (iii) the named parties
to any such action or proceeding (including any impleaded parties) include the
indemnified party and the indemnifying party and the indemnified party shall
have been advised by such counsel that there may be one or more legal defenses
available to the indemnified party that are different from or additional to
those available to the indemnifying party (in which case the indemnifying party
shall not have the right to assume the defense of such action or proceeding on
behalf of the indemnified party), it being understood, however, that the
indemnifying party shall not, in connection with any one such action or
separate but substantially similar or related actions in the same jurisdiction
arising out of the same general allegations or circumstances, be liable for the
reasonable fees and expenses of more than one separate firm of attorneys (in
addition to all local counsel which is necessary, in the good faith opinion of
both counsel for the indemnifying party and counsel for the indemnified party
in order to adequately represent the indemnified parties) for the indemnified
party and that all such fees and expenses shall be reimbursed as they are
incurred upon written request and presentation of invoices.  Whether or not a
defense is assumed by the indemnifying party, the indemnifying party will not
be subject to any liability for any settlement made without its consent.  No
indemnifying party will consent to entry of any judgment or enter into any
settlement which does not include as an unconditional term the giving by the
claimant or plaintiff, to the indemnified party, of a release from all
liability in respect of such claim or litigation.

       3.4.   Contribution.  If the indemnification required by this Article
III from the indemnifying party is unavailable to or insufficient to hold
harmless an indemnified party in respect of any indemnifiable losses, claims,
damages, liabilities,





                                       14
<PAGE>   203
or expenses, then the indemnifying party shall contribute to the amount paid or
payable by the indemnified party as a result of such losses, claims, damages,
liabilities, or expenses in such proportion as is appropriate to reflect (i)
the relative benefit of the indemnifying and indemnified parties and (ii) if
the allocation in clause (i) is not permitted by applicable law, in such
proportion as is appropriate to reflect the relative benefit referred to in
clause (i) and also the relative fault of the indemnified and indemnifying
parties, in connection with the actions which resulted in such losses, claims,
damages, liabilities, or expenses, as well as any other relevant equitable
considerations.  The relative fault of the indemnifying party and the
indemnified party shall be determined by reference to, among other things,
whether any action in question, including any untrue or alleged untrue
statement of a material fact, has been made by, or relates to information
supplied by, such indemnifying party or parties, and the parties' relative
intent, knowledge, access to information, and opportunity to correct or prevent
such action.  The amount paid or payable by a party as a result of the losses,
claims, damage, liabilities, and expenses referred to above shall be deemed to
include any legal or other fees or expenses reasonably incurred by such party
in connection with any investigation or proceeding.  Allied and the Laidlaw
Parties agree that it would not be just and equitable if contribution pursuant
to this Section 3.4 were determined by pro rata allocation or by any other
method of allocation which does not take account of the equitable
considerations referred to in the prior provisions of this Section 3.4.

       Notwithstanding the provisions of this Section 3.4, no indemnifying
party shall be required to contribute any amount in excess of the amount by
which the total price at which the securities were offered to the public by the
indemnifying party exceeds the amount of any damages which the indemnifying
party has otherwise been required to pay by reason of an untrue statement or
omission.  No person guilty of fraudulent misrepresentation (within the meaning
of Section 11(f) of the Securities Act or the Criminal Code (Canada)) shall be
entitled to contribution from any person who was not guilty of such a
fraudulent misrepresentation.


                                   ARTICLE IV

                                OTHER AGREEMENTS

       4.1.   Other Registration Rights.  Allied agrees that it will not grant
to any party registration rights which would allow such party to limit
Laidlaw's priority for the sale or distribution of Registrable Securities upon
the exercise of a mandatory registration right pursuant to Section 2.2.

       4.2.   Expenses.  All expenses incurred by Allied in connection with any
U.S. registration statement covering Registrable Securities offered by a
Laidlaw





                                       15
<PAGE>   204
Party, including, without limitation, all registration and filing fees
(including all expenses incident to filing with the National Association of
Securities Dealers, Inc.), printing expenses, fees and disbursements of counsel
(except for the fees and disbursements of counsel for such Laidlaw Party) and
of the independent certified public accountants (except, in the case of any
special audits, if required in connection with any such registration, such
Laidlaw Party's proportionate share of their expense as provided in Section
2.4), and the expense of qualifying such shares under state blue sky laws,
shall be borne by Allied; provided, however, that Allied shall not be required
to pay for any expenses of any registration proceeding begun pursuant to
Section 2.2 if the registration request is subsequently withdrawn at the
request of a Laidlaw Party (in which case such Laidlaw Party shall bear such
expenses), unless the Laidlaw Parties agree to forfeit their right to one
demand registration pursuant to Section 2.2; provided further, however, that if
at the time of such withdrawal, such Laidlaw Party has learned of a material
adverse change in the condition, business, or prospects of the Allied from that
known at the time of its request, then such Laidlaw Party shall not be required
to pay any of such expenses and shall retain its rights pursuant to Section
2.2.  Allied's obligations under this Section 4.1 shall apply to each
registration under the Securities Act or state blue sky legislation pursuant to
Section 2.2.  However, all underwriting expenses incurred by such Laidlaw
Party, including underwriter's discounts and commissions, shall be borne by
such Laidlaw Party.

       4.3.   Offering Expenses.  The Laidlaw Party selling any Registrable
Securities pursuant to any prospectus filed with any Commission in connection
with the satisfaction by Allied of its obligations under Section 2.2 shall
reimburse Allied for all Offering Expenses reasonably incurred by or on behalf
of Allied upon receipt by such Laidlaw Party of a written request from Allied
in respect of same, together with invoices outlining in reasonable detail the
expenses to be borne by the Laidlaw Party or Laidlaw Parties.  In addition, the
relevant Laidlaw Parties shall be responsible for any additional expenses
reasonably incurred by Allied as a result of such Laidlaw Parties'
participation in any offering proposed to be completed by Allied in any
Canadian jurisdiction as contemplated in Section 2.1 upon receipt by the
relevant Laidlaw Parties of a written request from Allied in respect of the
same, together with appropriate documentation outlining all expenses incurred
by Allied in respect of that distribution and the proportion of the same to be
borne by the relevant Laidlaw Parties, together with a brief explanation as to
the reasons why the expenses so charged to the Laidlaw Parties would not have
been incurred by Allied in the absence of the participation by the Laidlaw
Parties in that distribution.

       4.4.   Dispositions During Registration.  The Laidlaw Parties and their
Affiliates hereby agree that from the date of receipt of written notice (the
"Offering Notice") from Allied that Allied intends to file a registration
statement or prospectus (the "Offering Registration Statement") covering shares
of Common Stock or





                                       16
<PAGE>   205
securities convertible into or exercisable for Common Stock until the Offering
Termination Date (defined below), the Laidlaw Parties and their Affiliates will
not sell or otherwise dispose of any securities owned by such Laidlaw Party or
Affiliate except for Registrable Shares included in the Offering Registration
Statement.  As used herein, the "Offering Termination Date" shall occur on (i)
the lapse of 60 days from the date of receipt of the Offering Notice if the
Offering Registration Statement is not declared effective (or, if the Offering
Registration Statement is a (final) prospectus to be filed under any Canadian
Securities Act, a receipt is not issued therefor by the applicable Commissions)
before such lapse, (ii) the lapse of 180 days from the date of effectiveness of
the Offering Registration Statement (or, if the Offering Registration Statement
is a (final) prospectus to be filed under any Canadian Securities Act, the date
a receipt has been issued therefor by all applicable Commissions) if any
Registrable Shares are included in the Offering Registration Statement, or
(iii) the lapse of 90 days from the date of effectiveness of the Offering
Registration Statement (or, if the Offering Registration Statement is a (final)
prospectus to be filed under any Canadian Securities Act, the date a receipt
has been issued therefor by all applicable Commissions) if no Registrable
Shares are included in the Offering Registration Statement.

       4.5.   Transfer of Rights.  The incidental registration and
qualification rights or benefits of this Registration Agreement and no more
than one mandatory registration or qualification right, including
indemnification by Allied, shall be transferable by the Laidlaw Parties only
(i) in a transaction which is not a public offering or public distribution of
Common Stock or the Allied Warrant; (ii) if the transferee is not an Affiliate
of Laidlaw and (iii) if the transferee receives at least an aggregate of
2,000,000 shares of Common Stock or Warrants.  In the case of any assignment,
the party or parties who have the rights and benefits of an assigning Laidlaw
Party under this Registration Agreement shall become parties to and be subject
to this Registration Agreement, and shall not, as a group, have the right to
request any greater number of registrations or qualifications than the
assigning Laidlaw Party would have had if no assignment had occurred.  Upon any
transfer of the registration and qualification rights or benefits of this
Registration Agreement, the assigning Laidlaw Party shall give Allied written
notice prior to or promptly following such transfer stating the name and
address of the transferee and identifying the securities with respect to which
such rights are being assigned.  Such notice shall include or be accompanied by
a written undertaking by the transferee to comply with the obligations imposed
hereunder.  In the event any registration and qualification rights are
transferred in accordance with the terms hereof, any actions required to be
taken by the Laidlaw Parties will be taken with the approval of the holders of
such registration and qualification rights who hold a majority of the
Registrable Securities, whose actions shall bind all such holders of such
registration and qualification rights.





                                       17
<PAGE>   206
       4.6.   Termination of Registration Rights.  The Laidlaw Parties and
their permitted assigns shall be entitled to exercise any right provided for in
this Registration Agreement until six months after the twelfth anniversary of
the date of this Registration Agreement.

       4.7.   Multijurisdictional Disclosure System.  Nothing in this
Registration Agreement shall be construed to limit or restrict in any manner
whatsoever the ability of Allied to make use of the Multijurisdictional
Disclosure System (as set forth in National Policy No. 45 of the Canadian
Securities Administrators) with respect to the qualification, distribution or
sale in Canada of any securities of Allied, including pursuant to request made
pursuant to Section 2.1 or Section 2.2 hereof.


                                   ARTICLE V

                                 MISCELLANEOUS

       5.1.   Notices.  All notices or other communications which are required
or may be given under this Registration Agreement shall be in writing and shall
be deemed to have been duly given when delivered in person or transmitted by
telecopier (with receipt confirmed) to a party at the address or telecopy
number, as applicable, set forth below (as any such address or telecopier
number may be changed from time to time by notice similarly given):



              (a)    if to any Laidlaw Party, to:

                            Laidlaw Inc.
                            3221 North Service Road
                            Burlington, Ontario
                            Canada L7R 3Y8
                            Attention: Ivan R. Cairns
                            Telecopier No.: (905) 332-6550

              (b)    if to Allied, to:

                            Allied Waste Industries, Inc.
                            7201 East Camelback Road, Suite 375
                            Scottsdale, Arizona 85251
                            Attention: Roger A. Ramsey
                            Telecopier No.: (602) 481-9347






                                       18
<PAGE>   207

                            with a copy to:

                            Porter & Hedges, L.L.P.
                            700 Louisiana Street, 35th Floor
                            Houston, Texas 77002-2764
                            Attention: Robert G. Reedy
                            Telecopier No.: (713) 228-1331


       5.2.   Section Headings.  The article and section headings in this
Registration Agreement are for reference purposes only and shall not affect the
meaning or interpretation of this Registration Agreement.  References in this
Registration Agreement to a designated "Article" or "Section" refer to an
Article or Section of this Registration Agreement unless otherwise specifically
indicated.

       5.3.   Governing Law.  This Registration Agreement shall be construed
and enforced in accordance with and governed by the law of Delaware.

       5.4.   Amendments.  This Registration Agreement may be amended only by
an instrument in writing executed by all of its parties.

       5.5.   Entire Agreement.  This Registration Agreement constitutes the
entire agreement between its parties concerning its subject matter.

       5.6.   Severability.  The invalidity or unenforceability of any specific
provision of this Registration Agreement shall not invalidate or render
unenforceable any of its other provisions.  Any provision of this Registration
Agreement held invalid or unenforceable shall be deemed reformed, if
practicable, to the extent necessary to render it valid and enforceable and to
the extent permitted by law and consistent with the intent of the parties to
this Registration Agreement.

       5.7.   Counterparts.  This Registration Agreement may be executed in
multiple counterparts, each of which shall be deemed an original, but all of
which together shall constitute the same instrument.





                                       19
<PAGE>   208
       IN WITNESS WHEREOF, the Parties have executed this Registration
Agreement as of the date first above written.




                                           ALLIED WASTE INDUSTRIES, INC.


                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------


                                           LAIDLAW INC.


                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------


                                           LAIDLAW TRANSPORTATION, INC.


                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------





                                       20
<PAGE>   209
                                                                       EXHIBIT F



                      WASTE SERVICES MANAGEMENT AGREEMENT


       This WASTE SERVICES MANAGEMENT AGREEMENT (the "Agreement") is executed
and delivered as of the ___ day of _________, 199_; by and between LAIDLAW
INC., a Canadian corporation ("SELLER"), LAIDLAW ENVIRONMENTAL SERVICES, LTD.,
an Ontario corporation ("LESL"), LAIDLAW ENVIRONMENTAL SERVICES, INC., a
Delaware Corporation ("LESI") and ALLIED WASTE INDUSTRIES, INC., a Delaware
corporation ("COMPANY").

                                   RECITALS:

       WHEREAS, Seller operates a Solid Waste (as defined below) collection,
transportation and disposal business (the "Seller's Business") located in the
United States of America and Canada.  Capitalized terms used herein and not
otherwise defined shall have the same meanings as set forth in the Purchase
Agreement.

       WHEREAS, the Company operates a Solid Waste collection, transportation,
recycling, processing, land farming, storing for transfer, and disposal
business (the "Company's business").

       WHEREAS, simultaneously with the execution and delivery of this
Agreement, Company is acquiring all of the assets of Seller used in the
Seller's Solid Waste Business (the "Acquisition") pursuant to a Stock Purchase
Agreement dated September 17, 1996 (the "Purchase Agreement") by and between
Seller and Company.
<PAGE>   210
       WHEREAS, the Company will sustain great loss and damage if, during the
term of this Agreement, for whatever reason, Seller should violate the
provisions of this Agreement.

       WHEREAS, the execution and delivery by Seller of this Agreement is a
condition to Company's obligation to consummate the Acquisition and Company is
unwilling to consummate the Acquisition unless Seller executes and delivers
this Agreement.

       NOW, THEREFORE, in consideration of the Purchase Agreement, the mutual
promises, terms, covenants and conditions set forth herein and other good and
valuable consideration, received to the full satisfaction of each of them, the
parties hereby agree as follows:

       1.     Definitions in this Agreement:

              HAZARDOUS WASTE:  means a waste, or combination of wastes, which
because of its quantity, concentration or physical, chemical or infectious
characteristics which has been identified, by characteristics or listing, as
hazardous pursuant to Section 3001 of the Resource Conservation and Recovery
Act of 1976, as amended ("RCRA").

              Potentially infectious medical waste is not a hazardous waste,
except for those potentially infectious medical wastes identified by
characteristics or listing as hazardous under Section 3001 of the RCRA.

              SOLID WASTE:  means any waste which can be lawfully disposed of
in a landfill regulated under Subtitle D of the RCRA.

       2.     Seller agrees that for a period of five years following the date
of Closing, it shall not directly or indirectly through a subsidiary without
the prior express written consent of Company:




                                      2
<PAGE>   211
              (a)(i)  engage, whether as a corporation on its own account, or
as a shareholder, owner, partner, joint venture, agent, independent contractor,
consultant or advisor, in the business of operating material recycling
facilities processing curbside waste pickup, or performing residential,
commercial and/or curbside Solid Waste collection, services in the United
States and Canada.

              (a)(ii)  Neither Seller nor any subsidiary thereof shall acquire
by purchase or otherwise, lease, or enter into an operating agreement to
operate a subtitle D landfill other than as presently owned, leased or operated
by Laidlaw Environmental Services as that term is defined under Subtitle D
(RCRA), subject to the provisions of paragraph 4(b) hereof.

              (b)    solicit or contact in any manner, directly or indirectly,
any person who is, at that time, within the Territory, an employee or the
Seller's business in a managerial capacity, for the purposes or with the intent
of enticing such employee away from or out of the employ of Company or its
subsidiaries;

              (c)    disclose the identity of the customers of Seller's
business at the date hereof, to any person, firm, partnership, corporation or
other entity whatsoever, for any reason or purpose whatsoever or

              (d)    promote or assist, financially or otherwise, any person,
firm, partnership, corporation or other entity whatsoever to do any of the
above.

              (e)    Notwithstanding the foregoing provisions of this Section
2, (1) the parties hereto agree that the foregoing covenant shall not be deemed
to prohibit Seller from acquiring, as an investment, not more than ten percent
of the capital stock of a competing business, the stock of which is traded on a
national securities exchange or over-the- counter; or, provided it





                                       3
<PAGE>   212
complies with paragraph 4(b); purchase a business which has a solid waste
operation, (2) Seller may continue to do business in the ordinary course as
presently constituted.

       3.     It is further agreed that LESL and LESI have received good
valuable consideration for entering into this agreement, shall execute this
agreement and remain bound to the covenants and terms hereof.  Should Seller
dispose of its interest in LESL and/or LESI to any arm's length third party,
LESL and LESI and their subsidiaries shall remain bound to the covenants and
terms hereof, but such provisions shall not extend to the Purchaser and its
other subsidiaries.

       4.     (a)    Seller agrees that this Agreement is a material and
substantial part of the Acquisition.  Consequently, on the date of the
Acquisition, Company shall acknowledge receipt of good and valuable
consideration for the noncompetition covenants contained in this Agreement.

              (b)    If LESL or LESI acquires a business which has a Solid
Waste operation, within 30 days of closing LESI or LESL shall serve a notice of
the acquisition to the Company and a written offer to sell said Solid Waste
operation at a specified price and terms.

              (c)    Within 30 days of receipt of the offer to sell from LESL
or LESI, Company will send a notice of its election to purchase the businesses
described in LESL or LESI's offer at the price and terms offered by LESL or
LESI.  If Company does not deliver said notice, LESL or LESI may only sell the
Solid Waste business at the offered or greater price and terms.  LESL or LESI
shall notify Company in writing of the amount and terms of a subsequent sale to
a third party.

       5.     Because the Company will sustain great loss and damage as a
result of the breach by Seller of the covenants in this Agreement, and because
of the immediate and irreparable





                                       4
<PAGE>   213
damage that would be caused to Company by such a breach for which it would have
no adequate remedy, since monetary damages alone may not be an adequate remedy,
Seller agrees that, in the event of a breach by Seller of the covenants in this
Agreement, such covenants may be enforced by Company by, without limitation,
injunctions and restraining orders.

       6.     It is agreed by the parties that the covenants in this Agreement
impose a reasonable restraint on Seller in light of the activities and business
of Company and Seller on the date of the execution of this Agreement and the
future plans of Company.

       7.     The covenants in this Agreement are severable and separate, and
the unenforceability of any specific covenant shall not affect the provisions
of any other covenant.  Moreover, in the event any court of competent
jurisdictions determines that the restrictions as set forth are unreasonable,
then it is the intention of the parties that such restrictions be enforced to
the fullest extent which the court deems reasonable, and the Agreement shall
thereby be reformed.

       8.     The covenants in this Agreements shall each be construed as
independent of any other provision of this Agreement and the Acquisition, and
the existence of any claim or cause of action of Seller against Company,
whether predicated on this Agreement, the Acquisition or otherwise, shall not
constitute a defense to the enforcement by Company of such covenants.

       9.     This Agreement is the final, complete and exclusive statement and
expression of the agreement among the parties hereto with relation to the
subject matter of this Agreement, it being understood that there are no oral
representations, understandings or agreements covering the same subject matter
and this Agreement.  This Agreement supersedes, and cannot be varied,





                                       5
<PAGE>   214
contradicted or supplemented by evidence of any prior or contemporaneous
discussions, correspondence, or oral or written agreements of any kind.

       10.    This Agreement, upon execution, shall be binding upon the
parties, enforceable in accordance with its terms and shall inure to the
benefit of the parties hereto and their respective successors and permitted
assigns.  This Agreement may be modified, altered or otherwise amended only by
a written instrument executed by all parties hereto, No right, remedy or
election given by any term of this Agreement shall be deemed exclusive but each
shall be cumulative with all other rights, remedies and elections available at
law or in equity.

       11.    All notice or other communications required or permitted
hereunder shall be in writing and may be given by depositing the same in the
United States mail, addressed to the party to be notified, postage prepaid and
registered or certified with return receipt requested, by overnight courier, by
facsimile transmission or by delivering the same in person to such entity.


              (a)    If to the Company, addressed to it at:
                     Allied Waste Industries, Inc.
                     7201 East Camelback
                     Scottsdale, Arizona 85251
                     ATTN:  Steve Helm

                     with a copy to:

                     Robert Reedy
                     Porter & Hedges, LLP
                     700 Louisiana, 35th Floor
                     Houston, TX  77002





                                       6
<PAGE>   215

              (b)    If to Seller, addressed to it at:

                     Laidlaw, Inc.; Laidlaw Environmental Services, Ltd. or
                            Laidlaw Environmental Services, Inc.
                     3221 North Service Road
                     P.O. Box 5028
                     Burlington, Ontario L7R 3Y8
                     ATTN:  Corporate Counsel


Notice shall be deemed given and effective the day personally delivered, the
day after being sent by overnight courier, the day transmitted by facsimile if
a business day and if not, on the next business day, and three days after
deposit in the U.S. mail of a writing addressed as above and sent first class
mail, certified, return receipt requested, or when actually received, if
earlier.  Either party may change the address for notice by notifying the other
party of such change in accordance with this Section 10.

       12.    This Agreement shall be construed in accordance with the laws of
the State of Delaware.





                                       7
<PAGE>   216
       IN WITNESS WHEREOF, the parties have hereunto set their hands as of the
day and year first above written.  

ALLIED WASTE INDUSTRIES, INC.



By:
   -------------------------------
Its:
    ------------------------------



LAIDLAW, INC.



By:
   -------------------------------
Its:
    ------------------------------




LAIDLAW ENVIRONMENTAL SERVICES, LTD.



By:
   -------------------------------
Its:
    ------------------------------




LAIDLAW ENVIRONMENTAL SERVICES, INC.



By:
   -------------------------------
Its:
    ------------------------------





                                       8
<PAGE>   217
                                                                       EXHIBIT G



                               RELEASE AGREEMENT


       Release Agreement dated as of _______________, 199_, by Laidlaw Inc., a
Canadian corporation ("Laidlaw"), Laidlaw Transportation, Inc., a Delaware
corporation and an indirect wholly owned subsidiary of Laidlaw ("LTI"), and
each of the Subsidiaries of Laidlaw, other than the Acquired Subsidiaries (the
"Retained Subsidiaries"), in favor of Allied Waste Industries, Inc., a Delaware
corporation ("Allied"), Allied Holdings (United States), Inc., a Delaware
corporation and a wholly owned subsidiary of Allied ("Allied U.S."), and
3294862 Canada Inc., a Canadian corporation and a wholly owned subsidiary of
Allied U.S. ("Allied Canada"), Laidlaw Waste Systems, Inc., a Delaware
corporation and a wholly owned subsidiary of Allied U.S. ("LWSI"), Laidlaw
Waste Systems (Canada), Ltd., a Canadian corporation and a wholly owned
subsidiary of Allied Canada ("LWSC"), Laidlaw Medical Services Ltd., a Canadian
corporation and a wholly owned subsidiary of Allied Canada ("LMS"), and the
Acquired Subsidiaries.

       WHEREAS, pursuant to the Stock Purchase Agreement dated September 17,
1996 (the "Stock Purchase Agreement"), among Allied, Allied U.S., Allied
Canada, Laidlaw, LTI, LWSI, LWSC and LMS, Allied, through the acquisition by
Allied U.S. of all of the issued and outstanding capital stock of LWSI and the
acquisition by Allied Canada of all of the issued and outstanding shares in the
share capital of each of LWSC and LMS, has acquired, simultaneously herewith,
all of the United States and Canadian solid waste management operations of
Laidlaw; and

       WHEREAS, pursuant to Section 3.3 (iv) of the Stock Purchase Agreement,
Laidlaw and LTI are to deliver this Release Agreement to Allied, Allied (U.S.),
and Allied Canada (collectively, the "Allied Parties") at the closing of the
transactions contemplated by the Stock Purchase Agreement;

       NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, Laidlaw and LTI agree as follows:

       1.     Definitions.  For purposes of this Release Agreement:

              "Acquired Subsidiaries" means (i) LWSI, (ii) the direct and
       indirect wholly owned Subsidiaries of LWSI listed and identified on the
       attached Schedule I, (iii) LWSC, (iv) the direct and indirect wholly
       owned Subsidiaries of LWSC listed and identified on the attached
       Schedule I, (v) LMS, and (vi) the 55% owned Subsidiary of LMS identified
       on the attached Schedule I, collectively.
<PAGE>   218
              "Affiliate" means a Person that directly, or indirectly through
       one or more intermediaries, controls, is controlled by or is under
       common control with another Person with the terms "control" and
       "controlled" meaning for purposes of this definition, the power to
       direct the management and policies of a Person, directly or indirectly,
       whether through the ownership of voting securities or partnership or
       other ownership interests, or by contract or otherwise.

              "Governmental Entity" means any U.S. or Canadian, state,
       territorial, federal, provincial, local or foreign court, executive
       office, legislature, governmental agency or ministry, commission, or
       administrative, regulatory or self-regulatory authority or
       instrumentality.

              "Person" means an individual, corporation, partnership,
       association, joint stock company, limited liability company,
       Governmental Entity, business trust, unincorporated organization, or
       other legal entity.

              "Subsidiary" of a Person means an Affiliate of that Person more
       than 50% of the aggregate voting power (or for any other form of voting
       equity interest in the case of a Person that is not a corporation) of
       which is beneficially owned by that Person directly or indirectly
       through one or more other Persons.

       2.     Release.  Except as provided in Section 3 below, Laidlaw, LTI and
each of the Retained Subsidiaries, jointly and severally, hereby forever
release and discharge each of the Acquired Subsidiaries and their respective
officers, directors, agents and employees, from any and all liabilities,
charges, actions, causes of action, suits, debts, sums of money and any other
claims whatsoever, in law or in equity, liquidated or unliquidated, fixed or
continent, which Laidlaw, LTI or any of the Retained Subsidiaries now have
against any or all of the Acquired Subsidiaries or hereafter shall have for,
upon or by reason of any matter, claim, cause of action, damage, liability,
cost, incident, state of facts or thing whatsoever, whether known or unknown,
which occurred or existed on or before the date of this Release Agreement.
Laidlaw, LTI and the Retained Subsidiaries hereby acknowledge and agree that
this Release Agreement is given to induce the Allied Parties to consummate the
transactions contemplated by the Stock Purchase Agreement and agree that the
terms of this Release Agreement may be enforced at any time and from time to
time by any of the Allied Parties or by any of the Acquired Subsidiaries.

       3.     Exception to Release.  The parties acknowledge and agree that the
release contained in Section 2 of this Release Agreement shall have no effect
upon the obligations of the Acquired Subsidiaries under the Intercompany Waste
Agreements (as such term is defined in the Stock Purchase Agreement) and under
Sections 11.12 and 12.4 (i) of the Stock Purchase Agreement.

       4.     Captions.  The captions, headings, and arrangements used in this
Release Agreement are for convenience only and are not to affect or modify the
terms of this Release Agreement.




                                      2
<PAGE>   219
       5.     Applicable Law.  This Release Agreement shall be governed by and
construed in accordance with the laws of Delaware and the laws of the United
States of America applicable to transactions within such state.

       EXECUTED as of the date first written above.

                                        LAIDLAW INC.                          
                                        LAIDLAW TRANSPORTATION, INC.           
                                        LAIDLAW CHEM-WASTE, INC.               
                                        LAIDLAW ENVIRONMENTAL SERVICES, INC.   
                                        LAIDLAW ENVIRONMENTAL SERVICES OF      
                                          ILLINOIS, INC.                       
                                        GSX CHEMICAL SERVICES OF OHIO, INC.    
                                        LAIDLAW ENVIRONMENTAL SERVICES         
                                          (BDT), INC.                          
                                        LAIDLAW ENVIRONMENTAL SERVICES (FS),   
                                        INC. LAIDLAW ENVIRONMENTAL SERVICES    
                                        (GS), INC. LAIDLAW ENVIRONMENTAL       
                                        SERVICES OF                            
                                          CHATTANOOGA, INC.                    
                                        LAIDLAW ENVIRONMENTAL SERVICES OF      
                                           WHITE CASTLE, INC.                  
                                        LAIDLAW ENVIRONMENTAL SERVICES         
                                           (RECOVERY), INC.                    
                                        LAIDLAW ENVIRONMENTAL SERVICES (TS),   
                                        INC.                                   
                                        LAIDLAW ENVIRONMENTAL SERVICES         
                                          (IMPERIAL VALLEY), INC.              
                                        LAIDLAW ENVIRONMENTAL SERVICES         
                                           (LOKERN), INC.                      
                                        LAIDLAW ENVIRONMENTAL SERVICES OF      
                                          CALIFORNIA, INC.                     
                                        LAIDLAW ENVIRONMENTAL SERVICES         
                                           (IMPERIAL VALLEY), INC.             
                                        LAIDLAW ENVIRONMENTAL SERVICES         
                                           (LOKERN), INC.                      
                                        LAIDLAW ENVIRONMENTAL SERVICES OF      
                                          SOUTH CAROLINA, INC.                 
                                        LAIDLAW ENVIRONMENTAL SERVICES (NORTH   
                                           EAST), INC.                         
                                        CORSAN TRUCKING, INC.                  
                                        LAIDLAW ENVIRONMENTAL SERVICES         
                                          (TES), INC.                          
                                        LAIDLAW CHEMICAL SERVICES, INC.        
                                        LAIDLAW ENVIRONMENTAL SERVICES         
                                          (TOC), INC.                      





                                      3
<PAGE>   220
                                                                                
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                          (TG), INC.                            
                                        REDOX, INC.                             
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                           (ALTAIR), INC.                       
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                          (FS), INC.                            
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                          (WT), INC.                            
                                        LAIDLAW ENVIRONMENTAL SERVICES OF       
                                          BARTOW, INC.                          
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                          (THERMAL TREATMENT), INC.             
                                        LEMC, INC.                              
                                        LAIDLAW OSCO HOLDINGS, INC.             
                                        BRYSON INDUSTRIAL SERVICES, INC.        
                                        OSCO TREATMENT SYSTEMS OF               
                                          MISSISSIPPI, INC.                     
                                        LAIDLAW ENVIRONMENTAL SERVICES OF       
                                           NASHVILLE, INC.                      
                                        OSCO ENVIRONMENTAL SERVICES, INC.       
                                        MASTER WASH PRODUCTS, INC.              
                                        USPCI CLIVE INCINERATION FACILITY, INC. 
                                        LAIDLAW ENVIRONMENTAL SERVICES LTD.     
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                          (SARNIA) LTD.                         
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                           (QUEBEC) LTD.                        
                                        LES ENTERPRISES D'INCINERATION          
                                          INDUSTRIELLE TRICIL INC.              
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                           (MERCIER) LTD.                       
                                        MASTER WASH PRODUCTS LIMITED            
                                        I.W.M. DISPOSAL INC.                    
                                        LARRY & IRWIN HOLDINGS LTD.             
                                        VINOCO OIL INC.                         
                                        B.V. MANUFACTURING LTD.                 
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                          (RYLEY) LTD.                          
                                        LAIDLAW ENVIRONMENTAL SERVICES          
                                          (ATLANTIC) LIMITED                    
                                        PPM CANADA, INC.                        

                                        By:                                    
                                           ------------------------------------
                                        Name:                                  
                                             ----------------------------------
                                        Title:                                 
                                              ---------------------------------





                                      4
<PAGE>   221
AGREED AND ACCEPTED:

ALLIED WASTE INDUSTRIES, INC.
3294862 CANADA INC.
3294854 CANADA INC.
LAIDLAW WASTE SYSTEMS, INC.
LAIDLAW WASTE SYSTEMS (CANADA), LTD.
LAIDLAW MEDICAL SERVICES LTD.
LAIDLAW WASTE SYSTEMS LTD.
LAIDLAW WASTE SYSTEMS (DURHAM) LTD.
LAIDLAW WASTE SYSTEMS (WARWICK) LTD.
635952 ONTARIO, INC.
TRICIL (N.Y.), INC.
LAIDLAW WASTE SYSTEMS HOLDINGS, INC.
LAIDLAW GAS RECOVERY CORPORATION, INC.
LAIDLAW GAS RECOVERY CORPORATION II, INC.
LAIDLAW GAS RECOVERY SYSTEMS, INC.
CATPAC TWO, INC.
LAIDLAW MEDICAL SYSTEMS, INC.
LAIDLAW WASTE SYSTEMS (ADRIAN) INC.
LAIDLAW WASTE SYSTEMS (BELLEFONTAINE) INC.
LAIDLAW WASTE SYSTEMS (BRIDGETON) INC.
LAIDLAW WASTE SYSTEMS (CELINA) INC.
LAIDLAW WASTE SYSTEMS (CHIQUITA) INC.
LAIDLAW WASTE SYSTEMS (COLORADO) INC.
LAIDLAW WASTE SYSTEMS (DALLAS) INC.
LAIDLAW WASTE SYSTEMS (FORT WORTH) INC.
LAIDLAW WASTE SYSTEMS (HOUSTON) INC.
LAIDLAW WASTE SYSTEMS (JEFFERSON CITY) INC.
LAIDLAW WASTE SYSTEMS (KANSAS CITY) INC.
LAIDLAW WASTE SYSTEMS (MADISON) INC.
LAIDLAW WASTE SYSTEMS (MICHIGAN) INC.
LAIDLAW WASTE SYSTEMS (OKLAHOMA CITY) INC.
LAIDLAW WASTE SYSTEMS (TEXAS) INC.
LAIDLAW WASTE SYSTEMS (VALLEY VIEW) INC.
WILLIAMS COUNTY LANDFILL, INC.
LAIDLAW WASTE SYSTEMS CANADA, LTD.
LAIDLAW ENERGY TECHNOLOGICS LTD.
BESTAN, INC.
LAIDLAW WASTE SYSTEMS (OTTAWA), LTD.
LAIDLAW WASTE SYSTEMS (RICHMOND), LTD.
LAIDLAW WASTE SYSTEMS (STORRINGTON), LTD.
2686848 CANADA, INC.
ENDWASTE, INC.
LAIDLAW GESTION DE REBUTS QUEBEC LTEE
DECHEX LTD.





                                      5
<PAGE>   222
CENTRE DE TRI TRANSIT
LOCATION SANICO
LAIDLAW MEDICAL SERVICES LTD.

By: 
    ----------------------------------
Name: 
     ---------------------------------
Title: 
      --------------------------------




                                      6
<PAGE>   223
                                                                   Schedule I to
                                                               Release Agreement


                        List of Acquired Subsidiaries


LAIDLAW WASTE SYSTEMS, INC. (DELAWARE)
       Laidlaw Waste Systems Ltd. (Canada)
              Laidlaw Waste Systems (Durham) Ltd. (Ontario)
              Laidlaw Waste Systems (Warwick) Ltd. (Ontario)
              635952 Ontario, Inc. (Ontario)
       Tricil (N.Y.), Inc. (New York)
       Laidlaw Waste Systems Holdings, Inc. (Delaware)
              Laidlaw Gas Recovery Corporation, Inc. (California)
              Laidlaw Gas Recovery Corporation II, Inc. (California)
              Laidlaw Gas Recovery Systems, Inc. (California)
                     CATPAC Two, Inc. (Delaware)
              Laidlaw Medical Systems, Inc. (Delaware)
              Laidlaw Waste Systems (Adrian) Inc. (Michigan)
              Laidlaw Waste Systems (Bellefontaine) Inc. (Ohio)
              Laidlaw Waste Systems (Bridgeton) Inc. (Missouri)
              Laidlaw Waste Systems (Celina) Inc. (Ohio)
              Laidlaw Waste Systems (Chiquita) Inc. (California)
              Laidlaw Waste Systems (Colorado) Inc. (Colorado)
              Laidlaw Waste Systems (Dallas) Inc. (Delaware)
              Laidlaw Waste Systems (Fort Worth) Inc. (Delaware)
              Laidlaw Waste Systems (Houston) Inc. (Delaware)
              Laidlaw Waste Systems (Jefferson City) Inc. (Missouri)
              Laidlaw Waste Systems (Kansas City) Inc. (Missouri)
              Laidlaw Waste Systems (Madison) Inc. (Illinois)
              Laidlaw Waste Systems (Michigan) Inc. (Delaware)
              Laidlaw Waste Systems (Oklahoma City) Inc. (Oklahoma)
              Laidlaw Waste Systems (Texas) Inc. (Texas)
              Laidlaw Waste Systems (Valley View) Inc. (Kentucky)
              Williams County Landfill, Inc. (Ohio)

LAIDLAW WASTE SYSTEMS CANADA, LTD. (CANADA)
       Laidlaw Energy Technologics Ltd. (Canada)
       Bestan, Inc. (Quebec)
       Laidlaw Waste Systems (Ottawa), Ltd. (Ontario)
       Laidlaw Waste Systems (Richmond), Ltd. (Canada)
       Laidlaw Waste Systems (Storrington), Ltd. (Canada)
       2686848 Canada, Inc. (Canada)
       Endwaste, Inc. (Ontario)





                                      1
<PAGE>   224
       Laidlaw Gestion de Rebuts Quebec Ltee (Canada)
              Dechex Lte (Quebec)
              Centre de Tri Transit (Quebec)
              Location Sanico (Quebec)

LAIDLAW MEDICAL SERVICES LTD. (CANADA)





                                      2
<PAGE>   225
                                                                     EXHIBIT H-1

                                    GUARANTY
                         [Allied Finance 7% Debenture]

         THIS GUARANTY (as amended or restated, this "Guaranty") dated as of
_____________ 199__, by Allied Waste Industries, Inc., a Delaware corporation
(the "Guarantor"), for the benefit of Laidlaw Inc., a Canadian corporation
("Laidlaw").

                              W I T N E S S E T H:

         WHEREAS, pursuant to the Stock Purchase Agreement dated as of
September 17, 1996 (the "Stock Purchase Agreement"), among the Guarantor,
Allied Holdings (United States), Inc., a Delaware corporation and a wholly
owned subsidiary of the Guarantor ("Allied U.S."), 3294862 Canada Inc., a
Canadian corporation and a wholly owned subsidiary of and Allied U.S. ("Allied
Canada"), and Laidlaw, Laidlaw Transportation, Inc., a Delaware corporation
("LTI"), Laidlaw Waste Systems, Inc., a Delaware corporation and a wholly owned
subsidiary of LTI ("LWSI"), Laidlaw Waste Systems (Canada), Ltd., a Canadian
corporation and a wholly owned subsidiary of Laidlaw ("LWSC"), and Laidlaw
Medical Services Ltd., a Canadian corporation and a wholly owned subsidiary of
Laidlaw ("LMS"), the Guarantor, through the acquisition by Allied U.S. of all
of the issued and outstanding capital stock of LWSI and the acquisition by
Allied Canada of all of the issued and outstanding shares in the share capital
of each of LWSC and LMS, has acquired, on the date hereof, all of the United
States and Canadian solid waste management operations of Laidlaw; and

         WHEREAS, as a portion of the consideration for the purchase by Allied
Canada of the LWSC Shares (as such term is defined in the Stock Purchase
Agreement), Allied Canada has issued its 7% Junior Subordinated Debenture due
200_ dated the date hereof (the "Allied Canada Debenture"), payable to Laidlaw
in the original principal amount of $150,000,000; and

         WHEREAS, pursuant to the Debenture Exchange Agreement dated the date
hereof between Allied Finance and Laidlaw, Allied Finance has issued its 7%
Junior Subordinated Debenture due 200__ dated the date hereof (the "Debenture")
payable to Laidlaw in the original principal amount of $150,000,000 in exchange
for the Allied Canada Debenture;

         WHEREAS, Laidlaw requires, as a condition precedent to its acceptance
of the Debenture, that the Guarantor execute and deliver this Guaranty to
Laidlaw; and

         WHEREAS, in the Guarantor's judgment, the consideration received and
to be received by it in connection with the issuance of the Debenture and this
Guaranty is reasonably worth at least as much as its liability and obligation
under this Guaranty, and such liability and obligation may reasonably be
expected to benefit the Guarantor directly or indirectly;

         NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the Guarantor hereby guarantees to Laidlaw the prompt payment at
maturity (by acceleration or otherwise), 
<PAGE>   226
and at all times thereafter, of the principal of, and all accrued interest on, 
the Debenture (the "Guaranteed Debt"), upon the following terms and conditions:

         1.      Definitions.

                 (a)      For purposes of this Guaranty:

                 "Affiliate" means, with respect to any Person, another Person
         that directly, or indirectly through one or more intermediaries,
         controls, is controlled by or is under common control with such Person
         with the term "control," including the terms "controlling" and
         "controlled," meaning for purposes of this definition, the power to
         direct the management and policies of a Person, directly or
         indirectly, whether through the ownership of voting securities or
         partnership or other ownership interests, or by contract or otherwise.

                 "Bankruptcy or Insolvency Proceeding" is defined in Subsection
         3(b) of this Guaranty.

                 "Blockage Period" means any period when a default or an event
         of default or an event which, with the giving of notice or the lapse
         of time or both, would constitute a default or an event of default has
         occurred and is continuing under the terms of the Credit Facility or
         the Senior Subordinated Debentures or under the terms of any agreement
         or instrument pursuant to which any other Designated Senior
         Indebtedness is created, issued, evidenced, secured or guaranteed.

                 "Credit Facility" means the Credit Agreement dated as of
         _____________, 199_, among Allied U.S., as borrower, the Guarantor,
         Goldman Sachs Credit Partners L.P., as syndication agent, Citibank,
         N.A., as documentation agent, Credit Suisse, as administrative agent,
         Goldman Sachs Credit Partners L.P., Citicorp USA, Inc. and Credit
         Suisse, as initial lenders, and the other financial institutions now
         or hereafter parties thereto (as the same may be renewed, amended,
         modified, extended, increased, refinanced, or otherwise supplemented
         from time to time).

                 "Debenture" is defined above.

                 "Designated Senior Indebtedness" means (i) the Senior
         Indebtedness incurred with respect to the Credit Facility, (ii) the
         Senior Indebtedness evidenced by the Senior Subordinated Debentures
         and (iii) any other Senior Indebtedness which is incurred pursuant to
         an agreement (or series of related agreements simultaneously entered
         into) providing for Indebtedness, or commitments to lend, of at least
         $10,000,000 at the time of determination and is specifically
         designated in the instrument evidencing such Senior Indebtedness or
         the agreement under which such Senior Indebtedness arises as
         "Designated Senior Indebtedness."





                                       2
<PAGE>   227
                 "$" means U.S. dollars, the lawful currency of the United 
         States of America.

                 "Financing Lease"  means any lease of property, real or
         personal, the obligations of the lessee in respect of which are
         required in accordance with generally accepted accounting principles
         to be capitalized on a balance sheet of the lessee.

                 "Governmental Entity" means any U.S. or Canadian, territorial,
         federal, state, provincial or local court, executive office,
         legislature, governmental agency, department, ministry, commission, or
         administrative, regulatory or self-regulatory authority or
         instrumentality.

                 "Guarantee" means with respect to any Person any obligation,
         contingent or otherwise, of such Person guaranteeing or having the
         economic effect of guaranteeing any Indebtedness of any other Person
         (the "primary obligor") in any manner, whether directly or indirectly,
         and including any obligation of such Person, direct or indirect, (a)
         to purchase or pay (or advance or supply funds for the purchase or
         payment of) such Indebtedness or to purchase (or to advance or supply
         funds for the purchase of) any security for the payment of such
         Indebtedness, (b) to purchase or lease property, securities or
         services for the purpose of assuring the owner of such Indebtedness of
         the payment of such Indebtedness or (c) to maintain working capital,
         equity capital or any other financial statement condition or liquidity
         of the primary obligor so as to enable the primary obligor to pay such
         Indebtedness; provided, however, that the term "Guarantee" shall not
         include endorsements for collection or deposit in the ordinary course
         of business.

                 "Guaranteed Debt" is defined above.

                 "Indebtedness" means with respect to any Person at any date,
         (a) all indebtedness of such Person for borrowed money or for the
         deferred purchase price of property or services (other than current
         trade liabilities incurred in the ordinary course of business and
         payable in accordance with customary practices), (b) any other
         indebtedness of such Person which is evidenced by a note, bond,
         debenture, letter of credit or similar instrument, (c) all obligations
         of such Persons with respect to Guarantees, (d) all obligations of
         such Person under Financing Leases, (e) all obligations of such Person
         in respect of acceptances issued or created for the account of such
         Person (other than endorsements in the ordinary course of business),
         (f) all obligations in respect of interest rate swaps or other
         interest rate hedging products or foreign currency exchange agreements
         or exchange rate hedging arrangements, (g) all obligations in respect
         of reimbursement obligations under letters of credit, and (h) all
         liabilities of the type referred to in clauses (a) through (g) above
         that are secured by any lien, charge, security interest or encumbrance
         on any property owned by such Person even though such Person has not
         assumed or otherwise become liable for the payment thereof.





                                       3
<PAGE>   228
                 "Indenture" means the Indenture dated _____________, 199_,
         between Allied U.S. and the Trustee pursuant to which the Senior
         Subordinated Debentures are issued.

                 "Person" means an individual, corporation, partnership,
         association, joint stock company, limited liability company,
         Governmental Entity, business trust, unincorporated organization, or
         other legal entity.

                 "Representative" means at any date, with respect to the Credit
         Facility, the Person or Persons then acting as the administrative
         agent under the Credit Facility, with respect to the Senior
         Subordinated Debentures, the Trustee, and with respect to any other
         Designated Senior Indebtedness, the holders of such Designated Senior
         Indebtedness or any Person acting as agent of such holders at such
         date.

                 "Senior Indebtedness" means principal of, and premium, if any,
         and interest on (including interest that, but for the filing of a
         petition initiating any Bankruptcy or Insolvency Proceeding, would
         accrue on such obligations at the rate provided in the agreements or
         instruments creating or evidencing the respective obligations, whether
         or not such claim is allowed or allowable in such Bankruptcy or
         Insolvency Proceeding) and all other amounts of every kind or nature
         (including, but not limited to, fees, indemnities and expenses) due on
         or in connection with any Indebtedness of the Guarantor, whether
         outstanding on the date of this Guaranty or thereafter created,
         incurred, assumed or Guaranteed by the Guarantor (including all
         renewals, extensions or refundings of, or amendments, modifications or
         supplements to, the foregoing) unless, in the case of any particular
         Indebtedness, the instrument creating or evidencing the same or
         pursuant to which the same is outstanding expressly provides that such
         Indebtedness shall not be senior in right of payment to this Guaranty.
         Without limiting the generality of the foregoing, "Senior
         Indebtedness" shall include (a) all obligations and liabilities of
         every kind and nature (including, but not limited to, fees, expenses
         and indemnities) under the Credit Facility, the Senior Subordinated
         Debentures or the Indenture, (b) all obligations and liabilities of
         every kind and nature (including, but not limited to, fees, expenses
         and indemnities) in respect of any interest rate swaps or other
         interest rate hedging product entered into in connection with
         Indebtedness incurred or to be incurred pursuant to the Credit
         Facility, and (c) any renewal, extension, refinancing or rearrangement
         of any Indebtedness incurred or to be incurred pursuant to the Credit
         Facility, the Senior Subordinated Debentures or the Indenture.
         Notwithstanding the foregoing, Senior Indebtedness shall not include
         (i) amounts owed (except to banks, insurance companies and other
         financing institutions and except for obligations under Financing
         Leases) for goods, materials, services or operating lease rental
         payments in the ordinary course of business or for compensation to
         employees of  the Guarantor, (ii) any liability for federal, state,
         provincial, local or other taxes owed or owing by the Guarantor and
         (iii) Indebtedness with respect to Allied Finance's Zero Coupon Junior
         Subordinated Debentures due 200__ dated the date hereof and the
         Guaranty thereof by the Guarantor.





                                       4
<PAGE>   229
                 "Senior Subordinated Debentures" means the ___% Senior
         Subordinated Debentures due 200__(1) in the aggregate original 
         principal amount of at least $475,000,000 issued by Allied U.S. 
         pursuant to the Indenture.

                 "Subordinated Obligations" is defined in Subsection 3(a).

                 "Subsidiary" of a Person means another Person more than 50% of
         the aggregate voting power (or of any other form of voting equity
         interest in the case of a Person that is not a corporation) of which
         is beneficially owned by that Person directly or indirectly through
         one or more other Subsidiaries.

                 "Trustee" means ________________________________, a national
         banking association, in its capacity as trustee under the Indenture,
         and its successors in such capacity.

         (b)     Capitalized terms defined in this Guaranty are equally
applicable to both their singular and plural forms.   References to a
designated "Section" or "Subsections" refer to a Section or Subsection of this
Guaranty unless otherwise specifically indicated.  In this Guaranty "including"
is used only to indicate examples, without limitation to the indicated
examples, and without limiting any generality which precedes it.

         2.      Nature of Guaranty.  Subject to the provision of Section 3 of
this Guaranty, the Guarantor agrees that (i) its obligations with regard to
this Guaranty shall be unconditional, irrespective of the validity, regularity
or enforceability of the Debenture, the absence of any action to enforce the
same, any delays in obtaining or realizing upon (or failures to obtain or
realize upon) collateral, the recovery of any judgment against the Company, any
action to enforce the same or any other circumstances that might otherwise
constitute a legal or equitable discharge or defense of a guarantor and (ii)
this Guaranty will not be discharged except by complete performance of the
obligations contained in the Debenture.  The Guarantor hereby waives diligence,
presentment, demand of payment, filing of claims with a court in the event of
insolvency or bankruptcy of Allied Finance, any right to require a proceeding
first against Allied Finance or right to require the prior disposition of the
assets of Allied Finance to meet its obligations, protest, notice and all
demands whatsoever and covenants that this Guaranty will not be discharged
except by complete performance of the obligations contained in the Debenture.
If Laidlaw is required by any court or otherwise to return to either Allied
Finance or any trustee or similar official acting with respect to Allied
Finance, any amount paid by Allied Finance to Laidlaw, this Guaranty, to the
extent theretofore discharged, shall be reinstated in full force and effect.
The Guarantor agrees that it will not be entitled to any right of subrogation
in relation to Laidlaw in respect of any obligations guaranteed hereby until
all such obligations have been paid in full in cash.  The Guarantor agrees
that, subject to





- -------------------
(1)  The due date of the Senior Subordinated Debentures will be 10 years after
     the date of issuance.

                                       5
<PAGE>   230
Section 3, (i) the maturity of the obligations guaranteed hereby may be
accelerated for the purposes of this Guaranty, notwithstanding any stay,
injunction or other prohibition preventing such acceleration as to Allied
Finance of the obligations guaranteed hereby, and (ii) in the event of any
declaration of acceleration of those obligations, those obligations (whether or
not due and payable) will forthwith become due and payable by the Guarantor for
the purpose of this Guaranty.

         3.      Subordination.

                 (a)      The indebtedness evidenced by, and all obligations in
         respect of, this Guaranty (collectively, the "Subordinated
         Obligations") are expressly subordinate to all Senior Indebtedness to
         the extent and in the manner set forth herein.  For purposes hereof,
         the term "subordinate" means that, unless and until the Senior
         Indebtedness has been indefeasibly paid in full in cash, Laidlaw will
         not take, demand, commence any suit or any other proceeding for
         collection, pursue any other judicial or non-judicial remedy or
         receive from the Guarantor or any of its Subsidiaries or Affiliates,
         and the Guarantor will not have the right under any circumstances to,
         and will not and will not permit any of its Subsidiaries or Affiliates
         to, make, give, or permit, directly or indirectly, by set-off,
         redemption, purchase or in any other manner, any payment of or on
         account of the Subordinated Obligations; provided, however, that at
         any time, the Guarantor may make, and Laidlaw may receive, and Laidlaw
         may commence any suit or other proceeding for collection of, payments
         of the Guaranteed Debt to the extent (but only to the extent) that at
         such time Allied Finance is permitted to pay the same pursuant to the
         provisions of Section 5 of the Debenture.  In no event shall the
         Guarantor be obligated to make, and the Guarantor shall not make, and
         shall not permit any of its Subsidiaries or Affiliates to make,
         directly or indirectly, by set-off, redemption, purchase or in any
         other manner, any payments or prepayments of, or on account of, any of
         the Subordinated Obligations during any Blockage Period or if such
         payment or prepayment would cause the occurrence of a Blockage Period.

                 (b)      Upon any payment or distribution of any kind or
         character to creditors of the Guarantor (whether in cash, property or
         securities) in (x) a total or partial liquidation, winding up or
         dissolution of the Guarantor (whether voluntarily or involuntarily) or
         (y) in a bankruptcy, reorganization, insolvency, receivership or
         similar proceeding relating to the Guarantor or its property, or in an
         assignment for the benefit of creditors or any marshaling of the
         Guarantor's assets and liabilities (any of the foregoing in clauses
         (x) and (y) being referred to herein as a "Bankruptcy or Insolvency
         Proceeding"), the holders of Senior Indebtedness will be entitled to
         receive payment in full in cash of all the principal of and interest
         on and other amounts payable in respect of such Senior Indebtedness
         (including interest accruing after the commencement of any such
         proceeding at the rate specified in the agreements or instruments
         creating or evidencing the  applicable Senior Indebtedness and whether
         or not such interest is an allowed or allowable claim under applicable
         law) before Laidlaw will be entitled to receive any payment with
         respect to this Guaranty (whether in cash,





                                       6
<PAGE>   231
         property or securities); and until all obligations with respect to
         Senior Indebtedness are indefeasibly paid in full in cash, any
         distribution received by Laidlaw or to which Laidlaw would be entitled
         shall be paid over or made to the holders of Senior Indebtedness.
         Upon the occurrence of any Bankruptcy or Insolvency Proceeding
         relating to the Guarantor, the holders of the Senior Indebtedness are
         authorized and empowered to (i) demand, sue for, collect and receive
         every payment or distribution on account of the Subordinated
         Obligations payable or deliverable in connection with such event or
         proceeding and give acquittance therefor, and (ii) file claims and
         proofs of claim in any statutory or non-statutory proceeding and take
         such other actions as may be necessary or desirable for the
         enforcement of the subordination provisions of this Guaranty.
         Promptly after taking any action provided in clauses (i) and (ii)
         above, the holders of Senior Indebtedness taking such action shall
         give written notice thereof to the holder of this Debenture; provided,
         however that failure to give such notice shall in no event affect the
         validity of any action so taken.

                 (c)      In the event that, notwithstanding the occurrence of
         any of the events described in Subsections 3(a) and (b), any such
         payment or distribution of assets of the Guarantor of any kind or
         character, whether in cash, property or securities, shall be received
         by the holder of this Guaranty which is not permitted hereby, such
         payment or distribution shall be held in trust for the ratable benefit
         of, and shall be paid over or delivered to, the holders of the Senior
         Indebtedness.

                 (d)      The holders of the Senior Indebtedness shall have no
         duty or obligation to Laidlaw in any manner whatsoever and may, at any
         time and from time to time, in their sole discretion, without the
         consent of or notice to Laidlaw and without impairing or releasing any
         rights of the holders of the Senior Indebtedness or any of the
         obligations of the holder of this Guaranty hereunder, take any or all
         of the following actions:

                          (i)     change the amount, manner, place, terms of
                 payment or interest rate, change or extend the time of payment
                 of, or renew or alter, any of the Senior Indebtedness, or
                 amend or supplement or waive any of the terms of any
                 instrument or agreement now or hereafter executed pursuant to
                 which any of the Senior Indebtedness is issued or incurred;

                          (ii)    sell, exchange, release, surrender, relend,
                 realize upon or otherwise deal with in any manner and in any
                 order, any property (or the income, revenues, profits or
                 proceeds therefrom) by whomsoever at any time pledged or
                 mortgaged to secure, or howsoever securing, any Senior
                 Indebtedness;

                          (iii)   release any person liable in any manner for
                 the payment or collection of the Senior Indebtedness;





                                      7
<PAGE>   232
                          (iv)    exercise or refrain from exercising any
                 rights and remedies against Allied Finance, the Guarantor or
                 others, or otherwise act or refrain from acting or, for any
                 reason, fail to file, record or otherwise perfect any security
                 interest in or lien on any property of Allied Finance, the
                 Guarantor or any other Person; and

                          (v)     apply any sums received by the holders of the
                 Senior Indebtedness, by whomsoever paid and however realized,
                 to payment of the Senior Indebtedness in such manner as the
                 holders of the Senior Indebtedness, in their sole discretion,
                 may deem appropriate.

                 (e)      Laidlaw and any future holder of this Guaranty, by
         acceptance of this Guaranty, agree to provide to any holder of Senior
         Indebtedness, at any time and from time to time, upon the written
         request of the Guarantor or such holder of Senior Indebtedness, an
         agreement signed by Laidlaw or such future holder of this Guaranty
         addressed to the holder of such Senior Indebtedness in substantially
         the form of, and on substantially the terms set out in, Exhibit A
         hereto to the effect that such Person is a holder of Senior
         Indebtedness, that the holder or holders of such Senior Indebtedness
         are entitled to the benefits of Sections 3 and 4 of this Guaranty and
         that the holder or holders of such Senior Indebtedness may enforce the
         terms and provisions thereof to the same extent the Guarantor would be
         able to do so, provided, however, that prior to furnishing such
         agreement, Laidlaw has received from the Guarantor or such holder such
         information as Laidlaw may reasonably request demonstrating to
         Laidlaw' reasonable satisfaction that such Person is a holder of
         Senior Indebtedness.  Laidlaw, and each subsequent holder of this
         Guaranty, by acceptance of this Guaranty, irrevocably appoint the
         Guarantor (with full power of substitution) as its agent and attorney
         in fact (which appointment is coupled with an interest and shall be
         irrevocable so long as any Senior Indebtedness is outstanding) to
         execute and deliver on behalf and in the name of Laidlaw or such
         holder, as the case may be, an agreement in substantially the form of,
         and on substantially the terms set out in, Exhibit A hereto in favor
         of each such holder of Senior Indebtedness and to take such further
         action as may be necessary or appropriate to effectuate the
         subordination as provided herein.  Promptly after exercise of any such
         power, Allied Finance will give written notice thereof to the holder
         of the Debenture; provided, however, that failure to give such notice
         shall in no event affect the validity of any power so exercised.

                 (f)      Until all Senior Indebtedness has been paid in full
         in cash, the holder of this Guaranty shall not be entitled to assert,
         enforce or otherwise exercise any right of subrogation against the
         Guarantor or any other Person obligated on the Subordinated
         Obligations.  After all Senior Indebtedness has been indefeasibly paid
         in full in cash, and until the Subordinated Obligations have been so
         paid in full, the holder of this Guaranty shall be subrogated to the
         rights of holders of Senior Indebtedness to receive distributions
         applicable to Senior Indebtedness.  A distribution made under this
         Section 3 to holders of Senior Indebtedness which otherwise would have
         been made to the





                                       8
<PAGE>   233
         holder of this Guaranty is not, as between the Guarantor and the
         holder of this Guaranty, a payment by the Guarantor on Senior
         Indebtedness.

                 (g)      This Section 3 defines the relative rights of the
         holder of this Guaranty and holders of Senior Indebtedness.  Nothing
         in this Guaranty shall:

                          (i)     impair, as between the Guarantor and the
                 holder of this Guaranty, the obligation of the Guarantor,
                 which is absolute and unconditional, to pay the Guaranteed
                 Debt in accordance with this Guaranty; or

                          (ii)    except as otherwise set forth in this Section
                 3, prevent the holder of this Guaranty from exercising its
                 available remedies hereunder, subject to the rights of holders
                 of Senior Indebtedness to receive distributions otherwise
                 payable to such holder.

         4.      No Impairment.  Section 3 and this Section 4 (and all defined
terms used in such sections) shall constitute a continuing offer to all Persons
who become holders of, or continue to hold, Senior Indebtedness, and such
provisions are made for the benefit of the holders from time to time of Senior
Indebtedness, and such Persons are conclusively presumed to have relied upon
such provisions; and such holders are made obligees hereunder, and they or each
of them may enforce such provisions.  No right of any present or future holder
of any Senior Indebtedness to enforce the subordination or other provisions
referred to in this Section 4 shall at any time in any way be prejudiced or
impaired by any act or failure to act on the part of the Guarantor or Laidlaw,
or by any non-compliance by the Guarantor or Laidlaw with the terms, provisions
and covenants of this Guaranty, regardless of any knowledge thereof any such
holder may have or otherwise be charged with.  Section 3, this Section 4 and
the subordination and other provisions referred to in this Section 4 may not be
amended or modified in any manner which might terminate or impair the
subordination or such other provisions except with the prior written consent of
the Representatives of all the Designated Senior Indebtedness.

         5.      Binding Agreement.  This Guaranty benefits Laidlaw and its
successors and permitted assigns and binds the Guarantor and its successors and
permitted assigns.  Sections 3 and 4 and the other subordination provisions
hereof bind the Guarantor and Laidlaw and their respective successors and
assigns.  The Guarantor acknowledges that the rights and benefits of this
Guaranty may be transferred with any permitted assignment of the Guaranteed
Debt.

         6.      Notices.  All notices or other communications which are
required or may be given under this Guaranty shall be in writing and shall be
deemed to have been duly given when delivered in person or transmitted by
telecopier (with receipt confirmed) at the address or telecopy number set forth
below (as any such address or telecopier number may be changed from time to
time by notice similarly given):





                                       9
<PAGE>   234
         (a)     if to Laidlaw, to:

                          Laidlaw Inc.
                          3221 North Service Road
                          Burlington, Ontario
                          Canada L7R 3Y8
                          Attention:  Ivan R. Cairns
                          Telecopy No.: (905) 332-6550

         (b)     if to the Guarantor, to:

                          Allied Waste Industries, Inc.
                          7201 East Camelback Road, Suite 375
                          Scottsdale, Arizona 85251
                          Attention: Roger A. Ramsey
                          Telecopy No.: (602) 481-9347

                          with a copy to:

                          Porter & Hedges, L.L.P.
                          700 Louisiana Street, Suite 3500
                          Houston, Texas 77002
                          Attention: Robert G. Reedy
                          Telecopy No.: (713) 228-1331





                                     10
<PAGE>   235
         7.      Applicable Law.    This Guaranty shall be governed by and
construed in accordance with the laws of the State of Delaware and the laws of
United States of America applicable therein (without reference to the conflicts
of law principles thereof).

         8.      OFFSET.    THE OBLIGATIONS OF ALLIED FINANCE HEREUNDER ARE, IN
ALL RESPECTS, SUBJECT TO OFFSET AS MORE FULLY SET FORTH IN THE OFFSET LETTER
AGREEMENT.  THE OFFSET RIGHTS SET FORTH IN THE OFFSET LETTER AGREEMENT SHALL BE
EFFECTIVE NOTWITHSTANDING THE ASSIGNMENT OR TRANSFER OF THIS DEBENTURE BY
LAIDLAW AND ANY TRANSFEREE SHALL TAKE THIS DEBENTURE SUBJECT TO THE TERMS
THEREOF.


                                       ALLIED WASTE INDUSTRIES, INC., a Delaware
                                         corporation
                                     
                                     
                                     
                                       By:                                      
                                           ------------------------------------
                                       Name:                                    
                                             ----------------------------------
                                       Title:                                   
                                              ---------------------------------


Agreed and Accepted:

Laidlaw INC., a Canadian corporation



By:                                                         
   ------------------------------------
Name:                                              
     ----------------------------------
Title:                                                      
      ---------------------------------





                                       11
<PAGE>   236
                                                                       EXHIBIT A
                                                       to the Guaranty Issued by
                          Allied Waste Industries, Inc. in favor of Laidlaw Inc.
                          ------------------------------------------------------


                                    [Date]



- --------------------

- --------------------

- --------------------



Gentlemen:

         Reference is made to the 7% Junior Subordinated Debenture Due 200__
dated __________, 199__ (the "Subordinated Debenture"), in the original
principal amount of $150 million issued by Allied Waste Finance (Canada), Ltd.,
a Canadian corporation ("Allied Finance"), in favor of Laidlaw Inc., a Canadian
corporation ("Laidlaw"), the Guaranty dated the date hereof (the "Guaranty"),
issued by Allied Waste Industries, Inc., a Delaware corporation (the
"Guarantor"), in favor of Laidlaw with respect to the obligations under the
Subordinated Debenture, and the [describe Senior Indebtedness] (the "Subject
Indebtedness"), being issued contemporaneously herewith by the Guarantor in
favor of [identity of holder or holders of Subject Indebtedness] (whether one
or more, the "Senior Creditor").  Hereinafter, capitalized words and phrases
used herein which are defined in the Guaranty are used herein as therein
defined.

         The undersigned (the "Subordinated Creditor") hereby represents and
warrants to the Senior Creditor that the Subordinated Creditor is the owner and
holder of the Subordinated Debenture and the Guaranty and that the Subordinated
Creditor is entitled to make the agreements herein contained.  The Subordinated
Creditor hereby acknowledges and agrees that the principal of, and premium, if
any, and interest on (including interest that, but for the filing of a petition
initiating any Bankruptcy or Insolvency Proceeding would accrue on such
obligations at the time provided in the agreements or instruments creating or
evidencing the respective obligations, whether or not such claim is allowed in
such Bankruptcy or Insolvency Proceeding) and all other amounts of every kind
or nature (including, but not limited to, fees, indemnities and expenses and
any interest rate swaps or other interest rate hedging products entered into in
connection with the Subject Indebtedness) due on or in connection with the
Subject Indebtedness, whether outstanding on the date hereof or hereafter
created, incurred or assumed, guaranteed or in effect guaranteed by the
Guarantor (including all renewals, extensions or refundings of, or amendments,
modifications or supplements to, the foregoing) are in all respects Senior
Indebtedness, that the Senior Creditor (and any other Person who from time to
time is a holder of the Subject Indebtedness) is entitled to the benefits of
Sections 3 and 4 of the Guaranty and that the Senior Creditor (and any other
Person who from time to 




                                      A-1
<PAGE>   237
time is a holder of the Subject Indebtedness) may enforce the terms and
provisions of Sections 3 and 4 of the Guaranty to the same extent that the
Guarantor or any other holder of Senior Indebtedness would be able to do so.

         The Subordinated Creditor hereby agrees that the Subordinated
Debenture and the Guaranty will not be sold, assigned, transferred, pledged or
hypothecated in any manner, directly or indirectly, by the Subordinated
Creditor, unless the assignee, transferee, pledgee or hypothecate has agreed in
writing to be bound by the provisions of this agreement.

         The Subordinated Creditor has executed this agreement in the space
provided below in order to induce the Senior Creditor to advance funds or
extend credit to the Guarantor, and this agreement is intended by the
Subordinated Creditor to be a binding and enforceable undertaking by the
Subordinated Creditor in favor of the Senior Creditor.

         The rights credited hereby of the Senior Creditor and of any
subsequent holder of the Senior Indebtedness will be assigned automatically,
and without any further act, by the Senior Creditor or such holder upon any
sale, assignment, conveyance or other transfer of all or any part of the Senior
Indebtedness to the extent of the interest sold, assigned, conveyed or
otherwise transferred, unless and to the extent the Senior Creditor or such
holder expressly provides otherwise in the instrument pursuant to which such
interest is conveyed.


                                                Very truly yours,               
                                                                                
                                                [NAME OF SUBORDINATED CREDITOR] 
                                                                                
                                                                                
                                                By:                            
                                                    ---------------------------
                                                Name:                          
                                                      -------------------------
                                                Title:                         
                                                       ------------------------


Accepted and agreed to as of
the date first above written:

[NAME OF SENIOR CREDITOR]


By:                                        
    ---------------------------------------
Name:                                      
     --------------------------------------
Title:                                             
       ------------------------------------





                                      A-2
<PAGE>   238






                                                                     EXHIBIT H-2


                                    GUARANTY
                     [Allied Finance Zero Coupon Debenture]

       THIS GUARANTY (as amended or restated, this "Guaranty") dated as of
_____________ 199__, by Allied Waste Industries, Inc., a Delaware corporation
(the "Guarantor"), for the benefit of Laidlaw Inc., a Canadian corporation
("Laidlaw").

                              W I T N E S S E T H:

       WHEREAS, pursuant to the Stock Purchase Agreement dated as of September
17, 1996 (the "Stock Purchase Agreement"), among the Guarantor, Allied Holdings
(United States), Inc., a Delaware corporation and a wholly owned subsidiary of
the Guarantor ("Allied U.S."), 3294862 Canada Inc., a Canadian corporation and
a wholly owned subsidiary of Allied U.S. ("Allied Canada"), and 3294854 Canada,
Inc., a Canadian corporation and a wholly owned subsidiary of the Guarantor
("Allied Finance"), and Laidlaw, Laidlaw Transportation, Inc. ("LTI"), Laidlaw
Waste Systems, Inc., a Delaware corporation and a wholly owned subsidiary of
LTI ("LWSI"), Laidlaw Waste Systems (Canada), Ltd., a Canadian corporation and
a wholly owned subsidiary of Laidlaw ("LWSC"), and Laidlaw Medical Services
Ltd., a Canadian corporation and a wholly owned subsidiary of Laidlaw ("LMS"),
the Guarantor, through the acquisition by Allied U.S. of all of the issued and
outstanding capital stock of LWSI and the acquisition by Allied Canada of all
of the issued and outstanding shares in the share capital of each of LWSC and
LMS, has acquired, on the date hereof, all of the United States and Canadian
solid waste management operations of Laidlaw; and

       WHEREAS, as a portion of the consideration for the purchase by Allied
Canada of the LWSC Shares (as such term is defined in the Stock Purchase
Agreement), Allied Canada has issued its Zero Coupon Junior Subordinated
Debenture due 200_ dated the date hereof (the "Allied Canada Debenture"),
payable to Laidlaw in the original principal amount of $168,300,000; and

       WHEREAS, pursuant to the Debenture Exchange Agreement dated the date
hereof between Allied Finance and Laidlaw, Allied Finance has issued its Zero
Coupon Junior Subordinated Debenture due 200__ dated the date hereof (the
"Debenture") payable to Laidlaw in the original principal amount of
$168,300,000 in exchange for the Allied Canada Debenture;

       WHEREAS, Laidlaw requires, as a condition precedent to its acceptance of
the Debenture, that the Guarantor execute and deliver this Guaranty to Laidlaw;
and

       WHEREAS, in the Guarantor's judgment, the consideration received and to
be received by it in connection with the issuance of the Debenture and this
Guaranty is reasonably worth at least as much as its liability and obligation
under this Guaranty, and such liability and obligation may reasonably be
expected to benefit the Guarantor directly or indirectly;

       NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the Guarantor

<PAGE>   239

hereby guarantees to Laidlaw the prompt payment at maturity (by acceleration or
otherwise), and at all times thereafter, of the principal of, and all accrued
interest on, the Debenture (the "Guaranteed Debt"), upon the following terms
and conditions:

       1.     Definitions.

              (a)    For purposes of this Guaranty:

              "Affiliate" means, with respect to any Person, another Person
       that directly, or indirectly through one or more intermediaries,
       controls, is controlled by or is under common control with such Person
       with the term "control," including the terms "controlling" and
       "controlled," meaning for purposes of this definition, the power to
       direct the management and policies of a Person, directly or indirectly,
       whether through the ownership of voting securities or partnership or
       other ownership interests, or by contract or otherwise.

              "Bankruptcy or Insolvency Proceeding" is defined in Subsection
3(b) of this Guaranty.

              "Blockage Period" means any period when a default or an event of
       default  or an event which, with the giving of notice or the lapse of
       time or both, would constitute a default or an event of default has
       occurred and is continuing under the terms of the Credit Facility or the
       Senior Subordinated Debentures or under the terms of any agreement or
       instrument pursuant to which any other Designated Senior Indebtedness is
       created, issued, evidenced, secured or guaranteed.

              "Credit Facility" means the Credit Agreement dated as of
       _____________, 199_, among Allied U.S., as borrower, the Guarantor,
       Goldman Sachs Credit Partners L.P., as syndication agent, Citibank,
       N.A., as documentation agent, Credit Suisse, as administrative agent,
       Goldman Sachs Credit Partners L.P., Citicorp USA, Inc. and Credit
       Suisse, as initial lenders, and the other financial institutions now or
       hereafter parties thereto (as the same may be renewed, amended,
       modified, extended, increased, refinanced, or otherwise supplemented
       from time to time).

              "Debenture" is defined above.

              "Designated Senior Indebtedness" means (i) the Senior
       Indebtedness incurred with respect to the Credit Facility, (ii) the
       Senior Indebtedness evidenced by the Senior Subordinated Debentures and
       (iii) any other Senior Indebtedness which is incurred pursuant to an
       agreement (or series of related agreements simultaneously entered into)
       providing for Indebtedness, or commitments to lend, of at least
       $10,000,000 at the time of determination and is specifically designated
       in the instrument evidencing such Senior Indebtedness or the agreement
       under which such Senior Indebtedness arises as "Designated Senior
       Indebtedness."





                                       2
<PAGE>   240
              "$" means U.S. dollars, the lawful currency of the United States
        of America.

              "Financing Lease"  means any lease of property, real or personal,
       the obligations of the lessee in respect of which are required in
       accordance with generally accepted accounting principles to be
       capitalized on a balance sheet of the lessee.

              "Governmental Entity" means any U.S. or Canadian, territorial,
       federal, state, provincial or local court, executive office,
       legislature, governmental agency, department, ministry, commission, or
       administrative, regulatory or self-regulatory authority or
       instrumentality.

              "Guarantee" means with respect to any Person any obligation,
       contingent or otherwise, of such Person guaranteeing or having the
       economic effect of guaranteeing any Indebtedness of any other Person
       (the "primary obligor") in any manner, whether directly or indirectly,
       and including any obligation of such Person, direct or indirect, (a) to
       purchase or pay (or advance or supply funds for the purchase or payment
       of ) such Indebtedness or to purchase (or to advance or supply funds for
       the purchase of) any security for the payment of such Indebtedness, (b)
       to purchase or lease property, securities or services for the purpose of
       assuring the owner of such Indebtedness of the payment of such
       Indebtedness or (c) to maintain working capital, equity capital or any
       other financial statement condition or liquidity of the primary obligor
       so as to enable the primary obligor to pay such Indebtedness; provided,
       however, that the term "Guarantee" shall not include endorsements for
       collection or deposit in the ordinary course of business.

              "Guaranteed Debt" is defined above.

              "Indebtedness" means with respect to any Person at any date, (a)
       all indebtedness of such Person for borrowed money or for the deferred
       purchase price of property or services (other than current trade
       liabilities incurred in the ordinary course of business and payable in
       accordance with customary practices), (b) any other indebtedness of such
       Person which is evidenced by a note, bond, debenture, letter of credit
       or similar instrument, (c) all obligations of such Persons with respect
       to Guarantees, (d) all obligations of such Person under Financing
       Leases, (e) all obligations of such Person in respect of acceptances
       issued or created for the account of such Person (other than
       endorsements in the ordinary course of business),  (f) all obligations
       in respect of interest rate swaps or other interest rate hedging
       products or foreign currency exchange agreements or exchange rate
       hedging arrangements, (g) all obligations in respect of reimbursement
       obligations under letters of credit, and (h) all liabilities of the type
       referred to in clauses (a) through (g) above that are secured by any
       lien, charge, security interest or encumbrance on any property owned by
       such Person even though such Person has not assumed or otherwise become
       liable for the payment thereof.





                                       3
<PAGE>   241
              "Indenture" means the Indenture dated _____________, 199_,
       between Allied U.S. and the Trustee pursuant to which the Senior
       Subordinated Debentures are issued.

              "Person" means an individual, corporation, partnership,
       association, joint stock company, limited liability company,
       Governmental Entity, business trust, unincorporated organization, or
       other legal entity.

              "Representative" means at any date, with respect to the Credit
       Facility, the Person or Persons then acting as the administrative agent
       under the Credit Facility, with respect to the Senior Subordinated
       Debentures, the Trustee, and with respect to any other Designated Senior
       Indebtedness, the holders of such Designated Senior Indebtedness or any
       Person acting as agent of such holders at such date.

              "Senior Indebtedness" means principal of, and premium, if any,
       and interest on (including interest that, but for the filing of a
       petition initiating any Bankruptcy or Insolvency Proceeding, would
       accrue on such obligations at the rate provided in the agreements or
       instruments creating or evidencing the respective obligations, whether
       or not such claim is allowed or allowable in such Bankruptcy or
       Insolvency Proceeding) and all other amounts of every kind or nature
       (including, but not limited to, fees, indemnities and expenses) due on
       or in connection with any Indebtedness of the Guarantor, whether
       outstanding on the date of this Guaranty or thereafter created,
       incurred, assumed or Guaranteed by the Guarantor (including all
       renewals, extensions or refundings of, or amendments, modifications or
       supplements to, the foregoing) unless, in the case of any particular
       Indebtedness, the instrument creating or evidencing the same or pursuant
       to which the same is outstanding expressly provides that such
       Indebtedness shall not be senior in right of payment to this Guaranty.
       Without limiting the generality of the foregoing, "Senior Indebtedness"
       shall include (a) all obligations and liabilities of every kind and
       nature (including, but not limited to, fees, expenses and indemnities)
       under the Credit Facility, the Senior Subordinated Debentures or the
       Indenture, (b) all obligations and liabilities of every kind and nature
       (including, but not limited to, fees, expenses and indemnities) in
       respect of any interest rate swaps or other interest rate hedging
       product entered into in connection with Indebtedness incurred or to be
       incurred pursuant to the Credit Facility, and (c) any renewal,
       extension, refinancing or rearrangement of any Indebtedness incurred or
       to be incurred pursuant to the Credit Facility, the Senior Subordinated
       Debentures or the Indenture. Notwithstanding the foregoing, Senior
       Indebtedness shall not include (i) amounts owed (except to banks,
       insurance companies and other financing institutions and except for
       obligations under Financing Leases) for goods, materials, services or
       operating lease rental payments in the ordinary course of business or
       for compensation to employees of  the Guarantor, (ii) any liability for
       federal, state, provincial, local or other taxes owed or owing by the
       Guarantor and (iii) Indebtedness with respect to Allied Finance's 7%
       Junior Subordinated Debentures due 200__ dated the date hereof and the
       Guaranty thereof by the Guarantor.





                                       4
<PAGE>   242
              "Senior Subordinated Debentures" means the ___% Senior
       Subordinated Debentures due 200__(1) in the aggregate original principal
       amount of at least $475,000,000 issued by Allied U.S. pursuant to the
       Indenture.

              "Subordinated Obligations" is defined in Subsection 3(a).

              "Subsidiary" of a Person means another Person more than 50% of
       the aggregate voting power (or of any other form of voting equity
       interest in the case of a Person that is not a corporation) of which is
       beneficially owned by that Person directly or indirectly through one or
       more other Subsidiaries.

              "Trustee" means ________________________________, a national
       banking association, in its capacity as trustee under the Indenture, and
       its successors in such capacity.

       (b)    Capitalized terms defined in this Guaranty are equally applicable
to both their singular and plural forms.  References to a designated "Section"
or "Subsections" refer to a Section or Subsection of this Guaranty unless
otherwise specifically indicated.  In this Guaranty "including" is used only to
indicate examples, without limitation to the indicated examples, and without
limiting any generality which precedes it.

       2.     Nature of Guaranty.  Subject to the provision of Section 3 of
this Guaranty, the Guarantor agrees that (i) its obligations with regard to
this Guaranty shall be unconditional, irrespective of the validity, regularity
or enforceability of the Debenture, the absence of any action to enforce the
same, any delays in obtaining or realizing upon (or failures to obtain or
realize upon) collateral, the recovery of any judgment against the Company, any
action to enforce the same or any other circumstances that might otherwise
constitute a legal or equitable discharge or defense of a guarantor and (ii)
this Guaranty will not be discharged except by complete performance of the
obligations contained in the Debenture.  The Guarantor hereby waives diligence,
presentment, demand of payment, filing of claims with a court in the event of
insolvency or bankruptcy of Allied Finance, any right to require a proceeding
first against Allied Finance or right to require the prior disposition of the
assets of Allied Finance to meet its obligations, protest, notice and all
demands whatsoever and covenants that this Guaranty will not be discharged
except by complete performance of the obligations contained in the Debenture.
If Laidlaw is required by any court or otherwise to return to either Allied
Finance or any trustee or similar official acting with respect to Allied
Finance, any amount paid by Allied Finance to Laidlaw, this Guaranty, to the
extent theretofore discharged, shall be reinstated in full force and effect.
The Guarantor agrees that it will not be entitled to any right of subrogation
in relation to Laidlaw in respect of any obligations guaranteed hereby until
all such obligations have been paid in full in cash.  The Guarantor agrees
that, subject to




- ------------------------
(1)  The due date of the Senior Subordinated Debentures will be 10
     years after the date of issuance.


                                       5
<PAGE>   243
Section 3, (i) the maturity of the obligations guaranteed hereby may be
accelerated for the purposes of this Guaranty, notwithstanding any stay,
injunction or other prohibition preventing such acceleration as to Allied
Finance of the obligations guaranteed hereby, and (ii) in the event of any
declaration of acceleration of those obligations, those obligations (whether or
not due and payable) will forthwith become due and payable by the Guarantor for
the purpose of this Guaranty.

       3.     Subordination.

              (a)    The indebtedness evidenced by, and all obligations in
       respect of, this Guaranty (collectively, the "Subordinated Obligations")
       are expressly subordinate to all Senior Indebtedness to the extent and
       in the manner set forth herein.  For purposes hereof, the term
       "subordinate" means that, unless and until the Senior Indebtedness has
       been indefeasibly paid in full in cash, Laidlaw will not have the right
       under any circumstance to, and will not, take, demand, commence any suit
       or any other proceeding for collection, pursue any other judicial or
       non-judicial remedy or receive from the Guarantor or any of its
       Subsidiaries or Affiliates, and the Guarantor will not and will  not
       permit any of its Subsidiaries or Affiliates to, make, give, or permit,
       directly or indirectly, by set-off, redemption, purchase or in any other
       manner, any payment of or on account of the Subordinated Obligations;
       provided, however, that at any time, the Guarantor may make, and Laidlaw
       may receive, and Laidlaw may commence any suit or other proceeding for
       collection of, payments of the Guaranteed Debt to the extent (but only
       to the extent) that at such time Allied Finance is permitted to pay the
       same pursuant to the provisions of Section 4 of the Debenture.  In no
       event shall the Guarantor be obligated to make, and the Guarantor shall
       not make, and shall not permit any of its Subsidiaries or Affiliates to
       make, directly or indirectly, by set-off, redemption, purchase or in any
       other manner, any payments or prepayments of, or on account of, any of
       the Subordinated Obligations during any Blockage Period or if such
       payment or prepayment would cause the occurrence of a Blockage Period.

              (b)    Upon any payment or distribution of any kind or character
       to creditors of the Guarantor (whether in cash, property or securities)
       in (x) a total or partial liquidation, winding up or dissolution of the
       Guarantor (whether voluntarily or involuntarily) or (y) in a bankruptcy,
       reorganization, insolvency, receivership or similar proceeding relating
       to the Guarantor or its property, or in an assignment for the benefit of
       creditors or any marshaling of the Guarantor's assets and liabilities
       (any of the foregoing in clauses (x) and (y) being referred to herein as
       a "Bankruptcy or Insolvency Proceeding"), the holders of Senior
       Indebtedness will be entitled to receive payment in full in cash of all
       the principal of and interest on and other amounts payable in respect of
       such Senior Indebtedness (including interest accruing after the
       commencement of any such proceeding at the rate specified in the
       agreements or instruments creating or evidencing the  applicable Senior
       Indebtedness and whether or not such interest is an allowed or allowable
       claim under applicable law) before Laidlaw will be entitled to receive
       any payment with respect to this Guaranty (whether in cash,





                                       6
<PAGE>   244
       property or securities); and until all obligations with respect to
       Senior Indebtedness are indefeasibly paid in full in cash, any
       distribution received by Laidlaw or to which Laidlaw would be entitled
       shall be paid over or made to the holders of Senior Indebtedness.  Upon
       the occurrence of any Bankruptcy or Insolvency Proceeding relating to
       the Guarantor, the holders of the Senior Indebtedness are authorized and
       empowered to (i) demand, sue for, collect and receive every payment or
       distribution on account of the Subordinated Obligations payable or
       deliverable in connection with such event or proceeding and give
       acquittance therefor, and (ii) file claims and proofs of claim in any
       statutory or non-statutory proceeding and take such other actions as may
       be necessary or desirable for the enforcement of the subordination
       provisions of this Guaranty.  Promptly after taking any action provided
       in clauses (i) and (ii) above, the holders of Senior Indebtedness taking
       such action shall give written notice thereof to the holder of this
       Debenture; provided, however that failure to give such notice shall in
       no event affect the validity of any action so taken.

              (c)    In the event that, notwithstanding the occurrence of any
       of the events described in Subsections 3(a) and (b), any such payment or
       distribution of assets of the Guarantor of any kind or character,
       whether in cash, property or securities, shall be received by the holder
       of this Guaranty which is not permitted hereby, such payment or
       distribution shall be held in trust for the ratable benefit of, and
       shall be paid over or delivered to, the holders of the Senior
       Indebtedness.

              (d)    The holders of the Senior Indebtedness shall have no duty
       or obligation to Laidlaw in any manner whatsoever and may, at any time
       and from time to time, in their sole discretion, without the consent of
       or notice to Laidlaw and without impairing or releasing any rights of
       the holders of the Senior Indebtedness or any of the obligations of the
       holder of this Guaranty hereunder, take any or all of the following
       actions:

                     (i)    change the amount, manner, place, terms of payment
              or interest rate, change or extend the time of payment of, or
              renew or alter, any of the Senior Indebtedness, or amend or
              supplement or waive any of the terms of any instrument or
              agreement now or hereafter executed pursuant to which any of the
              Senior Indebtedness is issued or incurred;

                     (ii)   sell, exchange, release, surrender, relend, realize
              upon or otherwise deal with in any manner and in any order, any
              property (or the income, revenues, profits or proceeds therefrom)
              by whomsoever at any time pledged or mortgaged to secure, or
              howsoever securing, any Senior Indebtedness;

                     (iii)  release any person liable in any manner for the
              payment or collection of the Senior Indebtedness;





                                       7
<PAGE>   245
                     (iv)   exercise or refrain from exercising any rights and
              remedies against Allied Finance, the Guarantor or others, or
              otherwise act or refrain from acting or, for any reason, fail to
              file, record or otherwise perfect any security interest in or
              lien on any property of Allied Finance, the Guarantor or any
              other Person; and

                     (v)    apply any sums received by the holders of the
              Senior Indebtedness, by whomsoever paid and however realized, to
              payment of the Senior Indebtedness in such manner as the holders
              of the Senior Indebtedness, in their sole discretion, may deem
              appropriate.

              (e)    Laidlaw and any future holder of this Guaranty, by
       acceptance of this Guaranty, agree to provide to any holder of Senior
       Indebtedness, at any time and from time to time, upon the written
       request of the Guarantor or such holder of Senior Indebtedness, an
       agreement signed by Laidlaw or such future holder of this Guaranty
       addressed to the holder of such Senior Indebtedness in substantially the
       form of, and on substantially the terms set out in, Exhibit A hereto to
       the effect that such Person is a holder of Senior Indebtedness, that the
       holder or holders of such Senior Indebtedness are entitled to the
       benefits of Sections 3 and 4 of this Guaranty and that the holder or
       holders of such Senior Indebtedness may enforce the terms and provisions
       thereof to the same extent the Guarantor would be able to do so,
       provided, however, that prior to furnishing such agreement, Laidlaw has
       received from the Guarantor or such holder such information as Laidlaw
       may reasonably request demonstrating to Laidlaw' reasonable satisfaction
       that such Person is a holder of Senior Indebtedness.  Laidlaw, and each
       subsequent holder of this Guaranty, by acceptance of this Guaranty,
       irrevocably appoint the Guarantor (with full power of substitution) as
       its agent and attorney in fact (which appointment is coupled with an
       interest and shall be irrevocable so long as any Senior Indebtedness is
       outstanding) to execute and deliver on behalf and in the name of Laidlaw
       or such holder, as the case may be, an agreement in substantially the
       form of, and on substantially the terms set out in, Exhibit A hereto in
       favor of each such holder of Senior Indebtedness and to take such
       further action as may be necessary or appropriate to effectuate the
       subordination as provided herein.  Promptly after exercise of any such
       power, Allied Finance will give written notice thereof to the holder of
       the Debenture; provided, however, that failure to give such notice shall
       in no event affect the validity of any power so exercised.

              (f)    Until all Senior Indebtedness has been indefeasibly paid
       in full in cash, the holder of this Guaranty shall not be entitled to
       assert, enforce or otherwise exercise any right of subrogation against
       the Guarantor or any other Person obligated on the Subordinated
       Obligations.  After all Senior Indebtedness has been indefeasibly paid
       in full in cash, and until the Subordinated Obligations have been so
       paid in full, the holder of this Guaranty shall be subrogated to the
       rights of holders of Senior Indebtedness to receive distributions
       applicable to Senior Indebtedness.  A distribution made under this
       Section 3 to holders of Senior Indebtedness which otherwise would have
       been made to





                                       8
<PAGE>   246
       the holder of this Guaranty is not, as between the Guarantor and the
       holder of this Guaranty, a payment by the Guarantor on Senior
       Indebtedness.

              (g)    This Section 3 defines the relative rights of the holder
       of this Guaranty and holders of Senior Indebtedness.  Nothing in this
       Guaranty shall:

                     (ii)   impair, as between the Guarantor and the holder of
              this Guaranty, the obligation of the Guarantor, which is absolute
              and unconditional, to pay the Guaranteed Debt in accordance with
              this Guaranty; or

                     (ii)   except as otherwise set forth in this Section 3,
              prevent the holder of this Guaranty from exercising its available
              remedies hereunder, subject to the rights of holders of Senior
              Indebtedness to receive distributions otherwise payable to such
              holder.

       4.     No Impairment.  Section 3 and this Section 4 (and all defined
terms used in such sections) shall constitute a continuing offer to all Persons
who become holders of, or continue to hold, Senior Indebtedness, and such
provisions are made for the benefit of the holders from time to time of Senior
Indebtedness, and such Persons are conclusively presumed to have relied upon
such provisions; and such holders are made obligees hereunder, and they or each
of them may enforce such provisions.  No right of any present or future holder
of any Senior Indebtedness to enforce the subordination or other provisions
referred to in this Section 4 shall at any time in any way be prejudiced or
impaired by any act or failure to act on the part of the Guarantor or Laidlaw,
or by any non-compliance by the Guarantor or Laidlaw with the terms, provisions
and covenants of this Guaranty, regardless of any knowledge thereof any such
holder may have or otherwise be charged with.  Section 3, this Section 4 and
the subordination and other provisions referred to in this Section 4 may not be
amended or modified in any manner which might terminate or impair the
subordination or such other provisions except with the prior written consent of
the Representatives of all the Designated Senior Indebtedness.

       5.     Binding Agreement.  This Guaranty benefits Laidlaw and its
successors and permitted assigns and binds the Guarantor and its successors and
permitted assigns.  Sections 3 and 4 and the other subordination provisions
hereof bind the Guarantor and Laidlaw and their respective successors and
assigns.  The Guarantor acknowledges that the rights and benefits of this
Guaranty may be transferred with any permitted assignment of the Guaranteed
Debt.

       6.     Notices.  All notices or other communications which are required
or may be given under this Guaranty shall be in writing and shall be deemed to
have been duly given when delivered in person or transmitted by telecopier
(with receipt confirmed) at the address or telecopy number set forth below (as
any such address or telecopier number may be changed from time to time by
notice similarly given):





                                       9
<PAGE>   247
       (a)    if to Laidlaw, to:

                     Laidlaw Inc.
                     3221 North Service Road
                     Burlington, Ontario
                     Canada L7R 3Y8
                     Attention:  Ivan R. Cairns
                     Telecopy No.: (905) 332-6550

       (b)    if to the Guarantor, to:

                     Allied Waste Industries, Inc.
                     7201 East Camelback Road, Suite 375
                     Scottsdale, Arizona 85251
                     Attention: Roger A. Ramsey
                     Telecopy No.: (602) 481-9347

                     with a copy to:

                     Porter & Hedges, L.L.P.
                     700 Louisiana Street, Suite 3500
                     Houston, Texas 77002
                     Attention: Robert G. Reedy
                     Telecopy No.: (713) 228-1331

       7.     Applicable Law.    This Guaranty shall be governed by and
construed in accordance with the laws of the State of Delaware and the laws of
the United States of America applicable therein (without reference to the
conflicts of law principles thereof).

       8.     OFFSET.  THE OBLIGATIONS OF THE GUARANTOR HEREUNDER ARE, IN ALL
RESPECTS, SUBJECT TO OFFSET AS MORE FULLY SET FORTH IN THE OFFSET LETTER
AGREEMENT.  THE OFFSET RIGHTS SET FORTH IN THE OFFSET LETTER AGREEMENT SHALL BE
EFFECTIVE NOTWITHSTANDING THE ASSIGNMENT OR TRANSFER OF THIS GUARANTY BY
LAIDLAW AND ANY





                                       10
<PAGE>   248
TRANSFEREE SHALL TAKE THIS GUARANTY SUBJECT TO THE TERMS THEREOF.



                                ALLIED WASTE INDUSTRIES, INC., 
                                a Delaware corporation


                                By:                                       
                                   ---------------------------------------
                                Name:       
                                     -------------------------------------
                                Title:
                                      ------------------------------------


Agreed and Accepted:

LAIDLAW INC., a Canadian corporation



By:
   --------------------------------------
Name:
     ------------------------------------
Title:
      -----------------------------------




                                       11
<PAGE>   249
                                                                EXHIBIT A
                                                to the Guaranty Issued by 
                    Allied Waste Industries, Inc. in favor of Laidlaw Inc.


                                     [Date]


- -------------------
- -------------------
- -------------------


Gentlemen:

       Reference is made to the Zero Coupon Junior Subordinated Debenture Due
200__ dated __________, 199__ (the "Subordinated Debenture"), in the original
principal amount of $___________ issued by 3294862 Canada, Inc., a Canadian
corporation ("Allied Finance"), in favor of Laidlaw Inc., a Canadian
corporation ("Laidlaw"), the Guaranty dated the date hereof (the "Guaranty"),
issued by Allied Waste Industries, Inc., a Delaware corporation (the
"Guarantor"), in favor of Laidlaw with respect to the obligations under the
Subordinated Debenture, and the [describe Senior Indebtedness] (the "Subject
Indebtedness"), being issued contemporaneously herewith by the Guarantor in
favor of [identity of holder or holders of Subject Indebtedness] (whether one
or more, the "Senior Creditor").  Hereinafter, capitalized words and phrases
used herein which are defined in the Guaranty are used herein as therein
defined.

       The undersigned (the "Subordinated Creditor") hereby represents and
warrants to the Senior Creditor that the Subordinated Creditor is the owner and
holder of the Subordinated Debenture and the Guaranty and that the Subordinated
Creditor is entitled to make the agreements herein contained.  The Subordinated
Creditor hereby acknowledges and agrees that the principal of, and premium, if
any, and interest on (including interest that, but for the filing of a petition
initiating any Bankruptcy or Insolvency Proceeding would accrue on such
obligations at the time provided in the agreements or instruments creating or
evidencing the respective obligations, whether or not such claim is allowed in
such Bankruptcy or Insolvency Proceeding) and all other amounts of every kind
or nature (including, but not limited to, fees, indemnities and expenses and
any interest rate swaps or other interest rate hedging products entered into in
connection with the Subject Indebtedness) due on or in connection with the
Subject Indebtedness, whether outstanding on the date hereof or hereafter
created, incurred or assumed, guaranteed or in effect guaranteed by the
Guarantor (including all renewals, extensions or refundings of, or amendments,
modifications or supplements to, the foregoing) are in all respects Senior
Indebtedness, that the Senior Creditor (and any other Person who from time to
time is a holder of the Subject Indebtedness) is entitled to the benefits of
Sections 3 and 4 of the Guaranty and that the Senior Creditor (and any other
Person who from time to





                                      A-1
<PAGE>   250
time is a holder of the Subject Indebtedness) may enforce the terms and
provisions of Sections 3 and 4 of the Guaranty to the same extent that the
Guarantor or any other holder of Senior Indebtedness would be able to do so.

       The Subordinated Creditor hereby agrees that the Subordinated Debenture
and the Guaranty will not be sold, assigned, transferred, pledged or
hypothecated in any manner, directly or indirectly, by the Subordinated
Creditor, unless the assignee, transferee, pledgee or hypothecate has agreed in
writing to be bound by the provisions of this agreement.

       The Subordinated Creditor has executed this agreement in the space
provided below in order to induce the Senior Creditor to advance funds or
extend credit to the Guarantor, and this agreement is intended by the
Subordinated Creditor to be a binding and enforceable undertaking by the
Subordinated Creditor in favor of the Senior Creditor.

       The rights credited hereby of the Senior Creditor and of any subsequent
holder of the Senior Indebtedness will be assigned automatically, and without
any further act, by the Senior Creditor or such holder upon any sale,
assignment, conveyance or other transfer of all or any part of the Senior
Indebtedness to the extent of the interest sold, assigned, conveyed or
otherwise transferred, unless and to the extent the Senior Creditor or such
holder expressly provides otherwise in the instrument pursuant to which such
interest is conveyed.



                                      Very truly yours,

                                      [NAME OF SUBORDINATED CREDITOR]


                                      By:                                     
                                         -------------------------------------
                                      Name:   
                                           -----------------------------------
                                      Title:                      
                                            ----------------------------------



Accepted and agreed to as of
the date first above written:

[NAME OF SENIOR CREDITOR]


By: 
   ----------------------------------------
Name:
     --------------------------------------
Title: 
      -------------------------------------




                                      A-2
<PAGE>   251
                                                                       EXHIBIT I

OPINIONS OF POLARIS' U.S. COUNSEL

Subject to customary limitations and exceptions (e.g., including bankruptcy and
equitable principles and the right to rely on certificates from officers of
Laidlaw) to be agreed on:

(1)      Each of PTI and the Acquired U.S. Subsidiaries is duly incorporated
         and validly existing as a corporation in good standing under the laws
         of the state of its incorporation as set forth in Section 4.5 of the
         Polaris Disclosure Schedule to the Agreement.

(2)      Each of PTI and the Acquired U.S. Subsidiaries has full corporate
         power to carry on its business as it is now being conducted and to own
         all of its material properties and assets.  Each of the Acquired U.S.
         Subsidiaries is duly qualified to do business in each jurisdiction in
         which it conducts business, except where failure to be so qualified
         will not have a Material Adverse Effect on any Acquired Subsidiary.

(3)      The authorized, issued and outstanding capital stock of each Acquired
         U.S. Subsidiary is as set forth in Section 4.5 of the Polaris
         Disclosure Schedule.  All issued and outstanding shares of capital
         stock of each Acquired U.S. Subsidiary have been duly authorized and
         validly issued, are fully paid and nonassessable, and were not issued
         in violation of any preemptive rights to purchase such shares.

(4)      The U.S. Polaris Parties have full corporate power to execute and
         deliver the Agreement to which they are a signatory and to consummate
         the Acquisitions and other transactions contemplated therein.  As used
         in this opinion, the "Agreement" shall include all other agreements
         and documents which appear as Exhibits to the Agreement or are entered
         into in connection with the Agreement.

(5)      The execution, delivery and performance by the U.S. Polaris Parties of
         the Agreement to which they are signatory and the entry into and
         performance of the Agreement and other transactions contemplated
         therein have been duly authorized by all necessary corporate and
         shareholder action on the part of the Polaris Parties.

(6)      The Agreement has been duly executed by the U.S. Polaris Parties and
         the Agreement constitutes a valid and binding obligation of the
         Polaris Parties enforceable against them in accordance with its terms.

(7)      The execution and delivery of the Agreement by the U.S. Polaris
         Parties and the consummation of the Acquisitions and the other
         transactions contemplated therein by PTI and the Acquired U.S.
         Subsidiaries, individually or collectively, do not (a) constitute a
         breach or violation of any federal law, rule or regulation of the
         United States or under any law, rule or regulation of any state, nor
         to our knowledge
<PAGE>   252
         constitute a default under any court order, judgment or decree of any
         governmental or regulatory body of the United States or any state, to
         which PTI or any of the Acquired U.S. Subsidiaries is subject or by
         which any of their material properties or assets are bound or
         affected, which breach, violation or default would have a Material
         Adverse Effect on the business of any Acquired U.S. Subsidiary, or (b)
         require any consent or approval of any other party under any federal
         law, rule or regulation of the United States or under any law, rule or
         regulation of any state to which PTI or any Acquired U.S. Subsidiary
         is subject, except for required approvals set forth in or under the
         Agreement or any schedules or exhibits to the Agreement, and those
         consents or approvals, in respect of which the failure to obtain such
         consents and approvals would not cause a Material Adverse Effect on
         the business of any Acquired U.S. Subsidiary.

(8)      The execution and delivery of the Agreement by the Polaris Parties did
         not, and the consummation of the Acquisitions and other transactions
         contemplated therein by PTI or any Acquired U.S. Subsidiary will not,
         constitute a breach or violation of, or constitute a default (or any
         event which with notice or lapse of time or both will become a
         default) under (a) the certificate of incorporation or bylaws of PTI
         or any Acquired U.S.  Subsidiary or (b) except as indicated in the
         Agreement or the exhibits or schedules or exhibits to the Agreement,
         any material contract, lease, or instrument of which we have knowledge
         to which PTI, any Acquired U.S. Subsidiary or any of their properties
         or assets are bound or affected, in each case, which breach, violation
         or default would have a Material Adverse Effect on any Acquired U.S.
         Subsidiary.

(9)      No actions, suits or proceedings are pending or, to our knowledge,
         threatened which challenge the validity of the Agreement or any action
         required to be taken by PTI or any Acquired U.S. Subsidiary pursuant
         to the Agreement.

(10)     The rights of Polaris under the Debentures have been effectively
         subordinated to the rights of the holders of the Senior Indebtedness
         to the extent set forth in the Debentures, and the subordination
         provisions in the Debentures are binding and enforceable upon Polaris.

         The opinion of Polaris' U.S. Counsel may be relied upon by the
Asteroid Parties, their counsel and the Persons providing financing pursuant to
the Commitment Letter and the Highly Confident Letter.
<PAGE>   253
                                                                       EXHIBIT J

OPINIONS OF POLARIS' CANADIAN COUNSEL

Subject to customary limitations and exceptions to be agreed on:

(1)      Each of Polaris and the Acquired Canadian Subsidiaries is duly
         incorporated and validly existing as a corporation in good standing
         under the laws of the state of its incorporation as set forth in
         Section 4.5 of the Polaris Disclosure Schedule to the Agreement.

(2)      Each of Polaris and the Acquired Canadian Subsidiaries has full
         corporate power to carry on its business as it is now being conducted
         and to own all of its material properties and assets.  Each of the
         Acquired Canadian Subsidiaries is duly qualified to do business in
         each jurisdiction in which it conducts business, except where failure
         to be so qualified will not have a Material Adverse Effect on any
         Acquired Subsidiary.

(3)      The authorized, issued and outstanding capital stock of each Acquired
         Canadian Subsidiary is as set forth in Section 4.5 of the Polaris
         Disclosure Schedule.  All issued and outstanding shares of capital
         stock of each Acquired Canadian Subsidiary have been duly authorized
         and validly issued, are fully paid and nonassessable, and were not
         issued in violation of any preemptive rights to purchase such shares.

(4)      The Polaris Parties have full corporate power to execute and deliver
         the Agreement to which they are a signatory and to consummate the
         Acquisitions and other transactions contemplated therein.  As used in
         this opinion, the "Agreement" shall include all other agreements and
         documents which appear as Exhibits to the Agreement or are entered
         into in connection with the Agreement.

(5)      The execution, delivery and performance by the Polaris Parties of the
         Agreement to which they are signatory and the entry into and
         performance of the Agreement and other transactions contemplated
         therein have been duly authorized by all necessary corporate and
         shareholder action on the part of the Polaris Parties.

(6)      The Agreement has been duly executed by the Polaris Parties and the
         Agreement constitutes a valid and binding obligation of the Polaris
         Parties enforceable against them in accordance with its terms.

(7)      The execution and delivery of the Agreement by the Polaris Parties and
         the consummation of the Acquisitions and the other transactions
         contemplated therein by Polaris and the Acquired Canadian
         Subsidiaries, individually or collectively, do not (a) constitute a
         breach or violation of any federal law, rule or regulation of Canada
         or under any law, rule or regulation of any province or territory of
         Canada, nor, to our
<PAGE>   254
         knowledge, constitute a default under any court order, judgment or
         decree of any governmental or regulatory body of Canada or any
         province or territory of Canada, to which Polaris or any of the
         Acquired Canadian Subsidiaries is subject or by which any of their
         material properties or assets are bound or affected, which breach,
         violation or default would have a Material Adverse Effect on the
         business of any Acquired Canadian Subsidiary, or (b) require any
         consent or approval of any other party under any federal law, rule or
         regulation of Canada or under any law, rule or regulation of any
         province or territory of Canada to which Polaris or any Acquired
         Canadian Subsidiary is subject, except for required approvals set
         forth in or under the Agreement or any schedules or exhibits to the
         Agreement, and those consents or approvals, in respect of which the
         failure to obtain such consents and approvals would not cause a
         Material Adverse Effect on the business of any Acquired Canadian
         Subsidiary.

(8)      The execution and delivery of the Agreement by the Polaris Parties did
         not, and the consummation of the Acquisitions and other transactions
         contemplated therein by Polaris or any Acquired Canadian Subsidiary
         will not, constitute a breach or violation of, or constitute a default
         (or any event which with notice or lapse of time or both will become a
         default) under (a) the certificate of incorporation or bylaws of
         Polaris or any Acquired Canadian Subsidiary or (b) except as indicated
         in the Agreement or the exhibits or schedules or exhibits to the
         Agreement, any material contract, lease, or instrument to which
         Polaris, any Acquired Canadian Subsidiary or any of their properties
         or assets are bound or affected, in each case, which breach, violation
         or default would have a Material Adverse Effect on any Acquired
         Canadian Subsidiary.

(9)      The business of each Acquired Subsidiary complies and has been
         conducted in compliance with all applicable Laws, except for
         violations or failures to comply, if any, that, individually or in the
         aggregate, could not have a Material Adverse Effect on the Acquired
         Subsidiaries.

(10)     No actions, suits or proceedings are pending or, to our knowledge,
         threatened which challenge the validity of the Agreement or any action
         required to be taken by Polaris or any Acquired Canadian Subsidiary
         pursuant to the Agreement.

(11)     The rights of Polaris under the Debentures and the Guaranties have
         been effectively subordinated to the rights of the holders of the
         Senior Indebtedness to the extent set forth in the Debentures and the
         Guaranties, and the subordination provisions in the Debentures and the
         Guaranties are binding and enforceable upon Polaris.

         The opinion of Polaris' Canadian Counsel may be relied upon by the
Asteroid Parties, their counsel and the Persons providing financing pursuant to
the Commitment Letter and the Highly Confident Letter.
<PAGE>   255
                                                                       EXHIBIT K


OPINIONS OF ALLIED'S U.S. COUNSEL

Subject to customary limitations and exceptions to be agreed on:

(1)      Each of Allied and Allied U.S. is duly incorporated and validly
         existing as a corporation in good standing under the laws of the State
         of Delaware.

(2)      Each of Allied and Allied U.S. has full corporate power to carry on
         its business as it is now being conducted and to own all of its
         material properties and assets.  Each of Allied and Allied U.S. is
         duly qualified to do business in each jurisdiction in which it
         conducts business, except where the failure to be so qualified will
         not have a Material Adverse Effect on Allied or Allied U.S.  Allied
         U.S. has had no prior operations other than in connection with the
         Agreement and the transactions contemplated therein.

(3)      The Allied Parties have full corporate power to execute and deliver
         the Agreement to which they are a signatory and to consummate the
         Acquisitions and other transactions contemplated therein.  As used in
         this opinion, the "Agreement" shall include all other agreements and
         documents which appear as Exhibits to the Agreement or are entered
         into in connection with the Agreement.

(4)      The execution, delivery and performance by the Allied Parties of the
         Agreement to which they are signatory and the entry into and
         performance of the Agreement and other transactions contemplated
         therein have been duly authorized by all necessary corporate and
         shareholder action on the part of the Allied Parties.

(5)      The Agreement has been duly executed by the Allied Parties and the
         Agreement constitutes a valid and binding obligation of the Allied
         Parties enforceable against them in accordance with its terms.

(6)      The execution and delivery of the Agreement by the Allied Parties and
         the consummation of the Acquisitions and the other transactions
         contemplated therein by Allied and Allied U.S., individually or
         collectively, do not (a) constitute a breach or violation of any
         federal law, rule or regulation of the United States or under any law,
         rule or regulation of any state, nor constitute a default under any
         court order, judgment or decree of any governmental or regulatory body
         of the United States or any state, to which Allied or Allied U.S.  is
         subject or by which any of their material properties or assets are
         bound or affected, which breach, violation or default would have a
         Material Adverse Effect on the business of Allied or Allied U.S., or
         (b) require any consent or approval of any other party under any
         federal law, rule or regulation of the United States or under any law,
         rule or regulation of any state to which Allied or Allied U.S.
<PAGE>   256
         is subject, except for required approvals set forth in or under the
         Agreement or any schedules or exhibits to the Agreement, and those
         consents or approvals, in respect of which the failure to obtain such
         consents and approvals would not cause a Material Adverse Effect on
         the business of Allied or Allied U.S.

(7)      The execution and delivery of the Agreement by the Allied Parties did
         not, and the consummation of the Acquisitions and other transactions
         contemplated therein by Allied and Allied U.S. will not, constitute a
         breach or violation of, or constitute a default (or any event which
         with notice or lapse of time or both will become a default) under (a)
         the certificate of incorporation or bylaws of Allied or Allied U.S. or
         (b) except as indicated in the Agreement or the exhibits or schedules
         or exhibits to the Agreement, any material contract, lease, or
         instrument to which Allied or Allied U.S. or any of their properties
         or assets are bound or affected, in each case, which breach, violation
         or default would have a Material Adverse Effect on Allied or Allied
         U.S.

(8)      The shares of Allied Common Stock and the shares of Allied Common
         Stock for which the Allied Warrants are exercisable, are (or will be
         when issued) validly issued, fully paid and non-assessable shares of
         Allied Common Stock.

(9)      No actions, suits or proceedings are pending or, to our knowledge,
         threatened which challenge the validity of the Agreement or any action
         required to be taken by Allied or Allied U.S. pursuant to the
         Agreement.

         The opinion of Allied's U.S. Counsel may be relied upon by the Polaris
Parties, their counsel and the Persons providing financing pursuant to the
Commitment Letter and the Highly Confident Letter.





                                       2
<PAGE>   257
                                                                       EXHIBIT L



OPINIONS OF ALLIED'S CANADIAN COUNSEL

Subject to customary limitations and exceptions to be agreed on:

(1)      Each of Allied Canada and Allied Finance is duly incorporated and
         validly existing as a corporation in good standing under the laws of
         Canada.

(2)      Each of Allied Canada and Allied Finance has full corporate power to
         perform its obligations under the Agreements to which it is a party.
         Each of Allied Canada and Allied Finance is duly qualified to do
         business in each jurisdiction in which it conducts business.

(3)      Each of Allied Canada and Allied Finance has full corporate power to
         execute and deliver the Agreements to which it is a signatory and to
         perform its obligations thereunder.  As used in this opinion, the
         "Agreements" shall mean the Stock Purchase Agreement, all other
         agreements which appear as Exhibits to the Agreement.

(4)      The execution, delivery and performance by each of Allied Canada and
         Allied Finance of the Agreements to which it is a signatory and the
         performance by it of its obligations thereunder have been duly
         authorized by all necessary corporate action on the part of such
         Allied Party.

(5)      Assuming that each of the Agreements is governed by the laws of the
         Province of Ontario, each of the Agreements has been duly executed by
         each of Allied Canada and Allied Finance that is a signatory thereto
         and each Agreement constitutes a legal, valid and binding obligation
         of each such Allied Party enforceable against each such Allied Party
         by such Laidlaw Party that is a party thereto in accordance with its
         terms.

(6)      The execution and delivery of the Agreements to which they are
         signatories by each of Allied Canada and Allied Finance and the
         performance of its obligations thereunder do not (a) constitute a
         breach or violation of any federal law, rule or regulation of Canada
         or under any law, rule or regulation of any province or territory of
         Canada, nor constitute a default under any court order, judgment or
         decree of any governmental or regulatory body of Canada or any
         province or territory of Canada, to which Allied Canada or Allied
         Finance is subject or by which any of their material properties or
         assets are bound or affected,

(7)      The execution and delivery by each of Allied Canada and Allied Finance
         of the Agreements to which it is a signatory by performance by it of
         its obligations thereunder do not and will not constitute a breach or
         violation of, or constitute a default (or any






                                      1
<PAGE>   258
         event which with notice or lapse of time or both will become a
         default) under (a) the certificate or articles of incorporation or
         bylaws of Allied Canada or Allied Finance or (b) except as indicated
         in the Agreement or the exhibits or schedules or exhibits to the
         Agreement, any material contract, lease, or instrument to which Allied
         Canada or Allied Finance or any of their properties or assets are
         bound or affected, and which is listed below on this Exhibit L.

(8)      We have not been retained by Allied Canada or Allied Finance to
         represent either of them in connection with any action, suit or
         proceeding which challenges the validity of the Agreement or any
         action required to be taken by Allied Canada or Allied Finance
         pursuant to the Agreement.

         The opinion of Allied's Canadian Counsel may be relied upon by the
Polaris Parties, their counsel and the Persons providing financing pursuant to
the Commitment Letter and the Highly Confident Letter.




                                      2
<PAGE>   259
                                                                       EXHIBIT M



                     [Form of Debenture Exchange Agreement]


                                                       [Date]



Laidlaw Inc.
3221 North Service Road
Burlington, Ontario
Canada L7R 348


Gentlemen:

         Reference is made to the Stock Purchase Agreement dated as of
September __, 1996 (the "Stock Purchase Agreement"), among Allied Waste
Industries, Inc., a Delaware corporation, 3294862 Canada Inc., a Canadian
corporation, Allied Waste Holdings (U.S.), Inc., a Delaware corporation,
Laidlaw Inc., a Canadian corporation ("Laidlaw"), Laidlaw Transportation, Inc.,
a Delaware corporation, Laidlaw Waste Systems, Inc., Laidlaw Waste Systems
(U.S.), Inc., a Delaware corporation, and Laidlaw Medical Services Ltd., a
Canadian corporation.  Hereinafter, capitalized words and phrases used herein
which are defined in the Stock Purchase Agreement are used herein as therein
defined.

         Pursuant to Section 2.3 of the Stock Purchase Agreement, as part of
the consideration for the purchase of LWSC, Allied Canada has agreed to issue
to Laidlaw at the Closing the Allied Canada 7% Debenture and the Allied Canada
Zero Coupon Debenture (collectively referred to as the "Allied Canada
Debentures").  Laidlaw and the undersigned ("Allied Finance") hereby agree
that, immediately following the delivery by Allied Canada of the Allied Canada
Debentures, Allied Finance will purchase from Laidlaw, and Laidlaw will sell
and transfer to Allied Finance, at the Closing, the Allied Canada Debentures.
In consideration of the sale by Laidlaw of the Allied Canada Debentures, Allied
Finance will issue to Laidlaw the 7% Junior Subordinated Debenture due 200_ in
substantially the form of Exhibit B-1 to the Stock Purchase Agreement and the
Zero Coupon Junior Subordinated Debenture due 200_ in substantially the form of
Exhibit B-2 to the Stock Purchase Agreement.
<PAGE>   260
         Please execute the enclosed copy of this letter in the space provided
below to indicate your agreement to the terms herein set forth.



                                                 Very truly yours,
                                                    
                                                 3294854 CANADA INC.
                                                    
                                                    
                                                    
                                                 By:
                                                    ----------------------------
                                                 Title:
                                                       -------------------------
                                                    
ACCEPTED AND AGREED TO
         as of the date
         first written above.


LAIDLAW INC.


By:
   -----------------------
Title:
      --------------------
<PAGE>   261
                                                                       EXHIBIT N



                                     [date]


Laidlaw Inc.
Laidlaw Transportation, Inc.
3221 North Service Road
Burlington, Ontario
Canada  L7R  3Y8

Gentlemen:

       Reference is made to the Stock Purchase Agreement dated September 17,
1996 (the "Stock Purchase Agreement"), among you, the undersigned and certain
other parties named therein and to the 7% Junior Subordinated Debentures due
200_ and the Zero Coupon Junior Subordinated Debentures due 200_ issued by
Allied Finance as provided in Section 2.3 of the Stock Purchase Agreement.
Capitalized words and phrases used herein which are defined in the Stock
Purchase Agreement are used herein as therein defined.

       In the event any Allied Party or any Acquired Subsidiary suffers any
Damages arising out of or in respect of the matters referred to in clauses (i)
and (ii) of Section 14.1 of the Stock Purchase Agreement because of any tax
deficiencies (including penalties and interest) that Laidlaw is ultimately
required to pay for any period prior to the Closing based on the matters
referred to in the third paragraph of the "Legal Proceedings" portion of Note
16 of the Notes to Financial Statements contained in the 1995 Annual Report of
Laidlaw, , and the Laidlaw Sellers fail to indemnify the Allied Parties and the
Acquired Subsidiaries against, and to hold the Allied Parties and the Acquired
Subsidiaries harmless from, any such matter or matters, and such failure
continues for 30 days after written notice from Allied or the affected Allied
Party or Acquired Subsidiary as provided in Article XIV of the Stock Purchase
Agreement, Laidlaw hereby agrees that, at the option of Allied
<PAGE>   262
Finance, the obligations of Allied Finance may be reduced pro tanto and offset
against the obligations of the Laidlaw Sellers to provide such indemnity.



                                           Very truly yours,


                                           Allied Waste Industries, Inc.


                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------


                                           3294854 CANADA INC.


                                           By:                                 
                                              ---------------------------------
                                           Name:                               
                                                -------------------------------
                                           Title:                              
                                                 ------------------------------



ACCEPTED AND AGREED
  to as of the date
  first above written.


LAIDLAW INC.



By:                                
   --------------------------------
Name:                       
     ------------------------------
Title:                             
      -----------------------------




                                     N-2
<PAGE>   263
LAIDLAW TRANSPORTATION, INC.


By:                                
   --------------------------------
Name:                       
     ------------------------------
Title:                      
      -----------------------------





                                      N-3

<PAGE>   1
                                   AGREEMENT

         This Agreement (the "Agreement") dated September 17, 1996 is by and
between Allied Waste Industries, Inc., a Delaware corporation ("Allied"), TPG
Partners, L.P., a Delaware limited partnership ("TPG") and TPG Parallel I,
L.P., a Delaware limited partnership ("TPG Parallel").

         WHEREAS, Allied and TPG have entered into the Securities Purchase
Agreement (the "TPG Agreement") dated October 27, 1994 (the "TPG Agreement")
which provides for the purchase (the "Purchase") of 11,709,602 shares of
Allied's common stock, par value $0.01 per share (the "Common Stock"), by TPG
and TPG Parallel.

         WHEREAS, the Purchase was closed on January 30, 1995 and certain
covenants set forth in the TPG Agreement remain in effect.

         WHEREAS, Allied and TPG desire to amend certain provisions of the TPG
Agreement and enter into other agreements set forth herein, all conditioned
upon the closing (the "Closing") of the transactions set forth in the Stock
Purchase Agreement by and between Allied and Polaris Inc., among others, dated
September 17, 1996 (the "Polaris Agreement").

         NOW, THEREFORE, in consideration of the foregoing, Allied, TPG and TPG
Parallel hereby agree as follows:

1.       AGREEMENTS REGARDING THE TPG AGREEMENT.

                 (a)      TPG agrees that the consummation of the transactions
         contemplated by the  Polaris Agreement, including any schedule or
         exhibit thereto, shall not constitute a "Change of Control" as defined
         in Section 1.3(c)(iv) of the TPG Agreement.

                 (b)      Upon the occurrence of the Closing and the election
         of the Board of Directors contemplated by Section 2, below:
        
                          (i)     The last sentence of Section 4.2(a) is hereby
                                  amended to read as follows in its entirety:

                                  The Purchaser shall be entitled to three
                                  demands pursuant to this Section 4.2(a).

                          (ii)    the following sentence is added at the end of
                                  paragraph (a) of Section 4.2 of the TPG
                                  Agreement:

                                  If, in the case of an underwritten public
                                  offering of Shares or Exercise Shares
                                  registered pursuant to this Section 4.2(a),
                                  the
<PAGE>   2
                                  managing underwriter therefor concludes in
                                  its reasonable judgment that the number of
                                  shares to be registered would materially
                                  adversely affect such offering, the number of
                                  Shares and Exercise Shares to be registered,
                                  together with the number of shares of Common
                                  Stock or other securities proposed to be
                                  registered by other Persons shall be reduced.
                                  In such event, the Shares and Exercise Shares
                                  registered pursuant to this Section 4.2(a)
                                  shall have priority and no Shares or Exercise
                                  Shares shall be so reduced until all shares
                                  of Common Stock proposed to be registered by
                                  any other Person have been entirely
                                  eliminated;

                          (iii)   the last sentence of Section 6.2 of the TPG
                                  Agreement shall be amended to read as follows
                                  in its entirety:

                                  The terms of this Section 6.2 shall terminate
                                  upon the earlier to occur of (x) the fifth
                                  anniversary of the Closing Date or (y) if, 
                                  at any time, Texas Pacific Group, TPG
                                  Partners, L.P., TPG Parallel I, L.P., and
                                  their respective Affiliates (as that term is
                                  defined in Rule 12b-2 under the Securities
                                  Exchange Act of 1934, as amended) own less
                                  than either: (i) securities of the Company
                                  representing 6.5% of the Common Stock
                                  outstanding from time to time (calculated on a
                                  fully diluted basis) or (ii) 5,888,637 shares
                                  of the Common Stock;

                          (iv)    the second proviso of the first sentence of
                                  Section 6.2 is hereby amended to read as
                                  follows in its entirety:

                                  provided further, however, that the foregoing
                                  covenant will expire on the occurrence of any
                                  of the following:  (i) the making of an offer
                                  or proposal by a Person that would result in
                                  a Change of Control; (ii) the failure of any
                                  TPG Designee (as defined in the Agreement
                                  between the Purchaser and the Company dated
                                  September 17, 1996) to be nominated by the
                                  Company to the Company's Board of Directors;
                                  or (iii) a breach by the Company of the
                                  covenants contained in Article IV hereof.

                          (v)     Section 7.3 of the TPG Agreement is hereby 
                                  deleted in its entirety;

                 (c)      Except as set forth in this Agreement, the TPG
         Agreement shall remain in full force and effect.





                                       2
<PAGE>   3
         2.      AGREEMENT.  Allied, TPG and TPG Parallel agree as follows:

                 (a)      Allied agrees to nominate for election to its Board
         of Directors three representatives designated by TPG ("TPG's
         Designees"), one of whom may be an Affiliate of TPG and two of whom
         will not be Affiliates of TPG.  All TPG Designees must be acceptable
         to Allied, which approval will not be unreasonably withheld.  Allied
         agrees that John M. Lewis and William K. Reilly are acceptable as
         initial TPG Designees of TPG.  All TPG Designees will be compensated
         at a level commensurate with the compensation of Allied's outside
         directors.  The TPG Designees shall be nominated by Allied for
         election at each annual meeting of Allied's stockholders, subject to
         the termination of this provision as set forth below.  Upon election
         to the Board of Directors, the TPG Designees will enjoy service on the
         various committees of the Board of Directors commensurate with the
         number of Board seats held by TPG Designees as well as one seat on the
         newly formed Nominating Committee.

                 (b)      Effective as of the Closing, Allied will amend its
         bylaws to provide that the board of directors of Allied (the "Board of
         Directors") will have 12 members, and will use its best efforts to
         cause as soon as practicable after the Closing the members of the
         Board of Directors to be Roger A. Ramsey, Thomas H.  Van Weelden,
         Nolan Lehman, Alan B. Shepard, James G. Coulter, John M. Lewis,
         William K. Reilly, two members nominated by Polaris (the "Polaris
         Nominees") that are reasonably acceptable to Allied, and three new
         outside directors (the "New Directors") to be selected by a nominating
         committee of the Board of Directors comprised of Roger A. Ramsey,
         James G. Coulter and Alan B. Shepard.  The New Directors shall be
         acceptable to TPG, in its sole discretion.  Subsequent nominees to the
         Board of Directors (other than the TPG Designees) shall not be subject
         to approval by TPG.  If any duly elected TPG Designee fails to
         complete his term, TPG may designate a new TPG Designee that is
         reasonably acceptable to Allied to replace such TPG Designee.

                 (c)      TPG and TPG Parallel agree to cause all Allied
         securities beneficially owned by them or their affiliates to be
         present at all stockholder meetings called by the Board of Directors
         of Allied so that they may be counted for the purpose of determining
         the presence of a quorum at such meetings.

                 (d)      The provisions of this Section 2 shall terminate if,
         at any time, Texas Pacific Group, TPG Partners, L.P., TPG Parallel I,
         L.P. and their respective Affiliates own less than either: (i)
         securities of the Company representing 6.5% of the Company's Common
         Stock outstanding from time to time (calculated on a fully diluted
         basis) or (ii) 5,888,637 shares of Common Stock.





                                       3
<PAGE>   4
         IN WITNESS WHEREOF, Allied, TPG and TPG Parallel have duly executed
this Agreement as of the first date written above.


                                        ALLIED WASTE INDUSTRIES, INC.


                                        By:         /s/ Roger A. Ramsey        
                                            -----------------------------------
                                        Name:       Roger A. Ramsey            
                                              ---------------------------------
                                        Title:      Chief Executive Officer    
                                               --------------------------------
                                        
                                        
                                        
                                        TPG PARTNERS, L.P.
                                        By TPG GenPar, L.P., general partner
                                        By TPG Advisors, Inc., general partner
                                        
                                        
                                        By:         /s/ James J. O'Brien       
                                            -----------------------------------
                                        Name:       James J. O'Brien           
                                              ---------------------------------
                                        Title:      Vice President             
                                               --------------------------------
                                        
                                        
                                        
                                        TPG PARALLEL I, L.P.
                                        By TPG GenPar, L.P., general partner
                                        By TPG Advisors, Inc., general partner
                                        
                                        
                                        By:         /s/ James J. O'Brien       
                                            -----------------------------------
                                        Name:       James J. O'Brien           
                                              ---------------------------------
                                        Title:      Vice President             
                                               --------------------------------





                                       4


© 2022 IncJournal is not affiliated with or endorsed by the U.S. Securities and Exchange Commission