CLEAN HARBORS INC
S-2/A, 1994-07-29
REFUSE SYSTEMS
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<PAGE>
 
      
   AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 28, 1994     
 
                                                       REGISTRATION NO. 33-54191
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                               ----------------
                                 
                              AMENDMENT NO. 3     
                                       TO
                                    FORM S-2
                             REGISTRATION STATEMENT
                                     Under
                           THE SECURITIES ACT OF 1933
 
                               ----------------
 
                              CLEAN HARBORS, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
                               ----------------
 
            MASSACHUSETTS                            04-2997780
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
                                                        (continued on next page)
 
                               ----------------
 
                            1200 CROWN COLONY DRIVE,
                          QUINCY, MASSACHUSETTS 02169
                                 (617) 849-1800
   (ADDRESS, INCLUDING ZIP CODE AND TELEPHONE NUMBER, INCLUDING AREA CODE OF
                   REGISTRANT'S PRINCIPAL EXECUTIVE OFFICES)
 
                               ----------------
 
                             C. MICHAEL MALM, ESQ.
                         DAVIS, MALM & D'AGOSTINE, P.C.
                                ONE BOSTON PLACE
                          BOSTON, MASSACHUSETTS 02108
                                 (617) 367-2500
(NAME, ADDRESS INCLUDING ZIP CODE AND TELEPHONE NUMBER, INCLUDING AREA CODE, OF
                               AGENT FOR SERVICE)
 
                               ----------------
 
                                WITH COPIES TO:
                            ETTORE A. SANTUCCI, P.C.
                            GOODWIN, PROCTER & HOAR
                                 EXCHANGE PLACE
                          BOSTON, MASSACHUSETTS 02109
                                 (617) 570-1000
 
                               ----------------
 
  APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: As soon as
possible following the effectiveness of this Registration Statement.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>

(Continued from previous page)
                             ADDITIONAL REGISTRANTS
 
                   CLEAN HARBORS ENVIRONMENTAL SERVICES, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
            MASSACHUSETTS                            04-2698999
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                        CLEAN HARBORS OF BRAINTREE, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
            MASSACHUSETTS                            04-2507498
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                         CLEAN HARBORS OF NATICK, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
            MASSACHUSETTS                            04-2481234
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                        CLEAN HARBORS OF BALTIMORE, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
            PENNSYLVANIA                             23-2091580
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                         CLEAN HARBORS OF CHICAGO, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
            MASSACHUSETTS                            06-1287127
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                        CLEAN HARBORS OF CLEVELAND, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
              ILLINOIS                               06-1335175
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                        MURPHY'S WASTE OIL SERVICE, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
            MASSACHUSETTS                            04-2490849
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                  CLEAN HARBORS KINGSTON FACILITY CORPORATION
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
            MASSACHUSETTS                            04-3074299
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                       CLEAN HARBORS OF CONNECTICUT, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
             CONNECTICUT                             06-1025746
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                                MR. FRANK, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
              ILLINOIS                               36-2542803
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                      CLEAN HARBORS TECHNOLOGY CORPORATION
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
            MASSACHUSETTS                            04-3172766
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
 
                      SPRING GROVE RESOURCE RECOVERY, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
              DELAWARE                               76-0313183
   (STATE OR OTHER JURISDICTION OF    (I.R.S. EMPLOYER IDENTIFICATION NUMBER)
   INCORPORATION OR ORGANIZATION)
<PAGE>
 
                              CLEAN HARBORS, INC.
 
              CROSS-REFERENCE SHEET SHOWING LOCATION IN PROSPECTUS
                  OF INFORMATION REQUIRED BY ITEMS OF FORM S-2
 
<TABLE>
<CAPTION>
                                                     PROSPECTUS LOCATION
      FORM S-2 ITEM NUMBER HEADING                         HEADING
      ----------------------------                   -------------------
 <C> <S>                                  <C>
  1. Forepart of the Registration
      Statement and Outside Front Cover
      Page of Prospectus...............   Front Cover Page
  2. Inside Front and Outside Back
      Cover Pages of Prospectus........   Inside Front and Outside Back Cover
                                           Pages; Available Information;
                                           Incorporation of Certain Documents by
                                           Reference
  3. Summary Information, Risk Factors
      and Ratio of Earnings to Fixed      
      Charges..........................   Prospectus Summary; Risk Factors;    
                                           Selected Consolidated Financial Data 
  4. Use of Proceeds...................   Use of Proceeds; Capitalization
  5. Determination of Offering Price...   Front Cover Page
  6. Dilution..........................   Not Applicable
  7. Selling Security Holders..........   Not Applicable
  8. Plan of Distribution..............   Outside Front Cover Page; Underwriting
  9. Description of Securities to be
      Registered.......................   Description of the Senior Notes
 10. Interests of Named Experts and
      Counsel..........................   Legal Matters
 11. Information with Respect to the      
      Registrant.......................   Prospectus Summary; Capitalization;   
                                           Selected Consolidated Financial Data;
                                           Management's Discussion and Analysis 
                                           of Financial Condition and Results of
                                           Operations; Business; Environmental
                                           Regulation; Directors and Executive
                                           Officers of the Company; Description
                                           Other Indebtedness; Consolidated
                                           Financial Statements                
 12. Incorporation of Certain             
      Information by Reference.........   Incorporation of Certain Documents by
                                           Reference                           
 13. Disclosure of Commission Position
      on Indemnification for Securities
      Act Liabilities..................   Not Applicable
</TABLE>
<PAGE>
 
        
                                   
                                $50,000,000     
 
                                     [LOGO]
                          
                       12 1/2% Senior Notes Due 2001     
   
Interest payable May 15 and November 15                    Due May 15, 2001     
 
                                   --------
   
The 12 1/2% Senior Notes Due 2001 (the "Senior Notes") are not redeemable prior
to May 15, 1999. On or after May 15, 1999, the Senior Notes are redeemable in
whole or in part, at the option of the Company, at the redemption prices set
forth herein plus accrued interest to the date of redemption. The Company will
not be required to make mandatory redemption or sinking fund payments with
respect to the Senior Notes prior to maturity. Upon a Change of Control (as
defined herein), each holder of Senior Notes may require the Company to
repurchase such holder's Senior Notes at 101% of the principal amount thereof
plus accrued interest to the date of repurchase.     

   
The Senior Notes will be unsecured obligations of the Company, ranking pari
passu with all other senior indebtedness of the Company. The Senior Notes will
be unconditionally guaranteed on a senior unsecured basis by each of the
Company's direct subsidiaries. After giving pro forma effect to this offering
(the "Offering") and the application of the net proceeds therefrom described
herein, the Company and its subsidiaries on a consolidated basis will have
outstanding $5.0 million of unsecured senior indebtedness in addition to the
Senior Notes and expect to have approximately $11.8 million outstanding under a
$35.0 million senior secured revolving credit agreement (the "Bank Revolver").
See "Capitalization" and "Description of the Senior Notes."     

                                   --------
 
     SEE "RISK FACTORS" FOR A DISCUSSION OF CERTAIN FACTORS THAT SHOULD BE
        CONSIDERED IN CONNECTION WITH AN INVESTMENT IN THE SENIOR NOTES.
 
                                   --------
 
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE SECURI-TIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.
 
<TABLE>
<CAPTION>
                                                        Underwriting
                                             Price to   Discounts and  Proceeds to
                                             Public(1)   Commissions  Company(1)(2)
                                            ----------- ------------- -------------
<S>                                         <C>         <C>           <C>
Per Senior Note ...........................    100%         3.50%        96.50%
Total ..................................... $50,000,000  $1,750,000    $48,250,000
</TABLE>
   
(1)Plus accrued interest, if any, from August 4, 1994.     
(2)Before deduction of expenses payable by the Company estimated at $500,000.
 
                                   --------
   
  The Senior Notes are offered by the several Underwriters when, as and if
issued by the Company, delivered to and accepted by the Underwriters and
subject to their right to reject orders in whole or in part. It is expected
that delivery of the Senior Notes in book-entry form will be made through the
facilities of The Depository Trust Company on or about August 4, 1994.     
 
CS First Boston                                               Alex. Brown & Sons
                                                                 Incorporated
                  
               The date of this Prospectus is July 29, 1994.     
<PAGE>
 
 
                                                         (ART)
 
WASTE MANAGEMENT FACILITIES
. BRAINTREE, MA
. KINGSTON, MA
. NATICK, MA
. WOBURN, MA
. BRISTOL, CT
. CHICAGO, IL
. PORTLAND, ME
. BALTIMORE, MD
. CINCINNATI, OH
. CLEVELAND, OH

<TABLE> 
<CAPTION> 
 
                [_] MIDWEST           [_] CENTRAL               [_] MID-ATLANTIC          [_] NORTHEAST         
<S>             <C>                   <C>                       <C>                       <C>                  
SERVICE CENTERS     . CHICAGO, IL         . CINCINNATI, OH          . BALTIMORE, MD           . SHREWSBURY, MA  
                    . WAUKEGAN, IL        . CLEVELAND, OH           . METRO PHILADELPHIA      . BOSTON, MA      
                    . ST. LOUIS, MO       . PITTSBURGH, PA          . METRO NYC               . NEW BRITAIN, CT 
                                                                    . ALBANY, NY              . BANGOR, ME      
                                                                    . SYRACUSE, NY            . PORTLAND, ME    
                                                                    . RICHMOND, VA            . HOOKSETT, NH    
                                                                    . SAN JUAN, PR            . PORTSMOUTH, NH  
                                                                                              . PROVIDENCE, RI  
                         
SALES OFFICES       . GRAND RAPIDS, MI    . COLUMBUS, OH            . RALEIGH/DURHAM, NC      . QUINCY, MA 
                    . MINNEAPOLIS, MN     . INDIANAPOLIS, IN
                                          . LOUISVILLE, KY
                                          . BUFFALO, NY
</TABLE> 

                    
 
  IN CONNECTION WITH THIS OFFERING, THE UNDERWRITERS MAY OVER-ALLOT OR EFFECT
TRANSACTIONS WHICH STABILIZE OR MAINTAIN THE MARKET PRICE OF THE SENIOR NOTES
AT A LEVEL ABOVE THAT WHICH MIGHT OTHERWISE PREVAIL IN THE OPEN MARKET. SUCH
STABILIZING, IF COMMENCED, MAY BE DISCONTINUED AT ANY TIME.
 
                                       2
<PAGE>
 
                               PROSPECTUS SUMMARY
 
  The following is a summary of certain of the information contained elsewhere
in this Prospectus. This summary is not intended to be complete and is
qualified in its entirety by reference to the detailed information and
financial statements, including the notes thereto, contained elsewhere in this
Prospectus. Unless the context otherwise requires, references to the "Company"
include Clean Harbors, Inc. and its subsidiaries.
 
                                  THE COMPANY
 
  The Company provides a wide range of industrial waste management services to
a diversified customer base in 26 states. It is one of the largest providers of
industrial waste management services in the Northeast, with a growing presence
in the Mid-Atlantic, Central, and Midwest regions of the United States. The
Company seeks to be recognized by customers as the premier supplier of a broad
range of value-added industrial waste management services based upon quality,
responsiveness, customer service, variety of risk containment systems, and cost
effectiveness. The Company currently maintains a network of eight sales
offices, 22 service centers and ten waste management facilities. The service
centers perform site specific services and ultimately direct collected waste to
the waste management facilities for treatment and processing. The Company does
not own or operate end disposal sites such as landfills or incinerators.
 
  The United States industrial waste management industry had total revenues in
1992 of approximately $18.6 billion. The demand for industrial waste management
services has resulted primarily from the adoption and enforcement of
increasingly stringent federal, state and local environmental laws and
regulations over the past 20 years. These laws and regulations have
significantly increased the costs and potential liabilities associated with the
handling of industrial wastes. Under these laws and regulations, a broad list
of industrial wastes are classified as "hazardous," and generators of hazardous
wastes retain potential legal liability for the proper treatment of such wastes
through and including their ultimate disposal. In response to these laws and
regulations, many generators of both hazardous and nonhazardous wastes have
chosen not to maintain their own treatment and disposal facilities nor to
develop the technical expertise necessary to assure regulatory compliance.
These generators have instead sought to have their waste streams managed by
firms that possess collection, transportation, recycling, treatment, disposal
and waste-tracking capabilities and have the expertise and financial capacity
necessary to comply with applicable environmental laws and regulations.
 
  The principal services provided by the Company fit within three categories:
treatment and disposal of industrial wastes; field services provided at
customer sites; and specialized repackaging, treatment and disposal services
for laboratory chemicals and household hazardous wastes. The Company markets
these services on an integrated basis and, in many instances, services in one
area of the business support or lead to a project undertaken in another area.
 
  Since January 1994, the Company has executed approximately 2,500 work orders
per month for over 4,400 customers. The Company's sales efforts are directed
toward establishing and maintaining relationships with businesses which have
ongoing requirements for one or more of the Company's services. The Company's
customer list includes 296 of the companies on the 1994 Forbes 500 list of
largest United States companies. In addition, the Company's customers include
most of the major utilities in the Northeast and Mid-Atlantic regions. The
Company's customers are primarily chemical, petroleum, transportation, utility
and industrial firms, other waste management companies and government agencies.
Management believes that the Company's diverse customer base, in terms of
number, industry and geographic location, as well as its large presence in New
England, provide it with a recurring stream of revenue and stability of cash
flow. The Company estimates that in excess of 80% of its revenues is derived
from previously served customers with recurring needs for the Company's
services.
 
                                       3
<PAGE>
 
 
  The Company's consolidated revenues grew 52% between the fiscal year ended
February 28, 1990 and the fiscal year ended December 31, 1993, from $131.4
million to $200.1 million. Consolidated EBITDA (as defined below) increased 88%
over the same period from $12.4 million to $23.3 million.
 
  As a large industrial waste management firm, the Company has significant cost
advantages over many of its competitors in terms of its ability to efficiently
utilize its waste management facilities and to negotiate more favorable terms
for end disposal of waste. Several recent industry trends provide the Company
with opportunities to grow by focusing on technological innovation, sound
waste-tracking capabilities, cost reduction and a heightened commitment to
customer service and responsiveness. These trends include: (i) efforts by many
generators of industrial wastes to decrease the number of service providers
that they utilize to a select group of industry leaders in order to minimize
the potential liability inherent in using less qualified firms; (ii) efforts by
waste generators to reduce or recycle their waste through utilizing service
providers which offer alternative disposal and treatment technologies; and
(iii) a reduction in the cost of end disposal as a result of surplus landfill
and incinerator capacity and the emergence of new disposal alternatives. These
trends are leading to a significant consolidation of the industrial waste
management industry. The Company has benefited and expects to continue to
benefit from these trends through attractive acquisitions, increased market
share and new market opportunities.
 
  For a description of certain recent developments, see "Management's
Discussion and Analysis of Financial Condition and Results of Operations--
Recent Developments."
 
  The Company was incorporated in Massachusetts in 1980. The principal offices
of the Company are located at 1200 Crown Colony Drive, Quincy, Massachusetts
02169, and the telephone number is (617) 849-1800.
 
                               BUSINESS STRATEGY
 
  In order to maintain and enhance its leading position in the industrial waste
management industry, the Company has implemented a strategy of internal growth
through the increased utilization of existing facilities, the addition of new
sales offices and service centers, and the development of new waste management
services. In addition, the Company achieves external growth through strategic
acquisitions.
 
  Increased Utilization of Waste Management Facilities. The Company currently
has ten waste management facilities which represent a substantial investment in
permits, plant and equipment. These facilities provide the Company with
significant operating leverage. There are opportunities to expand capacity at
these facilities by modifying the terms of the existing permits and by adding
capital equipment and new technology. Through selected permit modifications,
the Company can expand the range of treatment services which it offers to its
customers without the large capital investment necessary to acquire or build
new waste management facilities. The Company believes that permits for new
industrial waste management facilities will become increasingly difficult to
obtain, thereby placing new entrants and weaker competitors at a disadvantage.
 
  Sales Office/Service Center Expansion. The Company opens sales offices in
attractive target markets which can be serviced by existing facilities and
expand the Company's service areas. As demand at a particular sales office
reaches a sufficient level, the sales office can be upgraded to a service
center with field service capabilities by the addition of field technicians,
service personnel and equipment. The Company's sales offices and service
centers direct waste into the Company's waste management facilities. This
allows the Company to expand its service areas with low risk capital investment
and to maximize throughput with minimal incremental cost by obtaining
additional wastes to be handled by the Company's service centers and waste
management facilities. Since January 1, 1993, the Company has added eight sales
offices and one service center, and three sales offices have been upgraded to
service centers.
 
                                       4
<PAGE>
 
 
  New Waste Management Services. Industrial waste generators are demanding
alternatives to traditional waste disposal methods in order to increase
recycling and reclamation and to minimize the end disposal of hazardous waste
into the environment. The Company utilizes its technological expertise and
innovation to improve and expand the range of services which it offers to its
customers. The Company has commercialized a hazardous waste treatment system,
the Clean Extraction System ("CES"), to extract toxic compounds from industrial
wastewaters by utilizing non-toxic liquid carbon dioxide at high pressures. CES
offers for certain wastewater streams a recycling alternative to incineration
or injection into deep underground wells. The Company has also recently signed
a development agreement with Molten Metal Technology, Inc., an environmental
technology company developing a proprietary technology known as Catalytic
Extraction Processing which uses a molten metal bath as a catalyst and solvent
to break down the molecular structures of various hazardous wastes into their
elements for recycling or reuse.
 
  Capitalization on Industry Consolidation. The Company believes that its large
industrial customers will ultimately require a comprehensive range of waste
treatment capabilities to be provided by a select number of service providers.
This trend will put smaller operators at a competitive disadvantage due to
their size and limited financial resources. To respond to its customers' needs,
the Company has increased the range of waste management services it offers and
has followed a strategy of acquiring companies in existing, contiguous and new
market areas. Since its formation in 1980, the Company has completed 12
acquisitions, each of which has proven successful in expanding the Company's
market share and cash flow. The Company continues to investigate and discuss
other potential acquisitions of permitted facilities in order to enhance
service to its existing customer base and expand its customer base to include
new regional and super-regional waste generators. The Company has signed a
letter of intent with Chemical Waste Management, Inc. which would allow the
Company to expand its Chicago waste management facility into an adjoining site.
See "Business--Properties--Hazardous Waste Management Facilities--Chicago, IL."
Acquisitions within the Company's existing areas of operation serve to capture
incremental market share, while geographic expansion creates new market
opportunities.
 
                                  RISK FACTORS
 
  Prospective purchasers of the Senior Notes should carefully consider the
information set forth under "Risk Factors," as well as the other information
and data in this Prospectus.
 
                                  THE OFFERING
 
                           
Senior Notes Offered..  $50,000,000 aggregate principal amount of 12 1/2% Se-
                        nior Notes Due 2001.     
    
Interest Payment        
 Dates................  May 15 and November 15, commencing November 15, 1994.
                            
                           
Optional Redemption...  The Senior Notes are not redeemable prior to May 15,
                        1999. On or after May 15, 1999, the Senior Notes are
                        redeemable at the option of the Company, in whole or in
                        part, at the redemption prices set forth herein plus
                        accrued interest to the date of redemption. See "De-
                        scription of the Senior Notes--Optional Redemption."
                            
Mandatory Redemption..  None.
 
Change of Control.....  Upon a Change of Control (as defined herein) and sub-
                        ject to the satisfaction of certain conditions, each
                        holder of Senior Notes may require the Company to re-
                        purchase such Senior Notes at 101% of the principal
                        amount thereof plus accrued interest to the date of re-
                        purchase. See "Description of the Senior Notes--Change
                        of Control."
 
 
                                       5
<PAGE>

Subsidiary             
 Guarantees...........  The Company's obligations under the Senior Notes will
                        be unconditionally guaranteed, jointly and severally,
                        by guarantees (the "Subsidiary Guarantees") provided by
                        each of the Company's direct subsidiaries (the "Guaran-
                        tor Subsidiaries"). Each Subsidiary Guarantee is a se-
                        nior unsecured obligation of the subsidiary providing
                        such Subsidiary Guarantee and ranks pari passu with all
                        other senior unsecured indebtedness of such subsidiary.
                        See "Description of the Senior Notes--Subsidiary Guar-
                        antees."
 
                           
Ranking...............  The Senior Notes will be senior unsecured obligations
                        of the Company, will rank pari passu with other senior
                        unsecured indebtedness of the Company, will rank senior
                        to all present and future subordinated obligations, and
                        will be effectively subordinated to all senior secured
                        obligations of the Company and its subsidiaries. After
                        giving pro forma effect to the Offering and the appli-
                        cation of the net proceeds therefrom as described in
                        "Use of Proceeds," the Company and its subsidiaries on
                        a consolidated basis will have outstanding $5.0 million
                        of unsecured senior indebtedness in addition to the Se-
                        nior Notes and expect to have approximately $11.8 mil-
                        lion of loans outstanding under a $35.0 million Bank
                        Revolver. Following consummation of the Offering, the
                        Company and its subsidiaries will also have the ability
                        to incur additional senior and other indebtedness, and
                        to make additional guarantees, subject to certain limi-
                        tations contained in the Note Indenture (as defined
                        herein). See "Description of the Senior Notes--Rank-
                        ing."     
 
Certain Covenants.....  The indenture under which the Senior Notes will be is-
                        sued (the "Note Indenture") will limit among other
                        things (i) the creation of liens on the assets of the
                        Company and its subsidiaries, (ii) sale/leaseback
                        transactions, (iii) the issuance of additional debt by
                        the Company, (iv) the issuance of debt and preferred
                        stock by the Company's subsidiaries, (v) the payment of
                        dividends on, and redemption of, capital stock of the
                        Company and its subsidiaries and the redemption of cer-
                        tain subordinated obligations of the Company and the
                        making of investments, (vi) the issuance and sale of
                        equity interests of subsidiaries, (vii) sales of as-
                        sets, including subsidiary stock, (viii) restrictions
                        on distributions from subsidiaries, (ix) transactions
                        with affiliates, and (x) consolidations, mergers and
                        transfers of all or substantially all of the Company's
                        assets. However, all of these limitations are subject
                        to a number of important qualifications. See "Descrip-
                        tion of the Senior Notes--Certain Covenants" and "--
                        Successor Company."
                           
Use of Proceeds.......  The net proceeds from the Offering will be used to pre-
                        pay certain of the Company's currently outstanding in-
                        debtedness for borrowed money. See "Use of Proceeds."
                            
                                       6
<PAGE>
 
          SUMMARY CONSOLIDATED HISTORICAL AND PRO FORMA FINANCIAL DATA
 
  The following table presents, for the periods and dates indicated, summary
consolidated historical and pro forma financial data for the Company. Such data
should be read in conjunction with the "Selected Consolidated Financial Data,"
"Management's Discussion and Analysis of Financial Condition and Results of
Operation," and the consolidated financial statements and the related notes
thereto included elsewhere in this Prospectus.
 
<TABLE>
<CAPTION>
                           THREE MONTHS        YEAR ENDED                              YEAR ENDED
                         ENDED MARCH 31,     DECEMBER 31,            TEN-MONTH        FEBRUARY 28,
                         ----------------  ------------------      PERIOD ENDED     ------------------
                          1994     1993      1993      1992    DECEMBER 31, 1991(1)   1991      1990
                         -------  -------  --------  --------  -------------------- --------  --------
                                                  (DOLLARS IN THOUSANDS)
<S>                      <C>      <C>      <C>       <C>       <C>                  <C>       <C>
INCOME STATEMENT DATA:
Revenues................ $51,285  $43,452  $200,114  $176,193        $127,473       $142,906  $131,441
Gross profit............  15,371   15,063    65,589    59,720          41,552         44,178    37,086
Restructuring costs and
 RKI write-off(2).......     --       --        --        --              --          19,898       --
Income (loss) from
 operations.............   2,925    3,224    12,974    14,913          11,095         (7,312)    5,402
Interest expense (net)..   1,819    1,737     7,198     7,064           5,925          6,428     4,585
Net income (loss).......     597      835     3,131     5,075           3,603        (12,632)      695
OTHER DATA:
EBITDA(3)............... $ 5,488  $ 5,687  $ 23,293  $ 23,797        $ 17,696       $ 20,514  $ 12,432
Ratio of EBITDA to
 interest expense(3)....    3.02x    3.27x     3.24x     3.37x           2.99x          3.19x     2.71x
Ratio of earnings to
 fixed charges(4).......    1.50x    1.77x     1.70x     1.89x           1.58x           --        --
Capital expenditures.... $   630  $ 2,179  $  7,874  $  9,815        $  9,531       $  5,300  $ 11,994
Depreciation and
 amortization of
 intangible assets......   2,563    2,463    10,319     8,884           6,601          7,928     7,030
PRO FORMA DATA(5):
Interest expense........ $ 2,072           $  8,449
Ratio of EBITDA to
 interest expense(3)....    2.65x              2.76x
Ratio of earnings to
 fixed charges(4).......    1.32x              1.46x
Ratio of total debt to
 EBITDA.................     --                3.25x
</TABLE>
 
<TABLE>
<CAPTION>
                                                 MARCH 31, 1994
                                              --------------------- DECEMBER 31,
                                               ACTUAL  PRO FORMA(5)     1993
                                              -------- ------------ ------------
<S>                                           <C>      <C>          <C>
BALANCE SHEET DATA:
Working capital.............................. $ 18,694   $ 26,730     $ 18,320
Total assets.................................  164,816    164,816      167,358
Total debt...................................   69,319     71,461       71,424
Total stockholders' equity...................   67,883     66,453       67,371
</TABLE>
- --------
(1) In January 1992, the Company elected to change its fiscal year to coincide
    with the calendar year rather than maintain a February 28 fiscal year end.
    As a result, the Company had a ten-month transition period, from March 1,
    1991 to December 31, 1991, between fiscal years.
(2) In the fall of 1990, the Company abandoned an effort it began in 1987 to
    obtain a permit to install a high temperature rotary kiln incinerator
    ("RKI") at its facility in Braintree, Massachusetts. During its fiscal year
    ended February 28, 1991, the Company wrote off its investment in the
    project and exited certain unprofitable businesses, resulting in
    restructuring charges of $19.9 million.
(3) EBITDA is defined as income from operations before depreciation and
    amortization of intangible assets and the restructuring costs and RKI
    write-off described in note (2). EBITDA is not required by generally
    accepted accounting principles but is presented because it is a widely
    accepted financial indicator of a company's ability to service and incur
    debt. EBITDA should not be considered by an investor as an alternative to
    net income as an indicator of the Company's operating performance or to
    cash flows as a measure of liquidity.
 
                                       7
<PAGE>
 
(4) The ratio of earnings to fixed charges is expressed as the ratio of: (i)
    fixed charges plus income from operations, to (ii) fixed charges. Fixed
    charges consist of interest expense, amortization of deferred financing
    fees and the interest component of operating leases. The pro forma ratio is
    computed in a similar manner. Earnings were insufficient by $14.6 million
    and $1.3 million to cover fixed charges for the fiscal years ended February
    28, 1991 and 1990, respectively.
(5) Gives effect to the sale of the Senior Notes and the application of the net
    proceeds therefrom as described in "Use of Proceeds." Assumes a prepayment
    penalty of $1.0 million and the write-off of deferred financing fees of
    $1.1 million ($1.3 million combined net of tax).
 
                                       8
<PAGE>
 
                                  RISK FACTORS
 
  In addition to the other information set forth in this Prospectus,
prospective purchasers should carefully consider the following factors in
evaluating an investment in the Senior Notes.
 
SIGNIFICANT LEVERAGE
   
  After consummation of the Offering and the application of the net proceeds
therefrom, the Company will have substantial indebtedness. As a result, the
Company will have significant debt service obligations. As of March 31, 1994 on
a pro forma basis the Company would have had total outstanding long-term
indebtedness (including the current portion thereof) of $73.7 million
(including the Senior Notes and excluding the effect of deferred financing fees
of $2.3 million) and stockholders' equity of $66.5 million, resulting in a debt
to equity ratio of 1.1 to 1. See "Capitalization" and "Description of Other
Indebtedness."     
 
  The Company's substantial level of leverage could have important consequences
to the holders of the Senior Notes, including the following: (i) a substantial
portion of the Company's net cash provided by operations will be committed to
the payment of the Company's interest expense and principal repayment
obligations and will not be available to the Company for its operations,
capital expenditures, acquisitions or other purposes; (ii) the Company's
ability to obtain additional financing in the future for working capital,
capital expenditures or acquisitions may be limited; (iii) the Company will be
more highly leveraged than certain of its competitors which may place it at a
competitive disadvantage and limit the Company's flexibility in reacting to
changes in its business; and (iv) the Company's borrowings under its Bank
Revolver are at variable rates of interest, which would result in higher
interest expense in the event of an increase in interest rates. See
"Description of Other Indebtedness" and "Description of the Senior Notes." The
ability of the Company to make scheduled payments or to refinance its
obligations with respect to its indebtedness depends on its financial and
operating performance, which, in turn, is subject to prevailing economic
conditions and to financial, business and other factors beyond its control.
 
LIMITATIONS IMPOSED BY CERTAIN INDEBTEDNESS
 
  The documents governing the indebtedness of the Company expected to be in
effect upon consummation of the Offering (including the Note Indenture and the
Bank Revolver) contain significant covenants that limit the Company's ability
to engage in various transactions and, in certain cases, require satisfaction
of specified financial performance criteria. In addition, under each of the
foregoing documents, the occurrence of certain events (including, without
limitation, failure to comply with the foregoing covenants, material
inaccuracies of representations and warranties, certain defaults under or
acceleration of other indebtedness and events of bankruptcy or insolvency)
would, in certain cases after notice and grace periods, constitute an event of
default permitting acceleration of the indebtedness covered by such documents.
The limitations imposed by such documents are substantial, and failure to
comply with them could have a material adverse effect on the Company. See
"Description of Other Indebtedness" and "Description of the Senior Notes."
 
PLEDGE OF ASSETS
 
  As collateral under the Bank Revolver, the Company and most of its
subsidiaries have granted security interests in substantially all of their
assets to the Company's bank lenders. The stock of the principal subsidiaries
of the Company also has been pledged. The Senior Notes offered hereby are
unsecured obligations of the Company. In the event of bankruptcy or liquidation
of the Company, there can be no assurance that sufficient assets would be
available for payment of the Senior Notes.
 
                                       9
<PAGE>
 
The Note Indenture limits, but does not prohibit, the incurrence of secured
indebtedness by the Company and its subsidiaries. See "Description of Other
Indebtedness" and "Description of the Senior Notes."
 
FRAUDULENT CONVEYANCE CONSIDERATIONS
 
  The incurrence by the Company and the Guarantor Subsidiaries of indebtedness
under the Senior Notes and the Subsidiary Guarantees may be subject to review
under relevant federal and state fraudulent conveyance laws if a bankruptcy
case or a lawsuit (including in circumstances where bankruptcy is not involved)
were commenced by or on behalf of unpaid creditors of the Company or the
Guarantor Subsidiaries. Under these laws, a "fraudulent conveyance" would be
deemed to have occurred with respect to the Company or a Guarantor Subsidiary
if at the time the Senior Notes or the Subsidiary Guarantee of such entity were
issued, both: (1) either (a) the Company or such Guarantor Subsidiary incurred
debt represented by the Senior Notes or such Subsidiary Guarantee with the
intent of hindering, delaying or defrauding creditors, or (b) the Company or
such Guarantor Subsidiary received less than reasonably equivalent value or
consideration for incurring the indebtedness represented by the Senior Notes or
such Subsidiary Guarantee; and (2) the Company or such Guarantor Subsidiary
either (i) was insolvent or was rendered insolvent by reason of such
transaction, (ii) was engaged in a business or transaction for which the assets
remaining with such entity constituted unreasonably small capital, or (iii)
intended to incur, or believed that it would incur, debts beyond its ability to
pay such debts as they matured. If a court were to find that the Company or a
Guarantor Subsidiary had effected a "fraudulent conveyance" by issuing the
Senior Notes or a Subsidiary Guarantee, such court might subordinate the Senior
Notes or such Subsidiary Guarantee to presently existing and future
indebtedness of such entity, void the issuance of the Senior Notes or such
Subsidiary Guarantee, direct the repayment of any amounts paid thereunder to
such entity or to a fund for the benefit of such entity's creditors, or take
other action detrimental to the holders of the Senior Notes.
 
  The measure of insolvency for purposes of the foregoing would vary depending
upon the law of the relevant jurisdiction. Generally, however, the Company or a
Guarantor Subsidiary would be considered insolvent for purposes of the
foregoing if the sum of such entity's debts were greater than all of such
entity's property at a fair valuation, or if the present fair saleable value of
such entity's assets were less than the amount that would be required to pay
its probable liability on its existing debts as they become absolute and
matured.
 
  The Company and the Guarantor Subsidiaries believe they will receive
equivalent value at the time the indebtedness represented by the Senior Notes
and the Subsidiary Guarantees is incurred. In addition, neither the Company nor
any of the Guarantor Subsidiaries believes that it, as a result of the issuance
of the Senior Notes or the Subsidiary Guarantees, (i) will be insolvent or
rendered insolvent under the foregoing standards, (ii) will be engaged in a
business or transaction for which its remaining assets constitute unreasonably
small capital, or (iii) intends to incur, or believes that it will incur, debts
beyond its ability to pay such debts as they mature. These beliefs are based on
the Company's and the Guarantor Subsidiaries' operating history, net worth and
management's analysis of internal cash flow projections and estimated values of
assets and liabilities of each entity at the time of the Offering. There can be
no assurance, however, that a court passing on these issues would make the same
determination.
 
  As a result of the obligations of the Company and the Guarantor Subsidiaries
in connection with the Note Indenture, the Senior Notes and the Subsidiary
Guarantees, in the event of an insolvency proceeding of the Company, creditors
of the Company might argue that, because the Guarantor Subsidiaries are
affiliates of the Company and "insiders" within the context of the federal
insolvency laws, the preference period under the Federal Bankruptcy Code should
be extended from 90 days to one year. This argument, if successful, could have
an adverse effect on the holders of the Senior
 
                                       10
<PAGE>
 
Notes with respect to interest and principal payments received during the
preference period. In an attempt to avoid this result, the Guarantor
Subsidiaries have waived in the Note Indenture any rights of subrogation or
contribution against the Company, but there is no controlling legal precedent
that assures that this attempt would be successful if challenged by other
unpaid creditors of the Company.
 
HOLDING COMPANY STRUCTURE
 
  As a holding company, Clean Harbors, Inc., derives substantially all of its
operating income and cash flow from its subsidiaries. The Company's ability to
make required principal and interest payments with respect to its indebtedness,
including the Senior Notes, depends on the earnings of its subsidiaries through
inter-company payments. The ability of the Company's subsidiaries to make such
payments will be subject to, among other limitations, applicable state laws and
restrictions that may be entered into by such subsidiaries. The Note Indenture
will, however, require Clean Harbors, Inc. to prohibit its subsidiaries from
agreeing to certain restrictions on distributions to the Company. See
"Description of the Senior Notes--Certain Covenants--Limitation on Restrictions
on Distributions from Subsidiaries."
 
  Substantially all of the Company's operations are conducted, and
substantially all of its assets are owned, by its subsidiaries. The Senior
Notes will be guaranteed by all of the Company's direct subsidiaries under the
Subsidiary Guarantees. However, in the event such Subsidiary Guarantees were
held to be invalid as "fraudulent conveyances", the Senior Notes would
effectively be subordinated to all existing and future liabilities of the
Company's subsidiaries, including the obligations of most of the Company's
subsidiaries with respect to indebtedness incurred under the Bank Revolver. Any
right of Clean Harbors, Inc. to participate in any distribution of the assets
of any of the Company's subsidiaries upon the subsidiary's liquidation,
reorganization or insolvency (and the consequent right of the holders of the
Senior Notes to participate in the distribution of those assets) would then be
subject to the claims of the creditors (including trade creditors) of such
subsidiary, except to the extent Clean Harbors, Inc. has a valid claim against
such subsidiary as a creditor of such subsidiary. The ability of subsidiaries
to incur indebtedness and to guarantee debt will, however, be limited by
certain of the restrictive covenants in the Note Indenture and the Bank
Revolver. See "Description of Other Indebtedness" and "Description of the
Senior Notes--Certain Covenants--Limitation on Subsidiary Debt and Preferred
Stock."
 
POTENTIAL LIABILITIES ARISING OUT OF ENVIRONMENTAL LAWS AND REGULATIONS
 
  Although the Company believes that it generally benefits from increased
environmental regulations and from enforcement of those regulations, increased
regulation and enforcement also create significant risks for the Company. The
assessment, analysis, remediation, transportation, handling and management of
hazardous substances necessarily involve significant risks, including the
possibility of damages or personal injuries caused by the escape of hazardous
materials into the environment, and the possibility of fines, penalties or
other regulatory action. These risks include potentially large civil and
criminal liabilities to customers and to third parties for damages arising from
performing services for customers. See "Environmental Regulation."
 
  All facets of the Company's business are conducted in the context of a
rapidly developing and changing statutory and regulatory framework. The
Company's operations and services are affected by and subject to regulation by
a number of federal agencies including the Environmental Protection Agency (the
"EPA") and the Occupational Safety and Health Administration, as well as
applicable state and local regulatory agencies.
 
  The Comprehensive Environmental Response, Compensation and Liability Act of
1980, as amended (the "Superfund Act"), addresses the cleanup of sites at which
there has been a release or threatened release of hazardous substances into the
environment. Increasingly, there are efforts to
 
                                       11
<PAGE>
 
expand the reach of the Superfund Act to make hazardous waste management
companies responsible for cleanup costs of Superfund sites not owned or
operated by such management companies by claiming that such management
companies are "owners" or "operators" (as those terms are defined in the
Superfund Act) of such sites or that such management companies arranged for
"treatment, transportation or disposal" (as those terms are defined in the
Superfund Act) of hazardous substances to or in such sites. Several recent
court decisions have accepted such claims. Should the Company be held
responsible under the Superfund Act for cleanup costs as a result of performing
services or otherwise, it might be forced to bear significantly more than its
proportional share of such cleanup costs if other responsible parties do not
pay their share. See "Business--Legal Proceedings."
 
  The Resource Conservation and Recovery Act of 1976, as amended in 1984
("RCRA"), is the principal federal statute governing hazardous waste
generation, treatment, transportation, storage and disposal. RCRA or EPA
approved state programs at least as stringent govern waste handling activities
involving wastes classified as "hazardous." See "Environmental Regulation--
Federal Regulation of Hazardous Wastes." Substantial fees and penalties may be
imposed under RCRA and similar state statutes for any violation of such
statutes and regulations thereunder.
 
POTENTIAL LIABILITIES INVOLVING CUSTOMERS AND THIRD PARTIES
 
  In performing services for its customers, the Company potentially could be
liable for breach of contract, personal injury, property damage (including
environmental impairment), and negligence, including claims for lack of timely
performance or for failure to deliver the service promised (including improper
or negligent performance or design, failure to meet specifications, and
breaches of express or implied warranties). The damages available to a client,
should it prevail in its claims, are potentially large and could include
consequential damages.
 
  Industrial waste management companies, in connection with work performed for
customers, also potentially face liabilities to third parties from various
claims including claims for property damage or personal injury stemming from a
release of hazardous substances or otherwise. Claims for damage to third
parties could arise in a number of ways, including: through a sudden and
accidental release or discharge of contaminants or pollutants during
transportation of wastes or the performance of services; through the inability,
despite reasonable care, of a remedial plan to contain or correct an ongoing
seepage or release of pollutants; through the inadvertent exacerbation of an
existing contamination problem; or through reliance on reports prepared by such
waste management companies. Personal injury claims could arise
contemporaneously with performance of the work or long after completion of
projects as a result of alleged exposure to toxic or hazardous substances. In
addition, increasing numbers of claimants assert that companies performing
environmental remediation should be adjudged strictly liable for damages even
though their services were performed using reasonable care, on the grounds that
such services involved "abnormally dangerous activities."
 
  Customers of industrial waste management companies frequently attempt to
shift various of the liabilities arising out of disposal of their wastes or
remediation of their environmental problems to contractors through contractual
indemnities. Such provisions seek to require the contractors to assume
liabilities for damage or personal injury to third parties and property and for
environmental fines and penalties (including potential liabilities for cleanup
costs arising under the Superfund Act). Moreover, the EPA has increasingly
constricted the circumstances under which it will indemnify its contractors
against liabilities incurred in connection with cleanup of Superfund sites.
There are other proposals both in Congress and at the regulatory agencies to
further restrict indemnification of contractors from third party claims. While
such restrictions might have some adverse impact upon the Company, such impact
should be immaterial because projects relating to the cleanup of Superfund
sites have historically represented less than 5% of the Company's business. See
"Business--Services."
 
                                       12
<PAGE>
 
  Although the Company attempts to investigate thoroughly each other company
that it acquires, there may be liabilities that the Company fails or is unable
to discover, including liabilities arising from non-compliance with
environmental laws by prior owners, and for which the Company, as a successor
owner, might be responsible. The Company seeks to minimize the impact of these
liabilities by obtaining indemnities and warranties from sellers of companies
which may be supported by deferring payment of or by escrowing a portion of the
purchase price. However, these indemnities and warranties, if obtained, may not
fully cover the liabilities due to their limited scope, amounts, or duration,
the financial limitations of the indemnitors or warrantors or other reasons.
See "Business--Legal Proceedings."
 
COMPETITION
 
  The market for industrial waste management services is highly competitive.
The Company competes with many other firms, including large multinational firms
having substantially greater financial, management and marketing resources than
the Company. Competitive factors include quality of services, technical
qualifications, reputation, geographic presence, price and the availability of
key professional personnel. See "Business--Competition."
 
FLUCTUATIONS IN QUARTERLY FINANCIAL RESULTS; SEASONALITY
 
  The Company's operations may be affected by the commencement and completion
of major site remediation projects, seasonal fluctuations due to weather and
budgetary cycles influencing the timing of customers' spending for remedial
activities, and the timing of regulatory decisions relating to hazardous waste
management projects. Accordingly, fluctuations in quarterly performance should
be expected. See "Management's Discussion and Analysis of Financial Condition
and Results of Operations--Results of Operations."
 
DEPENDENCE ON KEY OFFICERS
 
  The Company is dependent upon the services of several of its key officers,
particularly its Chairman, President and Chief Executive Officer, Alan S.
McKim, the loss of any of whom could have a material adverse effect on the
Company.
 
CHANGE OF CONTROL PROVISIONS WITH RESPECT TO THE SENIOR NOTES
 
  In the event of a Change of Control (as defined herein), the Company would be
required, subject to certain conditions, to offer to purchase all outstanding
Senior Notes at a price equal to 101% of the principal amount thereof, plus
accrued interest thereon. There can be no assurance that, at the time of a
Change of Control, the Company would have sufficient cash to repay all amounts
due under the Senior Notes. The terms of the Bank Revolver prohibit the
optional payment or prepayment or any redemption of the Senior Notes. If,
following a Change of Control, the Company has insufficient funds to purchase
all the Senior Notes tendered pursuant to such an offer, or is prohibited from
purchasing the Senior Notes pursuant to the terms of the Bank Revolver or other
agreements, an event of default in respect of the Senior Notes would occur.
 
ABSENCE OF PUBLIC MARKET FOR THE SENIOR NOTES
 
  The Senior Notes will constitute a new issue of securities with no
established trading market. The Company does not intend to list the Senior
Notes on any national securities exchange or to seek the admission thereof to
trading in the National Association of Securities Dealers Automated Quotation
System. The Underwriters have advised the Company that they currently intend to
make a market in the Senior Notes, but they are not obligated to so do and may
discontinue such market activity at any time. In addition, such market making
activity will be subject to the limits imposed by the Securities Act of 1933,
as amended (the "Securities Act"). Accordingly, no assurance can be given that
an active public or other market will develop for the Senior Notes or as to the
liquidity of the trading market for the Senior Notes. If a trading market does
not develop or is not maintained, holders of the Senior Notes may experience
difficulty in reselling the Senior Notes or may be unable to sell them at all.
Future trading prices of such securities will depend on many factors,
including, among other things, prevailing interest rates, the Company's results
of operations and the market for similar securities.
 
                                       13
<PAGE>
 
                                USE OF PROCEEDS
   
  The net proceeds to the Company from the sale of the Senior Notes offered
hereby are estimated to be approximately $47.8 million after deduction of
underwriting discounts and estimated expenses. The Company intends to use such
net proceeds as follows:     
 
<TABLE>
<CAPTION>
   USE                                                        AMOUNT OF PROCEEDS
   ---                                                        ------------------
                                                                (IN MILLIONS)
   <S>                                                        <C>
   Prepay in full outstanding 13.25% senior subordinated
    notes(1)................................................        $23.5
   Prepay a portion of the outstanding balance under the
    Bank
    Revolver(2).............................................         21.8
   Prepay in full certain other outstanding indebtedness(3).          2.5
                                                                    -----
       Total................................................        $47.8
</TABLE>
- --------
(1) These notes have a final maturity of May 15, 1997, and bear interest at
    the rate of 13.25%. The amount of proceeds shown includes prepayment
    penalties of approximately $1.0 million.
   
(2) The amount outstanding as of June 30, 1994 was approximately $33.6
    million. The Bank Revolver has a final maturity of July 1, 1996, and as of
    June 30, 1994 bore interest at an average rate of 7.5%. See "Description
    of Other Indebtedness."     
(3) Such indebtedness has final maturities ranging from April 30, 1996 to
    December 31, 1997, and currently bears interest from 8.25% to 12.75%.
       
  Pending the application of the net proceeds of the Offering to the uses
described above, the Company intends to invest such net proceeds in
investment-grade, short-term, interest-bearing securities.
 
                                      14
<PAGE>
 
                                CAPITALIZATION
 
  The following table sets forth the short-term debt and capitalization of the
Company at March 31, 1994, and the pro forma capitalization of the Company as
of such date as adjusted to give effect to the sale of the Senior Notes being
offered hereby and the application of the estimated net proceeds to the
Company. See "Use of Proceeds." This table should be read in conjunction with
the consolidated financial statements of the Company and the related notes
included elsewhere in this Prospectus.
<TABLE>
<CAPTION>
                                                          MARCH 31, 1994
                                                      -------------------------
                                                        ACTUAL      PRO FORMA
                                                      -----------  ------------
                                                      (DOLLARS IN THOUSANDS)
<S>                                                   <C>          <C>
Current portion of long-term debt:
  13.25% senior subordinated notes(1)................ $     7,500  $       --
  Junior subordinated note...........................         377          377
  Other..............................................       1,021          232
                                                      -----------  -----------
                                                      $     8,898  $       609
                                                      ===========  ===========
Long-term debt (excluding current portion):
  Bank Revolver(1)................................... $    31,005  $    16,964
  Senior Notes.......................................         --        50,000
  10.0% senior convertible notes.....................       5,000        5,000
  13.25% senior subordinated notes...................      22,500          --
  Junior subordinated note...........................         847          847
  Other..............................................       2,177          291
  Deferred financing fees............................      (1,108)      (2,250)
                                                      -----------  -----------
    Total long-term debt (excluding current portion). $    60,421  $    70,852
Stockholders' equity:
  Preferred stock, Series B convertible; authorized--
   156,416 shares; issued and outstanding--112,000
   shares (liquidation preference of $5.6 million)... $         1  $         1
  Common stock; authorized--20,000,000 shares; issued
   and outstanding--9,428,504 shares.................          95           95
  Additional paid-in capital.........................      58,576       58,576
  Retained earnings..................................       9,211        7,781
                                                      -----------  -----------
    Total stockholders' equity....................... $    67,883  $    66,453
                                                      -----------  -----------
    Total capitalization............................. $   128,304  $   137,305
                                                      ===========  ===========
</TABLE>
- --------
(1) On May 15, 1994, the Company prepaid the $7.5 million current portion of
    the 13.25% senior subordinated notes by increasing its borrowings under
    the Bank Revolver by a corresponding amount.
 
                                      15
<PAGE>
 
                     SELECTED CONSOLIDATED FINANCIAL DATA
 
  In January 1992, the Company elected to change its fiscal year to coincide
with the calendar year rather than maintain a February 28 fiscal year end. As
a result, the Company had a ten-month transition period, from March 1, 1991 to
December 31, 1991, between fiscal years. Set forth below are income statement
and balance sheet data for the Company which should be read in conjunction
with the consolidated financial statements and notes thereto included
elsewhere in this Prospectus. In the opinion of management, the interim
financial statements include all adjustments, consisting only of normal
recurring adjustments, necessary for a fair presentation of the results for
such interim period.
 
<TABLE>
<CAPTION>
                           THREE MONTHS        YEAR ENDED                        YEAR ENDED
                          ENDED MARCH 31,     DECEMBER 31,        TEN-MONTH     FEBRUARY 28,
                          ----------------  ------------------  PERIOD ENDED  ------------------
                           1994     1993      1993      1992    DEC. 31, 1991   1991      1990
                          -------  -------  --------  --------  ------------- --------  --------
                                               (DOLLARS IN THOUSANDS)
<S>                       <C>      <C>      <C>       <C>       <C>           <C>       <C>
INCOME STATEMENT DATA:
Revenues................  $51,285  $43,452  $200,114  $176,193    $127,473    $142,906  $131,441
Cost of revenues........   35,914   28,389   134,525   116,473      85,921      98,728    94,355
                          -------  -------  --------  --------    --------    --------  --------
Gross profit............   15,371   15,063    65,589    59,720      41,552      44,178    37,086
Restructuring costs and
 RKI
 write-off (1)..........      --       --        --        --          --       19,898       --
Selling, general and
 administrative
 expenses...............    9,883    9,376    42,296    35,923      23,856      23,664    24,654
Depreciation and
 amortization of
 intangible assets......    2,563    2,463    10,319     8,884       6,601       7,928     7,030
                          -------  -------  --------  --------    --------    --------  --------
Income (loss) from oper-
 ations.................    2,925    3,224    12,974    14,913      11,095      (7,312)    5,402
Interest expense (net)..    1,819    1,737     7,198     7,064       5,925       6,428     4,585
                          -------  -------  --------  --------    --------    --------  --------
Income (loss) before
 provision for income
 taxes..................    1,106    1,487     5,776     7,849       5,170     (13,740)      817
Provision (benefit) for
 income taxes...........      509      652     2,645     2,774       1,567      (1,108)      122
                          -------  -------  --------  --------    --------    --------  --------
Net income (loss).......  $   597  $   835  $  3,131  $  5,075    $  3,603    $(12,632) $    695
Net income (loss) per
 common and common
 equivalent share.......      .05      .08       .28       .52         .37       (1.40)      .08
OTHER DATA:
EBITDA(2)...............  $ 5,488  $ 5,687  $ 23,293  $ 23,797    $ 17,696    $ 20,514  $ 12,432
Ratio of EBITDA to
 interest expense(2)....     3.02x    3.27x     3.24x     3.37x       2.99x       3.19x     2.71x
Ratio of earnings to
 fixed charges(3).......     1.50x    1.77x     1.70x     1.89x       1.58x        --        --
Capital expenditures....  $   630  $ 2,179  $  7,874  $  9,815    $  9,531    $  5,300  $ 11,994
Depreciation and
 amortization of
 intangible assets......    2,563    2,463    10,319     8,884       6,601       7,928     7,030
</TABLE>
 
<TABLE>
<CAPTION>
                             MARCH 31,            DECEMBER 31,          FEBRUARY 28,
                         ----------------- -------------------------- -----------------
                           1994     1993     1993     1992     1991     1991     1990
                         -------- -------- -------- -------- -------- -------- --------
<S>                      <C>      <C>      <C>      <C>      <C>      <C>      <C>
BALANCE SHEET DATA:
Working capital (defi-
 cit)................... $ 18,694 $ 17,976 $ 18,320 $ 15,487 $ 14,529 $ 12,850 $ (3,451)
Total assets............  164,816  160,720  167,358  153,939  138,844  135,881  156,449
Long-term debt, less
 current portion........   60,421   66,942   62,507   64,565   63,381   62,645   51,932
Total stockholders' eq-
 uity...................   67,883   65,189   67,371   58,065   50,787   46,776   59,331
</TABLE>
- --------
(1) In the fall of 1990, the Company abandoned an effort it began in 1987 to
    obtain a permit to install a high temperature rotary kiln incinerator
    ("RKI") at its facility in Braintree, Massachusetts. During its fiscal
    year ended February 28, 1991, the Company wrote off its investment in the
    project and exited certain unprofitable businesses, resulting in
    restructuring charges of $19.9 million.
(2) EBITDA is defined as income from operations before depreciation and
    amortization of intangible assets and the restructuring costs and RKI
    write-off described in note (1). EBITDA is not required by generally
    accepted accounting principles but is presented because it is a widely
    accepted financial indicator of a company's ability to service and incur
    debt. EBITDA should not be considered by an investor as an alternative to
    net income as an indicator of the Company's operating performance or to
    cash flows as a measure of liquidity.
(3) The ratio of earnings to fixed charges is expressed as the ratio of: (i)
    fixed charges plus income from operations, to (ii) fixed charges. Fixed
    charges consist of interest expense, amortization of deferred financing
    fees and the interest component of operating leases. Earnings were
    insufficient by $14.6 million and $1.3 million to cover fixed charges for
    the fiscal years ended February 28, 1991 and 1990, respectively.
 
                                      16
<PAGE>
 
   MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF
                                   OPERATIONS
 
GENERAL
 
  The Company has analyzed its results of operations to reflect the
geographical locations of its service centers. The Company believes this method
of analysis is appropriate because geographical areas differ in types of
customers; the scope and maturity of the Company's operations; the Company's
investments in facilities and the number of service centers and sales offices;
degree of competition; and local economic and regulatory conditions.
 
  As part of its growth strategy, the Company seeks to expand into additional
service areas by opening new service centers and sales offices, and by
acquiring additional hazardous waste management facilities. In 1992, the
Company made two acquisitions (Connecticut Treatment Corporation and Mr. Frank,
Inc.). During the first half of 1993, the Company made one acquisition (Spring
Grove Resource Recovery, Inc.) and opened nine sales offices and a service
center in Waukegan, Illinois. During the third quarter of 1993, as part of its
efforts to consolidate its gains in market share and focus on areas where the
Company has obtained substantial business, the Company closed two of the nine
new sales offices (in Detroit, Michigan and Kansas City, Missouri), while
opening another sales office (in Buffalo, New York) and a new service center in
Portsmouth, New Hampshire. In July 1994, the Company opened an additional
service center in Lake Charles, Louisiana.
   
  Sales offices may become service centers as business around a sales office
develops and the Company adds staff and equipment to support the increasing
level of business. During the first quarter of 1994, the Company's sales office
in St. Louis, Missouri became a service center, by relocating to larger space
and adding field technicians and personnel to service customers. Also during
the quarter, the Company relocated its sales personnel from its sales office in
Newburgh, New York to other sales locations. The Company now has 22 service
centers and eight sales offices. As its sales territories evolve, the Company
will relocate sales personnel from one area to another. For example, the
Company plans to relocate its sales personnel from Minneapolis, Minnesota and
Columbus, Ohio to other territories, and to relocate other personnel to new
sales locations in Georgia, South Carolina, Tennessee and Texas during the
third quarter of 1994.     
 
  During 1993, the Company's cost of revenues increased to 67.2% of revenues,
as compared to 66.1% of revenues in 1992. During the first quarter of 1994, the
Company's cost of revenues increased to 70.0% of revenues, as compared to 65.3%
for the first quarter of 1993. Although the Company's total revenues increased
from $176,193,000 in 1992 to $200,114,000 in 1993, and from $43,452,000 in the
first quarter of 1993 to $51,285,000 in the first quarter of 1994, this
increase was less than the Company had anticipated at the beginning of 1993
primarily because of intense price competition for industrial waste management
services which developed during 1993.
 
  In August 1993, the Company began a company-wide reengineering program to
improve gross margins by increasing the ratio of billable to nonbillable
personnel, improving bidding and execution of jobs, improving the pricing of
remediation work, and declining jobs with less than acceptable margins. At
March 31, 1994, the Company had 1,459 regular employees (compared to 1,533 at
September 30, 1993), and approximately 58% of its workforce at March 31, 1994
was billable personnel (compared to 57% at September 30, 1993). As part of the
reengineering program, the Company has also implemented a new computerized
service center job margin system, which allows daily tracking of margins on all
work orders executed each month. Cost control efforts continue as the Company
attempts to utilize its own resources more efficiently and reduce expenses paid
to outside vendors for lab work, subcontract work, transportation and disposal.
 
                                       17
<PAGE>
 
  The Company does not foresee further deterioration in gross margins in the
near future. However, the various factors affecting its revenues and costs
described above are expected to continue through 1994.
 
  Primarily as a result of the reengineering program described above, selling,
general and administrative expenses were reduced to below 20% of revenues in
the first quarter of 1994. Management of the Company is determined to continue
to hold costs at no more than that level and to improve productivity in order
to offset the deterioration in gross margins caused by the current pricing
environment.
 
RESULTS OF OPERATIONS
 
  The following table sets forth for the periods indicated certain operating
data associated with the Company's results of operations.
 
<TABLE>
<CAPTION>
                                        PERCENTAGE OF TOTAL REVENUES
                         ----------------------------------------------------------
                         THREE MONTHS  TWELVE-MONTH                 TWELVE-MONTH
                             ENDED      YEAR ENDED    TEN-MONTH   FISCAL YEAR ENDED
                           MARCH 31,   DECEMBER 31,  PERIOD ENDED   FEBRUARY 28,
                         ------------- ------------- DECEMBER 31, -----------------
                          1994   1993   1993   1992      1991      1991    1990
                         ------ ------ ------ ------ ------------ ------  ------
<S>                      <C>    <C>    <C>    <C>    <C>          <C>     <C>    
Revenues................ 100.0% 100.0% 100.0% 100.0%    100.0%    100.0%  100.0%
Cost of revenues:
  Disposal costs paid to
   third parties........  12.8   15.7   15.4   18.2      20.6      17.7    17.3
  Other costs...........  57.2   49.6   51.8   47.9      46.8      51.4    54.5
                         ------ ------ ------ ------    ------    ------  ------
    Total cost of
     revenues...........  70.0   65.3   67.2   66.1      67.4      69.1    71.8
Restructuring costs.....    --     --     --     --        --      13.9      --
Selling, general and
 administrative
 expenses...............  19.3   21.6   21.1   20.4      18.7      16.6    18.8
Depreciation and
 amortization of
 intangible assets .....   5.0    5.7    5.2    5.0       5.2       5.5     5.3
                         ------ ------ ------ ------    ------    ------  ------
Income (loss) from
 operations.............   5.7    7.4    6.5    8.5       8.7      (5.1)    4.1
Interest expense (net)..   3.5    4.0    3.6    4.0       4.7       4.5     3.5
                         ------ ------ ------ ------    ------    ------  ------
  Income (loss) before
   provision for income
   taxes................   2.2    3.4    2.9    4.5       4.0      (9.6)    0.6
Provision (benefit) for
 income taxes...........   1.0    1.5    1.3    1.6       1.2      (0.8)    0.1
                         ------ ------ ------ ------    ------    ------  ------
  Net income (loss).....   1.2%   1.9%   1.6%   2.9%      2.8%     (8.8)%   0.5%
</TABLE>
 
  The Company's operations are subject to seasonal fluctuations. Typically
during the first quarter there is less demand for environmental remediation due
to the cold weather, particularly in the Northeast and Midwest regions. In
addition, factory closings for the year-end holidays reduce the volume of
industrial waste generated, which results in lower volumes of waste handled by
the Company during the first quarter of the following year. Customer spending
for environmental remediation services is also influenced by budgetary cycles
and constraints, and remediation projects are typically fewer in the first
quarter of the budget year, with more projects occurring in subsequent quarters
as customers seek to complete budgeted projects before the end of the year.
 
                                       18
<PAGE>
 
  The following table sets forth for the periods indicated the Company's
revenues by region, based upon the locations of its 21 service centers as of
March 31, 1994.
 
<TABLE>
<CAPTION>
                         NUMBER OF THREE MONTHS ENDED MARCH 31,    YEAR ENDED DECEMBER 31,
                          SERVICE  ---------------------------------------------------------
REGION                    CENTERS       1994           1993          1993          1992
- ------                   --------- ------------------------------------------- -------------
                                                    (DOLLARS IN THOUSANDS)
<S>                      <C>       <C>      <C>   <C>      <C>   <C>      <C>  <C>      <C>
Northeast...............      8    $ 17,216   34% $ 18,506   43% $ 84,906  42% $ 77,872  44%
Mid-Atlantic............      7      21,382   42%   14,047   32%   63,894  32%   55,317  31%
Central.................      3       6,413   12%    5,583   13%   26,044  13%   22,240  13%
Midwest.................      3       6,274   12%    5,316   12%   25,270  13%   20,764  12%
                            ---    -------- ----- -------- ----- -------- ---- -------- ----
                             21    $ 51,285  100% $ 43,452  100% $200,114 100% $176,193 100%
</TABLE>
 
  Beginning in 1993, the Company also began to analyze its revenues on a
product line basis based upon the type of principal services provided. The
principal services provided by the Company fit within three categories:
treatment and disposal of industrial wastes ("Treatment and Disposal"); field
services provided at customer sites ("Field Services"); and specialized
repackaging, treatment and disposal services for laboratory chemicals and
household hazardous wastes ("LabPacks"). The following table sets forth such
product line data for the periods indicated. Comparable data for prior periods
is not available.
 
<TABLE>
<CAPTION>
                                     THREE MONTHS ENDED MARCH
                                                31,
                                     -------------------------    YEAR ENDED
TYPE OF SERVICE                          1994         1993     DECEMBER 31, 1993
- ---------------                      ------------ ------------ -------------------
                                               (DOLLARS IN THOUSANDS)
<S>                                  <C>     <C>  <C>     <C>  <C>        <C>
Treatment and Disposal.............. $18,974  37% $20,671  47% $   90,181    45%
Field Services......................  25,591  50%  17,220  40%     80,940    40%
LabPacks............................   6,720  13%   5,561  13%     28,993    15%
                                     ------- ---- ------- ---- ---------- ------
                                     $51,285 100% $43,452 100% $  200,114   100%
</TABLE>
 
THREE MONTHS ENDED MARCH 31, 1994 COMPARED TO THREE MONTHS ENDED MARCH 31, 1993
 
  Revenues. Revenues for the first quarter of 1994 increased 18% to
$51,285,000, from revenues of $43,452,000 in the first quarter of the prior
year. Combined revenues of the Mid-Atlantic, Midwest, and Central regions grew
37%, offsetting a 7% decline in the Northeast region, which was particularly
hard-hit by winter weather in 1994. The Mid-Atlantic region includes the
Company's service center in Puerto Rico, which had approximately $7 million of
revenue during the first quarter of 1994 from the clean-up of the oil spill
from a barge off the coast of Puerto Rico.
 
  For the first quarter of 1994, Treatment and Disposal comprised 37% of total
revenues, while Field Services comprised 50% and LabPacks comprised 13%. For
the first quarter of 1993, Treatment and Disposal comprised 47% of total
revenues, while Field Services comprised 40% and LabPacks comprised 13%. The
increase in Field Services in the first quarter of 1994 was due primarily to
the impact of the Puerto Rico oil spill. Without such spill, the revenues by
product line would have been 43% for Treatment and Disposal; 42% for Field
Services; and 15% for LabPacks.
 
  The severe winter weather adversely impacted operations throughout the
Company's service territory in January and February, causing business to be
postponed or canceled. Although the weather caused a shortfall in revenue from
its base business in January and February, the Company believes some of the
postponed business was realized in March, since overall business in March was
better than planned. The Company was also able during the quarter to reallocate
its resources to facilitate the emergency response in Puerto Rico.
 
  Cost of Revenues. For the three months ended March 31, 1994, the cost of
revenues as a percentage of revenues increased to 70.0% as compared to 65.3%
for the same period of the prior year, reflecting the competitive pricing
trends in the hazardous waste industry. However, the first quarter's cost of
revenues as a percentage of revenues was the same as it was for the preceding
 
                                       19
<PAGE>
 
quarter ended December 31, 1993. Despite the bad weather during January and
February, the Company realized a slight gross margin improvement in its base
business from the fourth quarter of 1993. The gross margin on the revenue from
the Puerto Rico oil spill was substantially below the gross margin on the
Company's base business, since most of the labor involved in the spill cleanup
was subcontracted locally for the project as required by local law. The cost of
revenues as a percentage of total revenues would have been 69.1% without the
Puerto Rico spill. The Company managed to utilize resources efficiently and
control costs during the quarter, so that profitability did not suffer.
 
  One of the largest components of cost of revenues is the cost of sending
waste to other companies for disposal. Internal waste disposal capabilities
have expanded as a result of continued modifications and upgrades at the
Company's facilities, and acquisitions of facilities with waste treatment
systems not found at other Company plants. For example, in February 1993, the
Company acquired Spring Grove Resource Recovery, Inc., the operator of a
hazardous waste management facility in Cincinnati, Ohio ("Spring Grove"), which
provides hazardous wastewater treatment and pretreatment of waste to stabilize
it before it is sent to landfills. The Company continues to benefit from a
competitive pricing environment among disposal vendors, such as landfills and
incinerators, to whom the Company sends waste for ultimate disposal. As a
result, the Company's outside disposal costs decreased to 12.8% of revenues in
the first quarter of 1994 (calculated excluding revenue from the Puerto Rico
oil spill), from 15.7% of revenues in the first quarter of 1993.
 
  Selling, General and Administrative Expenses. Selling, general and
administrative expenses for the three months ended March 31, 1994 decreased to
19.3% of revenues as compared to 21.6% for the three months ended March 31,
1993. This decrease is primarily due to the reengineering program begun in
August 1993, which focuses on improving productivity and the ratio of billable
to nonbillable staff. See "General" above. Since June 30, 1993, the Company has
reduced its nonbillable staff by 13%, while increasing its billable staff by
2%. The Company has managed to reduce its payroll base 6% since June 30, 1993,
and improve its ratio of billable to nonbillable staff. At March 31, 1994, the
Company had 1,459 regular employees; approximately 58% of its workforce was
billable personnel, compared to 54% at June 30, 1993. Management of the Company
has accomplished the goal it set in August 1993 of driving selling, general and
administrative costs to below 20% of revenues.
 
  Interest Expense. Interest expense for the three month periods ended March
31, 1994 and March 31, 1993 was $1,819,000 and $1,737,000, respectively. No
interest was capitalized during either quarter. Approximately half of the
Company's debt outstanding as of March 31, 1994 consisted of amounts drawn
under its Bank Revolver. Interest on amounts outstanding under the Bank
Revolver are payable monthly in arrears and accrue at The First National Bank
of Boston's base rate plus 1%, or at the Company's option, at a rate which is
3% over the "Eurodollar Rate" offered to the bank by prime banks in the
Eurodollar interbank market. At May 31, 1994, the Company had elected the
Eurodollar option with respect to $32,000,000 of the amounts outstanding under
the Bank Revolver; the Eurodollar Rate was 4.38% and the bank's base rate was
7.25%. See "Liquidity and Capital Resources" below.
 
  Income Taxes. The effective income tax rate for the first quarter of 1994 was
46%, as compared to 44% in the first quarter of 1993. The effective rates are
higher than the combined state and federal statutory rates due in part to the
amortization of goodwill for accounting purposes, which is nondeductible for
income tax reporting purposes. The effective rate fluctuates depending on the
amount of goodwill amortization and other nondeductible amounts as compared to
income before taxes. The Company expects its effective income tax rate for 1994
to be approximately 46%.
 
                                       20
<PAGE>
 
1993 COMPARED WITH 1992
 
  Revenues. Revenues for 1993 were $200,114,000, a 13.6% increase over 1992
revenues of $176,193,000. As shown in the regional revenue table above, the
Mid-Atlantic, Central, and Midwest regions showed the benefit of the Company's
expansion efforts, as the combined revenues in those three regions grew 17%, in
contrast to the Northeast region, where revenues grew 9%. Despite the
recessionary economy, industry-wide pricing pressures, and efforts by customers
to minimize the amount of hazardous waste generated, the Company continued to
experience growth in revenues, primarily from gains in market share in all
regions, by expanding the range of services offered and the geographic
territory served. New services not previously offered included: pretreatment of
waste to stabilize it before it is sent to landfills, treatment and disposal of
special categories of hazardous wastewaters (so-called "listed" waste and "lean
water") previously sent to competitors for disposal; blending of waste used as
supplemental fuel by industrial furnaces; and the introduction of new waste
treatment technology, such as the Clean Extraction System ("CES"). The
territory served expanded through opening new sales offices in areas outside
the existing service area, such as Minnesota, Missouri, Kentucky, and Puerto
Rico.
 
  Revenue in the Mid-Atlantic region grew 16% from 1992 to 1993, primarily
through gains in market share. No new sales offices were opened in the region
in 1993. In addition to expanding its base business in the Mid-Atlantic region,
the Company also benefited from rapid growth of its Puerto Rico business, which
accounted for approximately one-half of the $8.5 million increase in revenue
from 1992 to 1993.
 
  Revenue in the Central region grew 17% from 1992 to 1993. The Central region
benefited from the February 1993 acquisition of Spring Grove, the operator of a
hazardous waste management facility in Cincinnati, and the opening of two sales
offices (Buffalo and Columbus). The Company experienced significant gains in
market share in the Central region over the past several years. For example,
1992 revenues were 53% higher than 1991 revenues. The Company expected even
higher revenue growth in the Central region in 1993, leveraging off the Spring
Grove acquisition. While volumes of waste handled at the Spring Grove facility
and its revenues have grown since the acquisition, Central region revenue
growth overall was lower than expected, largely because of lower remediation
activity in the region in 1993.
 
  Revenue in the Midwest region grew 22% from 1992 to 1993. The Midwest region
benefited from the July 1992 acquisition of Mr. Frank, Inc., an established
transportation and environmental services company located near Chicago,
Illinois, and the opening of a service center in Waukegan, Illinois and four
sales offices (Grand Rapids, St. Louis, Minneapolis, and Indianapolis).
However, gains in market share in this region were increasingly difficult to
achieve, due to competition from many smaller firms offering industrial
maintenance and waste disposal services at lower cost.
 
  The Northeast region continued to show improved business levels, despite a
decline in industrial activity in the region. Revenue in the Northeast region
grew 9% from 1992 to 1993. The Company believes it has regained market share
from competitors, partly as a result of capitalizing on the July 1992
acquisition of Connecticut Treatment Corporation, a hazardous waste management
facility located in Bristol, Connecticut, which treats "listed" wastewater.
Although results for 1993 show an increase in revenues in the Northeast,
revenues from 1991 to 1992 declined 6%. The prevailing trend over the past few
years has been flat, as major industries in the region, such as defense,
aerospace, computers, and high-technology, have experienced cutbacks in
production.
 
  Recent gains in revenue in the Northeast exceeded the Company's expectations,
while revenue growth in the other three regions did not meet expectations,
primarily because of significantly lower remediation activity, particularly in
the Central and Midwest regions. While waste disposal volumes
 
                                       21
<PAGE>
 
were strong, competition put downward pressure on prices, which contributed to
a shortfall in revenues, relative to expectations.
 
  Cost of Revenues. One of the largest components of cost of revenues is the
cost of sending waste to other companies for disposal. The Company has been
able to upgrade the quality and efficiency of its waste treatment services
through the development of new technology, strategic acquisitions, and
continued modifications and upgrades at its facilities. These actions reduce
the Company's costs and its dependence on outside disposal vendors. Internal
waste disposal capabilities expanded as a result of the CES beginning
commercial operations in June 1992, the acquisition of Connecticut Treatment
Corporation in the third quarter of 1992, the issuance of a new permit at the
Baltimore facility in September 1992, and the acquisition of Spring Grove in
the first quarter of 1993. The Company has also benefited from a competitive
pricing environment among disposal facilities, such as landfills and
incinerators, to which the Company sends waste for ultimate disposal. As a
result, the Company's outside disposal costs decreased to 15.4% of revenue in
1993 from 18.2% of revenue in 1992.
 
  However, the benefits the Company experiences from price competition among
disposal vendors can be outweighed when the Company reduces its waste treatment
prices in response to price reductions by others. For example, price reductions
by incinerators of "lean water" streams have forced the Company to reduce its
prices for processing such waste streams in the CES in Baltimore, reducing
profitablility since most of its costs for depreciation and labor are fixed.
 
  Employee costs grew significantly in 1993, as the Company increased its staff
in anticipation of double-digit revenue growth. At December 31, 1992, the
Company had 1,310 regular employees. Employment peaked during September 1993;
at September 30, 1993 the Company had 1,533 regular employees. The Company's
cost of revenues, excluding disposal costs paid to third parties, increased
from 47.9% of total revenues in 1992 to 51.8% in 1993, as intense price
competition and increased labor costs combined to offset the benefits the
Company experienced from a competitive pricing environment among disposal
facilities. As a result, the cost of revenues increased to 67.2% of revenues in
1993, as compared to 66.1% of revenues in 1992, reflecting the competitive
pricing trends in the hazardous waste industry.
 
  In August 1993, the Company began a company-wide reengineering program to
improve gross margins, by increasing the ratio of billable to nonbillable
personnel, improved bidding and execution of jobs, better pricing of
remediation work, and declining jobs with less than acceptable margins. See
"General" above.
 
  Selling, General and Administrative Expenses. Selling, general and
administrative expenses increased to $42,296,000 or 21.1% of revenues in 1993,
as compared to $35,923,000 or 20.4% of revenues for 1992. This increase was
primarily due to the costs associated with the expansion in the Mid-Atlantic,
Central and Midwest regions, and the administrative infrastructure required to
support new sales offices and service centers. During the third quarter of
1993, as part of its efforts to consolidate its gains in market share and
control costs, the Company closed two of the nine sales offices opened earlier
in the year (in Detroit, Michigan and Kansas City, Missouri), while opening
another sales office (in Buffalo, New York) and a new service center in
Portsmouth, New Hampshire. At December 31, 1993, the Company maintained 29
service centers and sales offices.
 
  One of the goals of the reengineering program begun in August 1993 is to
reduce the number of nonbillable personnel, through elimination of positions
and reassigning some people from nonbillable overhead positions to billable
positions included in gross margin, in an effort to reduce selling, general and
administrative costs to a quarterly rate of approximately $10 million in 1994.
Management of the Company has set a goal of driving selling, general and
administrative costs down from the 1993 level of $42.3 million, and reducing
these costs approximately 5% in 1994.
 
                                       22
<PAGE>
 
  Interest Expense. Interest expense for 1993 decreased to 3.6% of revenues, as
compared to 4.0% of revenues for 1992. The decrease resulted primarily from a
series of reductions in the interest rates of the Company's Bank Revolver and
certain subordinated notes which occurred in the fourth quarter of 1992. The
benefits of reduced interest rates were offset somewhat by the additional
indebtedness incurred for acquisitions since the first half of 1992. Total debt
at December 31, 1993 was approximately $5,000,000 higher than at December 31,
1992. No interest was capitalized during 1993, as compared to $301,000 of
interest capitalized during 1992, primarily for the CES in Baltimore before it
commenced commercial operation on June 1, 1992.
 
  Provision for Income Taxes. The effective income tax rate for 1993 was 46%,
an increase over the 35% effective income tax rate for 1992. The rate for 1992
was lower than the combined state and federal statutory rate due in part to the
utilization of certain alternative minimum tax credit carryforwards. The rate
for 1993 was higher than the combined state and federal statutory rate due in
part to the amortization of goodwill which is nondeductible for income tax
reporting purposes. The rate fluctuates depending on the amount of income
before taxes, as compared to the fixed amount of goodwill and other
nondeductible amounts. The Omnibus Budget Reconciliation Act of 1993 did not
impact 1993's effective income tax rate; the Company expects the Act to have a
minimal impact on its rate in 1994, currently estimated to be 46%.
 
TWELVE-MONTH YEAR ENDED DECEMBER 31, 1992 VERSUS TEN-MONTH TRANSITION PERIOD
ENDED DECEMBER 31, 1991
 
  Revenues. Revenues for the year ended December 31, 1992 increased 16.5% to
$176,193,000 from $151,278,000 for the unaudited twelve-month period ended
December 31, 1991. Combined revenues in the Mid-Atlantic, Central and Midwest
regions increased to 56% of total revenues for the year ended December 31, 1992
from 45% of total revenues for the unaudited twelve-month period ended December
31, 1991. The Company continued to experience growth in those three regions,
which demonstrated the Company's ability to diversify successfully from its New
England base while maintaining its leading position in the Northeast. The
growth in revenues in those regions resulted from gains in market share in the
new markets and increased volumes of business in both environmental remediation
and hazardous waste management.
 
  During the third quarter of 1992, the Company acquired Connecticut Treatment
Corporation. This acquisition expanded the Company's range of waste processing
capabilities and service lines, providing the Company with increased capacity
as well as the ability to treat "listed" wastewaters, which the Company
previously sent for outside disposal. During the third quarter of 1992, the
Company also acquired Mr. Frank, Inc. which generated increased volumes of
waste disposal, primarily for the Company's Chicago facility. These two
acquisitions, along with the commencement of commercial operations of the CES
in Baltimore in June 1992 and gains in market share in all regions, contributed
to the 1992 revenue increase. In addition, during the fourth quarter of 1992
the Company completed a large factory decontamination project in the Mid-
Atlantic region, which produced revenues in excess of $3,000,000.
 
  Cost of Revenues. The Company's cost of revenues for the year ended December
31, 1992 decreased to 66.1% of revenues, as compared to 67.4% of revenues for
the ten-month transition period ended December 31, 1991. This decrease
reflected the Company's efforts to control costs through overtime minimization
and the utilization of temporary labor, as well as the implementation of
selective price increases on hazardous waste disposal. In addition, the Company
benefited in 1992 from a competitive pricing environment among operators of
disposal facilities, such as landfills and incinerators, to which the Company
sends waste for ultimate disposal.
 
  Selling, General and Administrative Expenses. Selling, general and
administrative expenses for the year ended December 31, 1992 increased to 20.4%
of revenues, as compared to 18.7% of revenues during the ten-month transition
period ended December 31, 1991. This increase resulted
 
                                       23
<PAGE>
 
in substantial part from costs associated with the expansion of the Company in
the Mid-Atlantic, Central and Midwest regions, and the administrative
infrastructure required to support new sales offices and service centers.
During 1992, the Company furnished and staffed 16 new locations.
 
  Interest Expense. Interest expense for the year ended December 31, 1992
declined to 4.0% of revenues, as compared to 4.7% of revenues for the ten-month
transition period ended December 31, 1991. Although the average balance of
borrowings under the Company's Bank Revolver was approximately $29,000,000 for
both 1991 and 1992, a decline in the prevailing "prime" lending rate from 10.3%
in 1991 to 7.8% in 1992, and an adjustment to the Company's borrowing rate
after its interest coverage ratio exceeded 2:1, both contributed to lowering
interest expense. In addition, the interest rate charged on approximately
$5,000,000 of other indebtedness was reduced from 10.0% to 8.0% in October
1992, and the interest rate charged on approximately $2,750,000 of other
indebtedness was then reduced from 12.0% to 8.0%. These interest rate
reductions were offset in part by additional indebtedness resulting from the
July 1992 acquisitions of Connecticut Treatment Corporation, Mr. Frank, Inc.,
and the office building adjacent to the Company's Natick facility.
 
  Provision for Income Taxes. The effective income tax rate was 35.3% during
the year ended December 31, 1992, as compared to 30.3% for the transition
period ended December 31, 1991. The effective income tax rate for both periods
was lower than the statutory rate due to the Company's utilization of
alternative minimum tax and net operating loss carryforwards. The rate for the
transition period was lower than the 1992 rate because of tax benefits
remaining from the 1990 write-off of the rotary kiln incinerator project.
 
FACTORS THAT MAY AFFECT FUTURE RESULTS
 
  The Company's future operating results may be affected by a number of
factors, including the Company's ability to: realize and make permanent the
anticipated cost reduction benefits associated with its reengineering program
initiated in August of 1993; utilize its facilities and workforce profitably,
in the face of intense price competition; successfully increase market share in
its existing service territory while expanding its product offerings into other
markets; and integrate additional hazardous waste management facilities and
generate incremental volumes of waste to be handled through such facilities
from existing sales offices and service centers and others which may be opened
in the future.
 
  The Company's operations may be affected by the commencement and completion
of major site remediation projects; seasonal fluctuations due to weather and
budgetary cycles influencing the timing of customers' spending for remedial
activities; the timing of regulatory decisions relating to hazardous waste
management projects; secular changes in the process waste industry towards
waste minimization and the propensity for delays in the remedial market;
suspension of governmental permits; and fines and penalties for noncompliance
with the myriad regulations governing the Company's diverse operations. As a
result of these factors, the Company's revenues and net income could vary
significantly from quarter to quarter, and past financial performance should
not be considered a reliable indicator of future performance.
 
  The Company participates in a highly volatile industry, with multiple
competitors, many of which have recently taken large write-offs and asset
write-downs and undergone major restructurings, while others have announced
they will undergo such restructurings and incur special charges in the near
future. The Company's participation in a highly dynamic industry often results
in significant volatility of the Company's common stock price, as well as that
of its competitors.
 
ENVIRONMENTAL CONTINGENCIES
 
  While increasing environmental regulation often presents new business
opportunities to the Company, it likewise often results in increased operating
costs as the Company expands its compliance staff to cope with myriad federal,
state and local regulations. The Company strives to
 
                                       24
<PAGE>
 
conduct its operations in compliance with applicable laws and regulations,
including environmental rules and regulations, and has as its goal 100%
compliance. This effort requires programs to promote compliance, such as
training employees and customers, purchasing health and safety equipment, and
in some cases hiring outside consultants and lawyers. Even with these programs,
management believes that in the ordinary course of doing business, companies in
the environmental services and waste disposal industry are faced with
governmental enforcement proceedings resulting in fines or other sanctions and
will likely be required to pay civil penalties or to expend funds for remedial
work on waste management facilities.
 
  From time to time, the Company has paid fines or penalties in governmental
environmental enforcement proceedings, usually involving its waste treatment,
storage and disposal facilities. The possibility always exists that substantial
expenditures could result from governmental proceedings, which would have a
negative impact on earnings for a particular reporting period. More
importantly, federal, state and local regulators have the power to suspend or
revoke permits or licenses needed for operation of the Company's plants,
equipment, and vehicles, based on the Company's compliance record, and
customers may decide not to use a particular disposal facility or do business
with a company because of concerns about the compliance record. Suspension or
revocation of permits or licenses would impact the Company's operations and
could have a material adverse impact on financial results.
 
  Certain Company subsidiaries have transported or generated waste sent to
sites which have been designated state or federal Superfund sites. As a result,
the Company has been named as a potentially responsible party at 18 state and
federal Superfund sites. Ten of these sites involve two subsidiaries which the
Company acquired from Chemical Waste Management, Inc. ("ChemWaste"), a public
company 77%-owned by WMX Technologies, Inc., and one site involves a subsidiary
which the Company acquired from Southdown, Inc., a public company. As part of
these acquisitions, ChemWaste and Southdown, Inc. agreed to indemnify the
Company with respect to any liability of such subsidiaries for waste disposed
of before the Company acquired them. With respect to the other Superfund sites
at which the Company believes it may face liability, the Company has
established reserves or escrows which it believes are appropriate. Therefore,
the Company believes that any future settlement costs arising from any or all
of the 18 Superfund sites will not be material to the Company's operations or
financial position. As of June 1, 1994, the Company had accrued environmental
costs of $455,000 for cleanup of Superfund sites. See "Business--Legal
Proceedings."
 
LIQUIDITY AND CAPITAL RESOURCES
 
  The Company has financed its operations and capital expenditures primarily by
cash flow from operations and additions to long-term debt. Cash provided by
operations, before changes in current assets and current liabilities, was
$15,404,000 in 1993, as compared to $15,850,000 in 1992. Net additions to long-
term debt provided $4,928,000 and $220,000 in those years, respectively. Cash
provided by operations, before changes in current assets and current
liabilities, was $3,086,000 for the three months ended March 31, 1994 and
$3,398,000 for the three months ended March 31, 1993.
 
  During the three months ended March 31, 1994, net reductions in long-term
debt were $2,105,000, and the Company spent $630,000 on additions to plant and
equipment, as compared to the same period of the prior year when its capital
expenditures were $2,179,000 (excluding the cost to acquire Spring Grove), and
net additions to long-term debt were $2,255,000. The Company anticipates that
its capital expenditures for the remainder of 1994 will be approximately
$5,400,000. The Company expects to fund these requirements through cash flow
from operations.
 
  In February 1993, the Company purchased Spring Grove for $7,000,000. The
consideration consisted of $1,400,000 in cash and 112,000 shares of Series B
convertible preferred stock with a stated value of $5,600,000. During 1993, the
Company spent $8,078,000 on additions to property, plant, and equipment and
construction in progress, excluding the cost to purchase Spring Grove.
 
  At December 31, 1993, the Bank Revolver provided for a $50,000,000 revolving
line of credit. The obligations of the Company under the Bank Revolver are
collateralized by substantially all of the Company's assets. On November 5,
1993, the Company and its banks had amended the Bank
 
                                       25
<PAGE>
 
Revolver to increase the limits on certain debt and operating lease obligations
from $4,000,000 to $9,000,000, which allows the Company to add vehicles and
equipment needed to support the growth of the Company's business. On February
1, 1994, the Company and its banks further amended the Bank Revolver to modify
certain covenants and increase the amount of the Bank Revolver to $55,000,000.
The Bank Revolver currently permits loans of up to $40,000,000 and allows the
Company to have up to $20,000,000 in letters of credit outstanding, provided
that the combination of loans and letters of credit outstanding may not exceed
$55,000,000 at any one time. As described under "Description of Other
Indebtedness," the Company anticipates that the current terms of the Bank
Revolver will be amended effective upon completion of the Offering so that the
maximum amount of $55,000,000 now available for loans and letters of credit
under the Bank Revolver will be reduced to $35,000,000.
   
  At June 30, 1994, the loans outstanding under the Bank Revolver were
$33,563,963, the letters of credit aggregated $9,347,102 and the Company had
available borrowing capacity of $6,436,037 under the Bank Revolver. After
giving effect to the Offering and the application of net proceeds, the Company
will have outstanding no indebtedness for borrowed money, except for (i) the
Senior Notes, (ii) approximately $11.8 million of loans outstanding under the
Bank Revolver, (iii) $5.0 million of 10.0% senior unsecured convertible notes
having a final maturity in October 1999, and (iv) a $1.2 million junior
subordinated note. This will increase the Company's ability to utilize its
future cash flow from operations and borrowings under the Bank Revolver for
operations and potential acquisitions. The Company believes that it will have
adequate liquidity over the next 12 months based upon its cash flow from
operations and available borrowing capacity under the Bank Revolver.     
 
RECENT DEVELOPMENTS
 
 
  On July 11, 1994, the Company announced its unaudited results for the second
quarter ended June 30, 1994. Revenues for the second quarter of 1994 were
$49,683,000 with net income of $1,251,000, as compared to revenues of
$51,847,000 with net income of $1,440,000 for the second quarter of 1993.
Revenues for the six months ended June 30, 1994 were $100,968,000 with net
income of $1,848,000, as compared to revenues of $95,299,000 with net income of
$2,275,000 for the comparable six months of 1993.
   
  Treatment and Disposal revenue in the second quarter of 1994 fell 14% from
the second quarter of 1993, reflecting industry trends toward minimization of
hazardous waste generation. As a percentage of total revenues, Treatment and
Disposal declined to 41% of total revenues for the second quarter of 1994, from
45% of total revenues for the same period in the prior year. Although the
volume of waste handled declined, the Company has been able to improve
profitability of its Treatment and Disposal business by expanding its internal
waste disposal capabilities and reducing the amount of waste it sends to other
companies for disposal. The Company continues to benefit from a competitive
pricing environment among disposal vendors, such as landfills and incinerators,
to whom the Company sends waste for ultimate disposal. As a result, the
Company's outside disposal costs fell 18% to 13% of total revenues in the
second quarter of 1994, from 15.2% of total revenues in the second quarter of
1993.     
  Field Services revenue in the second quarter of 1994 was approximately the
same as it was in the second quarter of 1993. As a percentage of total
revenues, Field Services increased to 44% of total revenues for the second
quarter of 1994, from 42% of total revenues for the same period in the prior
year. LabPacks revenue in the second quarter of 1994 grew 18% from the second
quarter of 1993. As a percentage of total revenues, LabPacks increased to 15%
of total revenues for the second quarter of 1994, from 13% of total revenues
for the same period in the prior year.
 
 
  The following table sets forth the Company's service center revenues by
region for the six quarters ended June 30, 1994.
 
<TABLE>
<CAPTION>
                         NUMBER OF      THREE MONTHS ENDED                         THREE MONTHS ENDED
                          SERVICE  ---------------------------- ---------------------------------------------------------
REGION                    CENTERS  JUNE 30, 1994 MARCH 31, 1994 DEC. 31, 1993 SEPT. 30, 1993 JUNE 30, 1993 MARCH 31, 1993
- ------                   --------- ------------- -------------- ------------- -------------- ------------- --------------
                                                                   (DOLLARS IN THOUSANDS)
<S>                      <C>       <C>           <C>            <C>           <C>            <C>           <C>
Northeast...............      8       $20,703       $17,216        $22,865       $21,628        $21,907       $18,506
Mid-Atlantic............      7        16,602        21,382         16,506        17,113         16,228        14,047
Central.................      3         6,678         6,413          6,164         6,888          7,409         5,583
Midwest.................      3         5,700         6,274          7,242         6,409          6,303         5,316
                            ---       -------       -------        -------       -------        -------       -------
                             21       $49,683       $51,285        $52,777       $52,038        $51,847       $43,452
</TABLE>
 
                                       26
<PAGE>
 
                                    BUSINESS
 
  The Company provides a wide range of industrial waste management services to
a diversified customer base in 26 states. It is one of the largest providers of
industrial waste management services in the Northeast, with a growing presence
in the Mid-Atlantic, Central, and Midwest regions of the United States. The
Company seeks to be recognized by customers as the premier supplier of a broad
range of value-added industrial waste management services based upon quality,
responsiveness, customer service, variety of risk containment systems, and cost
effectiveness. The Company currently maintains a network of eight sales
offices, 22 service centers and ten waste management facilities. The service
centers perform site specific services and ultimately direct collected waste to
the waste management facilities for treatment and processing. The Company does
not own or operate end disposal sites such as landfills or incinerators.
 
THE INDUSTRIAL WASTE MANAGEMENT INDUSTRY
 
  According to industry sources, the United States industrial waste management
industry had total revenues in 1992 of approximately $18.6 billion. The demand
for industrial waste management services has resulted primarily from the
adoption and enforcement of increasingly stringent federal, state and local
environmental laws and regulations over the past 20 years. See "Environmental
Regulation." These laws and regulations have significantly increased the costs
and potential liabilities associated with the handling of industrial wastes.
Under these laws and regulations, a broad list of industrial wastes are
classified as "hazardous," and generators of hazardous wastes retain potential
legal liability for the proper treatment of such wastes through and including
their ultimate disposal. In response to these laws and regulations, many
generators of both hazardous and nonhazardous wastes have chosen not to
maintain their own treatment and disposal facilities nor to develop the
technical expertise necessary to assure regulatory compliance. These generators
have instead sought to have their waste streams managed by firms that possess
collection, transportation, recycling, treatment, disposal and waste-tracking
capabilities and have the expertise and financial capacity necessary to comply
with applicable environmental laws and regulations.
 
  The laws and regulations which govern the industrial waste management
industry are complex and wide-reaching. The most significant of such laws
affecting the Company are the following federal laws:
 
  .  The Resource Conservation and Recovery Act of 1976, as amended
     ("RCRA")--Governs hazardous waste generation, treatment, transportation,
     storage and disposal.
 
  .  The Comprehensive Environmental Response, Compensation and Liability Act
     of 1980, as amended (the "Superfund Act")--Provides for immediate
     response and removal actions coordinated by the EPA to releases of
     hazardous substances into the environment, and authorizes the EPA to
     order potentially responsible parties to perform any necessary clean-up.
 
  .  The Federal Water Pollution Control Act, as amended by the Clean Water
     Act and subsequent amendments (the "Clean Water Act")--Prohibits
     discharges of wastes into waters of the United States without
     governmental authorization.
 
  .  The Toxic Substances Control Act ("TSCA")--Authorizes the EPA to
     regulate over 60,000 commercially produced chemical substances,
     including the proper disposal of polychlorinated biphenyls ("PCBs").
 
  .The Clean Air Act--Authorizes the EPA to regulate major sources of air
   emissions.
 
  According to industry sources, the five industries which produced in 1992 the
largest amounts of industrial hazardous wastes (by dollar amount of spending
paid for management services) were chemicals (28.3%), oil (15.9%), paper and
pulp (13.2%), primary metals (8.7%) and automotive (5.0%). In 1992,
approximately 81% of the total industrial hazardous wastes in the United States
(by dollar amount of spending paid for management services) were produced by
plants located in 20 states. By order of spending in 1992, such states were
Texas, California, Ohio, Louisiana, Illinois,
 
                                       27
<PAGE>
 
   
Pennsylvania, Georgia, New York, Indiana, Michigan, New Jersey, Alabama, North
Carolina, Tennessee, Washington, Wisconsin, Kentucky, South Carolina, Florida
and Missouri. The Company currently operates service centers or sales offices
in 12 of these 20 states and has plans to expand into an additional four
states: Georgia, South Carolina, Tennessee and Texas.     
 
  As a large industrial waste management firm, the Company has significant cost
advantages over many of its competitors in terms of its ability to efficiently
utilize its waste management facilities and to negotiate more favorable terms
for end disposal of waste. Several recent industry trends provide the Company
with opportunities to grow by focusing on technological innovation, sound
waste-tracking capabilities, cost reduction and a heightened commitment to
customer service and responsiveness. These trends include: (i) efforts by many
generators of industrial wastes to decrease the number of service providers
that they utilize to a select group of industry leaders in order to minimize
potential liability inherent in using less qualified firms; (ii) efforts by
waste generators to reduce or recycle their waste through utilizing service
providers which offer alternative disposal and treatment technologies; and
(iii) a reduction in the cost of end disposal as a result of surplus landfill
and incinerator capacity and the emergence of new disposal alternatives. These
trends are leading to a significant consolidation of the industrial waste
management industry. The Company has benefited and expects to continue to
benefit from these trends through attractive acquisitions, increased market
share and new market opportunities.
 
BUSINESS STRATEGY
 
  In order to maintain and enhance its leading position in the industrial waste
management industry, the Company has implemented a strategy of internal growth
through the increased utilization of existing facilities, the addition of new
sales offices and service centers, and the development of new waste management
services. In addition, the Company achieves external growth through strategic
acquisitions.
 
  Increased Utilization of Waste Management Facilities. The Company currently
has ten waste management facilities which represent a substantial investment in
permits, plant and equipment. These facilities provide the Company with
significant operating leverage. There are opportunities to expand capacity at
these facilities by modifying the terms of the existing permits and by adding
capital equipment and new technology. Through selected permit modifications,
the Company can expand the range of treatment services which it offers to its
customers without the large capital investment necessary to acquire or build
new waste management facilities. The Company believes that permits for new
industrial waste management facilities will become increasingly difficult to
obtain, thereby placing new entrants and weaker competitors at a disadvantage.
 
  Sales Office/Service Center Expansion. The Company opens sales offices in
attractive target markets which can be serviced by existing facilities and
expand the Company's service areas. As demand at a particular sales office
reaches a sufficient level, the sales office can be upgraded to a service
center with field service capabilities by the addition of field technicians,
service personnel and equipment. The Company's sales offices and service
centers direct waste into the Company's waste management facilities. This
allows the Company to expand its service areas with low risk capital investment
and to maximize throughput with minimal incremental cost by obtaining
additional wastes to be handled by the Company's service centers and waste
management facilities. Since January 1, 1993, the Company has added eight sales
offices and one service center, and three sales offices have been upgraded to
service centers.
 
  New Waste Management Services. Industrial waste generators are demanding
alternatives to traditional waste disposal methods in order to increase
recycling and reclamation and to minimize the end disposal of hazardous waste
into the environment. The Company utilizes its technological expertise and
innovation to improve and expand the range of services which it offers to its
customers. The Company has commercialized a hazardous waste treatment system,
the Clean Extraction System ("CES"), to extract toxic compounds from industrial
wastewaters by utilizing non-
 
                                       28
<PAGE>
 
toxic liquid carbon dioxide at high pressures. CES offers for certain
wastewater streams a recycling alternative to incineration or injection into
deep underground wells. The Company has also recently signed a development
agreement with Molten Metal Technology, Inc., an environmental technology
company developing a proprietary technology known as Catalytic Extraction
Processing which uses a molten metal bath as a catalyst and solvent to break
down the molecular structures of various hazardous wastes into their elements
for recycling or reuse.
 
  Capitalization on Industry Consolidation. The Company believes that its
large industrial customers will ultimately require a comprehensive range of
waste treatment capabilities to be provided by a select number of service
providers. This trend will put smaller operators at a competitive disadvantage
due to their size and limited financial resources. To respond to its
customers' needs, the Company has increased the range of waste management
services it offers and has followed a strategy of acquiring companies in
existing, contiguous and new market areas. Since its formation in 1980, the
Company has completed 12 acquisitions, each of which has proven successful in
expanding the Company's market share and cash flow. The Company continues to
investigate and discuss other potential acquisitions of permitted facilities
in order to enhance service to its existing customer base and expand its
customer base to include new regional and super-regional waste generators. The
Company has signed a letter of intent with Chemical Waste Management, Inc.
which would allow the Company to expand its Chicago waste management facility
into an adjoining site. See "Business--Properties--Hazardous Waste Management
Facilities--Chicago, IL." Acquisitions within the Company's existing areas of
operation serve to capture incremental market share, while geographic
expansion creates new market opportunities. See "Acquisitions" below.
 
ACQUISITIONS
 
  The Company has made five acquisitions since January 1, 1989.
 
<TABLE>
<CAPTION>
DATE OF ACQUISITION                    COMPANY ACQUIRED                    PURCHASE PRICE
- -------------------                    ----------------                    --------------
<S>                  <C>                                                   <C>
       1989          ChemClear Inc., a publicly-traded company in the      $27.6 million
                     business of treating liquid and semi-liquid
                     hazardous and nonhazardous industrial wastes at
                     treatment plants in Baltimore, Maryland; Cleveland,
                     Ohio; Chicago, Illinois; and Chester, Pennsylvania
       1989          Murphy's Waste Oil Service, Inc., the operator of a   $0.2 million
                     waste oil treatment and storage facility in Woburn,
                     Massachusetts
       1992          Connecticut Treatment Corporation, the operator of a  $2.4 million
                     hazardous waste treatment facility in Bristol,
                     Connecticut
       1992          Mr. Frank, Inc., a Chicago-based transportation and   $2.2 million
                     environmental services company serving industrial
                     companies primarily in Illinois, Indiana and
                     Michigan
       1993          Spring Grove Resource Recovery, Inc., the operator    $7.0 million
                     of a hazardous waste treatment facility in
                     Cincinnati, Ohio
</TABLE>
 
  Prior to closing any acquisition, the Company attempts to investigate
thoroughly the current and contingent liabilities of the company to be
acquired, including potential liabilities arising from noncompliance with
environmental laws by prior owners for which the Company, as a successor
owner, might become responsible. The Company also seeks to minimize the impact
of potential liabilities by obtaining indemnities and warranties from the
sellers which may be supported by deferring payment of or by escrowing a
portion of the purchase price. See "Legal Proceedings" below for a description
of the indemnities which the Company has received in connection with past
acquisitions.
 
                                      29
<PAGE>
 
  As part of its growth strategy the Company continues to investigate and
discuss other potential acquisitions. However, no definitive agreements have
been entered into by the Company relating to any potential material
acquisition, and there can be no assurance that such discussions will result in
additional acquisitions.
 
SERVICES
 
  The principal services provided by the Company fit within three categories:
treatment and disposal of industrial wastes ("Treatment and Disposal"); field
services provided at customer sites ("Field Services"); and specialized
repackaging, treatment and disposal services for laboratory chemicals and
household hazardous wastes ("LabPacks"). The Company markets these services on
an integrated basis and, in many instances, services in one area of the
business support or lead to a project undertaken in another area.
 
 
  [WHEEL CHART SHOWING THE TYPES OF SERVICES PROVIDED BY THE COMPANY AND THEIR
                   RESPECTIVE PERCENTAGES OF TOTAL REVENUES]
 
 
  In addition to these three principal services, the Company also provides
technical services such as analytical testing and engineering services and
personnel training. Such technical services primarily support the Company's
principal services, although technical services are also offered to a limited
extent on a stand-alone commercial basis.
 
  The Company currently maintains a network of ten waste management facilities,
22 service centers and eight sales offices. The service centers and sales
offices accommodate sales personnel
 
                                       30
<PAGE>
 
who develop and maintain contact with the Company's customers. Customers are
generally covered by a two person team: an "account manager" who is responsible
for sales and a "customer service account manager" who is responsible for order
taking, handling customer inquiries and other administrative tasks. Account
managers utilize the expertise of product specialists in order to evaluate the
scope of a potential job, quote a job and ultimately detail the work order,
including personnel and equipment necessary to complete the job. The service
centers also serve as depots for the specialized equipment and trained
technical personnel which respond to customers' waste management requirements.
The Company utilizes a "hub and spoke" organization where service centers and
sales offices feed waste disposal business into the Company's ten waste
management facilities.
 
  As an integral part of the Company's services, industrial wastes are
collected from customers and transported by the Company to and between its
facilities for treatment or bulking for shipment to final disposal locations.
In providing this service, the Company utilizes a variety of specially designed
and constructed tank trucks and semi-trailers, as well as other third-party
transporters, including railroads. Liquid waste is frequently transported in
bulk, but may also be transported in drums. Heavier sludges or bulk solids are
transported in sealed, roll-off containers or bulk dump trailers.
 
  TREATMENT AND DISPOSAL. The Company transports, treats and disposes of
industrial wastes for commercial and industrial customers, health care
providers, educational and research organizations, other waste management
companies and governmental entities. The wastes handled include substances
which are classified as "hazardous" because of their corrosive, ignitable,
infectious, reactive or toxic properties, and other substances subject to
federal and state environmental regulation. Waste types processed or
transferred in drummed or bulk quantities include:
 
  .  flammables, combustibles and other organics,
  .  acids and caustics,
  .  cyanides and sulfides,
  .  solids and sludges,
  .  industrial wastewaters,
  .  PCB materials and electrical light ballasts,
  .  medical waste,
  .  other regulated wastes, and
  .  nonhazardous industrial waste.
 
  Before the Company receives hazardous waste from a customer, detailed
paperwork and analysis are completed to document the nature of the waste. A
representative sample of the expected waste is analyzed in a Company-owned
laboratory in order to establish a waste profile and to enable the Company to
recommend the best method of treatment and disposal. Prior to unloading at the
Company's treatment facility, a representative sample of the delivered waste is
tested and analyzed to insure that it conforms to the customer's waste profile
record. Once the wastes are characterized, compatible groups are consolidated
to achieve economies in storage, handling, transportation and ultimate
treatment and disposal. At the time of acceptance of a customer's waste at the
Company's facility, a unique computer "bar code" identification character is
assigned to each container of waste, enabling the Company to use sophisticated
computer systems to track and document the status, location and disposition of
the waste.
 
  Wastewater Treatment. The Company's treatment and resource recovery
operations involve processing hazardous wastes through the use of physical,
chemical, thermal or other methods, and the reclamation and reuse of certain
wastes. The nonrecoverable materials produced by these interim processing
operations are then disposed of off-site at facilities owned and operated by
unrelated businesses.
 
                                       31
<PAGE>
 
  The Company treats a broad range of industrial liquid and semi-liquid wastes
containing heavy metals, organics and suspended solids, including:
 
  .  acids and caustics,
  .  ammonias, sulfides, and cyanides,
  .  heavy metals, ink wastes, and plating solutions,
  .  landfill leachates and scrubber waters, and
  .  oily wastes and water soluble coolants.
 
  Wastewater treatment can be economical as well as environmentally sound, by
combining different wastewaters in a "batching" process that reduces costs for
multiple waste stream disposal. Acidic waste from one source can be neutralized
with alkaline from a second source to produce a neutral solution.
 
  Physical Treatment. Physical treatment methods include distillation,
separation and stabilization. These methods are used to reduce the volume of
waste material or to make it suitable for further treatment, reuse, or
disposal. Distillation uses heat to remove liquids from solids or sludges.
Separation utilizes techniques such as sedimentation, filtration, flocculation
and centrifugation to remove solid materials from liquids. Stabilization refers
to a category of waste treatment processes designed to reduce contaminant
mobility or solubility and convert waste to a more chemically stable form.
Stabilization technology includes many classes of immobilization systems and
applications. Examples include low-temperature processes such as adding a sand-
like cement material, and high-temperature processes such as vitrification.
Stabilization is a frequent treatment method for metal-bearing wastes received
at several Company facilities, which treat the waste to meet specific federal
land disposal restrictions. After treatment, the waste is tested to confirm
that it has been rendered nonhazardous. It can then be sent to a nonhazardous
waste landfill, at significantly lower cost than disposal at a hazardous waste
landfill.
 
  Thermal Treatment. Thermal treatment refers to processes that use high
temperature incineration as the principal means of waste destruction. The
Company operates an incinerator at its Braintree facility which was previously
used to destroy hospital waste. In late 1991, approvals were granted to allow
the incinerator to destroy nonhazardous wastes which were previously sent to
landfills or municipal incinerators. It also generates steam which is used in
steam distillation equipment for reclaiming solvents. Other waste residues are
incinerated in off-site facilities owned and operated by other companies.
 
  Resource Recovery. Resource recovery involves the treatment of wastes using
various methods which will effectively remove contaminants from the original
material to restore its fitness for its intended purpose, and to reduce the
volume of waste requiring disposal. In conjunction with recent regulatory
provisions restricting the burial of various types of hazardous wastes, the
Company substantially upgraded its existing facilities for the reclamation and
reuse of certain wastes, particularly solvent-based wastes generated by
industrial cleaning operations, metal finishing and other manufacturing
processes.
 
  Spent solvents that can be recycled are processed through thin film
evaporators and other processing equipment and are distilled into clean, usable
products. Upon recovery of these products, the Company either returns the
recovered solvents to the original generator or sells them to third parties.
 
  Other nonrecoverable organic liquids with sufficient heat value are blended
to meet strict specifications for use as supplemental fuels for cement kilns,
blast furnaces and other high-efficiency boilers. The Company has established
relationships with a number of supplemental fuel users that are licensed to
accept the blended fuel material. Although the Company pays a fee to the users
who accept this product, this disposal method is substantially less costly than
other disposal methods.
 
  Clean Extraction System. The Clean Extraction System ("CES") is a hazardous
waste treatment system commercialized by the Company which extracts organic
compounds from
 
                                       32
<PAGE>
 
industrial wastewater. CES uses carbon dioxide that has been compressed at high
pressure into a liquid. Under these "supercritical" conditions, carbon dioxide
acts as a powerful solvent for most commonly occurring contaminants. CES uses
supercritical carbon dioxide as a solvent to remove organic contaminants, such
as gasoline, acetone, methylene chloride, pesticides and other chemicals, from
industrial wastewater called "lean water." Lean water is generated by oil
companies, utilities, and manufacturers of specialty chemicals and
pharmaceuticals.
 
  The CES was installed at the Company's Baltimore facility, and began
commercial operation in June 1992. The system includes specialized pretreatment
and post-treatment systems and techniques, in addition to a central extractor
unit, to maximize extraction efficiency. In the Baltimore CES, wastewater
receives chemical and physical pretreatment before entering a central extractor
unit. The wastewater is fed into the top of a 40-foot tall pressurized chamber,
and flows down through a stack of perforated plates as a continual supply of
liquefied carbon dioxide rises from the bottom of the chamber. As the
wastewater and carbon dioxide mix, organic contaminants separate from the water
and dissolve in the carbon dioxide. The liquid carbon dioxide flows from the
top of the chamber into a decompression vessel. As the pressure decreases, the
carbon dioxide vaporizes into a gas, leaving the organic contaminants at the
bottom of the vessel, where they are collected. The concentrated organics can
be recycled or burned as a supplemental fuel for resource recovery. The
cleansed water flows from the bottom of the chamber, through a series of
decompression and post-treatment tanks. After treatment, the cleansed water is
discharged to the City of Baltimore sewer treatment works.
 
  This process enables the Company to handle a broad range of complex,
difficult to treat organic and inorganic "lean waters" formerly sent to other
companies for disposal. CES offers the Company's industrial customers, such as
chemical or pharmaceutical companies, an attractive recycling alternative to
disposal of their "lean water" by incineration or injection into deep
underground wells. Current treatment capacity is between six and ten million
gallons per year, depending on the characteristics of the wastewater being
treated.
 
  Proposed Catalytic Extraction Processing. In May 1994, the Company signed a
development agreement with Molten Metal Technology, Inc. of Waltham,
Massachusetts ("MMT"), an environmental technology company developing an
innovative, proprietary processing technology known as Catalytic Extraction
Processing ("CEP"). CEP utilizes a molten metal bath as a catalyst and solvent
to break down the molecular structures of various hazardous wastes into their
elements. With the addition of various other elements, industrial compounds are
made into products for reuse as a raw material by the feedstock generator or
for sale to other industrial users. Under the development agreement, the
Company and MMT have agreed to install a CEP system at one of the Company's
waste management facilities. Under the proposed arrangement, MMT will be
primarily responsible for the design, engineering, financing, construction,
start-up and operation of the CEP system, while the Company will provide the
site and infrastructure around a building which will house the CEP system. MMT
will then build, own and operate the CEP system and be responsible for the
disposition of CEP products generated from the processing of feedstocks, while
the Company will be responsible for delivery of feedstocks. The Company will
pay MMT market prices to process the feedstocks and will share in any profits
generated by the CEP system. However, development of the CEP system pursuant to
the development agreement is subject to a number of conditions and
uncertainties, including the negotiation and execution of definitive
agreements, and no assurances can be given that the CEP system will be
successfully developed or operated.
 
  Disposal. After treatment of industrial wastes at the Company's facilities,
the hazardous waste residues (such as sludges) which remain after such
treatment are disposed of in facilities operated by third parties. The Company
also arranges for the disposal of its customers' hazardous wastes which cannot
be treated at Company-owned facilities. Arrangements are made for disposal
 
                                       33
<PAGE>
 
primarily in incinerators, landfills, or other permitted disposal facilities
operated by third parties. These arrangements are typically made before the
Company accepts waste. Although the Company's facilities are licensed to store
waste, such storage is for a short period of time, usually a matter of days,
before the waste is sent for ultimate disposal. On occasion, a service center
may also arrange to ship a customer's waste direct to another disposal company,
such as a landfill or incinerator, if the size of the waste shipment or its
characteristics are such that the waste does not need to pass through one of
the Company's own waste management facilities. As the volume of waste handled
by the Company has grown, the Company has negotiated favorable disposal
arrangements with numerous companies. The Company is not dependent on any one
disposal company, and the loss of any particular outlet for disposal of waste
would not have a material impact on the Company.
 
  The Company's wastewater treatment operations are dependent upon access to
publicly owned treatment works and to hazardous or nonhazardous waste landfills
for the disposal of its byproduct wastes. Generally, the Company has not
experienced significant difficulty in obtaining the necessary permits from
local sewer authorities.
 
  FIELD SERVICES. The Company provides a wide range of environmental field
services to maintain industrial facilities and process equipment, as well as
clean up or contain actual or threatened releases of hazardous materials into
the environment. These services are provided primarily to large chemical,
petroleum, transportation, utility, industrial and waste management companies,
and to governmental agencies. The Company's strategy is to identify, evaluate,
and solve its customers' environmental problems, on a planned or emergency
basis, by providing a comprehensive interdisciplinary response to the specific
requirements of each project.
 
  Industrial Maintenance. Many of the Company's customers have a recurring need
to clean equipment and facilities periodically in order to continue operations,
maintain and improve operating efficiencies of their plants, and satisfy safety
requirements. Industrial maintenance involves chemical cleaning, hydroblasting,
vacuuming, and other methods to remove deposits from process equipment, such as
paint booths and plating lines, and storage facilities for material used in the
manufacturing or production process, such as feedstocks, chemicals, fuels,
paints, oils, inks, metals and many other items. Service centers are equipped
with specialty equipment, such as high volume pumps, pressure washers,
nonsparking and chemical resistant tools, and a variety of personal protective
equipment, to perform maintenance services quickly, usually during "off
periods" to minimize downtime from production.
 
  Project Management. An increasingly important area of the Company's
operations is the management of complex environmental remediation projects.
These projects may include surface remediation, groundwater restoration, site
and facility decontamination, and emergency response. An interdisciplinary team
of managers, chemists, engineers, and compliance experts design and implement
result-oriented remedial programs, incorporating both off-site removal and on-
site treatment, as needed. The remedial projects group functions as a single
source management team, relieving the customer of the administrative and
operational burdens associated with environmental remediation. As a full-
service environmental services provider, the Company eliminates the need for
multiple subcontractors.
 
  These projects vary widely in scope, duration and revenue, and they are
typically performed under service agreements between the customer and the
Company. Environmental remediation projects may be undertaken in conjunction
with or lead to contracts for additional remediation work or for hazardous
waste management services, and typically involve the Company's analytical
laboratory and engineering group.
 
 
                                       34
<PAGE>
 
  Surface Remediation. Surface remediation projects arise in two principal
areas: the planned cleanup of hazardous waste sites and the cleanup of
accidental spills and discharges of hazardous materials, such as those
resulting from transportation and industrial accidents. In addition, some
surface remediation projects involve the cleanup and maintenance of industrial
lagoons, ponds and other surface impoundments on a recurring basis. In all of
these cases, an extremely broad range of hazardous substances may be
encountered.
 
  Surface remediation projects generally require considerable interaction
among engineering, project management and analytical services. Following the
selection of the preferred remedial alternative, the project team identifies
the processes and equipment for cleanup. Simultaneously, the Company's health
and safety staff develops a site safety plan for the project. Remedial
approaches usually include physical removal, mechanical dewatering,
stabilization or encapsulation.
 
  Groundwater Restoration. The Company's groundwater restoration services
typically involve response to above-ground spills, leaking underground tanks
and lines, hazardous waste landfills and leaking surface impoundments.
Groundwater restoration efforts often require complex recovery systems,
including recovery drains or wells, air strippers, biodegradation or carbon
filtration systems, and containment barriers. These systems and technologies
can be used individually or in combination to remove a full range of floating
or dissolved organic compounds from groundwater. The Company internally
designs and fabricates most mobile or fixed site groundwater treatment
systems.
 
  Site and Facility Decontamination. Site and facility decontamination
involves the cleanup and restoration of buildings, equipment and other sites
and facilities that have been contaminated by exposure to hazardous materials
during a manufacturing process, or by fires, process malfunctions, spills or
other accidents. The Company's projects have included decontamination of
electrical generating stations, electrical and electronics components,
transformer vaults and commercial, educational, industrial, laboratory,
research and manufacturing facilities.
 
  Emergency Response. The Company undertakes environmental remediation
projects on both a planned and emergency basis. Emergency response actions may
develop into planned remedial action projects when soil, groundwater,
buildings, or facilities are extensively contaminated. The Company has
established specially trained emergency response teams which operate on a 24-
hour basis from service centers covering 20 states. Many of the Company's
remediation activities result from a response to an emergency situation by one
of its response teams. These incidents can result from transportation
accidents involving chemical substances, fires at chemical facilities or
hazardous waste sites, transformer fires or explosions involving PCBs, and
other unanticipated developments when the substances involved pose an
immediate threat to public health or the environment, such as possible
groundwater contamination.
 
  Emergency response projects require trained personnel, equipped with
protective gear and specialized equipment, prepared to respond promptly
whenever these situations occur. To meet the staffing requirements for
emergency response projects, the Company relies in part upon a network of
trained personnel who are available on a contract basis for specific project
assignments. The Company's health and safety specialists and other skilled
personnel closely supervise these projects during and subsequent to the
cleanup. The steps performed by the Company include rapid response,
containment and control procedures, analytical testing and assessment,
neutralization and treatment, collection, and transportation of the substances
to an appropriate treatment or disposal facility.
 
  LABPACKS. The Company provides specialized repackaging, treatment and
disposal services for laboratory chemicals and household hazardous wastes.
Such chemicals and wastes are put into
 
                                      35
<PAGE>
 
LabPacks, which are packages smaller than a 55-gallon drum, generally less than
five gallons or 50 pounds. The Company offers generators of LabPack quantity
waste the same economical and environmentally sound disposal services that have
been offered for years to large industrial generators. The LabPack operation
services a wide variety of customers, including:
 
  .  engineering and research and development divisions of industrial
     companies,
  .  college, university and high school labs,
  .  EPA labs and Veterans Administration facilities,
  .  hospitals and medical care labs,
  .  state and local municipalities, and
  .  tens of thousands of residents through household hazardous waste
     collection days.
 
  The Company provides a team of qualified personnel with science degrees and
special training to collect, label and package waste at the customer's site.
LabPacks are then transported to one of the Company's facilities for
consolidation into full-size containers, which are then sent for further
treatment or disposal as part of the Company's treatment and disposal services
described above. As described above, disposal options include reclamation,
fuels blending, incineration, aqueous treatment, and secure chemical landfill.
 
  TECHNICAL SERVICES. Technical services consist primarily of analytical
testing, engineering services and personnel training. Many of the Company's
principal services as described above involve the selection and application of
various technologies. The Company's analytical testing laboratories perform a
wide range of quantitative and qualitative analyses to determine the existence,
nature, level, and extent of contamination in various media. The Company's
engineering staff identifies, evaluates and implements the appropriate
environmental solution.
 
  Analytical Testing and Engineering Services. The Company provides analytical
testing and engineering services as technical support to complement its primary
services. For example, if the Company is engaged to perform an entire
environmental remediation project, it will first perform a site or situation
assessment. A site assessment begins with the determination of the existence of
contamination. If present, the nature and extent of the contamination is
defined by gathering samples and then analyzing them at one of the Company's
laboratories in order to establish or verify the nature and extent of the
contaminants. The Company's engineering staff then develops, evaluates and
presents alternative solutions to remedy the particular situation. Often
treatment systems are completely designed, engineered and fabricated by the
Company in house. It then implements the mitigation and decontamination program
mutually selected by the customer and the Company.
 
  Analytical testing and engineering services are also provided as a separate
service if a customer requires an analysis with respect to certain material, or
if a customer is searching for an appropriate solution to an environmental
problem or if an environmental assessment is required to allow a transfer of
property.
 
  The Company operates an EPA-qualified and state-certified analytical testing
laboratory in Braintree, Massachusetts which tests samples provided by
customers to identify and quantify toxic pollutants in virtually every
component of the environment. The laboratory staff evaluates the properties of
a given material, selects appropriate analytical methods, and executes a
laboratory work plan that results in a comprehensive technical report. The
Company operates a laboratory in Bedford, Massachusetts to test samples of
"lean water" to determine suitability for treatment through the CES in
Baltimore.
 
  The Company also maintains laboratories at its waste management facilities to
identify and characterize waste materials prior to acceptance for treatment and
disposal, and operates mobile laboratory facilities for field use in emergency
response and remedial action situations.
 
 
                                       36
<PAGE>
 
  Personnel Training. The Company provides comprehensive personnel training
programs for its own employees and those of its customers on a commercial
basis. Such programs are designed to promote safe work practices under
potential hazardous environmental conditions, whether or not toxic chemicals
are present, in compliance with stringent regulations promulgated under RCRA
and the federal Occupational Safety and Health Act ("OSHA"). The Company's
Technical Training Center at its Kingston, Massachusetts facility includes a
2,000 gallon tank for confined space entry, exit, and extraction, an air-system
demonstration maze, respirator fit testing room, leak and spill response
equipment, and a layout of a mock decontamination zone, all designed to fulfill
the requirements of OSHA Hazardous Waste and Emergency Response Standards.
 
CUSTOMERS
 
  Since January 1994, the Company has executed approximately 2,500 work orders
per month for over 4,400 customers. The Company's sales efforts are directed
toward establishing and maintaining relationships with businesses which have
ongoing requirements for one or more of the Company's services. The Company's
customer list includes 296 of the companies on the 1994 Forbes 500 list of
largest United States companies. In addition, the Company's customers include
most of the major utilities in the Northeast and Mid-Atlantic regions. The
Company's customers are primarily chemical, petroleum, transportation, utility
and industrial firms, other waste management companies and government agencies.
Management believes that the Company's diverse customer base, in terms of
number, industry and geographic location, as well as its large presence in New
England, provide it with a recurring stream of revenue and stability of cash
flow. The Company estimates that in excess of 80% of its revenues is derived
from previously served customers with recurring needs for the Company's
services. The Company believes the loss of any single customer would not have a
material adverse effect on the Company's financial condition or results of
operations.
 
  The Company's customer base is diverse, and generally not concentrated in
particular industries, such as the petroleum or defense sectors, where business
activity may be cyclical. In addition to serving industrial customers such as
utilities, railroads, pipelines, pharmaceutical manufacturers, and chemical
companies, the Company serves health care and educational institutions,
federal, state and local governmental bodies, and thousands of small quantity
generators who have recurring needs for multiple services in managing their
environmental exposure.
 
  Under applicable environmental laws and regulations (see "Environmental
Regulation"), generators of hazardous wastes retain potential legal liability
for the proper treatment of such wastes through and including their ultimate
disposal. In response to these potential liability concerns, many large
generators of industrial wastes and other purchasers of waste management
services (such as general contractors on major remediation projects) have
increasingly sought to decrease the number of providers of such services that
they utilize. Waste management companies which are selected as "approved
vendors" by such large generators and other purchasers are firms, such as the
Company, that possess sound collection, recycling, treatment, transportation,
disposal and waste tracking capabilities and have the expertise and financial
capacity necessary to comply with applicable environmental laws and
regulations. By becoming an "approved vendor" of a large waste generator or
other purchaser, the Company becomes eligible to provide waste management
services to the various plants and projects of such generator or purchaser
which are located in the Company's service areas. However, in order to obtain
such "approved vendor" status, it may be necessary for the Company to bid
against other qualified competitors in terms of the services and pricing to be
provided. Furthermore, large generators or other purchasers of waste management
services often periodically audit the Company's facilities and operations to
insure that the Company's waste management services to such customers are being
performed in compliance with applicable laws and regulations and with other
criteria established by the Company and by such customers.
 
                                       37
<PAGE>
 
COMPLIANCE
 
  The Company regards compliance with applicable environmental regulations as
a critical component of its overall operations, both from the standpoint of
the health and safety of its employees and as a service to its customers. See
"Environmental Regulation." The Company strives to maintain the highest
professional standards in its compliance activities; its internal operating
requirements are in many instances more stringent than those imposed by
regulation. The Company's compliance program has been developed for each of
its operational facilities under the direction of the Company's corporate
compliance staff. The compliance staff consists of approximately 40 full-time
employees who are responsible for facilities permitting and compliance, health
and safety, field safety, compliance training, transportation compliance, and
related record keeping. The Company also performs periodic audits and
inspections of the disposal facilities of other firms utilized by the Company.
 
  The Company's treatment, storage and recovery facilities are frequently
inspected and audited by regulatory agencies, as well as by customers.
Although the Company's facilities have been cited on occasion for regulatory
violations, the Company believes that each facility is in substantial
compliance with applicable requirements. All major facilities and service
centers have a full-time compliance or health and safety representative to
oversee the implementation of the Company's compliance program at the facility
or service center. These highly-trained regulatory specialists are independent
from operations and report to corporate compliance, which in turn reports
directly to the Chief Executive Officer.
 
MANAGEMENT OF RISKS
 
  The Company follows a program of risk management policies and practices
designed to reduce potential liability, as well as to manage customers'
ongoing regulatory responsibility. This program includes employee training,
environmental auditing, and policy decisions restricting the types of wastes
handled. The Company evaluates all revenue opportunities and declines those
which it believes involve unacceptable risks. The Company avoids handling
high-hazard waste such as explosives, and frequently utilizes specialty
subcontractors to handle such materials when confronted at a job site.
 
  The Company only disposes of its wastes at facilities owned and operated by
firms which the Company has approved as prudent and financially sound.
Typically, the Company applies established technologies to the treatment,
storage and recovery of hazardous wastes. The Company believes its operations
are conducted in a safe and prudent manner and in substantial compliance with
applicable laws and regulations.
 
INSURANCE
 
  The Company's present insurance programs cover the potential risks
associated with its multifaceted operations from two primary exposures: direct
physical damage and third-party liability. The Company maintains a casualty
insurance program providing coverage for vehicles, workers compensation,
employers liability, and comprehensive general liability in the aggregate
amount of $25,000,000 per year, subject to a retention of $250,000 per
occurrence, except on general liability where the retention is $500,000. Since
the early 1980s, casualty insurance policies have typically excluded liability
for pollution, which is covered under a separate pollution liability program.
 
  The Company has pollution liability insurance policies covering the
Company's potential risk in three areas: as a contractor performing services
at customer sites; as a transporter of waste; and while it handles waste at
the Company's facilities. Acstar Insurance Company provides contractor's
liability insurance of $2,000,000 per occurrence and $5,000,000 in the
aggregate, covering off-site remedial activities and associated liabilities.
Lloyds of London provides pollution liability coverage
 
                                      38
<PAGE>
 
for waste in-transit with single occurrence and aggregate liability limits of
$29,000,000. This Lloyds of London policy covers liability in excess of
$1,000,000 for pollution caused by sudden and accidental occurrences during
transportation of waste and at the Company's facilities, from the time waste is
picked up from a customer until its delivery to the final disposal site.
 
  Both federal and state regulations require liability insurance coverage for
all facilities that treat, store, or dispose of hazardous waste. In 1989, the
Company established a captive insurance company pursuant to the Federal Risk
Retention Act of 1986. This company qualifies as a licensed insurance company
and is authorized to write professional liability and pollution liability
insurance for the Company and its operating subsidiaries. RCRA and comparable
state hazardous waste regulations require hazardous waste handling facilities
to maintain pollution liability insurance in the amount of $3,000,000 per
occurrence and $6,000,000 in the aggregate per year for sudden and non-sudden
occurrences. Currently, the Company uses its captive insurance company to
provide (i) the first $1,000,000 of insurance against liability from sudden
occurrences at its facilities, with the excess coverage provided by Lloyds of
London, and (ii) the full policy limits of insurance for non-sudden
occurrences.
 
  The Company's ability to continue conducting its industrial waste management
operations could be adversely affected if the Company should become unable to
obtain sufficient insurance to meet its business and regulatory requirements in
the future. The availability of insurance may also be influenced by
developments within the insurance industry, although other businesses in the
industrial waste management industry would be similarly impacted by such
developments.
 
  Under the Company's insurance programs, coverage is obtained for catastrophic
exposures as well as those risks required to be insured by law or contract. It
is the policy of the Company to retain a significant portion of certain
expected losses related primarily to workers' compensation, physical loss to
property, and comprehensive general and vehicle liability. Provisions for
losses expected under these programs are recorded based upon the Company's
estimates of the aggregate liability for claims. The Company has been
successful in negotiating lower premiums recently, due in part to its favorable
historical loss experience. The cancellation terms applicable to the Company
are similar to those of other companies in other industries.
 
COMPETITION
 
  The Company competes with numerous large and small companies, each of which
is able to provide one or more of the industrial waste management services
offered by the Company and some of which have access to greater financial
resources. The Company believes it offers a more comprehensive range of
industrial waste management services than any of its competitors in its service
territory. The Company also believes that its ability to market and provide its
services on an integrated basis constitutes a significant competitive advantage
for the Company.
 
  The Company's competitive position with respect to its treatment and disposal
services is enhanced by the proximity of its facilities to hazardous waste
generators and the barriers to market entry provided by capital and licensing
requirements. However, treatment, recovery and disposal operations are
conducted by a number of national and regional waste management firms. The
Company believes that physical proximity of treatment and disposal facilities,
comprehensiveness of services, safety, and quality of services and efficiency
are the most significant factors in the market for treatment and disposal
services.
 
  In field services, the Company's competitors include major national and
regional environmental services firms which have environmental remediation
staffs. The availability of skilled technical professional personnel, quality
of performance, diversity of services and, to a certain extent, price, are the
key competitive factors.
 
                                       39
<PAGE>
 
EMPLOYEES
 
  As of June 30, 1994, the Company employed 1,419 people on a regular basis.
None of the Company's employees is subject to a collective bargaining
agreement, and the Company believes that its relationship with its employees
is satisfactory.
 
PROPERTIES
 
  The properties of the Company consist primarily of ten waste management
facilities, 22 service centers, various environmental remediation equipment
and a fleet of approximately 600 transportation vehicles. The ten waste
management facilities are described below. All of such facilities are owned by
the Company, except for the Chicago hazardous waste management facility which
is leased under a lease which (with extensions) expires September 2000 and the
Woburn, Massachusetts waste oil treatment and storage facility which is leased
under a lease which (with extensions) expires February 2004.
 
  Hazardous Waste Management Facilities. The Company currently maintains seven
hazardous waste management facilities at which it processes, treats and
temporarily stores hazardous wastes for later resale, reuse or off-site
treatment or disposal. Every facility that treats, stores or disposes of
hazardous wastes must obtain a license from the federal EPA or an authorized
state agency and must comply with certain operating requirements. See
"Environmental Regulation--Federal Regulation of Hazardous Waste" below for a
description of licenses issued under the Resource Conservation and Recovery
Act of 1976 ("RCRA"). Seven of the Company's ten waste management facilities
are subject to RCRA licensing; all seven have been issued RCRA Part B
licenses, one of which is under appeal.
 
  The Company has made substantial modifications and improvements to the
physical plant and treatment and process equipment at its treatment
facilities. These modifications are consistent with the Company's strategy to
upgrade the quality and efficiency of treatment services, to expand the range
of services provided and to ensure regulatory compliance and operating
efficiencies at these facilities. Major features of this program are the
addition of new treatment systems, such as the CES in Baltimore, expansion of
analytical testing laboratories, drum storage and processing facilities, and
equipment rearrangement and replacement to improve operating efficiency.
 
   Braintree, MA. The Company's largest facility is located in Braintree,
Massachusetts, just south of Boston. The facility is primarily engaged in
drummed waste processing and consolidation, solvent recovery, transformer
decommissioning, PCB storage and processing, blending of waste used as
supplemental fuel by industrial furnaces, and incineration of small quantities
of nonhazardous waste. The facility has been operated under a state Interim
Hazardous Waste Facility License, which gave it Part A Interim Status, since
1981. The Company acquired the facility in 1985. In June 1992, the
Massachusetts Department of Environmental Protection (the "DEP") approved the
Company's application for a final Hazardous Waste Facility License, which
would give the facility a final Part B license for a five-year term. The Town
of Braintree and two adjoining communities have appealed the DEP's decision to
issue the final Part B license, and requested an adjudicatory hearing before
the DEP, which is the normal appeal process. The appeal is an administrative
proceeding before the DEP, and the facility will continue to operate normally
pursuant to its state license and Interim Status authority under RCRA while
the DEP considers the appeal. The Company is confident the review will result
in confirmation of the license as granted. The authority from the federal EPA
to handle PCBs is not impacted by the towns' appeal of the Part B license.
 
   Natick, MA. The Natick, Massachusetts facility is located just west of
Boston. Its primary services are collecting LabPacks and repackaging the small
quantities of laboratory and household chemicals into 55-gallon drum
quantities, consolidating wastes for shipment to other Company facilities or
third parties for further treatment or disposal, and serving as a transfer
station for the Northeast region. The facility has a state Hazardous Waste
Facility License (the state equivalent of a Part B license), which was issued
in 1986 and expired in 1991. The Company applied for a new license in timely
fashion. The law allows operations to continue under the expired license while
the
 
                                      40
<PAGE>
 
state reviews the renewal application. The facility is also authorized by the
federal EPA to handle PCBs.
   
   Chicago, IL. The Chicago, Illinois facility is located on the south side of
Chicago, on Lake Calumet. It provides treatment of nonhazardous and hazardous
industrial wastewaters, drummed waste processing and consolidation, and
transfer and repackaging of laboratory chemicals into LabPacks. In 1991 a new
drum storage warehouse was constructed, which increased storage capacity from
552 drums to 1,240 drums and expanded the range of hazardous wastes which can
be processed at the facility. In November 1993, the Illinois EPA issued a Part
B license for a ten-year term, which significantly expanded the waste handling
and storage capacity of the facility. The new license increased drum storage
capacity from 1,240 drums to 1,875 drums and allows handling of material
destined for blending of waste used as supplemental fuel by industrial
furnaces, pretreatment of waste to stabilize it before it is sent to landfills,
and rail shipment of hazardous and nonhazardous waste. The Company plans to
make substantial expenditures to implement this increased permitted capacity.
As a possible alternative to making the needed improvements to its own site,
the Company has entered into a letter of intent with Chemical Waste Management,
Inc. ("ChemWaste") which would allow the Company to lease an adjoining site now
leased by ChemWaste and acquire their existing improvements in exchange for
sharing the costs of dismantling an existing hazardous waste incinerator and
cleaning up the adjoining site. The improvements on the ChemWaste site would
allow the Company to develop new product lines not currently handled at the
Company's existing facility. Under the proposed sharing arrangement with
ChemWaste, the Company could over a period of 15 years be required to
contribute up to a maximum of $2 million for dismantling and decontaminating
the incinerator and other equipment and up to a maximum of $7 million for
studies and cleanup of the site. Any additional costs beyond those contemplated
by the sharing arrangement during this time period would be borne by ChemWaste.
This alternative is under continuing investigation, is subject to the
negotiation of definitive agreements, and would require a rezoning of the
property and numerous regulatory approvals which may not be possible to obtain.
    
   Cleveland, OH. The Cleveland, Ohio facility is located south of downtown
Cleveland. It is a wastewater treatment facility that treats nonhazardous and
hazardous industrial wastewaters, and serves as a transfer station for various
types of containerized nonhazardous waste. The facility is licensed by the
state as a wastewater treatment facility. The facility is not subject to Part B
licensing requirements, since its on-site wastewater treatment activities are
regulated pursuant to the Clean Water Act, and therefore are exempt from RCRA.
 
   Baltimore, MD. The Baltimore, Maryland facility is located adjacent to
Interstate 95 in central Baltimore. It provides treatment of nonhazardous and
hazardous industrial aqueous wastes, drummed waste processing, pretreatment of
waste to stabilize it before it is sent to landfills, and transfer of LabPacks.
It is the only commercial hazardous waste treatment facility in Maryland. The
facility has a state Controlled Hazardous Substances permit (the state
equivalent of a Part B license), which was issued in 1987. In 1990, the Company
received a permit modification to expand the range of waste streams the
facility can accept and to install the CES, which allows the facility to treat
a wide range of hazardous wastewaters contaminated with gasoline, chlorinated
solvents and many other organic contaminants, which were formerly sent to other
companies for incineration. In 1992, the Maryland Department of the Environment
issued a new Controlled Hazardous Substances permit for a three-year term,
which significantly expanded the waste handling and storage capacity of the
facility. The new permit also allows handling of LabPacks and material destined
for fuels-blending, pretreatment of waste to stabilize it before it is sent to
landfills, and rail shipment of hazardous and nonhazardous waste.
 
   Bristol, CT. In July 1992, the Company acquired Connecticut Treatment
Corporation ("CTC"), located in Bristol, Connecticut, approximately 20 miles
southwest of Hartford. It provides hazardous wastewater treatment, drummed
waste processing and consolidation, and transfer of
 
                                       41
<PAGE>
 
LabPacks. This facility offers two services not offered at the Company's other
facilities: equipment "de-manufacturing," such as dismantling outdated
computers, and treatment of special categories of hazardous wastewaters known
as "listed" wastewaters resulting from industrial processes such as
electroplating. The facility has a Part B license issued by the EPA and the
Connecticut DEP, which was issued in 1987 and expired in 1991. CTC applied for
a new license in timely fashion, and continues to operate under the expired
license while the renewal application is reviewed. The facility is also
authorized by the federal EPA to handle PCBs. CTC's name has been changed to
Clean Harbors of Connecticut, Inc.
 
   Cincinnati, OH. In February 1993, the Company acquired Spring Grove Resource
Recovery, Inc. ("Spring Grove"), located north of downtown Cincinnati, Ohio. It
provides hazardous wastewater treatment, drummed waste processing and
consolidation, pretreatment of waste to stabilize it before it is sent to
landfills, and transfer of LabPacks. The facility holds a federal Part B
license, which was issued in 1985 and expires in 1995, and a state Hazardous
Waste Facility Installation and Operation permit which was renewed in December
1993 for a five-year term. The facility is also authorized to handle PCBs. On
March 31, 1994, the Ohio EPA approved the Company's application for a revised,
comprehensive state permit that expands the range of waste that may be received
and treated at the facility and allows installation of equipment for handling
and processing material to be sent to boilers and industrial furnaces and used
as supplemental fuel. The transfer of ownership to the Company is subject to
approval by regulatory authorities, which is expected during 1994. The
regulatory authorities have granted an exemption allowing the Company to
acquire the stock of Spring Grove and operate the facility in the interim. If
the transfer of ownership is not approved, then the seller has agreed to
repurchase Spring Grove for a price equal to what the Company paid for Spring
Grove ($7,000,000) with adjustments for depreciation and improvements.
 
  Waste Oil Treatment and Storage Facilities. The Company has three waste oil
treatment and storage facilities: two in Massachusetts and one in Maine. The
Massachusetts facilities are located in Kingston and Woburn, in the Boston
area. The Kingston facility has a state recycling permit and is able to store
oil collected from various activities, ranging from routine cleaning of oil
storage terminals to oil spill cleanups. The facility is also used for
maintenance activities and for training of employees of the Company and third
party customers. The Woburn facility is a waste oil storage and transfer
facility, and received a Part B license in October 1993 for a five-year term.
The facility in South Portland, Maine is a petroleum reclamation facility that
handles most of the waste oil received by the Company, which comes primarily
from the Company's remediation activities. It has a municipal sewer user permit
allowing the discharge of water separated from oil. The Company also owns
another property in South Portland located on Main Street. It has a license to
store virgin oil, but it also is permitted for the temporary storage and
transfer of containerized hazardous waste.
 
LEGAL PROCEEDINGS
 
  In April 1988, the Board of Selectmen of Braintree, Massachusetts, approved a
cease and desist order with respect to the handling of flammable materials
stored at the Company's Braintree facility. The Board concluded that, when the
Company purchased the land on which the Braintree facility is located, a
license for the storage of flammable liquids was not conveyed as an incident of
ownership. The Company petitioned the Massachusetts Land Court for a
declaratory judgment that either the Company possesses such a license by
operation of law or that the statute requiring the license is pre-empted by the
pervasive state regulation of hazardous waste facilities. In March 1994, the
Land Court issued a favorable ruling, concluding that the statute is pre-empted
by state hazardous waste laws and regulations and no local flammable storage
license is required. The town has appealed this ruling.
 
  In August 1990, an action was filed in the New York Supreme Court, Albany
County, in connection with the accidental death of an employee of a Company
subsidiary who was working on the Hudson River in September 1989 while
responding to an oil spill. The complaint sought $10 million under the federal
Longshoremen's and Harborworker's Compensation Act (the "Jones Act"). The
Company sought to dismiss the Jones Act claims on the grounds that the employee
was
 
                                       42
<PAGE>
 
not a "seaman" within the meaning of the Jones Act and that the case was
governed by the New York Workers' Compensation statute. In March 1994, the
trial court judge granted the Company's motion for a summary judgment that the
Jones Act does not apply. The decision has been appealed.
 
  On June 13, 1994, the Company was served with a third party complaint filed
in the Ulster County Superior Court of the State of New York by the Dormitory
Authority of the State of New York ("DASNY"). The complaint arises out of an
accident which occurred in December 1991 when a motor vehicle struck a utility
pole near the State University of New York at New Paltz causing an electrical
surge to overheat transformers which discharged toxic chemicals throughout
various student dormitories and classroom buildings. The Company was hired by
the State University of New York to perform technical supervisory and
laboratory work for the cleanup. The actual work of cleaning the buildings was
performed by numerous other contractors over approximately 15 months. In March
1993, a group of students sued DASNY claiming that they were exposed to toxic
chemicals when DASNY allowed them to re-occupy the buildings after the accident
and prior to a complete removal of the toxic chemicals, causing them increased
risk of future illnesses. DASNY has denied the students' claims but recently
decided to sue the Company along with 16 other third party defendants claiming
that if DASNY is liable to the students, these third party defendants should
indemnify DASNY. The Company was hired by the State University of New York to
perform representative sampling for toxic chemicals but, according to its
contract, was not responsible for decisions as to when students should re-
occupy the buildings. The Company does not believe that it should incur any
material liability as a result of this lawsuit; however, in view of the fact
that the Company has only recently been served with the complaint, and only
preliminary investigation and no discovery have been conducted, the Company is
not in a position to evaluate the merits of the lawsuit.
 
  Certain Company subsidiaries have transported or generated waste sent to
sites which have been designated state or federal Superfund sites. See
"Environmental Regulation--Federal Regulation of Hazardous Waste--The Superfund
Act." As a result, the Company has been named as a potentially responsible
party ("PRP") in a number of lawsuits arising from the disposal of wastes at 18
state and federal Superfund sites.
 
  Ten of these sites involve two subsidiaries which the Company acquired from
Chemical Waste Management, Inc. ("ChemWaste"), a public company 77%-owned by
WMX Technologies, Inc. As part of the acquisition, ChemWaste agreed to
indemnify the Company with respect to any liability of its Natick and Braintree
subsidiaries for waste disposed of before the Company acquired them.
Accordingly, ChemWaste is paying all costs of defending the Company's Natick
and Braintree subsidiaries in these cases, including legal fees and settlement
costs.
 
  The Company's subsidiary which owns the Bristol, Connecticut facility is
involved in one Superfund site. As part of the acquisition of the Bristol and
Cincinnati, Ohio facilities, the seller and its parent company, Southdown,
Inc., agreed to indemnify the Company with respect to any liability for waste
disposed of before the Company acquired the facilities, which would include any
liability arising from Superfund sites.
 
  With respect to the other Superfund sites at which the Company believes it
may face liability, the Company has established reserves or escrows which it
believes are appropriate. Therefore, the Company believes that any future
settlement costs arising from any or all of the 18 Superfund sites will not be
material to the Company's operations or financial position. Management
routinely reviews each Superfund site in which the Company's subsidiaries are
involved, considers each subsidiary's role at each site and its relationship to
the other PRPs at the site, the quantity and content of the waste it disposed
of at the site, and the number and financial capabilities of the other PRPs at
the site. Based on reviews of the various sites and currently available
information, and management's judgment and prior experience with similar
situations, expense accruals are provided by the Company for its share of
future site cleanup costs, and existing accruals are revised as necessary. As
of June 1, 1994, the Company had accrued environmental costs of $455,000 for
cleanup of Superfund sites. Superfund legislation permits strict joint and
several liability to be imposed without regard to fault, and as a result, one
PRP might be required to bear significantly more than its proportional share of
the cleanup costs if other PRPs do not pay their share of such costs.
 
 
                                       43
<PAGE>
 
  Five of the 18 sites involve former subsidiaries of ChemClear Inc. One of
the five sites is the Strasburg Landfill site in Pennsylvania. The Company and
two other parties identified as PRPs received an order from the EPA in 1989 to
perform certain emergency measures at the site. The Company responded by
installing a leachate treatment and discharge system and repairing the
landfill slope. Since early 1990, the Company has spent approximately $350,000
in complying with the EPA order. In 1992, the EPA issued its Record of
Decision for the site which proposes recapping and revegetating the landfill
and installing certain air emission and leachate treatment systems. The
estimated capital cost of the remediation plan for the site is approximately
$6.5 million with annual operating and maintenance costs of approximately
$300,000. The EPA has identified more than 20 additional PRPs at the site. In
addition, the Company and several other PRPs are attempting to identify other
companies that sent waste to the landfill and have them named as PRPs. In
January 1993, the Company and eight other PRPs submitted to the EPA a Response
to Notice Letter, which recommended additional study be performed at the site
by the PRP group and that a final remedy be based on the additional data
developed during the study. No reply has been received from the EPA. The
Company believes its ultimate exposure in this case will not have a material
impact on its financial position or results of operations.
 
  Mr. Frank, Inc., which was acquired by the Company in July 1992, is involved
in two Superfund sites, as a transporter of waste generated by others prior to
the Company's purchase of Mr. Frank, Inc. The Company acquired Mr. Frank, Inc.
in exchange for 233,000 shares of the Company's common stock, of which 33,222
shares were deposited into an escrow account for a minimum of two years as
security for the sellers' agreement to indemnify the Company against potential
liabilities, including environmental liabilities arising from prior ownership
and operation of Mr. Frank, Inc.
 
                           ENVIRONMENTAL REGULATION
 
  While the Company's business has benefited substantially from increased
governmental regulation of hazardous waste transportation, storage and
disposal, the industrial waste management industry itself has become the
subject of extensive and evolving regulation by federal, state and local
authorities. The Company makes a continuing effort to anticipate regulatory,
political and legal developments that might affect its operations, but is not
always able to do so. The Company cannot predict the extent to which any
environmental legislation or regulation that may be enacted or enforced in the
future may affect its operations.
 
  The Company is required to obtain federal, state and local licenses or
approvals for each of its hazardous waste facilities. Such licenses are
difficult to obtain and, in many instances, extensive studies, tests, and
public hearings are required before the approvals can be issued. The Company
has acquired or is in the process of applying for all operating licenses and
approvals required for the current operation of its business and has applied
for or is in the process of applying for all licenses and approvals needed in
connection with planned expansion or modifications of its operations.
 
FEDERAL REGULATION OF HAZARDOUS WASTE
 
  The most significant federal environmental laws affecting the Company are
RCRA, the Superfund Act and the Clean Water Act.
 
  RCRA. RCRA is the principal federal statute governing hazardous waste
generation, treatment, transportation, storage and disposal. Pursuant to RCRA,
the EPA has established a comprehensive, "cradle-to-grave" system for the
management of a wide range of materials identified as hazardous waste. States,
such as Massachusetts, Connecticut, Illinois, Maryland and Ohio, that have
adopted hazardous waste management programs with standards at least as
stringent as those promulgated by the EPA, have been authorized by the EPA to
administer their facility permitting programs in lieu of the EPA's program.
 
                                      44
<PAGE>
 
  Every facility that treats, stores or disposes of hazardous waste must obtain
a RCRA license from the EPA or an authorized state agency and must comply with
certain operating requirements. Under RCRA, hazardous waste management
facilities in existence on November 19, 1980 were required to submit a
preliminary license application to the EPA, the so-called Part A Application.
By virtue of this filing, a facility obtained Interim Status, allowing it to
operate until licensing proceedings are instituted pursuant to more
comprehensive and exacting regulations (the Part B licensing process). Interim
Status facilities may continue to operate pursuant to the Part A Application
until their Part B licensing process is concluded. Of the Company's ten waste
management facilities, seven are subject to RCRA licensing; all seven have been
issued Part B licenses, one of which is under appeal.
 
  RCRA requires that Part B licenses contain a schedule of required on-site
study and cleanup activities, known as "corrective action," including detailed
compliance schedules and provisions for assurance of financial responsibility.
The EPA estimates that there are approximately 4,300 facilities that treat,
store or dispose of hazardous wastes, which can be compelled to take corrective
action when necessary. Some facilities are very large and have extensive
contamination problems which rival the largest Superfund sites. Other
facilities have relatively minor environmental problems. Still others will not
need remedial action at all. It is the EPA's policy to compel corrective action
at the "worst sites first." As a result, the EPA has developed a system for
assessing the relative environmental cleanup priority of RCRA facilities,
called the National Corrective Action Prioritization System, with a High,
Medium or Low ranking for each facility. Although several facilities of its
competitors have been assessed a High cleanup priority, none of the Company's
RCRA facilities have been assessed as a High priority.
 
  The EPA has begun RCRA corrective action investigations at the Company's Part
B licensed facilities in Braintree, Natick, Baltimore, Chicago, and Woburn. The
Company is also involved in site studies at its non-RCRA facilities in
Cleveland, Ohio; Kingston, Massachusetts; and on Main Street in South Portland,
Maine. The Company spent approximately $600,000 on corrective action at the
foregoing facilities in 1993.
 
  The Company may become involved in a RCRA corrective action investigation at
a site in Chester, Pennsylvania owned by Philadelphia Electric Company
("PECO"). The site consists of approximately 30 acres which PECO has leased to
various companies over the years. In 1989, the Company acquired by merger a
public company called ChemClear Inc., which operated a hazardous waste
treatment facility on approximately eight acres of the Chester site leased from
PECO. The Company ceased operations at the Chester site, decontaminated the
plant and equipment, engaged an independent engineer to certify closure, and
obtained final approval from the Pennsylvania regulatory authorities,
certifying final closure of the facility. In 1993, the EPA ordered PECO to
perform a RCRA corrective action investigation at the Chester site, and PECO
has asked the Company to participate in the site studies. The cost of these
studies is now estimated to be in the range of $2 million. The Company and PECO
are currently negotiating the sharing of these costs and seeking to establish
the liability of an additional third party.
 
  While the final scope of the work to be done at these facilities has not yet
been agreed upon, the Company believes, based upon information known to date
about the nature and extent of contamination at these sites, that such costs
will not have a material effect on its results of operations or its competitive
position, and that it will be able to finance from operating revenues any
additional corrective action required at its facilities. Environmental
expenditures that relate to current operations are expensed or capitalized as
appropriate.
 
  The Bristol, Connecticut and Cincinnati, Ohio facilities were acquired from a
subsidiary of Southdown, Inc., which has agreed to indemnify the Company
against any costs incurred or liability arising from contamination on-site,
including the cost of corrective action, or waste disposed of off-site,
including any liability under the Superfund Act.
 
                                       45
<PAGE>
 
  The Superfund Act. The Superfund Act provides for immediate response and
removal actions coordinated by the EPA to releases of hazardous substances into
the environment, and authorizes the government to respond to the release or
threatened release of hazardous substances or to order persons responsible for
any such release to perform any necessary cleanup. The statute assigns joint
and several liability for these responses and other related costs, including
the cost of damage to natural resources, to the parties involved in the
generation, transportation and disposal of such hazardous substances. Under the
statute, the Company may be deemed liable as a generator or transporter of a
hazardous substance which is released into the environment, or as the owner or
operator of a facility from which there is a release of a hazardous substance
into the environment. See also "Business--Legal Proceedings."
 
  Clean Water Act. This legislation prohibits discharges to the waters of the
United States without governmental authorization. The EPA has promulgated
"pretreatment" regulations under the Clean Water Act, which establish
pretreatment standards for introduction of pollutants into publicly owned
treatment works. In the course of its treatment process, the Company's
wastewater treatment facilities generate waste water which they discharge to
publicly owned treatment works pursuant to permits issued by the appropriate
governmental authority. The Clean Water Act also serves to create business
opportunities for the Company in that it may prevent industrial users from
discharging their untreated wastewaters to the sewer. If these industries
cannot meet their discharge specifications, then they may utilize the services
of an off-site pretreatment facility such as those of the Company.
 
  Other Federal Laws. Company operations are also subject to the Toxic
Substances Control Act ("TSCA"), pursuant to which the EPA regulates over
60,000 commercially produced chemical substances, including the proper disposal
of PCBs. TSCA has established a comprehensive regulatory program for PCBs,
under the jurisdiction of the EPA, which oversees the storage, treatment and
disposal of PCBs at the Company's facilities in Braintree and Natick,
Massachusetts; Cincinnati, Ohio; and Bristol, Connecticut. Under the Clean Air
Act, the EPA also regulates emissions into the air of potentially harmful
substances. In its transportation operations, the Company is regulated by the
U.S. Department of Transportation and the Interstate Commerce Commission, as
well as by the regulatory agencies of each state in which it operates or
through which its trucks pass. Health and safety standards under the
Occupational Safety and Health Act are also applicable.
 
STATE AND LOCAL REGULATIONS
 
  Pursuant to the EPA's authorization of their RCRA equivalent programs,
Massachusetts, Connecticut, Illinois, Maryland and Ohio have regulatory
programs governing the operations and permitting of hazardous waste facilities.
Accordingly, the hazardous waste treatment, storage and disposal activities of
the Company's Braintree, Natick, Woburn, Bristol, Chicago, Baltimore and
Cincinnati facilities are regulated by the relevant state agencies in lieu of
federal EPA regulation.
 
  Some states, such as Connecticut and Massachusetts, classify as hazardous
some wastes which are not regulated under RCRA. For example, Massachusetts
considers PCBs and used oil as "hazardous wastes," while RCRA does not.
Accordingly, the Company must comply with state requirements for handling state
regulated wastes, and when necessary obtain state licenses for treating,
storing, and disposing of such wastes at its facilities.
 
  The Company believes that each of its facilities is in substantial compliance
with the applicable requirements of RCRA and state laws and regulations. All
ten of the Company's waste management facilities have been issued final
licenses, one of which is under appeal. Once issued, such licenses have maximum
fixed terms of a given number of years, which differ from state to state,
ranging from three years to ten years. The issuing state agency may review or
modify a license at any time during its term. The Company anticipates that once
a license is issued with respect to a facility, the
 
                                       46
<PAGE>
 
license will be renewed at the end of its term if the facility's operations are
in compliance with applicable requirements. However, there can be no assurance
that regulations governing future licensing will remain static, or that the
Company will be able to comply with such requirements.
 
  The Company's wastewater treatment facilities are also subject to local
regulation, most significantly sewer discharge regulations adopted by the
municipalities which receive treated wastewater from the treatment processes.
The Company's continued ability to operate its liquid waste treatment process
at each such facility is dependent upon its ability to continue these sewer
discharges.
 
  The Company's facilities are regulated pursuant to state statutes, including
those addressing clean water and clean air. Local sewer discharge and flammable
storage requirements are applicable to certain of the Company's facilities. The
Company's facilities are subject to local siting, zoning and land use
restrictions. Although the Company's facilities occasionally have been cited
for regulatory violations, the Company believes it is in substantial compliance
with all federal, state and local laws regulating its business.
 
                                       47
<PAGE>
 
                DIRECTORS AND EXECUTIVE OFFICERS OF THE COMPANY
 
<TABLE>
<CAPTION>
             NAME              AGE                   POSITION
             ----              ---                   --------
 <C>                           <C> <S>
 Alan S. McKim...............   39 Chairman of the Board of Directors,
                                    President and Chief Executive Officer
 John F. Kaslow..............   61 Director
 Lorne R. Waxlax.............   60 Director
 Daniel J. McCarthy..........   62 Director
 Christy W. Bell.............   71 Director
 James A. Pitts..............   54 Executive Vice President of Finance and
                                    Administration, Treasurer and Chief
                                    Financial Officer
 Mary-Ellen Drinkwater.......   35 Vice President and Corporate Controller
 Jorgen H. Vestergaard.......   57 President, Clean Harbors Technology
                                    Corporation
 Lawton T. Hemans II.........   56 Senior Vice President of Operations*
 Michael R. Hatch............   40 Senior Vice President of Corporate Training
                                    and Development*
 John P. Lawton..............   33 Vice President of Sales*
</TABLE>
- --------
* Officer of Clean Harbors Environmental Services, Inc., a wholly-owned
  subsidiary of the parent holding company, Clean Harbors, Inc.
 
  Alan S. McKim founded the Company in 1980 and is Chairman of the Board of
Directors, President, and Chief Executive Officer of the Company. He serves as
a director of most of the Company's subsidiaries. Mr. McKim served as
President of the Company and its predecessor from 1980 to 1988. Mr. McKim
holds an MBA from Northeastern University.
 
  John F. Kaslow serves as Executive Director of the Northeast Region for the
Electric Power Research Institute ("EPRI"), a collaborative research
organization which provides advanced science and technology to its member
electric utilities and their customers. Prior to joining EPRI, Mr. Kaslow
served for 34 years with an electric utility company, the New England Electric
System ("NEES"), where he held a number of engineering, operating and general
management positions, including serving prior to his retirement as a director,
Executive Vice President and Chief Operating Officer of NEES, and as a
director and President of its New England Power Company subsidiary. Mr. Kaslow
is a director of Doble Engineering Company, which designs and manufactures
electric test equipment, and a trustee of Merrimack College, North Andover,
Massachusetts.
 
  Lorne R. Waxlax served as Executive Vice President of The Gillette Company
from 1985 to 1993, with worldwide responsibility for Braun AG, Oral-B
Laboratories, and Jafra Cosmetics International. He is a director of three
other public companies, Waban Inc., HON Industries Inc., and AMTROL Inc., and
of The Iams Company, a private company. He also is a member of the advisory
board of Deutsche Bank in Germany, where he was a resident for ten years. Mr.
Waxlax holds an MBA degree from Northwestern University.
 
  Daniel J. McCarthy has been a Professor of Strategic Management at
Northeastern University since July 1972, prior to which he was President of
Computer Environments Corporation, a computer services company. He serves as a
director and on the Finance Committee of Tufts Associated Health Plan, a
health maintenance organization, and as a director of MANAGEDCOMP, Inc., which
manages worker's compensation for employers. Mr. McCarthy holds an MBA degree
from Dartmouth College and a DBA degree from Harvard Business School.
 
  Christy W. Bell was Chairman of the Board of ChemClear Inc., a public
company which was primarily engaged in the business of treating industrial
wastewaters at its plants in Baltimore, Cleveland, and Chicago, for more than
five years prior to its merger into a subsidiary of the Company in 1989. Mr.
Bell had also served as President of ChemClear prior to the merger. Mr.
 
                                      48
<PAGE>
 
Bell is President and an owner of Electro-Petroleum, Inc., Electro-Pyrolysis,
Inc., and Arc Technologies, Inc., all of which are involved in the development
of technologies for the production of energy. He is also a director of Thoratec
Laboratories Corporation.
 
  James A. Pitts joined the Company in March 1992 as Senior Vice President of
Finance and Administration, Treasurer and Chief Financial Officer. He was
appointed Executive Vice President of Finance and Administration of the Company
in May 1994. Prior to joining the Company, Mr. Pitts was, from September 1991
to February 1992, acting Chief Financial Officer for the office of The
Commonwealth of Massachusetts-appointed Receiver for the City of Chelsea,
Massachusetts and, from July 1988 to August 1991, Vice President and Chief
Financial Officer of Bain & Company, Inc., an international business consulting
firm, where he was responsible for the finance and administration operations of
Bain. From 1986 to 1988, he was Executive Vice President of Cullinet Software,
Inc., where he was responsible for the finance, human resources and
administration operations of Cullinet. Mr. Pitts is a certified public
accountant, holds a BBA from Niagara University, an MBA from the University of
Connecticut, and is a graduate of the Advanced Management Program at Harvard
Business School.
 
  Mary-Ellen Drinkwater joined the Company in March 1989 as Manager of
Financial Analysis. Prior to joining the Company, she spent seven years with
the public accounting firm of Coopers & Lybrand, including two years as an
audit manager. Since joining the Company, Ms. Drinkwater has held positions as
Director of Accounting and Director of Financial Planning and Analysis. She was
promoted to Vice President and Corporate Controller of Clean Harbors
Environmental Services, Inc. in January 1993, and became Vice President of
Clean Harbors, Inc. in May 1993. As Corporate Controller, she is the principal
accounting officer for the Company and its subsidiaries. Ms. Drinkwater is a
Certified Public Accountant and holds a BS degree in Business Administration
from Northeastern University.
 
  Jorgen H. Vestergaard joined the Company in October 1992, as President of
Clean Harbors Technology Corporation, a subsidiary aimed at expanding the
market for the Company's Clean Extraction System technology, and developing
other leading-edge technology to solve complex environmental problems. Mr.
Vestergaard is also responsible for operations of the Company's Baltimore
facility, where the Clean Extraction System is located. Prior to joining the
Company, he spent 28 years with GE Plastics, a component of General Electric
Company. He graduated from the Technical University of Denmark, with a Master's
in Chemical Engineering, and holds four patents on process technology
applications developed during his career with GE Plastics.
 
  Lawton T. Hemans II joined the Company in March 1994, as Senior Vice
President of Clean Harbors Environmental Services, Inc., responsible for all
field operations. From 1985 to 1993, he was with Rollins Environmental
Services, Inc., a hazardous waste incineration company, and served as President
of several operating divisions and subsidiaries of Rollins. From 1989 to 1993
he was Group Vice President--Services of Rollins. Mr. Hemans holds a BBA degree
from Michigan State University.
 
  Michael R. Hatch is a Senior Vice President of Clean Harbors Environmental
Services, Inc., responsible for corporate training and development. From 1990
to 1994, he was responsible for operations of the Company's waste treatment
facilities. From 1989 to 1990 he was Vice President of Hazardous Waste
Management of the Company's Environmental Services subsidiary and from 1990 to
1992 he was in charge of Northeast Region Operations. From 1987 to 1989, he was
Senior Vice President of the Company and, since 1986 has been President of its
Braintree subsidiary. Mr. Hatch joined the Company in 1981 as Operations
Manager and became Vice President of Operations in 1983. In 1985 and 1986, he
served as Vice President and General Manager of the Braintree subsidiary. Mr.
Hatch received a BS degree from Bridgewater State College and holds an MBA from
Boston University.
 
 
                                       49
<PAGE>
 
  John P. Lawton is a Vice President of Clean Harbors Environmental Services,
Inc., responsible for sales and service for all Company subsidiaries. Mr.
Lawton joined the Company in 1988 as a Customer Service Account Manager at its
Braintree facility. In 1989, he became Sales Manager for the Midwest region. In
1992, he became Director of Sales for all service areas outside New England.
Mr. Lawton held various management positions with New York Air and Pan American
World Airlines from 1983 to 1988 before joining the Company. He received a BA
degree from North Adams State College.
 
                       DESCRIPTION OF OTHER INDEBTEDNESS
 
BANK REVOLVER
 
  The Company has a revolving credit agreement (the "Bank Revolver") with three
banks, for which The First National Bank of Boston serves as agent (the
"Agent"). As in effect prior to the completion of the Offering, the Bank
Revolver permits loans of up to $40,000,000 and allows the Company to have a
maximum of $20,000,000 of letters of credit outstanding. The combination of
cash and letters of credit outstanding is limited to $55,000,000 at any one
time. The maximum amount of the Bank Revolver reduces on April 1, 1995 to
$50,000,000. The entire balance of the Bank Revolver matures on July 1, 1996.
All of the Company's obligations under the Bank Revolver are collateralized by
substantially all of the Company's assets.
 
  Interest on loans outstanding under the Bank Revolver are payable monthly in
arrears and accrue at the Agent's base rate plus 1%, or at the Company's
option, at a rate which is 3% over the "Eurodollar Rate" offered to the Agent
by prime banks in the Eurodollar interbank market. At June 30, 1994, the
Company had elected the Eurodollar option with respect to $32,000,000 of the
amounts outstanding under the Bank Revolver; the Eurodollar Rate was 7.44% and
the Agent's base rate was 7.25%. The Company pays a fee of 1.5% per annum for
outstanding letters of credit backing performance bonds and 3.0% per annum for
all other outstanding letters of credit. The Company also pays a commitment fee
at the rate of one-half of 1% per annum on the unused portion of the total
commitment.
 
  The Bank Revolver provides for the maintenance of certain restrictive
covenants including, among others, restrictions on the ratio of accounts
receivable to current liabilities, total liabilities to tangible net worth, and
earnings before interest and taxes to total interest expense. The Company is
also restricted from making certain dividend payments or stock redemptions,
incurring certain additional debt, and capital expenditures are limited to
$12,000,000 each year.
   
  At June 30, 1994, the loans outstanding under the Bank Revolver were
$33,563,963, the letters of credit aggregated $9,347,102, and the Company had
available borrowing capacity of $6,436,037 under the Bank Revolver. As
described under "Use of Proceeds," the Company anticipates that it will repay
from the net proceeds of the Offering approximately $21.8 million of its then
outstanding loan balance under the Bank Revolver.     
   
  The Company and its bank lenders have recently negotiated a proposed
modification of the current terms of the Bank Revolver to become effective upon
completion of the Offering. Under the amended terms, the maximum amount of
$55,000,000 now available for loans and letters of credit under the Bank
Revolver will be reduced to $35,000,000 upon the sale by the Company of the
Senior Notes. The entire amount will be available for loans, and up to
$20,000,000 will be available for letters of credit, provided that the
combination of cash and letters of credit outstanding will be limited to
$35,000,000 at any one time. In addition, the sum of loans and letters of
credit outstanding at any one time must not exceed 80% of the Company's
eligible accounts receivable (as defined in the Bank Revolver) plus
$10,000,000. The maturity of the Company's entire balance under the Bank
Revolver will be extended to August 1, 1997.     
 
 
                                       50
<PAGE>
 
  Under the amended terms of the Bank Revolver, interest on outstanding loans
will be payable monthly in arrears and accrue at the Agent's base rate plus 1%,
or at the Company's option, at a rate which is 2.5% over the Eurodollar Rate.
The Company will continue to pay fees for outstanding letters of credit, and a
commitment fee equal to one-half of 1% per annum on the unused portion of the
total commitment.
 
  The amended Bank Revolver will continue to provide for the maintenance of
certain restrictive covenants with certain changes including, among others,
changes with respect to the permitted ratios of total liabilities to tangible
net worth and earnings before interest and taxes to total interest expense. The
Company will continue to be restricted from making certain dividend payments or
stock redemptions or from incurring certain additional debt, and capital
expenditures will be limited to two times depreciation expense in any fiscal
year.
 
SENIOR CONVERTIBLE NOTES
 
  On November 12, 1991, the Company issued to a financial institution a
$3,500,000 subordinated convertible note due in 1999, which is convertible into
common stock at $15 per share. On July 17, 1992, the Company issued to the same
financial institution an additional $1,500,000 subordinated convertible note
due in 1999, which is convertible into common stock at $10 per share, bringing
the total amount of convertible notes to $5,000,000 (the "Senior Convertible
Notes"). These notes are payable in five equal annual installments of
$1,000,000 each, beginning on October 31, 1995 and ending on October 31, 1999.
The Company has the right to convert the notes into common stock at $25 per
share. In connection with the sale of the Senior Notes, the holder of these
notes has agreed that, upon completion of the Offering, (i) these notes will
remain outstanding and will rank pari passu with the Senior Notes (consequently
they will be renamed "senior convertible notes"); (ii) the rate of interest on
these notes will be increased from 8% to 10%; (iii) all security interests
securing these notes will be released; and (iv) the financial covenants in
these notes will be amended so that they are identical to the covenants in the
Note Indenture.
 
JUNIOR SUBORDINATED NOTE
 
  The Company has outstanding a $1,883,000 Junior Subordinated Note dated June
30, 1992, of which the outstanding principal balance was $1,129,800 as of June
30, 1994. The remaining principal is payable in equal quarterly installments of
$94,150, with the final installment due on June 30, 1997. The note bears
interest at a floating rate equal to the base rate of The First National Bank
of Boston plus 2.0% per annum. The note is unsecured and is subordinated to the
outstanding balance under the Bank Revolver, the Senior Convertible Notes and
the Senior Notes.
 
                        DESCRIPTION OF THE SENIOR NOTES
   
  The Senior Notes will be issued under the Note Indenture, dated as of August
4, 1994, between the Company, the directly held Subsidiaries of the Company and
Shawmut Bank, N.A., as trustee (the "Trustee"), a copy of the form of which is
filed as an exhibit to the Registration Statement of which this Prospectus is a
part. The following summary, which describes the Note Indenture and the Senior
Notes, does not purport to be complete and is subject to, and is qualified in
its entirety by reference to, the Note Indenture and the Senior Notes,
including the definitions therein of terms not defined in this Prospectus. As
used in "Description of the Senior Notes" (i) capitalized or defined terms
shall have the meanings ascribed to them within the portion of the Prospectus
captioned "Description of the Senior Notes," and (ii) the term "Company" shall
mean Clean Harbors, Inc., and shall not include its Subsidiaries.     
 
 
                                       51
<PAGE>
 
GENERAL
   
  The Senior Notes will be senior unsecured obligations of the Company, will be
limited to $50.0 million aggregate principal amount, will mature on May 15,
2001 and will bear interest at the rate per annum stated on the cover page
hereof from August 4, 1994, payable semiannually in arrears on May 15 and
November 15 of each year, commencing November 15, 1994, to the persons who are
registered holders thereof at the close of business on the May 1 or November 1
preceding such interest payment date. Interest on overdue principal and (to the
extent permitted by law) on overdue installments of interest will accrue at a
rate of 1.0% in excess of the rate per annum stated on the cover page.     
 
  Interest on the Senior Notes will be computed on the basis of a 360-day year
of 12 30-day months. Principal and interest will be payable at the office of
the Trustee, but, at the option of the Company, interest may be paid by check
mailed to the registered holders at their registered addresses. The Senior
Notes will be transferable and exchangeable at the office of the Trustee and
will be issued in fully registered form, without coupons, in denominations of
$1,000 and any integral multiple thereof.
   
  The Company's obligations under the Senior Notes will be unconditionally
guaranteed on an unsecured, senior basis, jointly and severally, by each of the
Guarantor Subsidiaries. See "Subsidiary Guarantees" below.     
 
OPTIONAL REDEMPTION
   
  On or after May 15, 1999, the Senior Notes may be redeemed at the option of
the Company, at any time as a whole, or from time to time in part, on not less
than 30 nor more than 60 days' notice, at the redemption prices (expressed as
percentages of principal amount) set forth below:     
   
  if redeemed during the 12-month period commencing May 15 of the years
indicated:     
 
<TABLE>
<CAPTION>
                                                                      REDEMPTION
     YEAR                                                               PRICE
     ----                                                             ----------
     <S>                                                              <C>
     1999............................................................   106.25%
     2000 and thereafter.............................................   100.00%
</TABLE>
 
together, in the case of any such redemption, with accrued interest (if any) to
the redemption date (subject to the right of holders of record on the relevant
record date to receive interest due on the relevant interest payment date). If
less than all of the Senior Notes are to be redeemed, the Senior Notes will be
chosen for redemption by the Trustee by lot or by a method that complies with
applicable legal and securities exchange requirements.
 
RANKING
   
  The Senior Notes will be senior unsecured obligations of the Company ranking
pari passu with other senior unsecured indebtedness of the Company and senior
to all Subordinated Obligations. After giving pro forma effect to the Offering
and the application of the net proceeds therefrom, the Company and its
subsidiaries on a consolidated basis will have outstanding $5.0 million of
unsecured senior indebtedness other than the Senior Notes and expect to have
approximately $11.8 million outstanding under a $35.0 million Bank Revolver.
Following consummation of the Offering, the Company will also have the ability
to incur, subject to certain limitations contained in the Note Indenture,
additional senior indebtedness. See "Certain Covenants--Limitation on Liens"
and "--Limitation on Debt" below.     
 
  The Company is a holding company which derives substantially all of its
income from its Subsidiaries. The Company must rely on dividends or other
intercompany transfers from its Subsidiaries to generate the funds necessary to
meet its debt service and other obligations, including
 
                                       52
<PAGE>
 
payment of principal and interest on the Senior Notes. The ability of such
Subsidiaries to pay such dividends or other intercompany transfers is subject
to applicable state laws. Claims of creditors of the Subsidiaries, including
trade creditors, secured creditors and creditors holding guarantees of the
Subsidiaries and claims of holders of Preferred Stock (if any), will generally
have priority as to the assets of such Subsidiaries over the claims and equity
interests of the Company and, thereby indirectly, the holders of indebtedness
of the Company. Certain Subsidiaries of the Company have guaranteed or are co-
borrowers with respect to all of the Company's obligations under the Bank
Revolver. Although the Note Indenture limits the incurrence of Debt and
issuance of Preferred Stock by the Company's Subsidiaries, such limitation is
subject to a number of significant qualifications; moreover, the Note Indenture
does not impose any limitation on the incurrence by such Subsidiaries of
liabilities that are not considered Debt or Preferred Stock under the Note
Indenture. See "Certain Covenants--Limitation on Subsidiary Debt and Preferred
Stock" below.
 
SUBSIDIARY GUARANTEES
 
  Each Guarantor Subsidiary will unconditionally guarantee on a joint and
several basis the payment and performance by the Company of the Senior Notes
and will pay all expenses (including, without limitation, fees and
disbursements of counsel) paid or incurred by the Trustee or the holders in
enforcing their rights under the Subsidiary Guarantees. Each of the Subsidiary
Guarantees will be a senior unsecured obligation of the Guarantor Subsidiary
providing such Subsidiary Guarantee, and will rank pari passu with other senior
unsecured Debt of such Guarantor Subsidiary. The Note Indenture provides that
all Subsidiaries created or acquired subsequent to the date of the Note
Indenture and prior to the termination of the Subsidiary Guarantees will become
Guarantor Subsidiaries with respect to the Senior Notes. Following any sale or
other disposition of all or substantially all of the assets of a Guarantor
Subsidiary or all of the Capital Stock of a Guarantor Subsidiary permitted by
and in accordance with the terms of the Note Indenture, such Guarantor
Subsidiary will be released from its Subsidiary Guarantee obligations. The
obligations of each Guarantor Subsidiary under its Subsidiary Guarantee will be
limited so as not to constitute a fraudulent conveyance under applicable law.
See "Risk Factors--Fraudulent Conveyance Considerations."
 
  Separate financial statements of the Guarantor Subsidiaries are not included
herein because the Guarantor Subsidiaries have jointly and severally and fully
and unconditionally guaranteed the Company's obligations with respect to the
Senior Notes. There is one Subsidiary of the Company which is not a Guarantor
Subsidiary. That Subsidiary is an indirect Subsidiary of the Company which is
wholly owned by the Guarantor Subsidiaries and the assets, liabilities,
operations and equity of that Subsidiary are insignificant.
 
CHANGE OF CONTROL
 
  Upon the occurrence of any of the following events (each a "Change of
Control"), each holder of Senior Notes will have the right to require the
Company to repurchase all or any part of such holder's Senior Notes at a
repurchase price equal to 101% of the principal amount thereof plus accrued and
unpaid interest, if any, to the date of repurchase (subject to the right of
holders of record on the relevant record date to receive interest due on the
relevant interest payment date):
 
    (i) except to the extent caused by the issuance of securities by the
  Company subsequent to the date on which the Senior Notes were originally
  issued, the Permitted Holders cease, at any time prior to the death or
  disability (as defined in Section 22(e)(3) of the Internal Revenue Code) of
  Alan McKim, to be the "beneficial owners" (as defined in Rules 13d-3 and
  13d-5 under the Exchange Act, except that a person shall be deemed to have
  "beneficial ownership" of all shares that any such person has the right to
  acquire, whether such right is exercisable immediately or only after the
  passage of time), directly or indirectly, of at least 20% in the aggregate
  of the total voting power of the Voting Stock of the Company, whether as a
  result of any merger,
 
                                       53
<PAGE>
 
  consolidation, liquidation or dissolution of the Company, any direct or
  indirect transfer of securities or otherwise (for purposes of this clause
  (i) and clause (ii) below, the Permitted Holders shall be deemed to
  beneficially own any Voting Stock of a corporation (the "specified
  corporation") held by any other corporation (the "parent corporation") so
  long as the Permitted Holders beneficially own (as so defined), directly or
  indirectly, in the aggregate a majority of the voting power of the Voting
  Stock of the parent corporation);
 
    (ii) any "person" (as such term is used in Sections 13(d) and 14(d) of
  the Exchange Act), other than one or more Permitted Holders, is or becomes
  the beneficial owner (as defined in clause (i) above), directly or
  indirectly, of more than 35% of the total voting power of the Voting Stock
  of the Company; provided, however, that the Permitted Holders "beneficially
  own" (as so defined), directly or indirectly, in the aggregate a lesser
  percentage of the total voting power of the Voting Stock of the Company
  than such other person and do not have the right or ability by voting
  power, contract or otherwise to elect or designate for election a majority
  of the Board of Directors of the Company (for the purposes of this clause
  (ii), such other person shall be deemed to beneficially own any Voting
  Stock of a specified corporation held by a parent corporation, if such
  other person "beneficially owns" (as so defined), directly or indirectly, a
  majority of the voting power of the Voting Stock of such parent corporation
  and the Permitted Holders "beneficially own" (as so defined), directly or
  indirectly, in the aggregate a lesser percentage of the voting power of the
  Voting Stock of such parent corporation and do not have the right or
  ability by voting power, contract or otherwise to elect or designate for
  election a majority of the Board of Directors of such parent corporation);
  or
 
    (iii) during any period of two consecutive years, individuals who at the
  beginning of such period constituted the Board of Directors of the Company
  (together with any new directors whose election by such Board of Directors
  or whose nomination for election by the shareholders of the Company was
  approved by a vote of at least 66 2/3% of the directors of the Company then
  still in office who were either directors at the beginning of such period
  or whose election or nomination for election was previously so approved)
  cease for any reason to constitute a majority of the Board of Directors of
  the Company then in office.
 
  Within 30 days following any Change of Control, the Company will mail a
notice to each holder stating (i) that a Change of Control has occurred and
that such holder has the right to require the Company to repurchase all or any
part of such holder's Senior Notes at a repurchase price in cash equal to 101%
of the principal amount thereof plus accrued and unpaid interest, if any, to
the date of repurchase; (ii) the circumstances and relevant facts regarding
such Change of Control (including information with respect to pro forma
historical income, cash flow and capitalization after giving effect to such
Change of Control); (iii) the repurchase date (which will be no earlier than 30
days nor later than 60 days from the date such notice is mailed in the event of
a Change of Control); and (iv) the instructions, determined by the Company
consistent with the Note Indenture, that a holder must follow in order to have
its Senior Notes repurchased.
 
  The Change of Control purchase feature of the Senior Notes may in certain
circumstances make more difficult or discourage a sale or takeover of the
Company, and, thus, the removal of incumbent management. The Change of Control
purchase feature, however, is not part of a plan by management to adopt a
series of antitakeover provisions. Instead, the Change of Control purchase
feature is a result of negotiations between the Company and the Underwriters.
Subject to the limitations discussed below, the Company or any "person" meeting
the definition of a Permitted Holder could, in the future, enter into certain
transactions, including acquisitions, refinancings or other recapitalizations,
that would not constitute a Change of Control under the Note Indenture, but
that could increase the amount of indebtedness outstanding at such time or
otherwise affect the Company's capital structure or credit ratings.
 
  The Company's other indebtedness may contain prohibitions of certain events
which would constitute a Change of Control. In addition, the exercise by the
holders of the Senior Notes of their
 
                                       54
<PAGE>
 
right to require the Company to repurchase the Senior Notes could cause a
default under the terms of agreements between the Company and bank or other
lenders, if the Change of Control itself does not, due to the financial effect
of such repurchase on the Company. Finally, the Company's ability to pay cash
to the holders of the Senior Notes upon a repurchase may be limited by the
Company's then existing financial resources. The failure of the Company to
repurchase Senior Notes in accordance with this provision would constitute an
Event of Default. See "Defaults" below.
 
  The Company will comply with any applicable tender offer rules under the
Securities Exchange Act of 1934, as amended (the "Exchange Act") which may then
be applicable, including Rule 14e-1, and any other securities laws or
regulations, in connection with any offer required to be made by the Company to
repurchase the Senior Notes as a result of a Change of Control.
 
CERTAIN COVENANTS
 
  Set forth below are certain covenants contained in the Note Indenture:
 
  Limitation on Debt. The Company shall not issue, directly or indirectly, any
Debt unless immediately after giving effect to the issuance of such Debt and
the receipt and application of the proceeds thereof, the Consolidated EBITDA
Coverage Ratio for the period of the most recently completed four fiscal
quarters of the Company ending at least 45 days prior to the date such Debt is
issued exceeds 2.5 to 1.0; provided, however, that nothing herein shall limit
the ability of the Subsidiaries to incur Debt in accordance with "--Limitation
on Subsidiary Debt and Preferred Stock" below.
 
  Notwithstanding the foregoing, the Company may issue the following Debt: (1)
Debt issued pursuant to the Bank Revolver or any other Bank Debt in an
aggregate principal amount outstanding at any one time not to exceed the
greater of $35.0 million or 80% of Eligible Accounts Receivable; provided,
however, that such amount shall be reduced by the aggregate outstanding
principal amount of all Debt issued pursuant to clauses (5), (6) and (7) below
and clause (3) under "--Limitation on Subsidiary Debt and Preferred Stock"
below; (2) Debt owed to and held by a Wholly Owned Subsidiary; provided,
however, that any subsequent issuance or transfer of any Capital Stock which
results in any such Wholly Owned Subsidiary ceasing to be a Wholly Owned
Subsidiary or any transfer of such Debt (other than to a Wholly Owned
Subsidiary) shall be deemed, in each case, to constitute the issuance of such
Debt by the Company; (3) the Senior Notes and Debt issued in exchange for, or
the proceeds of which are used to refund or refinance, any Debt permitted by
this clause (3); provided, however, that (i) the principal amount of the Debt
so issued shall not exceed the principal amount of the Debt so exchanged,
refunded or refinanced and (ii) the Debt so issued (A) shall not mature prior
to the Stated Maturity of the Debt so exchanged, refunded or refinanced and (B)
shall have an Average Life equal to or greater than the remaining Average Life
of the Debt so exchanged, refunded or refinanced; (4) Debt (other than Debt
described in clause (1), (2) or (3) above) outstanding on the date on which the
Senior Notes were originally issued and Debt issued in exchange for, or the
proceeds of which are used to refund or refinance, any Debt permitted by this
clause (4) or by clause (4) under "--Limitation on Subsidiary Debt and
Preferred Stock" below, or any Debt issued as permitted by the first paragraph
of "Limitation on Debt" above; provided, however, that (i) the principal amount
of the Debt so issued shall not exceed the principal amount of the Debt so
exchanged, refunded or refinanced and (ii) the Debt so issued (A) shall not
mature prior to the Stated Maturity of the Debt so exchanged, refunded or
refinanced and (B) shall have an Average Life equal to or greater than the
remaining Average Life of the Debt so exchanged, refunded or refinanced; (5)
Debt issued with respect to obligations that are tax-exempt pursuant to Section
103 of the Internal Revenue Code of 1986, as from time to time amended (the
"Code"), and that are issued in connection with pollution control facilities or
other plant and equipment or other facilities of the Company or a Subsidiary;
provided, however, that the aggregate principal amount of all Debt permitted by
this clause (5) outstanding
 
                                       55
<PAGE>
 
at any one time shall not exceed $10.0 million; (6) Debt issued by the Company,
whether or not secured by a Lien, constituting all or a part of the purchase
price of assets or property acquired or constructed in the ordinary course of
business after the date on which the Senior Notes were originally issued and
Debt issued by the Company in exchange for, or the proceeds of which are used
to refund or refinance, any then outstanding Debt permitted by this clause (6);
provided, however, that (i) the principal amount of the Debt so issued shall
not exceed the principal amount of the Debt so exchanged, refunded or
refinanced, and (ii) the Debt so issued (A) shall not mature prior to the
Stated Maturity of the Debt so exchanged, refunded or refinanced and (B) shall
have an Average Life equal to or greater than the remaining Average Life of the
Debt so exchanged, refunded or refinanced; provided further, however, that the
aggregate principal amount of all Debt permitted by this clause (6) outstanding
at any one time shall not exceed $10.0 million; and (7) Debt (other than Debt
described in clauses (1) through (6) above and in the immediately preceding
paragraph) in an aggregate principal amount outstanding at any one time not to
exceed $10.0 million minus the aggregate outstanding principal amount of all
Debt of Subsidiaries issued pursuant to clause (3) under "--Limitation on
Subsidiary Debt and Preferred Stock" below.
 
  Notwithstanding the two preceding paragraphs, the Company shall not issue any
Debt (i) if the proceeds thereof are used, directly or indirectly, to repay,
prepay, redeem, defease, retire, refund or refinance any Subordinated
Obligations unless such Debt shall be subordinated to the Senior Notes to at
least the same extent as such Subordinated Obligations or (ii) if such Debt is
subordinate or junior in ranking in any respect to any other indebtedness
unless such Debt is expressly subordinated in right of payment to the Senior
Notes.
 
  Limitation on Subsidiary Debt and Preferred Stock. The Company shall not
permit any Subsidiary to issue, directly or indirectly, any Debt or Preferred
Stock except: (1) any Subsidiary Guarantee and any Bank Obligation; (2) Debt or
Preferred Stock issued to and held by the Company or a Wholly Owned Subsidiary;
provided, however, that (i) any subsequent issuance or transfer of any Capital
Stock which results in any such Wholly Owned Subsidiary ceasing to be a Wholly
Owned Subsidiary, or (ii) any subsequent transfer of such Debt or Preferred
Stock (other than to the Company or a Wholly Owned Subsidiary) shall be deemed,
in each case, to constitute the issuance of such Debt or Preferred Stock by the
issuer thereof; (3) Debt or Preferred Stock of a Subsidiary issued and
outstanding on or prior to the date on which such Subsidiary was acquired by
the Company (other than Debt or Preferred Stock issued as consideration in, or
to provide all or any portion of the funds or credit support utilized to
consummate, the transaction or series of related transactions pursuant to which
such Subsidiary became a Subsidiary or was acquired by the Company); provided,
however, that the aggregate principal amount or liquidation value of such Debt
and Preferred Stock permitted by this clause (3) outstanding at any one time
shall not exceed $10.0 million; (4) Debt or Preferred Stock (other than Debt or
Preferred Stock described in clauses (1) through (3) above) outstanding on the
date of the Note Indenture; and (5) Debt or Preferred Stock issued in exchange
for, or the proceeds of which are used to refinance, Debt or Preferred Stock
referred to in the foregoing clause (3) or (4); provided, however, that (i) the
principal amount or liquidation value of such Debt or Preferred Stock so issued
shall not exceed the principal amount or liquidation value of the Debt or
Preferred Stock so exchanged, refunded or refinanced and (ii) the Debt or
Preferred Stock so issued (A) shall have a Stated Maturity later than the
Stated Maturity of the Debt or Preferred Stock so exchanged, refunded or
refinanced and (B) shall have an Average Life equal to or greater than the
remaining Average Life of the Debt or Preferred Stock so exchanged, refunded or
refinanced.
 
  Limitation on Liens. The Company shall not, and shall not permit any
Subsidiary to, create or permit to exist any Lien upon any of its property or
assets, now owned or hereafter acquired, securing any obligation unless
concurrently with the creation of such Lien effective provision is made to
secure the Senior Notes equally and ratably with such obligation for so long as
such obligation is so secured; provided, however, that if such obligation is a
Subordinated Obligation, the
 
                                       56
<PAGE>
 
Lien securing such obligation shall be subordinated and junior to the Lien
securing the Senior Notes with the same or lesser relative priority as such
Subordinated Obligation shall have with respect to the Senior Notes. The
preceding restriction shall not require the Company or any Subsidiary to
equally and ratably secure the Senior Notes if the Lien consists of the
following: (1) Liens created by the Note Indenture and Liens existing as of the
date on which the Senior Notes were originally issued; (2) Permitted Liens; (3)
Liens to secure Debt issued by the Company for the purpose of financing all or
a part of the purchase price of assets or property acquired or constructed in
the ordinary course of business after the date on which the Senior Notes were
originally issued; provided, however, that (i) the aggregate principal amount
(or accreted value in the case of Debt issued at a discount) of Debt so issued
shall not exceed the lesser of cost or Fair Market Value, as determined in good
faith by the Board of Directors of the Company, of the assets or property so
acquired or constructed, (ii) the Debt secured by such Liens shall have been
permitted to be issued under clause (6) of "--Limitation on Debt" above and
(iii) such Liens shall not encumber any other assets or property of the Company
or any of its Subsidiaries other than such assets or property or any
improvement on such assets or property and shall attach to such assets or
property within 90 days of the construction or acquisition of such assets or
property; (4) Liens on the assets or property of a Subsidiary existing at the
time such Subsidiary became a Subsidiary and not issued as a result of (or in
connection with or in anticipation of) such Subsidiary becoming a Subsidiary;
provided, however, that (i) the Debt secured by such Liens shall have been
permitted to be issued under clause (3) of "--Limitation on Subsidiary Debt and
Preferred Stock" above and (ii) such Liens do not extend to or cover any other
property or assets of the Company or any of its other Subsidiaries; (5) Liens
on the assets of the Company or any Subsidiary that is a guarantor thereof or
which acts as a co-borrower thereunder securing Debt under the Bank Revolver or
other Bank Debt permitted under clause (1) of "--Limitation on Debt" above; (6)
Liens securing industrial revenue or pollution control bonds issued by the
Company; provided, however, that (i) the aggregate principal amount of Debt
secured by such Liens shall not exceed the lesser of cost or Fair Market Value,
as determined in good faith by the Board of Directors of the Company, of the
assets or property so financed, (ii) the Debt secured by such Liens shall have
been permitted to be issued under clause (5) of "--Limitation on Debt" above,
and (iii) such Liens do not extend to or cover any other property or assets of
the Company; or (7) Liens securing Debt issued to refinance Debt which has been
secured by a Lien permitted under the Note Indenture and is permitted to be
refinanced under the Note Indenture; provided, however, that such Liens do not
extend to or cover any property or assets of the Company or any of its
Subsidiaries not securing the Debt so refinanced, and the principal amount (or
accreted value) of the Debt so secured is not increased except as otherwise
permitted pursuant to the Note Indenture.
 
  Limitation on Sale/Leaseback Transactions. The Company shall not, and shall
not permit any Subsidiary to, enter into, Guarantee or otherwise become liable
with respect to any Sale/Leaseback Transaction unless at least one of the
following conditions is satisfied:
 
    (1) The Company or such Subsidiary, under clauses (2) through (7) of "--
  Limitation on Liens" above, could create a Lien on the property to secure
  Debt in an amount at least equal to the Attributable Debt in respect of
  such Sale/Leaseback Transaction and the Company or such Subsidiary, as the
  case may be, receives consideration at least equal to the Fair Market
  Value, as determined in good faith by the Board of Directors of the
  Company, of the property transferred; or
 
    (2) the Sale/Leaseback Transaction is treated as an Asset Disposition and
  all the conditions of "--Limitation on Sales of Assets and Subsidiary
  Stock" below are satisfied with respect to such Sale/Leaseback Transaction
  (without giving effect to the exceptions for Net Available Cash, as set
  forth in the second paragraph of "--Limitation on Sales of Assets and
  Subsidiary Stock" below).
 
  Limitation on Restricted Payments. The Company shall not, and shall not
permit any Subsidiary, directly or indirectly, to (i) declare or pay any
dividend or make any distribution on or
 
                                       57
<PAGE>
 
in respect of its Capital Stock (including any payment in connection with any
merger or consolidation involving the Company) or to the direct or indirect
holders of its Capital Stock (except dividends or distributions payable solely
in its Non-Convertible Capital Stock or in options, warrants or other rights to
purchase its Non-Convertible Capital Stock and except dividends or
distributions payable to the Company or a Wholly Owned Subsidiary), (ii)
purchase, redeem or otherwise acquire or retire for value any of its Capital
Stock (except Capital Stock of a Wholly Owned Subsidiary) , (iii) purchase,
repurchase, redeem, defease or otherwise acquire or retire for value, prior to
scheduled maturity, scheduled repayment or scheduled sinking fund payment, any
Subordinated Obligations (other than the purchase, repurchase or other
acquisition of Subordinated Obligations purchased in anticipation of satisfying
a sinking fund obligation, principal installment or final maturity, in each
case due within one year of the date of acquisition), or (iv) make any
Investment other than Permitted Investments (any such dividend, distribution,
purchase, redemption, repurchase, defeasance, other acquisition, retirement or
Investment being herein referred to as a "Restricted Payment"), if at the time
the Company or such Subsidiary makes such Restricted Payment: (1) a Default
shall have occurred and be continuing (or would result therefrom); or (2) upon
giving effect to such Restricted Payment, the Company is not able to incur an
additional $1.00 of Debt pursuant to the Consolidated EBITDA Coverage Ratio as
set forth in the first paragraph of "--Limitation on Debt" above; or (3) upon
giving effect to such Restricted Payment, the aggregate amount of such
Restricted Payment and all other Restricted Payments since the date on which
the Senior Notes were originally issued would exceed the sum of: (a) 50% of the
Consolidated Net Income accrued during the period (treated as one accounting
period) from the first day of the first month of the fiscal quarter in which
the Senior Notes were originally issued through the last full fiscal quarter
for which quarterly or annual financial statements are available prior to the
date of such Restricted Payment (or, in case such Consolidated Net Income shall
be a deficit, minus 100% of such deficit); provided, however, that if a Public
Offering as described in "--Limitation on Issuance and Sale of Capital Stock of
Subsidiaries" below has been consummated, Consolidated Net Income for purposes
of this clause (iv) (3) (a) shall be reduced by an amount equal to the net
income of CHTC from the date of original issuance of the Senior Notes to the
date of the closing of the Public Offering determined in accordance with
generally accepted accounting principles; (b) the aggregate Net Cash Proceeds
received by the Company from the issue or sale of its Capital Stock (other than
Redeemable Stock or Exchangeable Stock) subsequent to the date on which the
Senior Notes were originally issued (other than an issuance or sale to a
Subsidiary or an employee stock ownership plan or similar trust); (c) the
aggregate Net Cash Proceeds received by the Company from the issue or sale of
its Capital Stock (other than Redeemable Stock or Exchangeable Stock) to an
employee stock ownership plan subsequent to the date on which the Senior Notes
were originally issued but (if such employee stock ownership plan incurs any
Debt) only to the extent that any such proceeds are equal to any increase in
the Consolidated Net Worth of the Company resulting from principal repayments
made by such employee stock ownership plan with respect to indebtedness
incurred by it to finance the purchase of such Capital Stock; and (d) the
amount by which consolidated Debt of the Company is reduced on the Company's
balance sheet upon the conversion or exchange (other than by a Subsidiary)
subsequent to the date on which the Senior Notes were originally issued of any
Debt of the Company convertible or exchangeable for Capital Stock (other than
Redeemable Stock or Exchangeable Stock) of the Company (less the amount of any
cash, or other property, distributed by the Company upon such conversion or
exchange).
 
  So long as no Default shall have occurred and be continuing (or would result
therefrom), the foregoing limitations on Restricted Payments shall not
prohibit: (i) any purchase or redemption of Capital Stock or Subordinated
Obligations of the Company made by exchange for, or out of the proceeds of the
substantially concurrent sale of, Capital Stock of the Company (other than
Redeemable Stock or Exchangeable Stock and other than Capital Stock issued or
sold to a Subsidiary or an employee stock ownership plan); provided, however,
that (A) such purchase or redemption shall be excluded in the calculation of
the amount of Restricted Payments and (B) the Net Cash Proceeds from such sale
shall be excluded from clauses (3)(b) and (3)(c) of the previous paragraph;
 
                                       58
<PAGE>
 
(ii) any purchase or redemption of Subordinated Obligations of the Company made
by exchange for, or out of the proceeds of the substantially concurrent sale
of, Debt of the Company other than to a Subsidiary; provided, however, that
such Debt (A) shall be subordinated to the Senior Notes to at least the same
extent as the Subordinated Obligations so exchanged, purchased or redeemed, (B)
shall have a Stated Maturity later than the Stated Maturity of the Senior Notes
and (C) shall have an Average Life greater than the remaining Average Life of
the Senior Notes; provided further, however, that such purchase or redemption
shall be excluded in the calculation of the amount of Restricted Payments;
(iii) any purchase or redemption of Subordinated Obligations from Net Available
Cash to the extent permitted by the covenant described below under "--
Limitation on Sales of Assets and Subsidiary Stock"; provided, however, that
such purchase or redemption shall be excluded in the calculation of the amount
of Restricted Payments; or (iv) dividends paid within 60 days after the date of
declaration thereof if at such date of declaration such dividend would have
complied with this provision; provided, however, that such dividend shall be
included in the calculation of the amount of Restricted Payments.
 
  Limitation on Issuance and Sale of Capital Stock of Subsidiaries. The Company
shall not permit any Subsidiary to issue or sell any Capital Stock to any
person, or permit any person in either case, other than the Company and its
Wholly Owned Subsidiaries, to own or hold an interest, other than any lien
permitted by the covenant described under "--Limitation on Liens" above or any
interest or right to receive any interest owned or held on the date on which
the Senior Notes were originally issued by a person other than the Company and
its Wholly Owned Subsidiaries, in any Capital Stock of any Subsidiary;
provided, however, that the foregoing limitation shall not apply to (i) the
sale of all but not less than all of the Capital Stock of any Subsidiary made
in accordance with "--Limitation on Sales of Assets and Subsidiary Stock,"and
(ii) the issuance and sale of Capital Stock of CHTC pursuant to one or more
firm commitment underwritten public offerings by CHTC (each a "Public
Offering"); provided, however, that (1) following each Public Offering the
Company shall continue to own at least 75% of the outstanding Capital Stock of
CHTC, (2) the net proceeds from each Public Offering shall be invested by CHTC
in the business of CHTC, (3) CHTC may not within 18 months after the closing of
each Public Offering (A) declare or pay any dividend or make any distribution
on or in respect of its Capital Stock (including any payment in connection with
any merger or consolidation involving CHTC) or to the direct or indirect
holders of its Capital Stock (except dividends or distributions payable solely
in its Non-Convertible Capital Stock or in options, warrants or other rights to
purchase its Non-Convertible Capital Stock) or (B) purchase, redeem or
otherwise acquire or retire for value any Capital Stock of CHTC, and (4) as of
the date of commencement of each Public Offering the Adjusted EBITDA for the
period of the most recently completed four fiscal quarters of the Company
ending at least 45 days prior to such date exceeds 95% of EBITDA for such
period, provided, however, that (A) if the Company or any Subsidiary has issued
any Debt since the beginning of such period that remains outstanding, EBITDA
and Adjusted EBITDA for such period shall be calculated after giving effect on
a pro forma basis to such Debt as if such Debt had been issued on the first day
of such period and the discharge of any other Debt refinanced, refunded,
exchanged or otherwise discharged with the proceeds of such new Debt as if any
such discharge had occurred on the first day of such period, (B) if since the
beginning of such period the Company or any Subsidiary shall have made any
Asset Disposition, EBITDA and Adjusted EBITDA for such period shall be reduced
by an amount equal to the EBITDA (if positive) directly attributable to the
assets which are the subject of such Asset Disposition for such period, or
increased by an amount equal to the EBITDA (if negative) directly attributable
thereto for such period, and (C) if since the beginning of such period the
Company or any Subsidiary (by merger or otherwise) shall have made an
Investment in any Subsidiary (or any person which becomes a Subsidiary) or an
acquisition of assets, including any acquisition of assets occurring in
connection with a transaction causing a calculation to be made hereunder, which
constitutes all of an operating unit of a business, EBITDA and Adjusted EBITDA
for such period shall be calculated after giving pro forma effect thereto
(including the issuance of any Debt), as if such Investment or acquisition
occurred on the first day of such period. For purposes of this calculation,
whenever pro forma effect
 
                                       59
<PAGE>
 
is to be given to an acquisition of assets, the amount of income or earnings
relating thereto, and the amount of Consolidated Interest Expense associated
with any Debt issued in connection therewith, the pro forma calculations shall
be determined in good faith by a responsible financial or accounting Officer of
the Company. If any Debt bears a floating rate of interest and is being given
pro forma effect, the interest on such Debt shall be calculated as if the rate
in effect on the date of determination had been the applicable rate for the
entire period.
 
  Limitation on Restrictions on Distributions from Subsidiaries. The Company
shall not, and shall not permit any Subsidiary to, create or otherwise cause or
permit to exist or become effective any consensual encumbrance or restriction
on the ability of any Subsidiary to (i) pay dividends or make any other
distributions on its Capital Stock or pay any Debt or other obligation owed to
the Company or any Subsidiary, (ii) make any Investment in or loans or advances
to the Company or any Subsidiary, or (iii) transfer any of its property or
assets to the Company or any Subsidiary. Notwithstanding the foregoing, the
Company may, and may permit any Subsidiary to, suffer to exist: (1) any
encumbrance or restriction pursuant to an agreement in effect at or entered
into on or prior to the date on which the Senior Notes were originally issued;
(2) any encumbrance or restriction with respect to a Subsidiary pursuant to an
agreement relating to any Debt issued by such Subsidiary on or prior to the
date on which such Subsidiary became a Subsidiary (other than Debt issued as
consideration in, or to provide all or any portion of the funds utilized to
consummate, the transaction or series of related transactions pursuant to which
such Subsidiary became a Subsidiary or was acquired by the Company) and
outstanding on such date; (3) any encumbrance or restriction pursuant to an
agreement effecting a refinancing or extension of Debt issued pursuant to an
agreement referred to in clause (1) or (2) above or contained in any amendment
to an agreement referred to in clause (1) or (2) above; provided, however, that
the encumbrances and restrictions contained in any such refinancing or
extension agreement or amendment are not materially less favorable to the
holders of the Senior Notes than encumbrances and restrictions contained in
such agreement referred to in clause (1) or (2) above; (4) any encumbrance or
restriction consisting of customary nonassignment provisions in leases
governing leasehold interests to the extent such provisions restrict the
transfer of the lease; (5) in the case of clause (iii) above, restrictions
contained in security agreements securing Debt of a Subsidiary otherwise
permitted by the Note Indenture to the extent such restrictions restrict the
transfer of the property subject to such security agreements; and (6)
restrictions imposed pursuant to clause (ii) of "--Limitation on Issuance and
Sale of Capital Stock of Subsidiaries" above.
 
  Limitation on Sales of Assets and Subsidiary Stock. The Company shall not,
and shall not permit any Subsidiary to, make any Asset Disposition unless: (i)
the Company or such Subsidiary receives consideration at the time of such Asset
Disposition at least equal to the Fair Market Value, as determined in good
faith, with or without independent appraisal, by the Board of Directors of the
Company (including as to the value of all non-cash consideration), of the
shares and assets subject to such Asset Disposition and at least 85% of the
consideration thereof received by the Company or such Subsidiary is in the form
of cash or Cash Equivalents; and (ii) an amount equal to 100% of the Net
Available Cash from such Asset Disposition is applied by the Company (or such
Subsidiary, as the case may be) (A) first, to the extent the Company is
required by the terms of any Debt to prepay, repay or purchase Debt (other than
any Redeemable Stock) of the Company, such Subsidiary or any Wholly Owned
Subsidiary (in each case other than Debt owed to the Company or an Affiliate of
the Company) within 60 days from the later of the date of such Asset
Disposition or the receipt of such Net Available Cash; (B) second, to the
extent of the balance of such Net Available Cash after application in
accordance with clause (A), at the Company's election to the investment by the
Company, such Subsidiary or any Wholly Owned Subsidiary in assets to replace
the assets that were the subject of such Asset Disposition or in assets that
(as determined by the Board of Directors) will be used in the businesses of the
Company and its Wholly Owned Subsidiaries existing on the date on which the
Senior Notes were originally issued or in businesses reasonably related
thereto, in all cases within the later of one year from the date of such Asset
Disposition or the receipt
 
                                       60
<PAGE>
 
of such Net Available Cash; (C) third, to the extent of the balance of such Net
Available Cash after application in accordance with clauses (A) and (B) above,
to make an offer pursuant to and subject to the Note Indenture, to the holders
of the Senior Notes to purchase Senior Notes at a purchase price of 100% of the
principal amount thereof plus accrued and unpaid interest; and (D) fourth, to
the extent of the balance of such Net Available Cash after application in
accordance with clauses (A), (B) and (C) above, to the prepayment, repayment or
purchase of Debt (other than any Redeemable Stock) of the Company (other than
Debt owed to an Affiliate of the Company) or Debt of any Subsidiary (other than
Debt owed to the Company or an Affiliate of the Company), in each case within
one year from the later of the receipt of such Net Available Cash and, if
applicable, the date the offer described in the next paragraph below is
consummated; provided, however, that in connection with any prepayment,
repayment or purchase of Debt pursuant to clause (A) or clause (D) above, the
Company shall cause the related loan commitment (if any) to be permanently
reduced in an amount equal to the principal amount so prepaid, repaid or
purchased; and provided, further, however, that in connection with an offer
pursuant to clause (C) above, if the principal amount of such Senior Notes,
together with accrued and unpaid interest, tendered for acceptance pursuant to
such offer exceeds the balance of Net Available Cash, then the Company will
accept for purchase the Senior Notes of each such tendering holder on a pro
rata basis in accordance with the principal amount so tendered.
 
  Notwithstanding the provisions of clause (ii) above, in the event that the
Net Available Cash resulting from any Asset Disposition is less than $2.5
million, the application of an amount equal to such Net Available Cash in
accordance with such clause (ii) may be deferred until such time as such Net
Available Cash from any prior or subsequent Asset Dispositions not otherwise
applied in accordance with such clause (ii), is at least equal to $2.5 million.
In the event that the Net Available Cash resulting from any Asset Disposition,
after giving effect to clauses (A) and (B) above, is less than $2.5 million,
the application of such amount equal to such Net Available Cash to make an
offer to purchase Senior Notes in accordance with clause (C) above may be
deferred until such time as such Net Available Cash, together with Net
Available Cash from any prior or subsequent Asset Dispositions not otherwise
applied in accordance with this provision, is at least equal to $2.5 million.
Pending application of Net Available Cash pursuant to this provision, such Net
Available Cash shall be invested in Cash Equivalents. To the extent any portion
of the amount of Net Available Cash remains after compliance with this
provision and provided that all holders of Senior Notes have been given the
opportunity to tender their Senior Notes for repurchase as provided in clause
(C) above, the Company may use such remaining amount for general corporate
purposes.
 
  In the event of an Asset Disposition that requires the purchase of the Senior
Notes pursuant to clause (ii)(C) above, the Company will be required to
purchase the Senior Notes tendered pursuant to an offer by the Company for the
Senior Notes (the "Offer") at the purchase price set forth above in accordance
with the procedures (including prorationing in the event of oversubscription)
set forth in the Note Indenture.
 
  The Company shall comply, to the extent applicable, with the requirements of
Section 14(e) of the Exchange Act and any other securities laws or regulations
in connection with the repurchase of Senior Notes pursuant to the preceding
paragraphs. To the extent that the provisions of any securities laws or
regulations conflict with provisions of the Note Indenture, the Company shall
comply with the applicable securities laws and regulations and shall not be
deemed to have breached its obligations under the Note Indenture by virtue
thereof.
 
  Limitation on Transactions with Affiliates. The Company shall not, and shall
not permit any Subsidiary to, conduct any business or enter into any
transaction or series of similar transactions (including the purchase, sale,
lease or exchange of any property or the rendering of any service) with any
Affiliate of the Company or any legal or beneficial owner of 5% or more of any
class of Capital Stock of the Company or with any Affiliate of any such owner
(other than (i) a Wholly Owned Subsidiary or (ii) an employee stock ownership
plan for the benefit of the Company's or a
 
                                       61
<PAGE>
 
Subsidiary's employees), unless the terms of such business, transaction or
series of transactions are (A) set forth in writing, (B) as favorable to the
Company or such Subsidiary as terms that would be obtainable at the time for a
comparable transaction or series of similar transactions in arm's-length
dealings with an unrelated third person, and (C) if such business or
transaction or series of transactions involves in excess of $1.0 million, (x)
the Board of Directors of the Company has, by resolution approved by a majority
of the disinterested directors, determined in good faith that such business or
transaction or series of transactions meets the criteria set forth in clause
(B) above, and (y) the Company has obtained an opinion of a nationally
recognized expert with experience in appraising the terms and conditions of the
type of business or transaction or series of transactions stating that such
business or transaction or series of transactions is fair (from a financial
point of view) to the Company or such Subsidiary, as the case may be. The
foregoing, however, will not prohibit (1) any transactions between the Company
or a Subsidiary and its own employee stock ownership plan or (2) any Restricted
Payment permitted under "--Limitation on Restricted Payments" above, and (3)
management compensation arrangements approved by the disinterested members of
the Board of Directors.
 
  Lines of Business. The Company shall not, and shall not permit any of its
Subsidiaries to, enter into any business, either directly or through any
Subsidiary, except for those businesses in which the Company and its
Subsidiaries were engaged on the date on which the Senior Notes were originally
issued or businesses reasonably related thereto.
 
  SEC Reports. Each of the Company and the Guarantor Subsidiaries shall file
with the Trustee and provide holders of the Senior Notes, within 15 days after
it files them with the Securities and Exchange Commission (the "Commission"),
copies of its annual report and of the information, documents and other reports
(or copies of such portions of any of the foregoing as the Commission may by
rules and regulations prescribe) which the Company or such Guarantor Subsidiary
is required to file with the Commission pursuant to Section 13 or 15(d) of the
Exchange Act. Notwithstanding that the Company may not be required to remain
subject to the reporting requirements of Section 13 or 15(d) of the Exchange
Act, the Company shall continue to file with the Commission and provide the
Trustee and holders of the Senior Notes with such annual reports and such
information, documents and other reports (or copies of such portions of any of
the foregoing as the Commission may by rules and regulations prescribe) which
are specified in Sections 13 and 15(d) of the Exchange Act.
 
SUCCESSOR COMPANY
 
  The Company may not consolidate with or merge with or into, or convey,
transfer or lease all or substantially all its assets to, any person unless:
(i) the resulting, surviving or transferee person (if not the Company) is
organized and existing under the laws of the United States of America or any
state thereof or the District of Columbia and such person expressly assumes by
a supplemental indenture, executed and delivered to the Trustee, in form
satisfactory to the Trustee, all the obligations of the Company under the Note
Indenture and the Senior Notes; (ii) immediately after giving effect to such
transaction (and treating any Debt which becomes an obligation of the
resulting, surviving or transferee person or any Subsidiary as a result of such
transaction as having been issued by such person or such Subsidiary at the time
of such transaction), no Default has occurred and is continuing; (iii)
immediately after giving effect to such transaction, on a pro forma basis, the
resulting, surviving or transferee Person would be able to issue at least an
additional $1.00 of Debt pursuant to the Consolidated EBITDA Coverage Ratio as
set forth in the first paragraph of "Certain Covenants--Limitation on Debt";
(iv) immediately after giving effect to such transaction, on a pro forma basis,
the resulting, surviving or transferee person has Consolidated Net Worth in an
amount which is not less than the Consolidated Net Worth of the Company
immediately prior to such transaction; and (v) the Company delivers to the
Trustee an Officers' Certificate and an opinion of counsel, each stating that
such consolidation, merger or transfer and such supplemental indenture (if any)
comply with the Note Indenture.
 
                                       62
<PAGE>
 
  The resulting, surviving or transferee person will be the successor company.
 
DEFAULTS
 
  An Event of Default is defined in the Note Indenture as: (i) a default in any
payment of interest on the Senior Notes when due, continued for 30 days, (ii) a
default in the payment of principal of any Note when due at its Stated
Maturity, upon redemption, upon acceleration or otherwise, or the failure to
redeem or purchase the Senior Notes when required pursuant to the Note
Indenture or the Senior Notes; (iii) the failure by the Company to comply with
its obligations under "Successor Company" above, to make or consummate an Offer
in accordance with the provisions of "Certain Covenants--Limitation on Sales of
Assets and Subsidiary Stock" or to make or consummate a Change of Control Offer
in accordance with the provisions of "Change of Control," (iv) the failure by
the Company to observe or comply with any of the agreements in the Senior Notes
or the Note Indenture (other than those referred to in clauses (i), (ii) or
(iii) above), which continues for 60 days after there has been given to the
Company by the Trustee or to the Company and the Trustee by the holders of at
least 25% in principal amount of Senior Notes then outstanding a written notice
specifying such failure, (v) Debt of the Company or any Subsidiary is not paid
within any applicable grace period after final maturity or is accelerated by
the holders thereof because of a default and the total amount of such Debt
unpaid or accelerated exceeds $5.0 million, (vi) any judgment or decree for the
payment of money in excess of $5.0 million is rendered and entered against the
Company or a Subsidiary and is not discharged and either (A) an enforcement
proceeding has been commenced by any creditor upon such judgment or decree or
(B) there is a period of 60 days following such judgment or decree during which
such judgment or decree is not discharged, waived or the execution thereof
stayed, (vii) any Subsidiary Guarantee ceases to be in full force and effect,
other than in accordance with its terms, or any Guarantor Subsidiary shall deny
or disaffirm its obligations under its Subsidiary Guarantee, or (viii) certain
events of bankruptcy, insolvency or reorganization of the Company or a
Subsidiary (a "bankruptcy default").
 
  If an Event of Default (other than a bankruptcy default) occurs and is
continuing, the Trustee or the holders of at least 25% in principal amount of
the outstanding Senior Notes may declare the principal of and accrued interest
on all the Senior Notes to be due and payable. Upon such a declaration, such
principal and interest shall be due and payable immediately. If a bankruptcy
default occurs, the principal of and interest on all the Senior Notes will ipso
facto become and be immediately due and payable without any declaration or
other act on the part of the Trustee or any holders of the Senior Notes. Under
certain circumstances, the holders of a majority in principal amount of the
outstanding Senior Notes may rescind any such acceleration with respect to the
Senior Notes and its consequences if the rescission would not conflict with any
judgment or decree and if all Events of Default, other than the nonpayment of
accelerated principal of, premium, if any, and interest on the Senior Notes,
have been cured or waived as provided in the Note Indenture. The holders of a
majority in principal amount of the Senior Notes may waive any past default
under the Note Indenture, except a default in the payment of principal, premium
or interest on a Note or default with respect to certain covenants under the
Indenture. See "Amendment, Supplement, Waiver" below.
 
  Subject to the provisions of the Note Indenture relating to the duties of the
Trustee, in case an Event of Default occurs and is continuing, the Trustee will
be under no obligation to exercise any of the rights or powers under the Note
Indenture at the request or direction of any of the holders of the Senior Notes
unless such holders have offered to the Trustee reasonable indemnity or
security against any loss, liability or expense. Except to enforce the right to
receive payment of principal, premium (if any) or interest when due, no holder
of a Senior Note may pursue any remedy with respect to the Note Indenture or
the Senior Notes unless (i) such holder has previously given the Trustee notice
that an Event of Default is continuing, (ii) holders of at least 25% in
principal amount of the Senior Notes make a written request to the Trustee to
pursue the remedy, (iii) such holders have offered the Trustee reasonable
security or indemnity against any loss, liability or expense, (iv)
 
                                       63
<PAGE>
 
the Trustee has not complied with such request within 60 days after the receipt
thereof and the offer of security or indemnity, and (v) the holders of a
majority in principal amount of the outstanding Senior Notes have not given the
Trustee a direction inconsistent with such request within such 60-day period.
Subject to certain restrictions, the holders of a majority in principal amount
of the outstanding Senior Notes are given the right to direct the time, method
and place of conducting any proceeding for any remedy available to the Trustee
or of exercising any trust or power conferred on the Trustee. The Trustee,
however, may refuse to follow any direction that conflicts with law or the Note
Indenture or that the Trustee determines is unduly prejudicial to the rights of
any other holder of a Senior Note or that would involve the Trustee in personal
liability.
 
  The Note Indenture provides that if a Default occurs and is continuing and is
known to the Trustee, the Trustee must mail to each holder of the Senior Notes
and to the Company notice of the Default within 90 days after it occurs. Except
in the case of a Default in the payment of principal of, premium (if any) or
interest on any Senior Note, the Trustee may withhold notice if and so long as
a committee of its trust officers determines in good faith that withholding
notice is in the interest of the holders of the Senior Notes. In addition, the
Company and the Guarantor Subsidiaries are required to deliver to the Trustee,
within 120 days after the end of each fiscal year, a certificate indicating
whether the signers thereof know of any Default that occurred during the
previous year. Each of the Company and the Guarantor Subsidiaries are also
required to deliver to the Trustee, within 30 days after the Company or such
Guarantor Subsidiary becomes aware or should reasonably become aware thereof,
written notice of any event which would constitute certain Defaults, their
status and what action the Company is taking or proposes to take in respect
thereof.
 
AMENDMENT, SUPPLEMENT, WAIVER
 
  Subject to certain exceptions, the Note Indenture may be amended or
supplemented with the written consent of the holders of a majority in principal
amount of the Senior Notes then outstanding and any past default or compliance
with any provisions may be waived with the consent of the holders of a majority
in principal amount of the Senior Notes then outstanding. However, without the
consent of each holder of an outstanding Senior Note, no amendment may, among
other things, (i) reduce the amount of Senior Notes whose holders must consent
to an amendment, (ii) reduce the rate of or extend the time for payment of
interest on any Senior Note, (iii) reduce the principal of or extend the Stated
Maturity of any Senior Note, (iv) reduce the premium payable upon the
redemption of any Senior Note or change the time at which any Senior Note may
or shall be redeemed as described under "Optional Redemption" above, (v) make
any Senior Note payable in money other than that stated in the Senior Note,
(vi) make any change in the amendment provisions which require each holder's
consent or in the waiver provisions, (vii) make any change in provisions
regarding Change of Control, or (viii) make any change adversely affecting the
rights of any holder of the Senior Notes.
 
  Without notice to or consent of any holder of the Senior Notes, the Company
and the Trustee may amend or supplement the Note Indenture to cure any
ambiguity, omission, defect or inconsistency, to provide for the assumption by
a successor corporation of the obligations of the Company under the Note
Indenture, to provide for uncertificated Senior Notes in addition to or in
place of certificated Senior Notes (provided that the uncertificated Senior
Notes are issued in registered form for purposes of Section 163(f) of the Code,
or in a manner such that the uncertificated Senior Notes are described in
Section 163(f)(2)(B)of the Code), to add Guarantees of the Senior Notes, to add
to the covenants of the Company for the benefit of the holders of the Senior
Notes or to surrender any right or power conferred upon the Company, to reflect
the release of any Guarantor Subsidiary from its Subsidiary Guarantee, or the
addition of any Subsidiary of the Company as a Guarantor Subsidiary in the
manner provided in the Note Indenture or to make any change that does not
adversely affect the rights of any holder of the Senior Notes or to comply with
any requirement of the Commission in connection with the qualification of the
Note Indenture under the Trust Indenture Act of 1939, as amended.
 
                                       64
<PAGE>
 
  The consent of the holders of the Senior Notes is not necessary under the
Note Indenture to approve the particular form of any proposed amendment. It is
sufficient if such consent approves the substance of the proposed amendment.
 
  After an amendment under the Note Indenture becomes effective, the Company is
required to mail to holders of the Senior Notes a notice briefly describing
such amendment. However, the failure to give such notice to all holders of the
Senior Notes, or any defect therein, will not impair or affect the validity of
the amendment.
 
TRANSFER
 
  The Senior Notes will be issued in registered form and will be transferable
only upon the surrender of the Senior Notes being transferred for registration
of transfer. The Company may require payment of a sum sufficient to cover any
tax, assessment or other governmental charge payable in connection with certain
transfers and exchanges.
 
DEFEASANCE
 
  The Company at any time may terminate all its obligations under the Senior
Notes and the Note Indenture ("legal defeasance"), except for certain
obligations, including those respecting the defeasance trust and obligations to
register the transfer or exchange of the Senior Notes, to replace mutilated,
destroyed, lost or stolen Senior Notes and to maintain a registrar and paying
agent in respect of the Senior Notes. The Company at any time may terminate its
obligations under the covenants described under "Certain Covenants" and "Change
of Control," the operation of the cross acceleration provision, the bankruptcy
defaults with respect to Subsidiaries and the judgment default provision
described under "Defaults" above ("covenant defeasance").
 
  The Company may exercise its legal defeasance option notwithstanding its
prior exercise of its covenant defeasance option. If the Company exercises its
legal defeasance option, payment of the Senior Notes may not be accelerated
because of an Event of Default with respect thereto. If the Company exercises
its covenant defeasance option, payment of the Senior Notes may not be
accelerated because of an Event of Default specified in clause (iii) or (iv) of
the first paragraph of "Defaults" above.
 
  In order to exercise either defeasance option, the Company must irrevocably
deposit in trust (the "defeasance trust") with the Trustee sufficient money or
U.S. Government Obligations which, together with the payments of interest when
due (and without reinvestment) to be received on the deposited U.S. Government
Obligations to the date of redemption or maturity of the Senior Notes, as the
case may be, will fully provide for the payment of principal, premium (if any)
and interest on the Senior Notes to redemption or maturity, as the case may be,
and must comply with certain other conditions, including delivering to the
Trustee an opinion of counsel to the effect that holders of the Senior Notes
will not recognize income, gain or loss for federal income tax purposes as a
result of such deposit and defeasance and will be subject to federal income tax
on the same amount and in the same manner and at the same times as would have
been the case if such deposit and defeasance had not occurred (and, in the case
of legal defeasance only, such opinion of counsel must be based on a ruling of
the Internal Revenue Service or a change in applicable federal income tax law).
 
CONCERNING THE TRUSTEE
 
  Shawmut Bank, N.A. is to be the Trustee under the Note Indenture and has been
appointed by the Company as registrar and paying agent with regard to the
Senior Notes. The Trustee is expected also to become a lender to the Company
under the amended Bank Revolver.
 
  The Trustee may become owner or pledgee of Senior Notes and may otherwise
deal with the Company or Affiliates of the Company with the same rights it
would have if it were not Trustee.
 
                                       65
<PAGE>
 
  The Note Indenture will provide that in case an Event of Default shall occur
and be continuing, the Trustee will exercise the rights and powers vested in it
by the Note Indenture and use the same degree of care and skill in their
exercise as a prudent person would exercise or use under the circumstances in
the conduct of such person's own affairs.
 
GOVERNING LAW
 
  The Note Indenture provides that it and the Senior Notes will be governed by,
and construed in accordance with, the laws of the State of New York without
giving effect to applicable principles of conflicts of law to the extent that
the application of the law of another jurisdiction would be required thereby.
 
CERTAIN DEFINITIONS
 
  "Adjusted EBITDA" means for any period (i) EBITDA for such period minus (ii)
for such period, the sum of (A) the net income of CHTC plus (B) taxes, if any,
of CHTC, the total interest expense of CHTC, depreciation expense of CHTC,
amortization expense of CHTC and all other non-cash charges to the extent
included in the calculation of net income of CHTC, in each case determined in
accordance with generally accepted accounting principles.
 
  "Affiliate" of any specified person means (i) any other person which,
directly or indirectly, is in control of, is controlled by or is under common
control with such specified person or (ii) any other person who is a director
or officer (A) of such specified person, (B) of any subsidiary of such
specified person, or (C) of any person described in clause (i) above. For
purposes of this definition, control of a person means the power, direct or
indirect, to direct or cause the direction of the management and policies of
such person whether by contract or otherwise; and the terms "controlling" and
"controlled" have meanings correlative to the foregoing.
 
  "Asset Disposition" means any sale, lease, transfer or other disposition (or
series of related sales, leases, transfers or dispositions), including any such
disposition by means of a merger, consolidation or similar transaction, of
shares of Capital Stock of a Subsidiary (other than directors' qualifying
shares), property or other assets (each referred to for the purposes of this
definition as a "disposition") by the Company or any of its Subsidiaries, but
excluding the following: (i) a disposition by a Subsidiary to the Company or by
the Company or a Subsidiary to a Wholly Owned Subsidiary, (ii) a disposition of
tangible property or assets which have become obsolete or are otherwise not
used or useful, so long as such disposition is at Fair Market Value (as
determined by the Board of Directors of the Company in good faith) in the
ordinary course of business, (iii) a disposition that constitutes a Restricted
Payment, a Sale/Leaseback Transaction, or a Public Offering, in each case so
long as effected in accordance with all applicable provisions of the Note
Indenture, and (iv) a disposition of inventory in the ordinary course of
business.
 
  "Attributable Debt" means, in respect of a Sale/Leaseback Transaction, as at
the time of determination, the present value (discounted at the lower of the
interest rate of such Sale/Leaseback Transaction and the interest rate borne by
the Bank Revolver at the time, compounded annually) of the total obligations of
the lessee for rental payments during the remaining term of the lease included
in such Sale/Leaseback Transaction (including any period for which such lease
has been extended).
 
  "Average Life" means, as of the date of determination, with respect to any
Debt or Preferred Stock, the quotient obtained by dividing (i) the sum of the
products of the numbers of years from the date of determination to the dates of
each successive scheduled principal payment of such Debt or redemption or
similar payment with respect to such Preferred Stock multiplied by the amount
of such payment by (ii) the sum of all such payments.
 
 
                                       66
<PAGE>
 
  "Bank Debt" means any and all amounts payable under or in respect of the Bank
Revolver (or if all the obligations under the Bank Revolver shall be replaced,
refinanced or refunded one or more times with obligations under one or more
other agreements and the Trustee shall receive notice thereof from time to time
from the Company designating such other agreements at any given time as the
agreements constituting Bank Debt for purposes of this definition of Bank Debt,
the agreements from time to time so designated), as amended and supplemented
from time to time, including principal, premium (if any), interest (including
interest accruing on or after the filing of any petition in bankruptcy or for
reorganization relating to the Company whether or not a claim for post-filing
interest is allowed in such proceeding), fees, charges, expenses, letters of
credit, reimbursement obligations, guarantees and all other amounts payable
thereunder or in respect thereof.
 
  "Bank Obligation" means for any Subsidiary, the Guarantee by such Subsidiary
of the Bank Debt and any other Debt of any Subsidiary which Debt, directly or
indirectly, Guarantees or secures any Bank Debt or the agreement by any
Subsidiary to act as a co-borrower with respect to any Bank Debt.
 
  "Bank Revolver" means the Amended and Restated Revolving Credit Agreement
among the Company, certain Subsidiaries of the Company named therein, and The
First National Bank of Boston, Shawmut Bank, N.A., and USTrust, and The First
National Bank of Boston, as Agent, as in effect on the date on which the Senior
Notes are originally issued.
 
  "Board of Directors" means the Board of Directors of the Company or any
committee thereof duly authorized to act on behalf of such Board of Directors.
 
  "Business Day" means each day which is not a Legal Holiday.
 
  "CHTC" means Clean Harbors Technology Corporation and any successor thereto.
 
  "Capital Lease Obligations" of a person means any obligation which is
required to be classified and accounted for as a capital lease on the face of a
balance sheet of such person prepared in accordance with generally accepted
accounting principles; the amount of such obligation shall be the capitalized
amount thereof, determined in accordance with generally accepted accounting
principles; and the Stated Maturity thereof shall be the date of the last
payment of rent or any other amount due under such lease prior to the first
date upon which such lease may be terminated by the lessee without payment of a
penalty.
 
  "Capital Stock" means any and all shares, interests, rights to purchase,
warrants, options, participations or other equivalents of or interests in
(however designated) corporate stock, including any Preferred Stock.
 
  "Cash Equivalents" means:
     
    (i) Investments in U.S. Government Obligations maturing within 18 months
  of the date of acquisition thereof;     
     
    (ii) Investments in certificates of deposit or Eurodollar deposits
  maturing within 18 months of the date of acquisition thereof issued by a
  bank or trust company which is organized under the laws of the United
  States or any state thereof and which has a combined capital and surplus of
  at least $100 million and rated at least A3 by Moody's Investors Service,
  Inc.;     
 
    (iii) Investments in repurchase agreements, involving Investments in U.S.
  Government Obligations or other Cash Equivalents entered into with any
  bank, trust company or investment bank rated at least A- and A-1 by
  Standard & Poor's Corporation and at least A3 and P-1 by Moody's Investors
  Service, Inc.;
 
    (iv) Investments in commercial paper maturing not more than 270 days from
  the date of acquisition thereof and rated at least A-1 by Standard & Poor's
  Corporation and at least P-1 by
 
                                       67
<PAGE>
 
     
  Moody's Investors Service, Inc. issued by a corporation (except the Company
  or an Affiliate of the Company) that is organized under the laws of any
  state of the United States or the District of Columbia;     
     
    (v) Investments in debt securities issued or directly and fully
  guaranteed by any state of the United States or the District of Columbia or
  a municipality thereof maturing not more than 18 months from the date of
  acquisition thereof and rated at least A3 by Moody's Investors Service,
  Inc.; and     
     
    (vi) Investments in money market accounts or funds substantially all of
  the assets of which consist of cash or securities of the types described in
  clauses (i) through (v) above.     
 
  "Company" means Clean Harbors, Inc., and does not include any Subsidiary.
 
  "Consolidated EBITDA Coverage Ratio" as of any date of determination means
the ratio of (i) the aggregate amount of EBITDA for the period of the most
recent four consecutive fiscal quarters ending at least 45 days prior to such
determination to (ii) Consolidated Interest Expense for such four fiscal
quarters; provided, however, that (1) if the Company or any Subsidiary has
issued any Debt since the beginning of such period that remains outstanding or
if the transaction giving rise to the need to calculate the Consolidated EBITDA
Coverage Ratio is an issuance of Debt, or both, EBITDA and Consolidated
Interest Expense for such period shall be calculated after giving effect on a
pro forma basis to such Debt as if such Debt had been issued on the first day
of such period and the discharge of any other Debt refinanced, refunded,
exchanged or otherwise discharged with the proceeds of such new Debt as if any
such discharge had occurred on the first day of such period, (2) if since the
beginning of such period the Company or any Subsidiary shall have made any
Asset Disposition, EBITDA for such period shall be reduced by an amount equal
to the EBITDA (if positive) directly attributable to the assets which are the
subject of such Asset Disposition for such period, or increased by an amount
equal to the EBITDA (if negative) directly attributable thereto for such period
and Consolidated Interest Expense for such period shall be reduced by an amount
equal to the Consolidated Interest Expense directly attributable to any Debt of
the Company or any Subsidiary refinanced, refunded, exchanged or otherwise
discharged with respect to the Company and its continuing Subsidiaries in
connection with such Asset Dispositions for such period (or if the Capital
Stock of any Subsidiary is sold, the Consolidated Interest Expense for such
period directly attributable to the Debt of such Subsidiary to the extent the
Company and its continuing Subsidiaries are no longer liable for such Debt
after such sale), and (3) if since the beginning of such period the Company or
any Subsidiary (by merger or otherwise) shall have made an Investment in any
Subsidiary (or any person which becomes a Subsidiary) or an acquisition of
assets, including any acquisition of assets occurring in connection with a
transaction causing a calculation to be made hereunder, which constitutes all
of an operating unit of a business, EBITDA and Consolidated Interest Expense
for such period shall be calculated after giving pro forma effect thereto
(including the issuance of any Debt), as if such Investment or acquisition
occurred on the first day of such period. For purposes of this definition,
whenever pro forma effect is to be given to an acquisition of assets, the
amount of income or earnings relating thereto, and the amount of Consolidated
Interest Expense associated with any Debt issued in connection therewith, the
pro forma calculations shall be determined in good faith by a responsible
financial or accounting Officer of the Company. If any Debt bears a floating
rate of interest and is being given pro forma effect, the interest on such Debt
shall be calculated as if the rate in effect on the date of determination had
been the applicable rate for the entire period.
 
  "Consolidated Interest Expense" means, for any period, the aggregate total
interest expense of the Company and its consolidated Subsidiaries determined in
accordance with generally accepted accounting principles, including (i)
interest expense attributable to capital leases, (ii) amortization of debt
discount and debt issuance cost, (iii) capitalized interest, (iv) non-cash
interest payments, (v) commissions, discounts and other fees and charges owed
with respect to letters of credit and bankers' acceptance financing, (vi) net
costs under Hedging Obligations (including amortization of fees), (vii)
Preferred Stock dividends in respect of all Preferred Stock held by persons
other than the Company or a Wholly Owned Subsidiary, (viii) interest incurred
in connection with investments
 
                                       68
<PAGE>
 
in discontinued operations, and (ix) interest actually paid by the Company or
any of its consolidated Subsidiaries under any Guarantee of Debt or other
obligation of any other person.
 
  "Consolidated Net Income" means, for any period, the net income of the
Company and its consolidated Subsidiaries; provided, however, that there shall
not be included in such Consolidated Net Income:
 
    (i) any net income of any person if such person is not a Subsidiary,
  except that (A) the Company's equity in the net income of any such person
  for such period shall be included in such Consolidated Net Income up to the
  aggregate amount of cash actually distributed by such person during such
  period to the Company or a Subsidiary as a dividend or other distribution
  (subject, in the case of a dividend or other distribution to a Subsidiary,
  to the limitations contained in clause (iii) below) and (B) the Company's
  equity in a net loss of any such person for such period shall be included
  in determining such Consolidated Net Income;
 
    (ii) any net income of any person acquired by the Company or a Subsidiary
  in a pooling of interests transaction for any period prior to the date of
  such acquisition;
 
    (iii) any net income of any Subsidiary if such Subsidiary is subject to
  restrictions, directly or indirectly, on the payment of dividends or the
  making of distributions by such Subsidiary, directly or indirectly, to the
  Company, except that (A) the Company's equity in the net income of any such
  Subsidiary for such period shall be included in such Consolidated Net
  Income up to the aggregate amount of cash actually distributed by such
  Subsidiary during such period to the Company or another Subsidiary as a
  dividend or other distribution (subject, in the case of a dividend or other
  distribution to another Subsidiary, to the limitation contained in this
  clause) and (B) the Company's equity in a net loss of any such Subsidiary
  for such period shall be included in determining such Consolidated Net
  Income;
 
    (iv) any gain or loss realized upon the sale or other disposition of any
  property, plant or equipment of the Company or its consolidated
  Subsidiaries (including pursuant to any Sale/Leaseback Transaction) which
  is not sold or otherwise disposed of in the ordinary course of business and
  any gain or loss realized upon the sale or other disposition of any Capital
  Stock of any person; and
 
    (v) the cumulative effect of a change in accounting principles.
 
  "Consolidated Net Tangible Assets" of any person means the total assets of
such person and its consolidated subsidiaries after deducting therefrom all
intangible assets, current liabilities (excluding any thereof which are by
their terms extendible or renewable at the option of the obligor thereon to a
time more than 12 months after the time as of which the amount thereof is being
computed) and minority interests, if any, in any assets of such person's
subsidiaries.
 
  "Consolidated Net Worth" of any person means the total of the amounts shown
on the balance sheet of such person and its consolidated subsidiaries,
determined on a consolidated basis in accordance with generally accepted
accounting principles, as of the end of the most recent fiscal quarter of such
person ending at least 45 days prior to the taking of any action for the
purpose of which the determination is being made, as (i) the par or stated
value of all outstanding Capital Stock of such person plus (ii) paid-in capital
or capital surplus relating to such Capital Stock plus (iii) any retained
earnings or earned surplus less (A) any accumulated deficit, (B) any amounts
attributable to Redeemable Stock, and (C) any amounts attributable to
Exchangeable Stock.
 
  "Debt" of any person means, without duplication:
 
    (i) the principal of and premium (if any) in respect of (A) indebtedness
  of such person for money borrowed and (B) indebtedness evidenced by notes,
  debentures, bonds or other similar instruments for the payment of which
  such person is responsible or liable;
 
    (ii) all Capital Lease Obligations of such person;
 
    (iii) all obligations of such person issued or assumed as the deferred
  purchase price of property, all conditional sale obligations of such person
  and all obligations of such person under
 
                                       69
<PAGE>
 
  any title retention agreement (but excluding trade accounts payable arising
  in the ordinary course of business);
 
    (iv) all obligations of such person for the reimbursement of any obligor
  on any letter of credit, banker's acceptance or similar credit transaction
  (other than obligations with respect to letters of credit securing
  obligations (other than obligations described in (i) through (iii) above)
  which are the functional equivalent of commercial surety or fidelity bonds
  and not issued in connection with the borrowing of money, or are entered
  into in the ordinary course of business of such person to the extent such
  letters of credit are not drawn upon or, if and to the extent drawn upon,
  such drawing is reimbursed no later than the third Business Day following
  receipt by such person of a demand for reimbursement following payment on
  the letter of credit);
 
    (v) the amount of all obligations of such person with respect to the
  redemption, repayment or other repurchase of any Redeemable Stock (but
  excluding any accrued dividends);
 
    (vi) all obligations of the type referred to in clauses (i) through (v)
  of other persons and all dividends of other persons for the payment of
  which, in either case, such person is responsible or liable, directly or
  indirectly, as obligor, guarantor or otherwise, including by means of any
  agreement which has the economic effect of a Guarantee; and
 
    (vii) all obligations of the type referred to in clauses (i) through (vi)
  of other persons secured by any Lien on any property or asset of such
  person (whether or not such obligation is assumed by such person or is
  otherwise its legal liability), the amount of such obligation being deemed
  to be the lesser of the value of such property or assets or the amount of
  the obligation so secured.
 
  "Default" means any event which is, or after notice or passage of time or
both would be, an Event of Default.
 
  "EBITDA" for any period means the Consolidated Net Income for such period,
plus the following to the extent included in calculating such Consolidated Net
Income: (i) income tax expense, (ii) Consolidated Interest Expense, (iii)
depreciation expense, (iv) amortization expense, (v) all other non-cash charges
(excluding any non-cash charge which requires an accrual of or a reserve for
cash charges for any future period), and (vi) without duplication, cash and
non-cash charges associated with the early extinguishment of debt incurred in
connection with the issuance of the Senior Notes and the application of the
proceeds therefrom.
 
  "Eligible Accounts Receivable" means all accounts, accounts receivable,
notes, bills, drafts, acceptances, instruments, documents, and all other Debt,
obligations and liabilities in whatever form owing from any person for goods
sold or for services rendered, at any time existing on the books of the Company
which, at the time of determination, are not more than 90 days from the date of
invoice.
 
  "Exchangeable Stock" means any Capital Stock which is exchangeable for or
convertible into another security (other than Capital Stock of the Company
which is neither Exchangeable Stock nor Redeemable Stock).
 
  "Fair Market Value" means, with respect to any asset or property, the sale
value that would be obtained in an arm's-length transaction between an informed
and willing seller under no compulsion to sell and an informed and willing
buyer under no compulsion to buy.
 
  "Guarantee" means any obligation, contingent or otherwise, of any person
directly or indirectly guaranteeing any Debt or other obligation of any person
and any obligation, direct or indirect, contingent or otherwise, of such person
(i) to purchase or pay (or advance or supply funds for the purchase or payment
of) such Debt or other obligation of such person (whether arising by virtue of
partnership arrangements, or by agreement to keep-well, to purchase assets,
goods, securities or services, to take-or-pay, or to maintain financial
statement conditions or otherwise) or (ii) entered
 
                                       70
<PAGE>
 
into for purposes of assuring in any other manner the obligee of such Debt or
other obligation of the payment thereof or to protect such obligee against loss
in respect thereof (in whole or in part); provided, however, that the term
"Guarantee" shall not include endorsements for collection or deposit in the
ordinary course of business. The term "Guarantee" used as a verb has a
corresponding meaning.
 
  "Guarantor Subsidiaries" means each of Clean Harbors Environmental Services,
Inc., Clean Harbors of Natick, Inc., Clean Harbors of Braintree, Inc., Clean
Harbors of Chicago, Inc., Clean Harbors of Cleveland, Inc., Clean Harbors of
Baltimore, Inc., Clean Harbors of Connecticut, Inc., Clean Harbors Kingston
Facility Corporation, Murphy's Waste Oil Service, Inc., Clean Harbors
Technology Corporation, Mr. Frank, Inc., and Spring Grove Resource Recovery,
Inc. and (ii) any other Subsidiary of the Company that executes a Subsidiary
Guarantee in accordance with the provisions of the Note Indenture, and their
respective successors and assigns.
 
  "Hedging Obligations" of any person means the obligations of such person
pursuant to any interest rate swap agreement, foreign currency exchange
agreement, interest rate collar agreement, option or futures contract or other
similar agreement or arrangement designed to protect such person against
changes in interest rates or foreign exchange rates.
 
  "Investment" in any person means any loan or advance to, any acquisition of
Capital Stock, equity interest, obligation or other security of, or capital
contribution or other investment in, such person.
 
  "issue" means issue, assume, Guarantee, incur or otherwise become liable for;
provided, however, that any Debt or Capital Stock of a person existing at the
time such person becomes a Subsidiary (whether by merger, consolidation,
acquisition or otherwise) shall be deemed to be issued by such Subsidiary at
the time it becomes a Subsidiary.
 
  "Legal Holiday" means a Saturday, a Sunday or a day on which banking
institutions are not required to be open in the State of New York or the
principal office of the Trustee.
 
  "Lien" means any mortgage, pledge, security interest, conditional sale,
encumbrance, charge or adverse claim affecting title or resulting in an
encumbrance against real or personal property, or a security interest of any
kind.
 
  "Net Available Cash" from an Asset Disposition means cash payments received
(including any cash payments received by way of deferred payment of principal
pursuant to a note or installment receivable or otherwise, but only as and when
received, but excluding any other consideration received in the form of
assumption by the acquiring person of Debt or other obligations relating to
such properties or assets or received in any other non-cash form) therefrom, in
each case net of all legal, title and recording tax expenses, commissions and
other fees and expenses incurred, and all federal, state, provincial, foreign
and local taxes required to be accrued as a liability under generally accepted
accounting principles, as a consequence of such Asset Disposition, and in each
case net of all payments made on any Debt which is secured by any assets
subject to such Asset Disposition, in accordance with the terms of any Lien
upon or other security agreement of any kind with respect to such assets, or
which must by its terms, or in order to obtain a necessary consent to such
Asset Disposition, or by applicable law be repaid out of the proceeds from such
Asset Disposition, and net of all distributions and other payments required to
be made to minority interest holders in Subsidiaries or joint ventures as a
result of such Asset Disposition.
 
  "Net Cash Proceeds," with respect to any issuance or sale of Capital Stock,
means the cash proceeds of such issuance or sale net of attorneys' fees,
accountants' fees, underwriters' or placement agents' fees, discounts or
commissions and brokerage, consultant and other fees actually incurred in
connection with such issuance or sale and net of taxes paid or payable as a
result thereof.
 
                                       71
<PAGE>
 
  "Non-Convertible Capital Stock" means, with respect to any corporation, any
non-convertible Capital Stock of such corporation and any Capital Stock of such
corporation convertible solely into non-convertible common stock of such
corporation; provided, however, that Non-Convertible Capital Stock shall not
include any Redeemable Stock or Exchangeable Stock.
 
  "Officer" means the Chairman of the Board, the President, any Vice President,
the Treasurer or the Secretary of the Company.
 
  "Officers' Certificate" means a certificate signed by two Officers.
 
  "Permitted Holders" means (i) Alan McKim, (ii) the trustees of a trust for
the benefit of Mr. McKim, which trust is revocable solely by Mr. McKim, (iii)
Mr. McKim's spouse or children, (iv) a trust created for the exclusive benefit
of Mr. McKim's spouse or children or for the exclusive benefit of Mr. McKim and
such persons, and (iv) any charitable trust or foundation qualified under
Section 501(c)(3) of the Internal Revenue Code established by Mr. McKim and for
which he serves as a trustee or director.
 
  "Permitted Investments" means:
 
    (a) Cash Equivalents;
 
    (b) Investments in a Wholly Owned Subsidiary (or any person which will
  become a Wholly Owned Subsidiary as a result of such Investment);
 
    (c) loans and reasonable advances to employees of the Company or its
  Subsidiaries for travel, entertainment and relocation expenses in the
  ordinary course of business; and
     
    (d) other Investments not to exceed $5.0 million at any one time
  outstanding, provided that no Investment under this clause (d) shall consist 
  of Capital Stock of the Company.     
 
  "Permitted Liens" means, with respect to any person, (i) pledges or deposits
by such person under workers' compensation laws, unemployment insurance laws or
similar legislation, or good faith deposits in connection with bids, tenders,
contracts (other than for the payment of Debt) or leases to which such person
is a party, or deposits to secure public or statutory obligations of such
person or deposits or cash or United States government bonds to secure surety
or appeal bonds to which such person is a party, or deposits as security for
contested taxes or import duties or for the payment of rent, in each case
incurred in the ordinary course of business; (ii) Liens imposed by law, such as
carriers', warehousemen's and mechanics' Liens, in each case for sums not yet
due or being contested in good faith by appropriate proceedings; or other Liens
arising out of judgments or awards against such person with respect to which
such person shall then be proceeding with an appeal or other proceedings for
review or time for appeal has not yet expired; (iii) Liens for property taxes
not yet subject to penalties for non-payment or which are being contested in
good faith by appropriate proceedings; (iv) Liens in favor of issuers of surety
bonds or letters of credit issued pursuant to the request of and for the
account of such person in the ordinary course of its business; provided,
however, that such letters of credit do not constitute Debt; (v) survey
exceptions, encumbrances, easements or reservations of, or rights of others
for, licenses, rights of way, sewers, electric lines, telegraph and telephone
lines and other similar purposes, or zoning or other restrictions as to the use
of real properties or Liens incidental to the conduct of the business of such
Person or to the ownership of its properties which were not incurred in
connection with Debt and which do not in the aggregate materially adversely
affect the value of said properties or materially impair their use in the
operation of the business of such person; (vi) Liens securing a Hedging
Obligation so long as the related Debt is, and is permitted to be under the
Note Indenture, secured by a Lien on the same property securing the Hedging
Obligation; and (vii) leases and subleases of real property which do not
interfere with the ordinary conduct of the business of such person or the
ownership of its properties which were not incurred in connection with Debt and
which do not in the aggregate materially adversely affect the value of said
properties or materially impair their
 
                                       72
<PAGE>
 
use in the operation of the business of such person, and which are made on
customary and usual terms applicable to similar properties.
 
  "person" means any individual, corporation, partnership, joint venture,
association, joint-stock company, trust, unincorporated organization,
government or any agency or political subdivision thereof or any other entity.
 
  "Preferred Stock," as applied to the Capital Stock of any corporation, means
Capital Stock of any class or classes (however designated) which is preferred
as to the payment of dividends, or as to the distribution of assets upon any
voluntary or involuntary liquidation or dissolution of such corporation, over
shares of Capital Stock of any other class of such corporation.
 
  "Principal" of any Senior Note means the principal of such Senior Note plus
the premium (if any) payable on the Senior Note which is due or overdue or is
to become due at the relevant time.
 
  "Redeemable Stock" means any Capital Stock that by its terms or otherwise is
required to be redeemed on or prior to the first anniversary of the Stated
Maturity of the Senior Notes or is redeemable at the option of the holder
thereof at any time on or prior to the first anniversary of the Stated Maturity
of the Senior Notes.
 
  "Sale/Leaseback Transaction" means an arrangement relating to property now
owned or hereafter acquired whereby the Company or a Subsidiary transfers such
property to a person and the Company or a Subsidiary leases it from such
person.
 
  "Stated Maturity" means, with respect to any security, the date specified in
such security as the fixed date on which the principal of such security is due
and payable, including pursuant to any mandatory redemption provision (but
excluding any provision providing for the repurchase of such security at the
option of the holder thereof upon the happening of any contingency).
 
  "Subordinated Obligation" means any Debt of the Company (whether outstanding
on the date hereof or hereafter incurred) which is subordinate or junior in
right of payment to the Senior Notes.
 
  "Subsidiary" means any corporation, association, partnership or other
business entity of which more than 50% of the total voting power of shares of
Capital Stock or other interests (including partnership interests) entitled
(without regard to the occurrence of any contingency) to vote in the election
of directors, managers or trustees thereof is at the time owned or controlled,
directly or indirectly, by (i) the Company, (ii) the Company and one or more
Subsidiaries, or (iii) one or more Subsidiaries.
 
  "U.S. Government Obligations" means direct obligations (or certificates
representing an ownership interest in such obligations) of the United States of
America (including any agency or instrumentality thereof) for the payment of
which the full faith and credit of the United States of America is pledged and
which are not callable at the issuer's option.
 
  "Voting Stock" of a corporation means all classes of Capital Stock of a
corporation outstanding and normally entited to vote in the election of
directors or other governing body of such corporation.
 
  "Wholly Owned Subsidiary" means a Subsidiary all the Capital Stock of which
(other than directors' qualifying shares) is owned by the Company or another
Wholly Owned Subsidiary.
 
                                       73
<PAGE>
 
                                  UNDERWRITING
   
  Under the terms and subject to the conditions contained in an Underwriting
Agreement dated July 28, 1994 (the "Underwriting Agreement"), the underwriters
named below (the "Underwriters") have severally but not jointly agreed to
purchase from the Company the following respective principal amounts of the
Senior Notes:     
 
<TABLE>
<CAPTION>
                              UNDERWRITERS                            AMOUNT
                              ------------                          -----------
      <S>                                                           <C>
      CS First Boston Corporation.................................. $33,750,000
      Alex. Brown & Sons Incorporated..............................  16,250,000
                                                                    -----------
        Total...................................................... $50,000,000
                                                                    ===========
</TABLE>
 
  The Underwriting Agreement provides that the obligations of the Underwriters
are subject to certain conditions precedent and that the Underwriters will be
obligated to purchase all of the Senior Notes, if any are purchased. The
Underwriting Agreement provides that, in the event of a default by an
Underwriter, in certain circumstances, the purchase commitments of the non-
defaulting Underwriter may be increased or the Underwriting Agreement may be
terminated.
   
  The Company has been advised by the Underwriters that they propose to offer
the Senior Notes to the public initially at the public offering price set forth
on the cover page of this Prospectus, and to certain dealers at such price less
a concession not in excess of 1.75% of the principal amount per Senior Note;
that the Underwriters and such dealers may allow a discount of 0.25% of such
principal amount on sales to certain other dealers; and that after the
Offering, the public offering price and concession and discount to dealers may
be changed.     
 
  The Senior Notes are a new issue of securities with no established trading
market. The Underwriters have advised the Company that they intend to act as
market makers for the Senior Notes. However, the Underwriters are not obligated
to do so and may discontinue any market making at any time without notice. No
assurance can be given as to the liquidity of the trading market for the Senior
Notes.
 
  The Company has agreed to indemnify the Underwriters against certain
liabilities, including civil liabilities under the Securities Act, or
contribute to payments which the Underwriters may be required to make in
respect thereof.
 
                          NOTICE TO CANADIAN RESIDENTS
 
RESALE RESTRICTIONS
 
  The distribution of the Senior Notes in Canada is being made only on a
private placement basis exempt from the requirement that the Company prepare
and file a prospectus with the securities regulatory authorities in each
province where trades of Senior Notes are effected. Accordingly, any resale of
the Senior Notes in Canada must be made in accordance with applicable
securities laws which will vary depending on the relevant jurisdiction, and
which may require resales to be made in accordance with available statutory
exemptions or pursuant to a discretionary exemption granted by the applicable
Canadian securities regulatory authority. Purchasers are advised to seek legal
advice prior to any resale of the Senior Notes.
 
REPRESENTATIONS OF PURCHASERS
 
  Each purchaser of Senior Notes in Canada who receives a purchase confirmation
will be deemed to represent to the Company and the dealer from whom such
purchase confirmation is received that (i) such purchaser is entitled under
applicable provincial securities laws to purchase
 
                                       74
<PAGE>
 
such Senior Notes without the benefit of a prospectus qualified under such
securities laws, (ii) where required by law, that such purchaser is purchasing
as principal and not as agent, and (iii) such purchaser has reviewed the text
above under "Resale Restrictions".
 
RIGHTS OF ACTION AND ENFORCEMENT
 
  The securities being offered are those of a foreign issuer and Ontario
purchasers will not receive the contractual right of action prescribed by
section 32 of the Regulation under the Securities Act (Ontario). As a result,
Ontario purchasers must rely on other remedies that may be available, including
common law rights of action for damages or rescission or rights of action under
the civil liability provisions of the U.S. federal securities laws.
 
  All of the issuer's directors and officers as well as the experts named
herein may be located outside of Canada and, as a result, it may not be
possible for Ontario purchasers to effect service of process within Canada upon
the issuer or such persons. All or a substantial portion of the assets of the
issuer and such persons may be located outside of Canada and, as a result, it
may not be possible to satisfy a judgment against the issuer or such persons in
Canada or to enforce a judgment obtained in Canadian courts against such issuer
or persons outside of Canada.
 
NOTICE TO BRITISH COLUMBIA RESIDENTS
 
  A purchaser of Senior Notes to whom the Securities Act (British Columbia)
applies is advised that such purchaser is required to file with the British
Columbia Securities Commission a report within ten days of the sale of any
Senior Notes acquired by such purchaser pursuant to this offering. Such report
must be in the form attached to British Columbia Securities Commission Blanket
Order BOR #88/5, a copy of which may be obtained from the Company. Only one
such report must be filed in respect of Senior Notes acquired on the same date
and under the same prospectus exemption.
 
                                 LEGAL MATTERS
 
  The validity of the Senior Notes offered hereby will be passed upon for the
Company by Davis, Malm & D'Agostine, P.C., One Boston Place, Boston,
Massachusetts, and certain legal matters in connection with the Offering will
be passed upon for the Underwriters by Goodwin, Procter & Hoar, Exchange Place,
Boston, Massachusetts. C. Michael Malm, a shareholder of Davis, Malm &
D'Agostine, P.C., is the Clerk of the Company and the holder of an option to
purchase 11,112 shares of the Company's Common Stock at $2.70 per share. Mr.
Malm and other shareholders in Davis, Malm & D'Agostine, P.C., beneficially
owned an aggregate of 13,760 additional shares of Common Stock of the Company
as of June 15, 1994. In addition, two shareholders of that firm are trustees of
a trust for the benefit of the children of Alan S. McKim, the Company's
principal stockholder, which owns an additional 60,000 shares of Common Stock.
 
                                    EXPERTS
 
  The consolidated balance sheets of the Company and its subsidiaries as of
December 31, 1993 and 1992, and the related consolidated statements of income,
stockholders' equity and cash flows for the years ended December 31, 1993 and
1992, and the ten-month period ended December 31, 1991, included herein and in
the Registration Statement of which this Prospectus is a part have been
included herein and in the Registration Statement in reliance upon the reports
of Coopers & Lybrand, independent accountants, upon the authority of said firm
as experts in accounting and auditing.
 
 
                                       75
<PAGE>
 
                             AVAILABLE INFORMATION
 
  The Company is subject to the informational requirements of the Securities
Exchange Act of 1934, as amended (the "Exchange Act"), and, in accordance
therewith, files reports and other information with the Securities and
Exchange Commission (the "Commission"). Reports, proxy statements and other
information concerning the Company may be inspected and copied at the Public
Reference Section of the Commission at Room 1024, Judiciary Plaza, 450 Fifth
Street, N.W., Washington, D.C. 20549-1004, and at the following regional
offices of the Commission: New York Office, 7 World Trade Center, 13th Floor,
New York, New York 10048 and Chicago Office, Northwestern Atrium Center, 500
West Madison Street, Suite 1400, Chicago, Illinois 60661. Copies of such
material also can be obtained at prescribed rates by writing to the Public
Reference Section of the Commission at 450 Fifth Street, N.W., Washington,
D.C. 20549. In addition, such reports, proxy statements and other information
concerning the Company may be inspected at the offices of the National
Association of Securities Dealers, Inc., 1735 K Street, N.W., Washington, D.C.
20006-1506.
 
  The Company has filed a registration statement on Form S-2 (together with
all amendments and exhibits filed or to be filed in connection therewith, the
"Registration Statement") under the Securities Act with respect to the Senior
Notes offered hereby. This Prospectus does not contain all the information set
forth in the Registration Statement, certain parts of which have been omitted
in accordance with the rules and regulations of the Commission. Statements
contained or incorporated by reference herein concerning the provisions of
documents are necessarily summaries of such documents, and each statement is
qualified in its entirety by reference to the copy of the applicable document
filed with the Commission.
 
  In accordance with the Note Indenture, the Company will furnish to holders
of the Senior Notes annual reports containing audited financial statements and
quarterly reports containing unaudited summary financial information for the
first three quarters of each fiscal year. See "Description of the Senior
Notes--SEC Reports."
 
                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
 
  The Company has filed with the Commission under the Exchange Act its Annual
Report on Form 10-K for the year ended December 31, 1993, and its Quarterly
Report on Form 10-Q for the quarter ended March 31, 1994 (Commission File No.
0-16379), and hereby incorporates such reports by reference herein. Any
statement contained in a document incorporated or deemed to be incorporated by
reference herein shall be deemed to be modified or superseded for purposes of
this Prospectus to the extent that a statement contained herein modifies or
supersedes such statement. Any such statement so modified or superseded shall
not be deemed, except as so modified or superseded, to constitute a part of
this Prospectus.
 
  The Company will provide without charge to each person, including any
beneficial owner, to whom a copy of this Prospectus is delivered, upon the
written or oral request of such person, a copy of any and all of the documents
incorporated herein by reference (not including the exhibits to such
documents, unless such exhibits are specifically incorporated by reference in
such documents). Requests for such copies should be directed to John S.
Ingalls, Vice President, Clean Harbors Environmental Services, Inc., P.O. Box
9137, Quincy, Massachusetts 02269-9137, Telephone (617) 849-1800, ext. 4454.
 
                                      76
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                   INDEX TO CONSOLIDATED FINANCIAL STATEMENTS
 
<TABLE>
<CAPTION>
                                                                           PAGE
                                                                           ----
<S>                                                                        <C>
Consolidated Financial Statements for the Years Ended December 31, 1993
 and 1992 and the Ten-Month Period Ended December 31, 1991:
  Report of Independent Accountants.......................................  F-2
  Consolidated Statements of Income for the Two Years Ended December 31,
   1993 and 1992 and the Ten-Month Period Ended December 31, 1991.........  F-3
  Consolidated Balance Sheets as of December 31, 1993 and 1992............  F-4
  Consolidated Statements of Stockholders' Equity for the Two Years Ended
   December 31, 1993 and 1992 and the Ten-Month Period Ended December 31,
   1991...................................................................  F-6
  Consolidated Statements of Cash Flows for the Two Years Ended December
   31, 1993 and 1992 and the Ten-Month Period Ended December 31, 1991.....  F-7
  Notes to Consolidated Financial Statements..............................  F-9
Consolidated Financial Statements for the Three Months Ended March 31,
 1994 and 1993 (Unaudited):
  Consolidated Statements of Income for the Three Months Ended March 31,
   1994 and 1993 (Unaudited).............................................. F-23
  Consolidated Balance Sheets as of March 31, 1994 (Unaudited) and Decem-
   ber 31, 1993........................................................... F-24
  Consolidated Statements of Cash Flows for the Three Months Ended March
   31, 1994 and 1993 (Unaudited).......................................... F-26
  Consolidated Statements of Stockholders' Equity for the Three Months
   Ended March 31, 1994 (Unaudited)....................................... F-28
  Notes to Consolidated Financial Statements (Unaudited).................. F-29
</TABLE>
 
                                      F-1
<PAGE>
 
                       REPORT OF INDEPENDENT ACCOUNTANTS
 
To the Board of Directors and Stockholders of Clean Harbors, Inc.:
 
  We have audited the accompanying consolidated balance sheets of Clean
Harbors, Inc. and its subsidiaries as of December 31, 1993 and 1992, and the
related consolidated statements of income, stockholders' equity and cash flows
for the years ended December 31, 1993 and 1992 and the ten-month period ended
December 31, 1991. These financial statements are the responsibility of the
Company's management. Our responsibility is to express an opinion on these
financial statements based on our audits.
 
  We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of
material misstatement. An audit includes examining, on a test basis, evidence
supporting the amounts and disclosures in the financial statements. An audit
also includes assessing the accounting principles used and significant
estimates made by management, as well as evaluating the overall financial
statement presentation. We believe that our audits provide a reasonable basis
for our opinion.
 
  In our opinion, the financial statements referred to above present fairly, in
all material respects, the consolidated financial position of Clean Harbors,
Inc. and its subsidiaries as of December 31, 1993 and 1992, and the
consolidated results of their operations and their cash flows for the years
ended December 31, 1993 and 1992 and the ten-month period ended December 31,
1991, in conformity with generally accepted accounting principles.
 
                                          Coopers & Lybrand
 
Boston, Massachusetts
February 1, 1994
 
                                      F-2
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                       CONSOLIDATED STATEMENTS OF INCOME
 
  FOR THE TWO YEARS ENDED DECEMBER 31, 1993 AND 1992 AND THE TEN-MONTH PERIOD
                            ENDED DECEMBER 31, 1991
                    (IN THOUSANDS EXCEPT PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                                         1993            1992           1991
                                    (TWELVE MONTHS) (TWELVE MONTHS) (TEN MONTHS)
                                    --------------- --------------- ------------
<S>                                 <C>             <C>             <C>
Revenues..........................     $200,114        $176,193       $127,473
Cost of revenues..................      134,525         116,473         85,921
Selling, general and administra-
 tive expenses....................       42,296          35,923         23,856
Depreciation and amortization of
 intangible assets................       10,319           8,884          6,601
                                       --------        --------       --------
Income from operations............       12,974          14,913         11,095
Interest expense (net)............        7,198           7,064          5,925
                                       --------        --------       --------
Income before provision for income
 taxes............................        5,776           7,849          5,170
Provision for income taxes........        2,645           2,774          1,567
                                       --------        --------       --------
  Net income......................     $  3,131        $  5,075       $  3,603
                                       ========        ========       ========
Net income per common and common
 equivalent share.................     $    .28        $    .52       $    .37
                                       ========        ========       ========
Weighted average common and common
 equivalent shares outstanding....        9,884           9,743          9,739
                                       ========        ========       ========
</TABLE>
 
 
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-3
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                          CONSOLIDATED BALANCE SHEETS
 
                        AS OF DECEMBER 31, 1993 AND 1992
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                1993     1992
                                                              -------- --------
                                     ASSETS
<S>                                                           <C>      <C>
Current assets:
  Cash and cash equivalents.................................. $    816 $    625
  Restricted cash............................................    1,037    1,023
  Accounts receivable, less reserves of $1,372 and $1,592,
   respectively..............................................   46,736   38,512
  Prepaid expenses...........................................    2,353    2,875
  Supplies inventories.......................................    2,428    2,214
  Income tax receivable......................................      607      416
                                                              -------- --------
    Total current assets.....................................   53,977   45,665
                                                              -------- --------
Property, plant and equipment:
  Land.......................................................    8,209    7,166
  Buildings and improvements.................................   31,737   27,872
  Vehicles and equipment.....................................   70,946   61,955
  Furniture and fixtures.....................................    2,201    2,000
  Construction in progress...................................    1,903    2,842
                                                              -------- --------
                                                               114,996  101,835
  Less--Accumulated depreciation and amortization............   40,925   32,279
                                                              -------- --------
                                                                74,071   69,556
                                                              -------- --------
Other assets:
  Goodwill (net).............................................   23,650   24,463
  Permits (net)..............................................   14,906   13,573
  Other......................................................      754      682
                                                              -------- --------
                                                                39,310   38,718
                                                              -------- --------
    Total assets............................................. $167,358 $153,939
                                                              ======== ========
</TABLE>
 
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-4
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                          CONSOLIDATED BALANCE SHEETS
 
                        AS OF DECEMBER 31, 1993 AND 1992
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                 1993     1992
                                                               -------- --------
                      LIABILITIES AND STOCKHOLDERS' EQUITY
<S>                                                            <C>      <C>
Current liabilities:
  Current maturities of long-term obligations................  $  8,917 $  1,816
  Accounts payable...........................................     9,564   12,462
  Accrued disposal costs.....................................     6,724    4,046
  Other accrued expenses.....................................    10,452   11,726
  Income tax payable.........................................       --       128
                                                               -------- --------
    Total current liabilities................................    35,657   30,178
                                                               -------- --------
Long-term obligations, less current maturities...............    62,507   64,565
Deferred income taxes........................................     1,823    1,131
Commitments and contingent liabilities (Notes 6, 7, 8, 10, 11
 and 12)
Stockholders' equity:
  Preferred stock, $.01 par value:
   Series A convertible preferred stock
    Authorized--2,000,000 shares; Issued and outstanding--
    None.....................................................       --       --
   Series B convertible preferred stock
    Authorized--156,416 shares; Issued and outstanding--
    112,000 shares at December 31, 1993 (liquidation
    preference of $5,600,000)................................         1      --
  Common stock, $.01 par value:
    Authorized--20,000,000 shares; Issued and outstanding--
    9,425,829 shares at December 31, 1993 and 9,327,275
    shares at December 31, 1992..............................        95       93
  Additional paid-in capital.................................    58,556   52,034
  Retained earnings..........................................     8,719    5,938
                                                               -------- --------
    Total stockholders' equity...............................    67,371   58,065
                                                               -------- --------
    Total liabilities and stockholders' equity...............  $167,358 $153,939
                                                               ======== ========
</TABLE>
 
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-5
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
 
               FOR THE TWO YEARS ENDED DECEMBER 31, 1993 AND 1992
                AND THE TEN-MONTH PERIOD ENDED DECEMBER 31, 1991
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                              SERIES B
                          PREFERRED STOCK     COMMON STOCK
                          ------------------  ------------
                           NUMBER    $.01     NUMBER $.01  ADDITIONAL RETAINED      TOTAL
                             OF       PAR       OF    PAR   PAID-IN   EARNINGS  STOCKHOLDERS'
                           SHARES    VALUE    SHARES VALUE  CAPITAL   (DEFICIT)    EQUITY
                          --------  --------  ------ ----- ---------- --------- -------------
<S>                       <C>       <C>       <C>    <C>   <C>        <C>       <C>
Balance, at February 28,
 1991...................       --   $    --   9,004   $90   $49,426    $(2,740)    $46,776
                           -------  --------  -----   ---   -------    -------     -------
  Proceeds from exercise
   of stock options.....       --        --      80     1       387        --          388
  Deferred compensation
   on stock options.....       --        --     --    --         20        --           20
  Net income............       --        --     --    --        --       3,603       3,603
                           -------  --------  -----   ---   -------    -------     -------
Balance, at December 31,
 1991...................       --   $    --   9,084   $91   $49,833    $   863     $50,787
                           -------  --------  -----   ---   -------    -------     -------
  Proceeds from exercise
   of stock options.....       --        --      10   --         40        --           40
  Deferred compensation
   on stock options.....       --        --     --    --          8        --            8
  Issuance of common
   stock for
   acquisition..........       --        --     233     2     2,153        --        2,155
  Net income............       --        --     --    --        --       5,075       5,075
                           -------  --------  -----   ---   -------    -------     -------
Balance, at December 31,
 1992...................       --   $    --   9,327   $93   $52,034    $ 5,938     $58,065
                           -------  --------  -----   ---   -------    -------     -------
  Issuance of preferred
   stock for
   acquisition..........       112         1    --    --      5,599        --        5,600
  Preferred stock divi-
   dends:
    Series B, $3.50 per
     share..............       --        --     --    --        --        (350)       (350)
  Proceeds from exercise
   of stock options.....       --        --      98     2       644        --          646
  Tax benefit from
   exercise of stock
   options..............       --        --     --    --        279        --          279
  Net income............       --        --     --    --        --       3,131       3,131
                           -------  --------  -----   ---   -------    -------     -------
Balance, at December 31,
 1993...................       112  $      1  9,425   $95   $58,556    $ 8,719     $67,371
                           =======  ========  =====   ===   =======    =======     =======
</TABLE>
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-6
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                     CONSOLIDATED STATEMENTS OF CASH FLOWS
 
               FOR THE TWO YEARS ENDED DECEMBER 31, 1993 AND 1992
                AND THE TEN-MONTH PERIOD ENDED DECEMBER 31, 1991
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                        1993            1992           1991
                                   (TWELVE MONTHS) (TWELVE MONTHS) (TEN MONTHS)
                                   --------------- --------------- ------------
<S>                                <C>             <C>             <C>
Cash flows from operating activi-
 ties:
  Net income......................     $ 3,131        $  5,075       $  3,603
Adjustments to reconcile net
 income to net cash provided by
 operating activities:
    Depreciation and amortization.      10,319           8,884          6,588
    Allowance for doubtful ac-
     counts.......................         709             942            365
    Deferred compensation.........         --                8             20
    Amortization of deferred fi-
     nancing costs................         408             645            488
    Deferred income taxes.........         692             339            192
    (Gain) loss on sale of fixed
     assets.......................         145             (43)            49
  Changes in assets and
   liabilities, net of effects of
   businesses acquired:
    Accounts receivable...........      (8,454)         (6,565)        (1,764)
    Refundable income taxes.......        (191)           (416)         2,095
    Prepaid expenses..............         531             430           (650)
    Supplies inventories..........        (157)            (72)           365
    Accounts payable..............      (2,898)          2,353         (1,036)
    Accrued disposal costs........       2,336             102            786
    Other accrued expenses........      (1,865)          3,088         (2,281)
    Income tax payable............         151            (189)           217
                                       -------        --------       --------
  Net cash provided by operating
   activities.....................       4,857          14,581          9,037
                                       -------        --------       --------
Cash flows from investing
 activities:
  Payment for businesses acquired,
   net of cash acquired...........      (1,394)           (315)           --
  Additions to property, plant and
   equipment......................      (7,874)         (9,815)        (9,531)
  (Increase) decrease in re-
   stricted cash accounts.........         (14)           (529)          (112)
  (Increase) decrease in other as-
   sets...........................         (97)           (340)          (228)
  Proceeds from sale of fixed as-
   sets...........................          34              50            166
  Increase in intangible assets...        (147)           (205)          (304)
                                       -------        --------       --------
  Net cash used in investing ac-
   tivities.......................      (9,492)        (11,154)       (10,009)
                                       -------        --------       --------
</TABLE>
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-7
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
               CONSOLIDATED STATEMENTS OF CASH FLOWS--(CONTINUED)
 
               FOR THE TWO YEARS ENDED DECEMBER 31, 1993 AND 1992
                AND THE TEN-MONTH PERIOD ENDED DECEMBER 31, 1991
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                        1993            1992           1991
                                   (TWELVE MONTHS) (TWELVE MONTHS) (TEN MONTHS)
                                   --------------- --------------- ------------
<S>                                <C>             <C>             <C>
Cash flows from financing activi-
 ties:
  Preferred stock dividend dis-
   tribution.....................      $  (251)        $   --        $   --
  Proceeds from long-term
   borrowings....................          --            1,500         7,107
  Payments on long-term obliga-
   tions.........................       (1,906)         (2,651)       (5,161)
  Additions to deferred financing
   costs.........................         (293)            (72)         (147)
  Net borrowings (payments) under
   long-term revolver............        6,630          (1,968)       (1,213)
  Proceeds from exercise of stock
   options.......................          646              40           388
                                       -------         -------       -------
  Net cash (used in) provided by
   financing activities..........        4,826          (3,151)          974
                                       -------         -------       -------
Increase in cash.................          191             276             2
Cash, beginning of year..........          625             349           347
                                       -------         -------       -------
Cash, end of year................      $   816         $   625       $   349
                                       =======         =======       =======
 
Supplemental Information:
 
<CAPTION>
                                        1993            1992           1991
                                   (TWELVE MONTHS) (TWELVE MONTHS) (TEN MONTHS)
                                   --------------- --------------- ------------
<S>                                <C>             <C>             <C>
Cash Payments for Interest and
 Income Taxes:
  Interest.......................      $ 6,536         $ 7,123       $ 6,475
  Income Taxes...................        2,117           2,697         1,549
Liabilities assumed in
 conjunction with business
 acquisitions:
  Fair value of assets acquired..      $ 7,834         $ 2,448           --
  Cash paid......................        1,400            (500)          --
  Issuance of common stock for
   acquisition...................          --            2,155           --
  Issuance of preferred stock for
   acquisition...................        5,600             --            --
  Liabilities assumed............          834           1,948           --
Noncash Investing and Financing
 Activities:
  Capital lease obligations in-
   curred........................      $   154         $   208           --
  Note payable to seller of
   equipment acquired............           50             --            --
  Dividends declared but not
   paid..........................           99             --            --
</TABLE>
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-8
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
 
(1) OPERATIONS
 
  Clean Harbors, Inc. and its wholly-owned subsidiaries (collectively, the
"Company") are engaged in the business of hazardous waste management,
environmental remediation and technical services.
 
(2) SIGNIFICANT ACCOUNTING POLICIES
 
  The accompanying consolidated financial statements of the Company reflect the
application of certain significant accounting policies as described below:
 
(a) Principles of Consolidation
 
  The accompanying consolidated statements include the accounts of Clean
Harbors, Inc. and its wholly-owned subsidiaries. All material intercompany
accounts and transactions have been eliminated in consolidation.
 
  In 1992 the Company reformatted its consolidated statement of income in order
to conform its internal and external reporting. The new format reclassifies
depreciation expense previously included in cost of revenue and selling,
general and administrative expenses and combines it with amortization in order
to reveal on one line, within the consolidated statement of income, the non-
cash portion of expenses. The Company believes that the new format is more
informative and is consistent with other companies in the industry.
 
(b) Change in Year End
 
  Effective with the ten-month period ended December 31, 1991, the Company
adopted a December 31 or calendar year end. The accompanying consolidated
financial statements include audited financial statements for the ten-month
transition period ended December 31, 1991. Certain comparative, unaudited
information for the twelve-month period ended December 31, 1991 is presented in
Note 17 below.
 
(c) Property, Plant and Equipment
 
  Property, plant and equipment are stated at cost. The Company depreciates and
amortizes the cost of these assets, less the estimated salvage value, using the
straight-line method as follows:
 
<TABLE>
<CAPTION>
                                                                      ESTIMATED
  ASSET CLASSIFICATION                                               USEFUL LIFE
  --------------------                                               -----------
<S>                                                                  <C>
Buildings and improvements.......................................... 5-30 years
Vehicles and equipment.............................................. 3-15 years
Furniture and fixtures.............................................. 5-8  years
</TABLE>
 
  Leaseholds are amortized over the shorter of the life of the lease or the
asset. Upon retirement or other disposition, the cost and related accumulated
depreciation of the assets are removed from the accounts and the resulting gain
or loss is reflected in income. Site preparation and improvement costs are
included in land.
 
(d) Revenue Recognition
 
  The Company recognizes revenues and accrues the related cost of treatment and
disposal upon the receipt of waste materials. Other revenues are recognized as
the related costs are incurred.
 
                                      F-9
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)
 
(e) Income Taxes
 
  The Company has adopted the Statement of Financial Accounting Standards No.
109, "Accounting for Income Taxes." Under the liability method specified by
SFAS No. 109, the deferred tax liability is determined based upon the
difference between the financial statement and tax basis of assets and
liabilities as measured by the enacted tax rates which will be in effect when
these differences reverse. Deferred tax expense is the result of changes in the
liability for deferred taxes. The principal types of differences between assets
and liabilities for financial statement and tax return purposes are accumulated
depreciation, business combinations accounted for by the purchase method, and
provisions for doubtful accounts. The deferred tax liability is reduced by net
operating losses being carried forward for tax purposes.
 
(f) Net Income Per Common and Common Equivalent Share
 
  Net income per common and common equivalent share is computed using the
weighted average number of common and common equivalent shares outstanding
during each of the respective years. Fully diluted net income per common share
has not been presented as the amount would not differ significantly from that
presented.
 
(g) Capitalization of Interest
 
  The Company capitalizes interest on funds used to finance the construction of
major capital additions. The Company capitalized interest costs aggregating
$301,000 in the year 1992 and $408,000 in the ten-month period ended December
31, 1991. No interest was capitalized during the year 1993.
 
(h) Intangible Assets
 
  Intangible assets, as further discussed in Notes 4 and 5, are stated at cost
and are being amortized using the straight line method over periods ranging
from 20 years for permits and from 20 to 40 years for costs in excess of
identifiable net assets acquired.
 
(i) Supplies Inventory
 
  Supplies inventory, stated at the lower of cost or market, is charged to
operations on a first in, first out basis.
 
(j) Cash and Cash Equivalents
 
  The Company considers all highly liquid instruments purchased with a maturity
of less than three months to be cash equivalents.
 
(k) Letters of Credit
 
  In its fiscal year ended February 28, 1991, the Company adopted Statement of
Financial Accounting Standard No. 105, which requires disclosure of information
about financial instruments with off-balance-sheet risk and about
concentrations of credit risk for all financial instruments.
 
  The Company utilizes letters of credit to provide collateral assurance to
issuers of performance bonds for certain contracts, and to assure regulatory
authorities that certain funds will be available for closure of hazardous waste
storage and disposal facilities. As of December 31, 1993 and 1992, the Company
had outstanding letters of credit amounting to $12,471,000 and $10,845,000,
respectively.
 
                                      F-10
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)
 
  As of December 31, 1993, the Company had no significant concentrations of
credit risk.
 
(l) Reclassifications
 
  Certain reclassifications have been reflected in prior years' financial
statements to conform the presentations to that as of December 31, 1993.
 
(3) FAIR VALUE OF FINANCIAL INSTRUMENTS
 
  The carrying amounts of cash and cash equivalents, restricted cash, and long-
term obligations approximate fair value. The Company believes similar terms for
long-term obligations would be attainable, except for its senior subordinated
debt. The fair value of its senior subordinated debt was determined by
discounting the future cash flows of this debt using the Company's incremental
borrowing rate. At December 31, 1993, the estimated fair values of the
Company's financial instruments are as follows (in thousands):
 
<TABLE>
<CAPTION>
                                                               CARRYING  FAIR
                                                                AMOUNT   VALUE
                                                               -------- -------
   <S>                                                         <C>      <C>
   Cash and cash equivalents.................................. $   816  $   816
   Restricted cash............................................   1,037    1,037
   Long-term obligations......................................  42,476   42,476
   Senior subordinated notes..................................  30,000   33,594
</TABLE>
 
(4) BUSINESS ACQUISITIONS
 
  On February 16, 1993, the Company acquired all of the outstanding shares of
Spring Grove Resource Recovery, Inc. ("Spring Grove"), a hazardous waste
treatment, storage and disposal facility located in Cincinnati OH, from
Southdown Environmental Treatment Systems, Inc. ("SETS") in exchange for
$1,400,000 in cash and 112,000 shares of newly issued Series B Convertible
Preferred Stock with a stated value of $5,600,000. The transfer of ownership
from the seller to the Company is subject to approval by regulatory
authorities, which is expected to be received during 1994.
 
  On June 30, 1992, the Company acquired all of the outstanding shares of
Connecticut Treatment Corporation ("CTC"), a hazardous waste treatment, storage
and disposal facility located in Bristol CT, from SETS in exchange for $500,000
in cash and a promissory note in the amount of $1,883,000. The first principal
installment on the note was $376,600, due on June 30, 1993, with installments
of $94,150 due at the end of each quarter thereafter, until the remaining
balance is paid in full. The note bears interest at the corporate base rate
announced by The First National Bank of Boston (the "Bank") (6.0% at December
31, 1993) plus 2%.
 
  SETS' parent Southdown, Inc. has indemnified the Company against on-site and
off-site environmental liabilities arising from the prior ownership and
operation of Spring Grove and CTC. The assets acquired consist primarily of
real estate and operating machinery for wastewater treatment and related
facilities and equipment. Both acquisitions were accounted for as a purchase.
In each case the total acquisition cost equaled the fair value of the assets
acquired; therefore, no goodwill was recorded.
 
  On July 30, 1992, the Company acquired all of the outstanding shares of Mr.
Frank, Inc., located in Matteson IL in exchange for 233,000 shares of the
Company's common stock, with a fair market value of $2,155,000. The assets
acquired consist primarily of vehicles, equipment and a leasehold interest in
real estate. The acquisition was accounted for as a purchase, with
approximately $2,113,000 excess of acquisition cost over the fair value of Mr.
Frank, Inc.'s identifiable assets being
 
                                      F-11
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)

assigned to goodwill. Upon closing, 32,222 of the exchanged shares of the
Company's common stock valued at $300,000 were deposited into an escrow account
for a minimum of two years as security for the sellers' agreement to indemnify
the Company against potential liabilities, including certain environmental
liabilities arising from prior ownership and operation of Mr. Frank, Inc.
 
  The results of operations of Spring Grove, CTC and Mr. Frank, Inc. are
included in the consolidated financial statements subsequent to the dates of
acquisition by the Company. Pro forma information has not been included
concerning these acquisitions since the assets and operations acquired were not
material to those of the Company.
 
(5) INTANGIBLE ASSETS
 
  Below is a summary of intangible assets at December 31, 1993 and 1992 (in
thousands):
 
<TABLE>
<CAPTION>
                                                                 1993    1992
                                                                ------- -------
   <S>                                                          <C>     <C>
   Permits..................................................... $17,303 $15,350
   Costs in excess of identifiable net assets acquired.........  27,529  27,529
                                                                ------- -------
                                                                 44,832  42,879
   Less--Accumulated amortization..............................   6,276   4,843
                                                                ------- -------
                                                                $38,556 $38,036
                                                                ======= =======
</TABLE>
 
  Amortization expense approximated $1,433,000 and $1,325,000 for the years
1993 and 1992, respectively, and $1,076,000 for the ten-month period ended
December 31, 1991.
 
  The Company continually reevaluates the propriety of the carrying amount of
permits and goodwill as well as the amortization period to determine whether
current events and circumstances warrant adjustments to the carrying value and
estimates of useful lives. At this time, the Company believes that no
significant impairment of goodwill or other intangibles has occurred and that
no reduction of the estimated useful lives is warranted.
 
(6) RELATED PARTY TRANSACTIONS
 
  The Company leases certain facilities from a partnership of which the
Company's principal stockholder is a limited partner. Under the terms of the
lease, the Company agreed to make aggregate lease payments of $5,633,000 from
the inception of the lease through June 1, 1996. In addition, the Company has
an option to renew the lease for a five-year period. Total rent expense charged
to operations was $703,000 during each of the years 1993 and 1992, and $553,000
during the ten-month period ended December 31, 1991. See Note 12 for further
discussion of lease commitments. The Company has subleased a portion of these
facilities to an unrelated third party.
 
(7) RESTRICTED CASH
 
  The Company has deposited funds into interest-bearing accounts administered
by various state environmental regulatory agencies. These accounts were
established under requirements that companies engaged in the treatment and
disposal of hazardous materials provide assurance that certain funds will be
available for closure of hazardous waste storage and disposal facilities and to
satisfy claims made by creditors in the event of insolvency. At December 31,
1993 and 1992, the balance in these accounts was $31,000 and $234,000,
respectively. As described in Note 2(k), the Company's practice is to utilize
letters of credit to satisfy closure obligations, in lieu of maintaining
restricted cash accounts. In addition, there are funds which are restricted for
the payment of
 
                                      F-12
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)

insurance claims. The balance of these insurance funds was $1,006,000 and
$789,000 as of December 31, 1993 and 1992, respectively.
 
(8) FINANCING ARRANGEMENTS
 
  At December 31, 1993, the Company had a Revolving Credit Agreement (the
"Revolver") with three banks, which permitted borrowings of up to $38,000,000
in cash and allowed the Company to have a maximum of $20,000,000 of letters of
credit outstanding. The combination of cash and letters of credit outstanding
was limited to $50,000,000 at any one time. At December 31, 1993 and 1992,
borrowings under the Revolver were $32,705,000 and $26,077,000, respectively
(exclusive of outstanding letters of credit). The entire balance of the
Revolver matures on July 1, 1996. All borrowings under the Revolver are
collateralized by substantially all of the Company's assets.
 
  On February 1, 1994, the Company and its banks amended the Revolver to
increase the amount of the Revolver to $55,000,000. The amended Revolver
permits borrowings of up to $40,000,000 in cash, and allows the Company to have
up to $20,000,000 of letters of credit outstanding. The combination of cash and
letters of credit outstanding may not exceed $55,000,000 at any one time. The
amount of the Revolver reduces on April 1, 1995 to $50,000,000.
 
  Interest on amounts outstanding under the Revolver are payable monthly in
arrears and accrue at the Bank's base rate plus 1%, or at the Company's option,
at a rate which is 3% over the "Eurodollar Rate" offered to the Bank by prime
banks in the Eurodollar interbank market. At December 31, 1993, the Company had
elected the Eurodollar option with respect to $29,000,000 of the amounts
outstanding under the Revolver; the Eurodollar Rate was 3.25% and the Bank's
base rate was 6%. The Company also pays a commitment fee at the rate of one-
half of 1% per annum on the unused portion of the total commitment.
 
  The Revolver provides for the maintenance of certain restrictive covenants
including, among others, restrictions on the ratio of accounts receivable to
current liabilities, total liabilities to tangible net worth, and earnings
before interest and taxes to total interest expense. The Company is also
restricted from making certain dividend payments, incurring certain additional
debt, and capital expenditures are limited to $12,000,000 each year.
 
  On May 25, 1989, the Company issued senior subordinated notes and warrants to
purchase 100,000 shares of common stock for aggregate proceeds, before issuance
costs, of $30,300,000. The $30,000,000 of notes bear interest at 13.25%,
payable semiannually, and mature at the rate of $7,500,000 per year commencing
on May 15, 1994. At December 31, 1993, current liabilities included the first
$7,500,000 principal installment due May 15, 1994. The note agreement provides
for the maintenance of certain restrictive covenants including, among others,
restrictions on the ratio of current assets to current liabilities, the levels
of net worth and the percentage of debt in an aggregate unpaid principal amount
to total capitalization. Should an event of default occur with respect to the
specified restrictive covenants, all notes become immediately payable and the
Company can be required to pay a premium ranging from 8% to 13% of the
outstanding principal balance, depending on when such event of default occurs.
 
  At December 31, 1993, the Company owed $2,150,000 on a term loan from a
financial institution at a floating interest rate equal to the greater of 8% or
the financial institution's "prime" rate plus 1%. Principal payments of $50,000
each are due monthly, with a balloon payment at maturity of the loan,
originally scheduled to be April 30, 1994. On November 3, 1993, the financial
institution agreed to extend the maturity date of the loan to April 30, 1996.
 
                                      F-13
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)
 
  On November 12, 1991, the Company issued to a financial institution a
$3,500,000 unsecured subordinated convertible note due in 1999, which is
convertible into common stock at $15 per share. On July 17, 1992, the Company
issued to the same financial institution an additional $1,500,000 unsecured
subordinated convertible note due in 1999, which is convertible into common
stock at $10 per share, bringing the total amount of unsecured convertible
notes to $5,000,000. The notes bear interest at 8%, and principal is payable in
five equal installments of $1,000,000 each, beginning on October 31, 1995 and
ending on October 31, 1999. The Company has the right to convert the notes into
common stock at $25 per share. The notes provide for the maintenance of certain
restrictive covenants including, among others, restrictions on the ratio of
current assets to current liabilities, senior liabilities to net worth, and
level of net worth.
 
  The following table is a summary of the Company's long-term debt obligations
reflecting the transactions discussed above.
 
  Long-term obligations consist of the following (in thousands):
 
<TABLE>
<CAPTION>
                                                                 DECEMBER 31,
                                                                ---------------
                                                                 1993    1992
                                                                ------- -------
   <S>                                                          <C>     <C>
   Revolving credit agreement bearing interest at the
    Eurodollar Rate (3.25% at December 31, 1993) plus 3%, or
    the Bank's base rate (6% at December 31, 1993) plus 1%,
    collateralized by substantially all assets................  $32,705 $26,077
   Senior subordinated notes payable, bearing interest at
    13.25% per year, collateralized by substantially all
    assets....................................................   30,000  30,000
   Subordinated note payable to a financial institution,
    bearing interest at the greater of (i) 8% or (ii) the
    financial institution's prime rate (6.75% at December 31,
    1993) plus 1%.............................................    2,150   2,750
   Subordinated convertible notes bearing interest at 8%......    5,000   5,000
   Junior subordinated note payable to Southdown Environmental
    Treatment Systems, Inc. bearing interest at the Bank's
    base rate plus 2%.........................................    1,318   1,883
   Junior subordinated notes to the former owners of Mr.
    Frank, Inc. bearing interest at the Bank's base rate plus
    1%........................................................      170     287
   Various notes payable collateralized by real property,
    vehicles and equipment at varying interest rates..........      --      190
   Obligations under capital leases...........................      546     708
   Other long-term obligations................................      587     653
                                                                ------- -------
                                                                 72,476  67,548
   Less--Current maturities...................................    8,917   1,816
   Less--Unamortized financing costs..........................    1,052   1,167
                                                                ------- -------
   Long-term obligations......................................  $62,507 $64,565
                                                                ======= =======
</TABLE>
 
                                      F-14
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)
 
  Below is a summary of minimum payments due under the Company's long-term
obligations (in thousands), exclusive of obligations under capital leases
discussed in Note 12:
 
<TABLE>
<CAPTION>
   YEAR                                                                 AMOUNT
   ----                                                                 -------
   <S>                                                                  <C>
   1994................................................................ $ 8,705
   1995................................................................   9,645
   1996................................................................  42,706
   1997................................................................   8,874
   1998................................................................   1,000
   Thereafter..........................................................   1,000
                                                                        -------
   Total minimum payments due under long-term obligations including
    current maturities................................................. $71,930
                                                                        =======
</TABLE>
 
(9) FEDERAL AND STATE INCOME TAXES
 
  The provision for income taxes consists of the following (in thousands):
 
<TABLE>
<CAPTION>
                                   1993            1992           1991
                              (TWELVE MONTHS) (TWELVE MONTHS) (TEN MONTHS)
                              --------------- --------------- ------------
   <S>                        <C>             <C>             <C>
   Federal--
     Current.................     $  958          $2,370         $  908
     Deferred................      1,222             314            275
   State --
     Current.................        995             235            375
     Deferred................       (530)           (145)             9
                                  ------          ------         ------
   Net provision for income
    taxes....................     $2,645          $2,774         $1,567
                                  ======          ======         ======
</TABLE>
 
  Effective January 1, 1992 the Company adopted the provisions of Statement of
Financial Accounting Standards No. 109, "Accounting for Income Taxes" ("SFAS
109"). SFAS 109 requires recognition of deferred tax liabilities and assets for
the expected future tax consequences of events that have been included in the
financial statements or tax returns. Under this method, deferred tax
liabilities and assets are determined based on the difference between the
financial statement and tax bases of assets and liabilities using enacted tax
rates in effect for the year in which the differences are expected to reverse.
The Company had previously adopted SFAS 96. The adoption of SFAS 109 did not
have a material impact on the Company's financial condition or results of
operations.
 
  The sources of significant timing differences which gave rise to deferred
taxes were as follows (in thousands):
 
<TABLE>
<CAPTION>
                                        1993            1992           1991
                                   (TWELVE MONTHS) (TWELVE MONTHS) (TEN MONTHS)
                                   --------------- --------------- ------------
   <S>                             <C>             <C>             <C>
   Accelerated depreciation.......      $501            $(495)        $(404)
   Provision for doubtful ac-
    counts........................        88               25           341
   Vacation accrual...............        88              115            48
   Rent holiday...................       (28)             (66)           57
   Insurance reserves.............      (127)             386             7
   Restructuring reserves.........       --              (148)          159
   Litigation.....................        98              211           --
   Tax attributes, net of valua-
    tion allowance................       639              --            --
   Other..........................      (567)             141            76
                                        ----            -----         -----
   Total deferred tax provision...      $692            $ 169         $ 284
                                        ====            =====         =====
</TABLE>
 
                                      F-15
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)
 
  The effective income tax rate varies from the amount computed using the
statutory federal income tax rate as follows:
 
<TABLE>
<CAPTION>
                                         1993            1992           1991
                                    (TWELVE MONTHS) (TWELVE MONTHS) (TEN MONTHS)
                                    --------------- --------------- ------------
   <S>                              <C>             <C>             <C>
   Statutory rate.................       34.0%           34.0%          20.0%
   Increase (decrease) in taxes
    resulting from:
     State income taxes, net of
      federal benefit.............        5.0             2.0            5.8
     Goodwill amortization........        4.7             6.0            --
     Other permanent differences..        3.9              .6            --
     Utilization of alternative
      minimum tax credit..........        --             (7.3)           --
     Benefit of net operating loss
      carryforward................        --              --            (4.4)
     Settlement of state and
      federal audits..............        --              --             8.9
     Valuation allowance adjust-
      ment........................       (1.8)            --             --
                                         ----            ----           ----
   Net provision for income taxes.       45.8%           35.3%          30.3%
                                         ====            ====           ====
</TABLE>
 
  The components of the total deferred tax asset at December 31, 1993 and 1992
were as follows (in thousands):
 
<TABLE>
<CAPTION>
                                                                  1993    1992
                                                                 ------  ------
   <S>                                                           <C>     <C>
   Current:
     Provision for doubtful accounts............................ $  543  $  631
     Accrued vacation pay.......................................     67     155
     Litigation accruals........................................    495     592
     Miscellaneous..............................................    675     230
   Deferred:
     Accrued rent holiday.......................................    105      77
     Deferred compensation......................................     36      46
     Insurance reserve..........................................  1,131   1,004
     Other......................................................    142      79
     Various tax attributes.....................................  5,226   5,970
     Valuation allowance........................................   (763)   (868)
                                                                 ------  ------
     Total deferred tax asset................................... $7,657  $7,916
                                                                 ======  ======
 
  The components of the total deferred tax liability at December 31, 1993 and
1992 were as follows (in thousands):
 
<CAPTION>
                                                                  1993    1992
                                                                 ------  ------
   <S>                                                           <C>     <C>
   Current:
     Prepaid insurance.......................................... $  --   $   12
   Deferred:
     Permits....................................................  3,130   3,198
     Property, plant and equipment..............................  6,350   5,837
                                                                 ------  ------
     Total deferred tax liability............................... $9,480  $9,047
                                                                 ------  ------
   Net deferred tax liability................................... $1,823  $1,131
                                                                 ======  ======
</TABLE>
 
 
                                      F-16
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)

  For federal income tax purposes at December 31, 1993, as a result of the
acquisition of ChemClear Inc. ("ChemClear") in January 1989, the Company has
regular tax net operating loss carryforwards of $4,338,000 and alternative
minimum tax net operating loss carryforwards of $3,440,000, which may be used
to offset future taxable income, if any, of the former ChemClear entities,
subject to certain limitations. These net operating loss carryforwards expire
commencing in 2002.
 
(10) EMPLOYEE BENEFIT PLAN
 
  The Company has a profit-sharing plan under Section 401(k) of the Internal
Revenue Code covering substantially all employees. The plan allows employees to
make contributions up to a specified percentage of their compensation, a
portion of which is matched by the Company. During the years 1993 and 1992 and
the ten-month period ended December 31, 1991, the Company's nonelective
contributions aggregated approximately $743,000, $609,000 and $281,000,
respectively.
 
(11) LEGAL MATTERS AND OTHER CONTINGENCIES
 
  (a) Legal Matters
 
  In August 1990, a lawsuit was filed against the Company in New York state
court in connection with the accidental death of an employee who was responding
to an oil spill on the Hudson River in 1989. The complaint seeks punitive
damages and $10 million for wrongful death. The Company believes the claims are
barred by worker's compensation laws and that it has insurance coverage for any
liability up to $10 million. The Company does not believe that the ultimate
liability in this case will exceed the limits of available insurance, although
there can be no assurance in this regard.
 
  In the ordinary course of conducting its business, the Company becomes
involved in environmentally related lawsuits and administrative proceedings.
Some of these proceedings may result in fines, penalties or judgments against
the Company. The Company does not believe that these proceedings, individually
or in the aggregate, are material to its business.
 
  As of December 31, 1993, the Company has been named in a number of lawsuits
arising from the disposal of wastes by certain Company subsidiaries at 18 state
and federal Superfund sites. Ten of these cases involve two subsidiaries which
the Company acquired from Chemical Waste Management, Inc. ("ChemWaste"). As
part of the acquisition, ChemWaste agreed to indemnify the Company with respect
to any liability of its Braintree and Natick subsidiaries for waste disposed of
before the Company acquired them. Accordingly, ChemWaste is paying all costs of
defending the Natick and Braintree subsidiaries in these 10 cases, including
legal fees and settlement costs. Two cases involve Mr. Frank, Inc. and one case
involves CTC. As discussed in Note 4, Southdown, Inc. has agreed to indemnify
the Company with respect to any liability for waste disposed of by CTC before
the Company acquired CTC, and the sellers of Mr. Frank, Inc. have agreed to
indemnify the Company against certain environmental liabilities arising from
prior ownership of Mr. Frank, Inc.
 
  The remaining five pending cases involve former ChemClear subsidiaries. The
Company is unable to predict accurately its potential liability with respect to
these cases, but believes that any future settlement costs will not be material
to the Company's operations or financial position.
 
  Management routinely reviews each Superfund site in which the Company's
subsidiaries are involved, considers each subsidiary's role at each site and
its relationship to the other potentially
 
                                      F-17
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)

responsible parties ("PRPs") at the site, the quantity and content of the waste
it disposed of at the site, and the number and financial capabilities of the
other PRPs at the site. Based on reviews of the various sites and currently
available information, and management's judgment and prior experience with
similar situations, expense accruals are provided by the Company for its share
of future site cleanup costs, and existing accruals are revised as necessary.
As of December 31, 1993, the Company had accrued environmental costs of
$470,000 for cleanup of Superfund sites. Superfund legislation permits strict
joint and several liability to be imposed without regard to fault, and as a
result, one PRP might be required to bear significantly more than its
proportional share of the cleanup costs if other PRPs do not pay their share of
such costs.
 
(b) Environmental Matters
 
  Under the Resource Conservation and Recovery Act of 1976, as amended
("RCRA"), every facility that treats, stores or disposes of hazardous waste
must obtain a RCRA permit from EPA or an authorized state agency and must
comply with certain operating requirements. Of the Company's 10 waste
management facilities, seven are subject to RCRA licensing; all seven have been
issued Part B permits, one of which is under appeal. RCRA requires that Part B
permits contain a schedule of required on-site study and cleanup activities,
known as "corrective action", including detailed compliance schedules and
provisions for assurance of financial responsibility.
 
  The EPA has begun RCRA corrective action investigations at the Company's Part
B licensed facilities in Baltimore MD, Chicago IL, Braintree MA, Natick MA, and
Woburn MA. The Company is also involved in site studies at its non-RCRA
facilities in Cleveland OH, Kingston MA and South Portland ME. The Company
spent approximately $600,000 on corrective action at the foregoing facilities
in 1993. The Company may become involved in a RCRA corrective action
investigation at a site in Chester PA where a Company subsidiary operated a
hazardous waste treatment facility prior to closing the facility in 1989. As
discussed in Note 4, the Company's other two RCRA facilities in Bristol CT and
Cincinnati OH were acquired from a subsidiary of Southdown, Inc., which has
agreed to indemnify the Company against any costs incurred or liability arising
from contamination on-site, including the cost of corrective action.
 
  While the final scope of the work to be done at these facilities has not yet
been agreed upon, the Company believes, based upon information known to date
about the nature and extent of contamination at these sites, that such costs
will not have a material effect on its results of operations or its financial
position, and that it will be able to finance from operating revenues any
additional corrective action required at its facilities.
 
  Environmental expenditures that relate to current operations are expensed or
capitalized as appropriate. Costs incurred to obtain or renew required permits
are capitalized to the related permit account as incurred and are amortized
over the permit's remaining life. Costs incurred to remediate properties owned
by the Company are capitalized in property, plant and equipment only if the
costs extend the life, increase the capacity or improve the safety or
efficiency of the property or the costs mitigate or prevent environmental
contamination that has yet to occur and that otherwise may result from future
operations or activities. Remediation costs incurred in excess of the fair
market value of the property being remediated are expensed as incurred.
 
(c) Other Contingencies
 
  The Company is subject to various regulatory requirements, including the
procurement of requisite licenses and permits at its facilities. These licenses
and permits are subject to periodic renewal without which the Company's
operations would be adversely affected. The Company
 
                                      F-18
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)

anticipates that, once a license or permit is issued with respect to a
facility, the license or permit will be renewed at the end of its term if the
facility's operations are in compliance with the applicable regulatory
requirements.
 
  Under the Company's insurance programs, coverage is obtained for catastrophic
exposures as well as those risks required to be insured by law or contract. It
is the policy of the Company to retain a significant portion of certain
expected losses related primarily to workers' compensation, physical loss to
property, and comprehensive general and vehicle liability. Provisions for
losses expected under these programs are recorded based upon the Company's
estimates of the aggregate liability for claims.
 
(12) LEASES
 
(a) Capital Leases
 
  The Company possesses certain equipment under capital leases. The capitalized
cost of this equipment was $6,603,000 and $6,450,000 with related accumulated
amortization of $4,630,000 and $4,392,000 at December 31, 1993 and 1992,
respectively. The obligations of the Company under such leases are
collateralized by the leased equipment.
 
  Future minimum lease payments under capital leases are as follows (in
thousands):
 
<TABLE>
<CAPTION>
   YEAR                                                                   AMOUNT
   ----                                                                   ------
   <S>                                                                    <C>
   1994.................................................................. $ 253
   1995..................................................................   197
   1996..................................................................    84
   1997..................................................................    72
   1998..................................................................     9
   Thereafter............................................................   --
                                                                          -----
   Total minimum lease payments.......................................... $ 615
     Less--Amounts representing interest.................................    69
                                                                          -----
   Present value of minimum lease payments............................... $ 546
                                                                          =====
</TABLE>
 
(b) Operating Leases
 
  The Company leases facilities and personal property under certain operating
leases in excess of one year. Some of these lease agreements contain an
escalation clause for increased taxes and operating expenses and are renewable
at the option of the Company. Future minimum lease payments under operating
leases are as follows (in thousands):
 
<TABLE>
<CAPTION>
   YEAR                                                                  AMOUNT
   ----                                                                  -------
   <S>                                                                   <C>
   1994................................................................. $ 3,834
   1995.................................................................   3,419
   1996.................................................................   2,520
   1997.................................................................   1,787
   1998.................................................................   1,433
   Thereafter...........................................................   4,651
                                                                         -------
                                                                         $17,644
                                                                         =======
</TABLE>
 
                                      F-19
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)
 
  During the years 1993 and 1992 and the ten-month period ended December 31,
1991, rent expense was approximately $9,796,000, $9,483,000, and $5,764,000,
respectively.
 
(13) STOCK PURCHASE AGREEMENT
 
  In connection with the acquisition of its Braintree and Natick subsidiaries
from ChemWaste, the Company entered into a disposal agreement with ChemWaste
under which the Company is entitled to quantity discounts if it delivers
specified minimum amounts of hazardous waste to ChemWaste's disposal
facilities. At the same time, the Company and its principal stockholder entered
into a stock purchase agreement with ChemWaste under which the Company and its
principal stockholder agreed that, through the term of the disposal agreement,
they will not, subject to certain exceptions, sell the stock or substantially
all of the assets of the Company or any of its subsidiaries to any third party
without first offering to sell such stock or assets to ChemWaste on the same
terms as those offered by a third party or, in the case of a proposed public
offering, at 90% of the proposed public offering price. These agreements, as
amended, expire on March 31, 1995.
 
(14) STOCKHOLDERS' EQUITY
 
(a) Stock Option Plans
 
  In 1987, the Company adopted a nonqualified stock option plan (the "1987
Plan"). In 1992, the Company adopted a nonqualified equity incentive plan which
provides for a variety of incentive awards, including stock options (the "1992
Plan"). As of December 31, 1993, all awards under the 1992 Plan were in the
form of stock options. These options generally become exercisable after a
period of one to five years from the date of grant, subject to certain
employment requirements, and terminate ten years from the date of grant. At
December 31, 1993, the Company had reserved 955,600 and 495,000 shares of
common stock for issuance under the 1987 and 1992 Plans, respectively.
 
  Under the terms of the 1987 and 1992 Plans, as amended, options may be
granted to purchase shares of common stock at an exercise price not less than
85% of the fair market value on the date of grant. The difference between the
exercise price and fair market value at the date of grant is charged to
operations ratably over the option vesting period. Total compensation expense
charged to operations in the year 1992 and the ten-month period ended December
31, 1991 was approximately $8,000 and $20,000, respectively. All existing
deferred compensation was fully amortized during 1992. No options were granted
during 1993 with exercise prices lower than the fair market value of the common
stock at the date of grant.
 
  On September 17, 1990, the Board of Directors approved a plan whereby all
employees who previously were awarded stock options in October 1987 and as a
result of the ChemClear merger in January 1989 at prices in excess of $7.65 per
share be given the opportunity to surrender those options in exchange for new
options awarded at fair market value ($7.65 per share) with a five year vesting
period commencing upon the date of the award of their original option
agreement. On January 4, 1994, the Board of Directors approved a plan whereby
certain employees (excluding senior management) who previously were awarded
stock options in May 1993 at $15.00 per share be given the opportunity to
surrender those options in exchange for new options awarded at fair market
value ($7.00 per share) with a five year vesting period commencing upon the
date of the award of their original option agreement.
 
                                      F-20
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)
 
  Below is a summary of the stock option activity under the 1987 and 1992 Plans
through December 31, 1993:
 
<TABLE>
<CAPTION>
                                                       NUMBER OF  EXERCISE PRICE
                                                        SHARES      PER SHARE
                                                       ---------  --------------
   <S>                                                 <C>        <C>
   Outstanding at February 28, 1991...................   695,307   $2.70- 7.75
     Granted..........................................   183,000    6.50-15.00
     Exercised........................................   (79,532)   2.70- 7.65
     Forfeited........................................    (7,121)   7.65-10.00
                                                       ---------   -----------
   Outstanding at December 31, 1991...................   791,654   $2.70-15.00
                                                       ---------   -----------
   Exercisable at December 31, 1991...................   657,679   $2.70- 7.65
                                                       ---------   -----------
     Granted..........................................   348,500    8.25-13.25
     Exercised........................................   (10,049)   2.70- 7.65
     Forfeited........................................   (69,610)   7.65-15.00
                                                       ---------   -----------
   Outstanding at December 31, 1992................... 1,060,495   $2.70-15.00
                                                       ---------   -----------
   Exercisable at December 31, 1992...................   475,563   $2.70-10.00
                                                       ---------   -----------
     Granted..........................................   445,750    7.00-15.00
     Exercised........................................   (98,457)   2.70- 8.25
     Forfeited........................................  (517,867)   6.50-15.00
                                                       ---------   -----------
   Outstanding at December 31, 1993...................   889,921   $2.70-15.00
                                                       =========   ===========
   Exercisable at December 31, 1993...................   398,969   $2.70-10.00
                                                       =========   ===========
</TABLE>
 
(b) Warrants
 
  In connection with the issuance of senior subordinated notes payable in May
1989, the Company issued warrants to purchase 100,000 shares of common stock at
$20.75 per share in exchange for $300,000. In April 1990, the exercise price of
the warrants was reduced to $9 per share. In February 1991, in connection with
the refinancing of the Company's short term debt, the exercise price was
further reduced to fair market value ($5 per share). These warrants are
exercisable at any time until February 1, 2001.
 
  In connection with the refinancing of the Company's short term debt in
February 1991, the Company issued warrants to purchase 425,000 shares of common
stock at fair market value ($5 per share) to the three banks which provided the
Revolver. These warrants are exercisable at any time until February 6, 2001.
 
(c) Preferred Stock
 
  On February 16, 1993 the Company issued 112,000 shares of Series B
Convertible Preferred Stock, $.01 par value ("Preferred Stock"), for the
acquisition of Spring Grove. The liquidation value of each preferred share is
the liquidation preference of $50 plus unpaid dividends. The Company has the
option to redeem the Preferred Stock in whole or in part at any time on or
before August 16, 1994 at liquidation value. Thereafter, any unredeemed
Preferred Stock may be converted by the holder into Common Stock at a
conversion rate of $18.63, and the Company will have the option to redeem such
Preferred Stock at liquidation value plus a redemption premium of 7% which
declines 1% each year thereafter. Each preferred share entitles its holder to
receive a cumulative annual cash dividend of $3.50 per share from February 16,
1993 to February 16, 1994 and $4.00
 
                                      F-21
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(CONTINUED)

per share thereafter, or at the election of the Company, a common stock
dividend of equivalent value. At December 31, 1993, the Company had reserved
450,000 shares of common stock for issuance upon the conversion of, or as
dividends upon, the Preferred Stock.
 
(15) ACCRUED EXPENSES
 
  Accrued expenses consist of the following (in thousands):
 
<TABLE>
<CAPTION>
                                                                 1993    1992
                                                                ------- -------
   <S>                                                          <C>     <C>
   Insurance................................................... $ 2,971 $ 3,171
   Accrued payroll and fringe benefits.........................     799   1,016
   Other.......................................................   6,682   7,539
                                                                ------- -------
                                                                $10,452 $11,726
                                                                ======= =======
</TABLE>
 
(16) QUARTERLY DATA (UNAUDITED)
 
<TABLE>
<CAPTION>
                                           FIRST    SECOND     THIRD    FOURTH
                                          QUARTER   QUARTER   QUARTER   QUARTER
                                         --------- --------- --------- ---------
                                         (IN THOUSANDS EXCEPT PER SHARE AMOUNTS)
<S>                                      <C>       <C>       <C>       <C>
1993
Revenue................................  $  43,452 $  51,847 $  52,038 $  52,777
Income from operations.................      3,224     4,369     2,391     2,990
Net income.............................        835     1,440       275       581
Net income per common and common equiv-
 alent share...........................  $     .08 $     .13 $     .02 $     .05
1992
Revenue................................  $  37,691 $  41,683 $  46,255 $  50,564
Income from operations.................      2,348     3,509     4,390     4,666
Net income.............................        489     1,153     1,674     1,759
Net income per common and common equiv-
 alent share...........................  $     .05 $     .12 $     .17 $     .18
</TABLE>
 
  The above information reflects all adjustments that are necessary to fairly
state the results of the interim periods presented. Any adjustments required
are of a normal recurring nature.
 
(17) TRANSITION PERIOD DATA (UNAUDITED)
 
  The change in the Company's fiscal year end resulted in a ten-month period
ended December 31, 1991. The unaudited results for the twelve-month period
ended December 31, 1991 are presented for comparative purposes below:
 
<TABLE>
<CAPTION>
                                               TWELVE MONTHS ENDED DECEMBER 31,
                                               --------------------------------
                                                  1993       1992       1991
                                               ---------- ---------- ----------
                                                        (IN THOUSANDS)
   <S>                                         <C>        <C>        <C>
   Revenues................................... $  200,114 $  176,193 $  151,278
   Income from operations.....................     12,974     14,913     12,957
   Income taxes...............................      2,645      2,774      1,792
   Net income from operations................. $    3,131 $    5,075 $    4,000
   Net income per share....................... $      .28 $      .52 $      .41
</TABLE>
 
                                      F-22
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                       CONSOLIDATED STATEMENTS OF INCOME
 
               FOR THE THREE MONTHS ENDED MARCH 31, 1994 AND 1993
                                   UNAUDITED
 
              (IN THOUSANDS EXCEPT FOR EARNINGS PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                                                            THREE MONTHS ENDED
                                                                 MARCH 31,
                                                            -------------------
                                                              1994      1993
                                                            --------- ---------
<S>                                                         <C>       <C>
Revenues...................................................   $51,285   $43,452
Cost of revenues...........................................    35,914    28,389
Selling, general and administrative expenses...............     9,883     9,376
Depreciation and amortization..............................     2,563     2,463
                                                            --------- ---------
Income from operations.....................................     2,925     3,224
Interest expense (net).....................................     1,819     1,737
                                                            --------- ---------
Income before provision for income taxes...................     1,106     1,487
Provision for income taxes.................................       509       652
                                                            --------- ---------
Net income................................................. $     597 $     835
                                                            ========= =========
Net income per common and common equivalent share.......... $     .05 $     .08
                                                            ========= =========
Weighted average common and common equivalent shares out-
 standing..................................................     9,715    10,181
                                                            ========= =========
</TABLE>
 
 
 
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-23
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                          CONSOLIDATED BALANCE SHEETS
 
                   AS OF MARCH 31, 1994 AND DECEMBER 31, 1993
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                        MARCH 31,
                                                          1994     DECEMBER 31,
                                                       (UNAUDITED)     1993
                                                       ----------- ------------
<S>                                                    <C>         <C>
ASSETS
Current Assets:
  Cash................................................  $  1,318     $    816
  Restricted cash.....................................     1,037        1,037
  Accounts receivable, net of allowance for doubtful
   accounts...........................................    45,763       46,736
  Prepaid expenses....................................     2,157        2,353
  Supplies inventories................................     2,571        2,428
  Income tax receivable...............................       537          607
                                                        --------     --------
    Total current assets..............................    53,383       53,977
Property, plant and equipment:
  Land................................................     8,209        8,209
  Buildings and improvements..........................    31,737       31,737
  Vehicles and equipment..............................    70,677       70,946
  Furniture and fixtures..............................     2,203        2,201
  Construction in progress............................     2,410        1,903
                                                        --------     --------
                                                         115,236      114,996
Less--Accumulated depreciation and amortization.......    42,694       40,925
                                                        --------     --------
Net fixed assets......................................    72,542       74,071
                                                        --------     --------
Other Assets:
  Goodwill (net)......................................    23,469       23,650
  Permits (net).......................................    14,683       14,906
  Other...............................................       739          754
                                                        --------     --------
                                                          38,891       39,310
                                                        --------     --------
                                                        $164,816     $167,358
                                                        ========     ========
</TABLE>
 
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-24
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                          CONSOLIDATED BALANCE SHEETS
 
                   AS OF MARCH 31, 1994 AND DECEMBER 31, 1993
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                        MARCH 31,
                                                          1994     DECEMBER 31,
                                                       (UNAUDITED)     1993
                                                       ----------- ------------
<S>                                                    <C>         <C>
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
  Current maturities of long-term obligations.........  $  8,898     $  8,917
  Accounts payable....................................     8,816        9,564
  Accrued disposal costs..............................     4,541        6,724
  Other accrued expenses..............................    12,371       10,452
  Income tax payable..................................        63          --
                                                        --------     --------
    Total current liabilities.........................    34,689       35,657
                                                        --------     --------
Long-term obligations, less current maturities........    60,421       62,507
Deferred income taxes.................................     1,823        1,823
Stockholders' equity:
  Preferred Stock, $.01 par value:
   Series A Convertible;
    Authorized--2,000,000 shares; Issued and outstand-
    ing--none.........................................       --           --
   Series B Convertible;
    Authorized--156,416 shares; Issued and outstanding
    112,000 shares at March 31, 1994 (liquidation
    preference of $5.6 million).......................         1            1
  Common Stock, $.01 par value;
   Authorized--20,000,000 shares; Issued and outstand-
   ing--9,428,504 shares at March 31, 1994 and
   9,425,829 shares at December 31, 1993..............        95           95
  Additional paid-in capital..........................    58,576       58,556
  Retained earnings...................................     9,211        8,719
                                                        --------     --------
    Total stockholders' equity........................    67,883       67,371
                                                        --------     --------
                                                        $164,816     $167,358
                                                        ========     ========
</TABLE>
 
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-25
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                     CONSOLIDATED STATEMENTS OF CASH FLOWS
 
               FOR THE THREE MONTHS ENDED MARCH 31, 1994 AND 1993
 
                                   UNAUDITED
 
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                          THREE MONTHS ENDED
                                                               MARCH 31,
                                                          --------------------
                                                            1994       1993
                                                          ---------  ---------
<S>                                                       <C>        <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net income............................................. $     597  $     835
  Adjustments to reconcile net income to net cash pro-
   vided by operating activities:
    Depreciation and amortization........................     2,563      2,463
    Deferred taxes payable...............................       --         100
    Gain on sale of fixed assets.........................       (74)       --
  Changes in assets and liabilities, net of businesses
   acquired:
    Accounts receivable..................................       973      1,702
    Refundable income taxes..............................        70        153
    Prepaid expenses.....................................       196       (346)
    Supplies inventories.................................      (143)        12
    Accounts payable.....................................      (748)    (2,668)
    Accrued disposal costs...............................    (2,183)      (364)
    Other accrued expenses...............................     1,914       (372)
    Taxes payable........................................        63       (128)
                                                          ---------  ---------
  Net cash provided by operating activities..............     3,228      1,387
                                                          ---------  ---------
CASH FLOWS FROM INVESTING ACTIVITIES:
  Additions to property, plant and equipment.............      (630)    (2,179)
  Increase in permits....................................       --         (15)
  Increase in intangible assets..........................       --         (53)
  Decrease (increase) in other assets....................        13        (60)
  Proceeds from sale of fixed assets.....................        76        --
  Payment for business acquired, net of cash acquired....       --      (1,394)
                                                          ---------  ---------
  Net cash used in investing activities..................      (541)    (3,701)
                                                          ---------  ---------
</TABLE>
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-26
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
               CONSOLIDATED STATEMENTS OF CASH FLOWS (CONTINUED)
 
               FOR THE THREE MONTHS ENDED MARCH 31, 1994 AND 1993
 
                                   UNAUDITED
 
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                           THREE MONTHS ENDED
                                                                MARCH 31,
                                                           --------------------
                                                             1994       1993
                                                           ---------  ---------
<S>                                                        <C>        <C>
CASH FLOWS FROM FINANCING ACTIVITIES:
  Preferred stock dividend distribution...................      (100)       (50)
  Net (payments) borrowings on long-term debt.............    (2,105)     2,255
  Proceeds from exercise of stock options.................        20        478
  Tax benefit from stock option exercises.................       --         261
                                                           ---------  ---------
  Net cash (used in) provided by financing activities.....    (2,185)     2,944
                                                           ---------  ---------
INCREASE IN CASH AND CASH EQUIVALENTS.....................       502        630
  Cash and equivalents, beginning of year.................       816        625
                                                           ---------  ---------
  Cash and equivalents, end of period..................... $   1,318  $   1,255
                                                           =========  =========
  Supplemental Information:
</TABLE>
 
  Supplemental schedule of noncash investing and financing activities:
 
  On February 16, 1993, the Company acquired all the outstanding capital stock
of Spring Grove Resource Recovery, Inc., in exchange for cash and 112,000
shares of Series B Convertible Preferred Stock of Clean Harbors, Inc., with a
liquidation value of $5,600,000.
 
                                      F-27
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
 
                   FOR THE THREE MONTHS ENDED MARCH 31, 1994
 
                                   UNAUDITED
 
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                             SERIES B
                         PREFERRED STOCK    COMMON STOCK
                         -----------------  ------------
                          NUMBER    $0.01   NUMBER $0.01 ADDITIONAL              TOTAL
                            OF       PAR      OF    PAR   PAID-IN   RETAINED STOCKHOLDERS'
                          SHARES    VALUE   SHARES VALUE  CAPITAL   EARNINGS    EQUITY
                         --------  -------  ------ ----- ---------- -------- -------------
<S>                      <C>       <C>      <C>    <C>   <C>        <C>      <C>
Balance at December 31,
 1993...................      112   $     1 9,425   $95   $58,556    $8,719     $67,371
Preferred stock divi-
 dends:
  Series B..............      --        --    --    --        --       (105)       (105)
Proceeds from exercise
 of stock options.......      --        --      3   --         20       --           20
Net Income..............      --        --    --    --        --        597         597
                          -------   ------- -----   ---   -------    ------     -------
Balance at March 31,
 1994...................      112   $     1 9,428   $95   $58,576    $9,211     $67,883
                          =======   ======= =====   ===   =======    ======     =======
</TABLE>
 
 
 
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                      F-28
<PAGE>
 
                      CLEAN HARBORS, INC. AND SUBSIDIARIES
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
 
                                  (UNAUDITED)
 
NOTE 1 BASIS OF PRESENTATION
 
  The consolidated interim financial statements included herein have been
prepared by the Company, pursuant to the rules and regulations of the
Securities and Exchange Commission, and include, in the opinion of management,
all adjustments (consisting of only normal recurring accruals) necessary for
the fair presentation of interim period results. The operating results for the
three months ended March 31, 1994 are not necessarily indicative of those to be
expected for the full fiscal year. Reference is made to the audited
consolidated financial statements and notes thereto for the years ended
December 31, 1993 and 1992 and for the ten-month period ended December 31, 1991
included elsewhere in this Prospectus.
 
NOTE 2 SIGNIFICANT ACCOUNTING POLICIES
 
  (A) Net Income Per Common and Common Equivalent Share
 
  Net income per common and common equivalent share is based on net income less
preferred stock dividend requirements divided by the weighted average number of
common and common equivalent shares outstanding during each of the respective
periods. Fully diluted net income per common share has not been presented as
the amount would not differ significantly from that presented.
 
NOTE 3 FINANCIAL ARRANGEMENTS
 
  At December 31, 1993, the Company had a Revolving Credit Agreement (the
"Revolver") with three banks, which permitted borrowings of up to $38,000,000
in cash and allowed the Company to have a maximum of $20,000,000 of letters of
credit outstanding. The combination of cash and letters of credit outstanding
was limited to $50,000,000 at any one time. At March 31, 1994, borrowings under
the Revolver were $31,004,569 (exclusive of outstanding letters of credit). The
entire balance of the Revolver matures on July 1, 1996. All borrowings under
the Revolver are collateralized by substantially all of the Company's assets.
 
  On February 1, 1994, the Company and its banks amended the Revolver to
increase the amount of the Revolver to $55,000,000. The amended Revolver
permits borrowings of up to $40,000,000 in cash, and allows the Company to have
up to $20,000,000 of letters of credit outstanding. The combination of cash and
letters of credit outstanding may not exceed $55,000,000 at any one time. The
amount of the Revolver reduces on April 1, 1995 to $50,000,000.
 
                                      F-29
<PAGE>
 
- -------------------------------------------------------------------------------
 
 NO DEALER, SALESPERSON OR OTHER INDIVIDUAL HAS BEEN AUTHORIZED TO GIVE ANY
INFORMATION OR TO MAKE ANY REPRESENTATION NOT CONTAINED IN THIS PROSPECTUS
AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATION MUST NOT BE RELIED
UPON AS HAVING BEEN AUTHORIZED BY THE COMPANY OR ANY UNDERWRITER. THIS PRO-
SPECTUS DOES NOT CONSTITUTE AN OFFER TO SELL OR SOLICITATION OF AN OFFER TO
BUY ANY OF THE SECURITIES OFFERED HEREBY IN ANY JURISDICTION TO ANY PERSON TO
WHOM IT IS UNLAWFUL TO MAKE SUCH OFFER IN SUCH JURISDICTION. NEITHER THE DE-
LIVERY OF THIS PROSPECTUS NOR ANY SALE MADE HEREUNDER SHALL, UNDER ANY CIRCUM-
STANCES, CREATE ANY IMPLICATION THAT THE INFORMATION HEREIN IS CORRECT AS OF
ANY TIME SUBSEQUENT TO THE DATE HEREOF OR THAT THERE HAS BEEN NO CHANGE IN THE
AFFAIRS OF THE COMPANY SINCE SUCH DATE.
 
                                  -----------
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                            PAGE
                                                                            ----
<S>                                                                         <C>
Prospectus Summary........................................................    3
Risk Factors..............................................................    9
Use of Proceeds...........................................................   14
Capitalization............................................................   15
Selected Consolidated Financial Data......................................   16
Management's Discussion and Analysis of Financial Condition and Results of
 Operations...............................................................   17
Business..................................................................   27
Environmental Regulation..................................................   44
Directors and Executive Officers of the Company...........................   48
Description of Other Indebtedness.........................................   50
Description of the Senior Notes...........................................   51
Underwriting..............................................................   74
Notice to Canadian Residents..............................................   74
Legal Matters.............................................................   75
Experts...................................................................   75
Available Information.....................................................   76
Incorporation of Certain Documents by Reference...........................   76
Index to Consolidated Financial Statements................................  F-1
</TABLE>
 
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
 
                                   (ARTWORK)
                                  
                               $50,000,000     
                         
                      12 1/2% Senior Notes Due 2001     
 
                                  PROSPECTUS
 
                                CS First Boston
 
                              Alex. Brown & Sons
                                 Incorporated
 
- -------------------------------------------------------------------------------
<PAGE>
 
                                    PART II
 
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION
 
  The following table sets forth an estimate of all expenses in connection with
the issuance and distribution of the Senior Notes being registered, other than
underwriting compensation:
 
<TABLE>
     <S>                                                                <C>
     Registration Fee..................................................  $25,862
     NASD Filing Fee...................................................    8,000
     Printing and Engraving............................................   75,000
     Accounting Fees and Expenses......................................   40,000
     Legal Fees and Expenses...........................................  175,000
     Blue Sky Fees and Expenses........................................   12,000
     Trustee Fees......................................................    7,500
     Miscellaneous.....................................................  156,638
                                                                        --------
       Total........................................................... $500,000
                                                                        ========
</TABLE>
 
ITEM 15. INDEMNIFICATION OF DIRECTORS AND OFFICERS
 
  (a) Section 67 of the Massachusetts Business Corporation Law, as amended,
gives Massachusetts corporations the power to indemnify each of their present
and former officers or directors under certain circumstances if such person
acted in good faith and in a manner which he reasonably believed to be in or
not opposed to the best interest of the corporation. In its Restated Articles
of Organization, the Registrant provides for such indemnification of its
officers and directors to the extent permitted by law.
 
  (b) Reference is made to Article 6 of the Registrant's Restated Articles of
Organization filed as Exhibit 3.1 to the Registrant's Form S-1 Registration
Statement (No. 33-17565), and incorporated herein by reference, for the
applicable provisions regarding the indemnification of directors and officers.
 
  (c) Reference is made to Section 7 of the Underwriting Agreement (the form of
which will be included in Exhibit 1 to this Registration Statement) for
provisions regarding the indemnification under certain circumstances of the
Registrant, its directors and certain of its officers by the Underwriters.
 
ITEM 16. EXHIBITS
 
  Unless otherwise indicated, the exhibits described below have heretofore been
filed with the Commission by the Registrant under its filings identified below,
and such exhibits are incorporated herein by reference.
 
                                      II-1
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT                               DESCRIPTION
 -------                               -----------
 <C>     <S>
  *1     --Revised form of Underwriting Agreement.
   3.1   --Restated Articles of Organization of Clean Harbors, Inc. and
           amendments thereto [Exhibit 3.1 to Form S-1 Registration Statement
           (File No. 33-17565)].
   3.2   --Certificate of Vote of Directors Establishing a Series of a Class of
           Stock (Series B Convertible Preferred Stock). [Exhibit 3.2 to Form
           10-K Annual Report for the Year ended December 31, 1992 (File No. 0-
           16379)].
   3.3   --Amended and Restated By-laws of Clean Harbors, Inc. [Exhibit 3.4A to
           Form 10-K Annual Report for the Fiscal Year ended February 28, 1991
           (File No. 0-16379)].
  *4.1   --Revised proposed form of Indenture (including form of Senior Note)
           between Clean Harbors, Inc., the Guarantor Subsidiaries, and Shawmut
           Bank, N.A., as Trustee, relating to the proposed issuance of the
           Senior Notes.
   4.2A  --Note Agreements dated as of May 15, 1989 by and between Clean
           Harbors, Inc. and certain affiliates of Kemper Financial Services,
           Inc. [Exhibit 10.32 to Form 10-K Annual Report for the Fiscal Year
           ended February 29, 1989 (File No. 0-16379)].
   4.2B  --Amendment Agreement dated as of February 1, 1991 to Note Agreements
           originally dated as of May 15, 1989 by and among Clean Harbors, Inc.
           and certain affiliates of Kemper Financial Services, Inc. and to
           Warrants originally dated May 25, 1989 [Exhibit 4.2 to Form 10-K
           Annual Report for the Fiscal Year ended February 28, 1991 (File No.
           0-16379)].
   4.2C  --Subordinated Guaranty Agreement dated as of January 15, 1991 by the
           subsidiaries of Clean Harbors, Inc., as guarantors of the Senior
           Notes and Note Agreements originally dated as of May 15, 1989 by and
           among Clean Harbors, Inc. and certain affiliates of Kemper Financial
           Services, Inc. [Exhibit 4.3 to Form 10-K Annual Report for the Fiscal
           Year ended February 28, 1991 (File No. 0-16379)].
   4.2D  --Second Amendment Agreement dated as of November 7, 1991 to Note
           Agreements originally dated as of May 15, 1989 by and among Clean
           Harbors, Inc. and certain affiliates of Kemper Financial Services,
           Inc. and to Warrants originally dated May 25, 1989 [Exhibit 4.6 to
           Form 10-Q Quarterly Report for the Quarter ended November 30, 1991
           (File No. 0-16379)].
   4.2E  --Third Amendment Agreement dated as of June 29, 1992 to Note
           Agreements originally dated as of May 15, 1989 by and among Clean
           Harbors, Inc. and certain affiliates of Kemper Financial Services,
           Inc. [Exhibit 4.7 to Form 10-Q Quarterly Report for the Quarter ended
           September 30, 1992 (File No. 0-16379)].
   4.3A  --Amended and Restated Revolving Credit Agreement dated as of February
           19, 1993 by and among Clean Harbors, Inc., the Subsidiaries listed on
           Schedule 1 thereto, Clean Harbors of Baltimore, as Guarantor, and The
           First National Bank of Boston, National Westminster Bank USA, and
           USTrust, and The First National Bank of Boston, as Agent [Exhibit 4.8
           to Form 10-K Annual Report for the Year ended December 31, 1992 (File
           No. 0-16379)].
   4.3B  --First Amendment dated November 5, 1993 to Amended and Restated
           Revolving Credit Agreement dated as of February 19, 1993 by and among
           Clean Harbors, Inc., the Subsidiaries listed on Schedule 1 thereto,
           Clean Harbors of Baltimore, as Guarantor, and The First National Bank
           of Boston, National Westminster Bank USA, and USTrust, and The First
           National Bank of Boston, as Agent [Exhibit 4.9 to Form 10-Q Quarterly
           Report for the Quarter ended September 30, 1993 (File No. 0-16379)].
   4.3C  --Second Amendment dated February 1, 1994 to Amended and Restated
           Revolving Credit Agreement dated as of February 19, 1993 by and among
           Clean Harbors, Inc., the Subsidiaries listed on Schedule 1 thereto,
           Clean Harbors of Baltimore, as Guarantor, and The First National Bank
           of Boston, National Westminster Bank USA, and USTrust, and The First
           National Bank of Boston, as Agent [Exhibit 4.10 to Form 10-K Annual
           Report for the Year ended December 31, 1993 (File No. 0-16379)].
</TABLE>
 
                                      II-2
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT                               DESCRIPTION
 -------                               -----------
 <C>      <S>
   *5     --Opinion of Davis, Malm & D'Agostine, P.C.
    10.1  --Employment Agreement between Clean Harbors, Inc. and James A. Pitts
            dated March 20, 1992 [Exhibit 10.34 to Form 10-K Annual Report for
            the Year ended December 31, 1992 (File No. 0-13679)].
    10.2  --Stock Purchase Agreement among Clean Harbors, Inc., Southdown
            Environmental Treatment Systems, Inc. and Southdown, Inc. dated as
            of June 23, 1992 [Exhibit 10.35 to Form 10-K Annual Report for the
            Year ended December 31, 1992 (File No. 0-13679)].
    10.3  --Stock Purchase Agreement among Clean Harbors, Inc., Southdown
            Environmental Treatment Systems, Inc. and Southdown, Inc. dated as
            of February 16, 1993 [Exhibit 10.36 to Form 10-K Annual Report for
            the Year ended December 31, 1992 (File No. 0-13679)].
    10.4  --Clean Harbors, Inc. 1987 Stock Option Plan [Exhibit 10.37 to Form
            10-K Annual Report for the Year ended December 31, 1992 (File No. 0-
            13679)].
    10.5  --Clean Harbors, Inc. 1992 Equity Incentive Plan [Exhibit 10.38 to
            Form 10-K Annual Report for the Year ended December 31, 1992 (File
            No. 0-13679)].
    10.6A --Stock Purchase Agreement dated April 19, 1985 by and among SCA
            Services, Inc., Chemical Waste Management, Inc. and Clean Harbors,
            Inc. [Exhibit 10.4 to Form S-1 Registration Statement (File No. 33-
            23089)].
    10.6B --Amendment dated October 6, 1987 to Stock Purchase Agreement among
            SCA Services, Inc., Chemical Waste Management, Inc. and Clean
            Harbors, Inc., Clean Harbors of Braintree, Inc., Clean Harbors of
            Kingston, Inc., and Clean Harbors of Natick, Inc. [Exhibit 10.4A to
            Form S-1 Registration Statement (File No. 33-23089)].
    10.7  --Amended and Restated Disposal Agreement dated October 6, 1987 among
            SCA Services, Inc., Chemical Waste Management, Inc., and Clean
            Harbors of Braintree, Inc., Clean Harbors of Kingston, Inc., and
            Clean Harbors of Natick, Inc. and related Letter Agreement [Exhibit
            10.7A to Form S-1 Registration Statement (File No. 33-23089)].
  **12    --Computation of Ratio of Earnings to Fixed Charges.
   *23.1  --Consent of Coopers & Lybrand.
   *23.2  --Consent of Davis, Malm & D'Agostine, P.C., is contained in their
            opinion filed as Exhibit 5 to this Registration Statement.
  **24    --Powers of Attorney.
  **25    --Statement of Eligibility and Qualification of Trustee on Form T-1.
</TABLE>
- --------
 * Filed herewith.
** Previously filed under this Registration Statement.
 
ITEM 17. UNDERTAKINGS
 
  Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Securities
Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless
in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the
Securities Act and will be governed by the final adjudication of such issue.
 
                                     II-3
<PAGE>
 
  The undersigned Registrant hereby undertakes that:
 
    (1) For purposes of determining any liability under the Securities Act,
  the information omitted from the form of prospectus filed as part of this
  Registration Statement in reliance upon Rule 430A and contained in a form
  of prospectus filed by the Registrant pursuant to Rule 424(b)(1) or (4) or
  497(h) under the Securities Act shall be deemed to be part of this
  Registration Statement as of the time it was declared effective.
 
    (2) For the purpose of determining any liability under the Securities
  Act, each post-effective amendment that contains a form of prospectus shall
  be deemed to be a new registration statement relating to the securities
  offered therein, and the offering of such securities at that time shall be
  deemed to be the initial bona fide offering thereof.
 
                                      II-4
<PAGE>
 
                                   REGISTRANT
                                   SIGNATURES
   
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED, THE
REGISTRANT CERTIFIES THAT IT HAS REASONABLE GROUNDS TO BELIEVE THAT IT MEETS
ALL OF THE REQUIREMENTS FOR FILING ON FORM S-2 AND HAS DULY CAUSED THIS
AMENDMENT TO ITS REGISTRATION STATEMENT TO BE SIGNED ON ITS BEHALF BY THE
UNDERSIGNED, THEREUNTO DULY AUTHORIZED, IN THE CITY OF BOSTON, COMMONWEALTH OF
MASSACHUSETTS, ON JULY 27, 1994.     
 
                                          Clean Harbors, Inc.
 
                                              
                                          By:      Alan S. McKim*
                                              ---------------------------------
                                                 ALAN S. MCKIM, CHAIRMAN OF
                                                 THE BOARD OF DIRECTORS AND
                                                 PRESIDENT
 
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED THIS
AMENDMENT TO THE REGISTRATION STATEMENT HAS BEEN SIGNED BELOW BY THE FOLLOWING
PERSONS IN THE CAPACITIES INDICATED.
 
              SIGNATURE                          CAPACITY           DATE
              ---------                          --------           ----
 
                                                                             
           Alan S. McKim*               Chairman of the Board    July 27, 1994
- -------------------------------------    of Directors,                        
            ALAN S. MCKIM                President and Chief                  
                                         Executive Officer

            
           James A. Pitts               Executive Vice           July 27, 1994
- -------------------------------------    President of Finance                 
           JAMES A. PITTS                and Administration                   
                                         and Chief Financial
                                         Officer (principal
                                         financial officer)

                                                                    
       Mary-Ellen Drinkwater*           Vice President and       July 27, 1994
- -------------------------------------    Controller (principal        
        MARY-ELLEN DRINKWATER            accounting officer)

                                                                             
         Daniel J. McCarthy*            Director                 July 27, 1994
- -------------------------------------                                         
         DANIEL J. MCCARTHY                                                   
                                                                       
                                                                             
           John F. Kaslow*              Director                 July 27, 1994
- -------------------------------------                                         
           JOHN F. KASLOW                                                     

                                                                             
          Christy W. Bell*              Director                 July 27, 1994
- -------------------------------------                                         
           CHRISTY W. BELL                                                    

                                                                             
          Lorne R. Waxlax*              Director                 July 27, 1994
- -------------------------------------                                         
           LORNE R. WAXLAX                                                    

                          
*By:       James A. Pitts     
     --------------------------------
     JAMES A. PITTS, ATTORNEY-IN-FACT   

                                     II-5
<PAGE>
 
                             ADDITIONAL REGISTRANT
                                  SIGNATURES
   
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED, EACH
OF THE ADDITIONAL REGISTRANTS CERTIFIES THAT IT HAS REASONABLE GROUNDS TO
BELIEVE THAT IT MEETS ALL OF THE REQUIREMENTS FOR FILING ON FORM S-2 AND HAS
DULY CAUSED THIS AMENDMENT TO ITS REGISTRATION STATEMENT TO BE SIGNED ON ITS
BEHALF BY THE UNDERSIGNED, THEREUNTO DULY AUTHORIZED, IN THE CITY OF BOSTON,
COMMONWEALTH OF MASSACHUSETTS, ON JULY 27, 1994.     
 
                                          Clean Harbors Environmental
                                           Services, Inc.
 
                                                   Alan S. McKim*
                                          By: _________________________________
                                                 ALAN S. MCKIM, PRESIDENT
 
Clean Harbors of Braintree, Inc., Clean Harbors of Natick, Inc., Clean Harbors
of Baltimore, Inc., Clean Harbors of Chicago, Inc., Clean Harbors of
Cleveland, Inc., Murphy's Waste Oil Service, Inc., Clean Harbors Kingston
Facility Corporation, Clean Harbors of Connecticut, Inc., Mr. Frank, Inc.,
Spring Grove Resource Recovery, Inc.
                                                    
                                                 James A. Pitts     
                                          By: _________________________________
                                                 JAMES A. PITTS, VICE
                                                 PRESIDENT
 
                                          Clean Harbors Technology Corporation
 
                                               Jorgen H. Vestergaard*
                                          By: _________________________________
                                                 JORGEN H. VESTERGAARD,
                                                 PRESIDENT
 
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED, THIS
AMENDMENT TO THE REGISTRATION STATEMENT HAS BEEN SIGNED BELOW BY THE FOLLOWING
PERSONS IN THE CAPACITIES INDICATED.
 
              SIGNATURE                          CAPACITY           DATE
 
           Alan S. McKim*              President (principal         
_____________________________________   executive officer) of    July 27, 1994
                                        Clean Harbors                 
            ALAN S. MCKIM               Environmental
                                        Services, Inc.; sole
                                        Director of each of
                                        the Additional
                                        Registrants (other
                                        than Clean Harbors
                                        Technology
                                        Corporation); and
                                        Director of Clean
                                        Harbors Technology
                                        Corporation
 
       Jorgen H. Vestergaard*          President (principal         
_____________________________________   executive officer)       July 27, 1994
        JORGEN H. VESTERGAARD           and Director of Clean         
                                        Harbors Technology
                                        Corporation
 
                                       
         James A. Pitts                Treasurer (principal                  
_____________________________________   financial and            July 27, 1994
           JAMES A. PITTS               accounting officer)                  
                                        of each of the                       
                                        Additional                           
                                        Registrants                           
 
                                       Director of Clean
_____________________________________   Harbors Technology
                                        Corporation
 
           JOHN T. PRESTON
            
         James A. Pitts     
*By: ________________________________
  JAMES A. PITTS, ATTORNEY-IN-FACT
 
                                     II-6
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT                               DESCRIPTION
 -------                               -----------
 <C>     <S>
  *1     --Revised form of Underwriting Agreement.
   3.1   --Restated Articles of Organization of Clean Harbors, Inc. and
           amendments thereto [Exhibit 3.1 to Form S-1 Registration Statement
           (File No. 33-17565)].
   3.2   --Certificate of Vote of Directors Establishing a Series of a Class of
           Stock (Series B Convertible Preferred Stock). [Exhibit 3.2 to Form
           10-K Annual Report for the Year ended December 31, 1992 (File No. 0-
           16379)].
   3.3   --Amended and Restated By-laws of Clean Harbors, Inc. [Exhibit 3.4A to
           Form 10-K Annual Report for the Fiscal Year ended February 28, 1991
           (File No. 0-16379)].
  *4.1   --Revised proposed form of Indenture (including form of Senior Note)
           between Clean Harbors, Inc., the Guarantor Subsidiaries, and Shawmut
           Bank, N.A., as Trustee, relating to the proposed issuance of the
           Senior Notes.
   4.2A  --Note Agreements dated as of May 15, 1989 by and between Clean
           Harbors, Inc. and certain affiliates of Kemper Financial Services,
           Inc. [Exhibit 10.32 to Form 10-K Annual Report for the Fiscal Year
           ended February 29, 1989 (File No. 0-16379)].
   4.2B  --Amendment Agreement dated as of February 1, 1991 to Note Agreements
           originally dated as of May 15, 1989 by and among Clean Harbors, Inc.
           and certain affiliates of Kemper Financial Services, Inc. and to
           Warrants originally dated May 25, 1989 [Exhibit 4.2 to Form 10-K
           Annual Report for the Fiscal Year ended February 28, 1991 (File No.
           0-16379)].
   4.2C  --Subordinated Guaranty Agreement dated as of January 15, 1991 by the
           subsidiaries of Clean Harbors, Inc., as guarantors of the Senior
           Notes and Note Agreements originally dated as of May 15, 1989 by and
           among Clean Harbors, Inc. and certain affiliates of Kemper Financial
           Services, Inc. [Exhibit 4.3 to Form 10-K Annual Report for the Fiscal
           Year ended February 28, 1991 (File No. 0-16379)].
   4.2D  --Second Amendment Agreement dated as of November 7, 1991 to Note
           Agreements originally dated as of May 15, 1989 by and among Clean
           Harbors, Inc. and certain affiliates of Kemper Financial Services,
           Inc. and to Warrants originally dated May 25, 1989 [Exhibit 4.6 to
           Form 10-Q Quarterly Report for the Quarter ended November 30, 1991
           (File No. 0-16379)].
   4.2E  --Third Amendment Agreement dated as of June 29, 1992 to Note
           Agreements originally dated as of May 15, 1989 by and among Clean
           Harbors, Inc. and certain affiliates of Kemper Financial Services,
           Inc. [Exhibit 4.7 to Form 10-Q Quarterly Report for the Quarter ended
           September 30, 1992 (File No. 0-16379)].
   4.3A  --Amended and Restated Revolving Credit Agreement dated as of February
           19, 1993 by and among Clean Harbors, Inc., the Subsidiaries listed on
           Schedule 1 thereto, Clean Harbors of Baltimore, as Guarantor, and The
           First National Bank of Boston, National Westminster Bank USA, and
           USTrust, and The First National Bank of Boston, as Agent [Exhibit 4.8
           to Form 10-K Annual Report for the Year ended December 31, 1992 (File
           No. 0-16379)].
   4.3B  --First Amendment dated November 5, 1993 to Amended and Restated
           Revolving Credit Agreement dated as of February 19, 1993 by and among
           Clean Harbors, Inc., the Subsidiaries listed on Schedule 1 thereto,
           Clean Harbors of Baltimore, as Guarantor, and The First National Bank
           of Boston, National Westminster Bank USA, and USTrust, and The First
           National Bank of Boston, as Agent [Exhibit 4.9 to Form 10-Q Quarterly
           Report for the Quarter ended September 30, 1993 (File No. 0-16379)].
   4.3C  --Second Amendment dated February 1, 1994 to Amended and Restated
           Revolving Credit Agreement dated as of February 19, 1993 by and among
           Clean Harbors, Inc., the Subsidiaries listed on Schedule 1 thereto,
           Clean Harbors of Baltimore, as Guarantor, and The First National Bank
           of Boston, National Westminster Bank USA, and USTrust, and The First
           National Bank of Boston, as Agent [Exhibit 4.10 to Form 10-K Annual
           Report for the Year ended December 31, 1993 (File No. 0-16379)].
</TABLE>
<PAGE>
 
<TABLE>
<CAPTION>
 EXHIBIT                               DESCRIPTION
 -------                               -----------
 <C>     <S>
  *5     --Opinion of Davis, Malm & D'Agostine, P.C.
   10.1  --Employment Agreement between Clean Harbors, Inc. and James A. Pitts
           dated March 20, 1992 [Exhibit 10.34 to Form 10-K Annual Report for
           the Year ended December 31, 1992 (File No. 0-13679)].
   10.2  --Stock Purchase Agreement among Clean Harbors, Inc., Southdown
           Environmental Treatment Systems, Inc. and Southdown, Inc. dated as of
           June 23, 1992 [Exhibit 10.35 to Form 10-K Annual Report for the Year
           ended December 31, 1992 (File No. 0-13679)].
   10.3  --Stock Purchase Agreement among Clean Harbors, Inc., Southdown
           Environmental Treatment Systems, Inc. and Southdown, Inc. dated as of
           February 16, 1993 [Exhibit 10.36 to Form 10-K Annual Report for the
           Year ended December 31, 1992 (File No. 0-13679)].
   10.4  --Clean Harbors, Inc. 1987 Stock Option Plan [Exhibit 10.37 to Form
           10-K Annual Report for the Year ended December 31, 1992 (File No. 0-
           13679)].
   10.5  --Clean Harbors, Inc. 1992 Equity Incentive Plan [Exhibit 10.38 to
           Form 10-K Annual Report for the Year ended December 31, 1992 (File
           No. 0-13679)].
   10.6A --Stock Purchase Agreement dated April 19, 1985 by and among SCA
           Services, Inc., Chemical Waste Management, Inc. and Clean Harbors,
           Inc. [Exhibit 10.4 to Form S-1 Registration Statement (File No. 33-
           23089)].
   10.6B --Amendment dated October 6, 1987 to Stock Purchase Agreement among
           SCA Services, Inc., Chemical Waste Management, Inc. and Clean
           Harbors, Inc., Clean Harbors of Braintree, Inc., Clean Harbors of
           Kingston, Inc., and Clean Harbors of Natick., Inc. [Exhibit 10.4A to
           Form S-1 Registration Statement (File No. 33-23089)].
   10.7  --Amended and Restated Disposal Agreement dated October 6, 1987 among
           SCA Services, Inc., Chemical Waste Management, Inc., and Clean
           Harbors of Braintree, Inc., Clean Harbors of Kingston, Inc., and
           Clean Harbors of Natick, Inc. and related Letter Agreement [Exhibit
           10.7A to Form S-1 Registration Statement (File No. 33-23089)].
 **12    --Computation of Ratio of Earnings to Fixed Charges.
  *23.1  --Consent of Coopers & Lybrand.
  *23.2  --Consent of Davis, Malm & D'Agostine, P.C., is contained in their
           opinion filed as Exhibit 5 to this Registration Statement.
 **24    --Powers of Attorney.
 **25    --Statement of Eligibility and Qualification of Trustee on Form T-1.
</TABLE>
- --------
 * Filed herewith.
** Previously filed under this Registration Statement.
<PAGE>
 

                            GRAPHICS APPENDIX LIST
                            ----------------------
                                                 
  Page Where
Graphic Appears                    Description of Graphics
- ---------------                    -----------------------

   TX 2                             Map depicting Waste Management Facilities,
                                    Service Centers and Sales Offices.


   TX 30                            Wheel chart showing the types of services
                                    provided by the Company and their 
                                    respective percentages of total revenues.









<PAGE>
 
                                  $50,000,000

                              CLEAN HARBORS, INC.
                              
                          12.5% Senior Notes Due 2001      


                            UNDERWRITING AGREEMENT
                            ----------------------

                                                              July 28, 1994

CS FIRST BOSTON CORPORATION
ALEX. BROWN & SONS INCORPORATED
      c/o CS First Boston Corporation,
          Park Avenue Plaza
          New York, NY  10055

Dear Sirs:
    
     1.   Introductory.  Clean Harbors, Inc., a Massachusetts corporation (the
"Company"), proposes to issue and sell to CS First Boston Corporation and Alex.
Brown & Sons Incorporated (the "Underwriters") an aggregate of $50,000,000
principal amount of its 12.5% Senior Notes due May 15, 2001 (the "Notes"). Each
subsidiary of the Company set forth on the signature pages hereof (each a
"Guarantor," collectively the "Guarantors," and together with the Company, the
"Issuers") proposes to issue and sell to the Underwriters unconditional
guarantees, on a senior basis, of the Notes (collectively, the "Guarantees").
Each Note, together with the related Guarantees thereof, is referred to herein
as a "Security," and the Notes, together with the related Guarantees thereof,
are referred to herein collectively as the "Securities." The Securities are to
be issued under an indenture, to be dated as of August 4, 1994 (the 
"Indenture"), between the Company, the Guarantors and Shawmut Bank., N.A., as 
trustee (the "Trustee").      

     2.   Representations and Warranties.  The Issuers, jointly and severally,
represent and warrant to, and agree with, the several Underwriters that:

          (a)  The Issuers meet the requirements for use of Form S-2 and a
     registration statement (No. 33-54191) on Form S-2, including a form of
     prospectus, relating to the Securities has been filed with the Securities
     and Exchange Commission (the "Commission") and either (i) has been declared
     effective under the Securities Act of 1933, as amended (the "Act"), and is
     not proposed to be amended, or (ii) is proposed to be amended by amendment
     or post-effective amendment. If the Issuers do not propose to amend such
     registration statement or if any post-effective amendment to such
     registration statement has been filed with the Commission prior to the
     execution and delivery of this Agreement, the most recent such amendment
     has been declared effective by the Commission. For purposes of this
     Agreement, 
<PAGE>
 
     "Effective Time" means (i) if the Company has advised you that it does not
     propose to amend such registration statement, the date and time as of which
     such registration statement, or the most recent post-effective amendment
     thereto (if any) filed prior to the execution and delivery of this
     Agreement, was declared effective by the Commission, or (ii) if the Issuers
     have advised you that they propose to file an amendment or post-effective
     amendment to such registration statement, the date and time as of which
     such registration statement, as amended by such amendment or post-effective
     amendment, as the case may be, is declared effective by the Commission.
     "Effective Date" means the date of the Effective Time. Such registration
     statement, as amended at the Effective Time, including all material
     incorporated by reference therein and including all information (if any)
     deemed to be a part of such registration statement as of the Effective Time
     pursuant to Rule 430A(b) under the Act, is hereinafter referred to as the
     "Registration Statement", and the form of prospectus relating to the
     Securities, as first filed with the Commission pursuant to and in
     accordance with Rule 424(b) ("Rule 424(b)") under the Act or (if no such
     filing is required) as included in the Registration Statement, including
     all material incorporated by reference in such prospectus, is hereinafter
     referred to as the "Prospectus". No stop order suspending the effectiveness
     of such Registration Statement or any part thereof has been issued and no
     proceeding for that purpose has been instituted or threatened by the
     Commission.
         
          (b)  If the Effective Time is prior to the execution and delivery of
     this Agreement: (i) on the Effective Date, the Registration Statement
     conformed in all respects to the requirements of the Act, the Trust
     Indenture Act of 1939 (the "Trust Indenture Act") and the rules and
     regulations of the Commission (the "Rules and Regulations") and did not
     include 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 not misleading, and (ii) on the date of this Agreement,
     the Registration Statement conforms, and at the time of filing of the
     Prospectus pursuant to Rule 424(b), or (if no such filing is required) as
     the Prospectus is included in the Registration Statement, the Registration
     Statement and the Prospectus will conform, in all respects to the
     requirements of the Act, the Trust Indenture Act and the Rules and
     Regulations, and neither of such documents includes, or will include, any
     untrue statement of a material fact or omits, or will omit, to state any
     material fact required to be stated therein or necessary to make the
     statements therein not misleading. If the Effective Time is subsequent to
     the execution and delivery of this Agreement: on the Effective Date, the
     Registration Statement and the Prospectus will conform in all respects to
     the requirements of the Act, the Trust Indenture Act and the Rules and
     Regulations, and neither of such documents will include any untrue
     statement of a material fact or will omit to state any material fact
     required to be stated therein or necessary to make the statements therein
     not misleading. The two preceding sentences do not apply to statements in
     or omissions from the Registration Statement      

                                       2
<PAGE>
 
     or Prospectus based upon written information furnished to the Issuers by
     any Underwriter specifically for use therein.

          (c)  The Company has been duly incorporated and is validly existing
     as a corporation in good standing under the laws of The Commonwealth of
     Massachusetts with corporate power and authority to own, lease and operate
     its properties and to conduct its business as described in the Registration
     Statement and the Prospectus; and the Company is duly qualified as a
     foreign corporation to transact business and is in good standing in each
     jurisdiction in which such qualification is required, except where failure
     to be so qualified or be in good standing would not have a material adverse
     effect on the condition, financial or otherwise, or on the assets,
     earnings, business affairs or business prospects of the Company and the
     Subsidiaries (as defined below), taken as a whole (a "Material Adverse
     Effect") and would not materially and adversely affect the consummation of
     this Agreement or the transactions contemplated hereby.
         
          (d)  The only subsidiaries of the Company are Clean Harbors
     Environmental Services, Inc., a Massachusetts corporation; Clean Harbors
     of Natick, Inc., a Massachusetts corporation; Clean Harbors of Braintree,
     Inc., a Massachusetts corporation; Clean Harbors of Chicago, Inc., a
     Massachusetts corporation; Clean Harbors of Cleveland, Inc., an Illinois
     corporation; Clean Harbors of Baltimore, Inc., a Pennsylvania corporation;
     Clean Harbors of Connecticut, Inc., a Connecticut corporation; Clean
     Harbors Kingston Facility Corporation, a Massachusetts corporation;
     Murphy's Waste Oil Service, Inc., a Massachusetts corporation; Northeast
     Casualty Risk Retention Group, Inc., a Vermont corporation; Clean Harbors
     Technology Corporation, a Massachusetts corporation; Mr. Frank, Inc., an
     Illinois corporation; and Spring Grove Resource Recovery, Inc., a Delaware
     corporation (collectively, the "Subsidiaries"). Each of the Subsidiaries
     has been duly incorporated and is validly existing as a corporation in good
     standing under the laws of its state of incorporation with corporate power
     and authority to own, lease and operate its properties and to conduct its
     business as described in the Registration Statement and the Prospectus; and
     each of the Subsidiaries is duly qualified as a foreign corporation to
     transact business and is in good standing in each jurisdiction in which
     such qualification is required, except where failure to be so qualified or
     to be in good standing would not have a Material Adverse Effect and would
     not materially and adversely affect the consummation of this Agreement or
     the transactions contemplated hereby. All of the issued and outstanding
     capital stock of each of the Subsidiaries which are Guarantors has been
     duly authorized and validly issued, is fully paid and nonassessable and,
     except for the capital stock of Clean Harbors Technology Corporation
     ("CHTC"), is owned by the Company. The issued and outstanding capital stock
     of CHTC is currently owned 99% by the Company and 1% by the president of
     CHTC.      

                                       3
<PAGE>
 
          (e)  The Company has full power and authority to execute, deliver and
     perform this Agreement and to authorize, issue, sell and deliver the Notes
     as contemplated by this Agreement. Each Guarantor has full power and
     authority to execute, deliver and perform this Agreement and to authorize,
     issue, sell and deliver its Guarantees as contemplated by this Agreement.

          (f)  This Agreement has been duly authorized, executed and delivered
     by each Issuer and constitutes the legal, valid and binding obligation of
     each Issuer, enforceable against it in accordance with its terms.

          (g)  The authorized, issued and outstanding capitalization of the 
     Company is as set forth in the Registration Statement and the Prospectus
     under "Capitalization" (except for subsequent issuances, if any, pursuant
     to reservations, commitments or agreements referred to in the Registration
     Statement or the Prospectus); all of the shares of issued and outstanding
     capital stock of the Company have been duly authorized and validly issued
     and are fully paid and nonassessable; and the capital stock of the Company
     conforms to all statements relating thereto contained in the Registration
     Statement and the Prospectus. When issued and delivered by the Issuers
     against payment therefor in accordance with the terms of this Agreement,
     the Securities to be sold by the Issuers hereunder will be duly authorized
     and validly issued. Except as set forth in the Registration Statement and
     the Prospectus, there are no outstanding (i) securities or obligations of
     the Company convertible into or exchangeable for any shares of capital
     stock of the Company, (ii) warrants, rights or options to subscribe for or
     purchase from the Company any such capital stock or any such convertible or
     exchangeable securities or obligations, or (iii) obligations for the
     Company to issue any such shares, any such convertible or exchangeable
     securities or obligations, or any such warrants, rights or obligations.

          (h)  The Notes have been duly authorized by the Company and, on the
     Closing Date (as such term is defined in Section 3 below), will have been
     duly executed by the Company and will conform in all material respects to
     the description thereof in the Prospectus. The Guarantees have been duly
     authorized by each Guarantor and, on the Closing Date, will have been duly
     executed by each Guarantor and will conform in all material respects to the
     description thereof in the Prospectus. When the Securities are issued,
     authenticated and delivered in accordance with the Indenture and paid for
     in accordance with the terms of this Agreement, the Notes will constitute
     valid and legally binding obligations of the Company, enforceable against
     the Company in accordance with their terms and entitled to the benefits of
     the Indenture, and the Guarantees will constitute valid and legally binding
     obligations of each Guarantor, enforceable against each Guarantor in
     accordance with their terms and entitled to the benefits of the Indenture.

                                       4
<PAGE>
 
          (i)  Except as described in the Registration Statement and 
     Prospectus, there are no contracts, agreements or understandings between
     any Issuer and any natural person, corporation, partnership, trust, firm,
     association or other entity, whether acting in an individual, fiduciary or
     other capacity (a "Person"), granting such Person the right to require any
     Issuer to include any securities of such Issuer owned or to be owned by
     such Person in the securities registered pursuant to the Registration
     Statement.

          (j)  The Company and each of the Subsidiaries own or possess all 
     licenses or other rights to use the patents, patent rights, licenses,
     inventions, copyrights, know-how (including trade secrets and other
     unpatented and/or unpatentable proprietary or confidential information,
     systems or procedures), trademarks, service marks, trade names and
     proprietary knowledge (hereinafter collectively referred to as the
     "Proprietary Rights") presently employed by them in connection with the
     operation of their businesses, in each case where the failure to own,
     possess or have rights to use such Proprietary Rights, singly or in the
     aggregate, could be reasonably expected to have a Material Adverse Effect
     or could materially and adversely affect the consummation of this Agreement
     or the transactions contemplated hereby. Neither the Company nor any of the
     Subsidiaries (i) has received any notice of infringement of or conflict
     with asserted rights of others with respect to any Proprietary Rights, (ii)
     is aware of the assertion by others of any rights inconsistent with the
     Proprietary Rights and (iii) is aware of any facts which it believes would
     render any of its Proprietary Rights invalid, in each case for clauses (i),
     (ii), or (iii), which singly or in the aggregate, would result in any
     Material Adverse Effect or which might materially and adversely affect the
     consummation of this Agreement or the transactions contemplated hereby.

          (k)  The financial statements included or incorporated by reference
     in the Registration Statement and the Prospectus comply in all material
     respects with the requirements of the Act and the Rules and Regulations,
     present fairly the consolidated financial position of the Company and the
     Subsidiaries as of the dates indicated and the consolidated results of
     their operations for the periods specified and have been prepared in
     conformity with generally accepted accounting principles applied on a
     consistent basis. The financial information and statistical data set forth
     in the Prospectus under the captions "Summary Consolidated Historical and
     Pro Forma Financial Data," "Selected Consolidated Financial Data," and
     "Capitalization" are fairly stated in all material respects in relation to
     the consolidated financial statements of the Company and the Subsidiaries
     from which they have been derived.

          (l)  Since the respective dates as of which information is given in 
     the Registration Statement and the Prospectus, except as otherwise stated
     therein, (i) there has been no material adverse change, or any development
     involving a prospective material adverse change, in the condition,
     financial or otherwise, or in the assets, 

                                       5
<PAGE>
 
     earnings, affairs or business prospects of the Company and the
     Subsidiaries, taken as a whole, whether or not arising in the ordinary
     course of business, (ii) there have been no transactions entered into by
     the Company or any of the Subsidiaries, other than those in the ordinary
     course of business, which are material with respect to the Company and the
     Subsidiaries, taken as a whole, (iii) there has been no dividend or
     distribution of any kind declared, paid or made by the Company on its
     capital stock since March 31, 1994 (other than the dividends paid on April
     15 and July 15, 1994 to the holders of Company's Series B Convertible
     Preferred Stock), and (iv) there has not been any change in the capital
     stock of the Company or any of the Subsidiaries or, except as previously
     disclosed to you, any change in the long-term debt of the Company and the
     Subsidiaries, taken as a whole.

          (m)  Neither the Company nor any of the Subsidiaries is (i) in 
     violation of its charter, or (ii) in violation of any law, administrative
     regulation or rule, ordinance or order of any court or governmental agency,
     arbitration panel or other authority applicable to it or (iii) in default
     in the performance or observance of any obligation, agreement, covenant or
     condition contained in any contract, indenture, mortgage, loan agreement,
     note, lease or other instrument to which it is a party or by which it or
     its property may be bound, which violations or defaults, singly or in the
     aggregate, could have a Material Adverse Effect or which might materially
     and adversely affect the consummation of this Agreement or the transactions
     contemplated hereby; and the execution, delivery and performance of this
     Agreement by the Company and the Guarantors will not conflict with or
     constitute or result in a breach or violation of, or default under, or
     result in the creation or imposition of any lien, charge or encumbrance
     upon any property or assets of the Company or any of the Subsidiaries
     pursuant to, any contract, indenture, mortgage, loan agreement, note, lease
     or other agreement or instrument to which the Company or any of the
     Subsidiaries is a party or by which it or any of them may be bound, or to
     which any of the property or assets of the Company or any of the
     Subsidiaries is subject, which, singly or in the aggregate, could have a
     Material Adverse Effect or which might materially and adversely affect the
     consummation of this Agreement or the transactions contemplated hereby, nor
     will such action result in any violation of the provisions of the charter
     or by-laws of the Company or any of the Subsidiaries or any applicable law,
     any rule, regulation or order of any governmental agency or authority or
     any decree or order of any court having jurisdiction over the Company or
     any of the Subsidiaries or any of their properties, the violation of which,
     singly or in the aggregate, would have a Material Adverse Effect or which
     might materially and adversely affect the consummation of this Agreement or
     the transactions contemplated hereby.

          (n)  The Company and each of the Subsidiaries are each in compliance
     with all laws, ordinances and regulations applicable to its operations,
     properties (whether owned or leased) and its business as described in the
     Prospectus except where noncompliance with such laws, ordinances and
     regulations would not have a Material 

                                       6
<PAGE>
 
     Adverse Effect and would not materially and adversely affect the
     consummation of this Agreement or the transactions contemplated hereby.

          (o)  Except as described in the Registration Statement and the 
     Prospectus, neither the Company nor any of the Subsidiaries has violated or
     has received any notice that it has violated any environmental safety or
     similar law or regulation applicable to its business relating to the
     protection of human health and safety, the environment or hazardous or
     toxic substances or wastes, pollutants or contaminants ("Environmental
     Laws"), lacks any permits, licenses or other approvals required of them
     under applicable Environmental Laws to own, lease and operate their
     respective properties and to conduct their business in the manner described
     in the Prospectus, is violating any terms and conditions of any such
     permit, license or approval or has permitted to occur any event that
     allows, or after notice or lapse of time would allow, revocation,
     termination of any such permit, license or approval or results in any other
     impairment of their rights thereunder, which in each case might result,
     singly or in the aggregate, in a Material Adverse Effect or which might
     materially and adversely affect the consummation of this Agreement or the
     transactions contemplated hereby.

          (p)  Neither the Company nor any of the Subsidiaries has violated any
     federal, state or local law relating to discrimination in hiring, promotion
     or pay of employees prior to any applicable wage or hour laws, nor any
     provisions of the Employee Retirement Income Security Act of 1974 ("ERISA")
     or the rules and regulations promulgated thereunder, nor has the Company or
     any of the Subsidiaries engaged in any unfair labor practice, which in each
     case might result, singly or in the aggregate, in a Material Adverse Effect
     or which might materially and adversely affect the consummation of this
     Agreement or the transactions contemplated hereby. There is (i) no
     significant unfair labor practice complaint pending against the Company or
     any of the Subsidiaries or, to the best knowledge of the Company,
     threatened against any of them before the National Labor Relations Board or
     any state or local labor relations board, and no significant grievance or
     significant arbitration proceeding arising out of or under any collective
     bargaining agreement is so pending against the Company or any of the
     Subsidiaries or, to the best knowledge of the Company, threatened against
     any of them, (ii) no strike, labor dispute, slowdown or stoppage pending
     against the Company or any of its Subsidiaries or, to the best knowledge of
     the Company, threatened against the Company or any of the Subsidiaries and
     (iii) to the best knowledge of the Company, no union representation
     question existing with respect to the employees of the Company or any of
     the Subsidiaries and, to the best knowledge of the Company, no union
     organizing activities are taking place, except (with respect to any matter
     specified in clause (i), (ii), or (iii) above, singly or in the aggregate)
     such as would not have a Material Adverse Effect and would not materially
     and adversely affect the consummation of this Agreement or the transactions
     contemplated hereby.

                                       7
<PAGE>
 
          (q)  There is no action, suit or proceeding before or by any court or
     governmental agency or body, domestic or foreign, now pending, or, to the
     knowledge of the Company, threatened, against or affecting the Company or
     any of the Subsidiaries, which is required to be disclosed in the
     Registration Statement or the Prospectus (other than as disclosed therein
     or in any document incorporated by reference therein), which could be
     reasonably expected to result in any Material Adverse Effect or which might
     materially and adversely affect the consummation of this Agreement or the
     transactions contemplated hereby; and there are no contracts or documents
     of the Company or any of the Subsidiaries which are required to be
     described in the Prospectus or the Registration Statement or filed as
     exhibits to the Registration Statement by the Act or by the Rules and
     Regulations which have not been so described or so filed.

          (r)  No authorization, approval or consent of, or registration or
     qualification with, any Person or any court or governmental authority or
     agency is necessary in connection with the issuance or sale of the
     Securities or the consummation of the other transactions contemplated by
     this Agreement, except such as may be required under the Act or the Trust
     Indenture Act and have been or will be obtained prior to the Closing Date,
     and such as may be required under the Rules and Regulations or state
     securities laws or the by-laws and rules of the National Association of
     Securities Dealers, Inc. (the NASD ) in connection with the purchase and
     distribution by the Underwriters of the Securities.

          (s)  The Company and each of the Subsidiaries possess and are 
     operating in substantial compliance with the terms, provisions, and
     conditions of all licenses, certificates, authorities or permits issued by
     the appropriate governmental or regulatory agencies or authorities that are
     necessary to enable them to own, lease and operate their respective
     properties and to carry on their respective businesses as presently
     conducted and which are material to the Company and the Subsidiaries, taken
     as a whole, and neither the Company nor any of the Subsidiaries has
     received any notice of proceedings relating to the revocation or
     modification of any such license, certificate, authority or permit which,
     singly or in the aggregate, would be expected to result in a Material
     Adverse Effect or which might materially and adversely affect the
     consummation of this Agreement or the transactions contemplated hereby.

          (t)  The Company and each of the Subsidiaries maintain a system of
     internal accounting controls sufficient to provide reasonable assurances
     that (i) all material transactions are executed in accordance with
     management's general or specific authorization; (ii) transactions are
     recorded as necessary to permit preparation of financial statements in
     conformity with generally accepted accounting principles appropriate in the
     circumstances to reflect in all material respects the substance of events
     and transactions that should be included and to maintain accountability for

                                       8
<PAGE>
 
     assets; (iii) irregularities or material errors do not occur or would be
     detected within a timely period by employees in the normal course of
     performing their assigned functions; and (iv) the recorded accountability
     for assets is compared with the existing assets at reasonable intervals and
     appropriate action is taken with respect to any differences.

          (u)  All tax returns required to be filed by the Company or any of the
     Subsidiaries in any jurisdiction have been filed, other than those 
     filings being contested in good faith, and all material taxes, including
     withholding taxes, penalties and interest, assessments, fees and other
     charges due or claimed to be due from such entities have been paid, other
     than those being contested in good faith and for which adequate reserves
     have been provided or those currently payable without penalty or interest.

          (v)  Neither the Company nor any of the Subsidiaries is (a) an 
     "investment company" or a company "controlled" by an investment company
     within the meaning of the Investment Company Act of 1940, as amended, or
     (b) a "holding company" or a "subsidiary company" of a holding company, or
     an "affiliate" thereof within the meaning of the Public Utility Holding
     Company Act of 1935, as amended.

          (w)  The Company has not (i) taken, directly or indirectly, any action
     designed to cause or to result in, or that has constituted or which might
     reasonably be expected to constitute, the stabilization or manipulation of
     the price of any security of the Company to facilitate the sale or resale
     of the Securities or (ii) since the initial filing of the Registration
     Statement (A) sold, bid for, purchased, or paid anyone any compensation for
     soliciting purchases of, the Securities or (B) paid or agreed to pay to any
     Person any compensation for soliciting another to purchase any other
     securities of the Company.

          (x)  The Company and each Subsidiary maintain insurance covering their
     properties, operations, personnel and businesses. Such insurance insures
     against such losses and risks as are adequate in accordance with customary
     industry practice to protect the Company and its Subsidiaries and their
     businesses. Neither the Company nor any Subsidiary has received notice from
     any insurer or agent of such insurer that substantial capital improvements
     or other expenditures will have to be made in order to continue such
     insurance. All such insurance is outstanding and duly in force on the date
     hereof and will be outstanding and duly in force on the Closing Date.

          (y)  Each certificate signed by any officer of an Issuer and 
     delivered to the Underwriters or counsel for the Underwriters shall be
     deemed to be a joint and several representation and warranty by the Issuers
     to each Underwriter as to the matters covered thereby.

                                       9
<PAGE>
 
          (z)  Except as disclosed in the Prospectus, there are no contracts,
     agreements or understandings between the Company and any Person that would
     give rise to a valid claim against the Company or any Underwriter for a
     brokerage commission, finder's fee or other like payment.

     3.   Purchase, Sale and Delivery of Securities.  On the basis of the 
representations, warranties and agreements herein contained, but subject to the
terms and conditions herein set forth, the Issuers agree to issue and sell to
the Underwriters, and the Underwriters agree, severally and not jointly, to
purchase from the Issuers, at a purchase price of 96.5% of the principal amount
thereof, the respective principal amounts of Securities set forth opposite the
names of the Underwriters on Schedule A hereto.

     The Issuers will deliver the Securities to you for the accounts of the 
Underwriters, against payment of the purchase price by certified or official
bank check or checks in New York Clearing House (next day) funds or by other
next day funds drawn or payable to the order of the Company at the office of
Davis, Malm & D'Agostine, P.C., at 10:00 A.M., Boston time, on August 4, 1994 or
at such other time not later than seven full business days thereafter as you and
the Issuers determine, such time being herein referred to as the "Closing Date".
The Securities so to be delivered will be in definitive fully registered form,
in such denominations and registered in such names as you request and will be
made available for checking and packaging at the office of The Depository Trust
Company at least 24 hours prior to the Closing Date.

     4.   Offering by Underwriters.  It is understood that the several 
Underwriters propose to offer the Securities for sale to the public as set forth
in the Prospectus.

     5.   Certain Agreements of the Issuers.  The Issuers agree with the several
Underwriters that:

          (a)  If the Effective Time is prior to the execution and delivery of
     this Agreement, the Issuers will file the Prospectus with the Commission
     pursuant to and in accordance with subparagraph (1) (or, if applicable and
     if consented to by you, subparagraph (4)) of Rule 424(b) not later than the
     earlier of (A) the second business day following the execution and delivery
     of this Agreement or (B) the fifth business day after the Effective Date.
     The Issuers will advise you promptly of any such filing pursuant to Rule
     424(b).

          (b)  The Issuers will advise you promptly of any proposal to amend or
     supplement the registration statement as filed or the related prospectus or
     the Registration Statement or the Prospectus and will not effect such
     amendment or supplementation without your consent; and the Issuers will
     also advise you promptly of the effectiveness of the Registration Statement
     (if the Effective Time is subsequent to the execution and delivery of this
     Agreement) and of any amendment or 

                                      10
<PAGE>
 
     supplementation of the Registration Statement or the Prospectus and of the
     institution by the Commission of any stop order proceedings in respect of
     the Registration Statement and will use their best efforts to prevent the
     issuance of any such stop order and to obtain as soon as possible its
     lifting, if issued.

          (c)  If, at any time when a prospectus relating to the Securities is
     required to be delivered under the Act, any event occurs as a result of
     which the Prospectus as then amended or supplemented would include an
     untrue statement of a material fact or omit to state any material fact
     necessary to make the statements therein, in the light of the circumstances
     under which they were made, not misleading, or if it is necessary at any
     time to amend the Prospectus to comply with the Act, the Issuers promptly
     will prepare and file with the Commission an amendment or supplement which
     will correct such statement or omission or an amendment which will effect
     such compliance. Neither your consent to, nor the Underwriters' delivery
     of, any such amendment or supplement shall constitute a waiver of any of
     the conditions set forth in Section 6.

          (d)  As soon as practicable, but not later than the Availability 
     Date (as defined below), the Issuers will make generally available to their
     security holders an earnings statement covering a period of at least 12
     months beginning after the Effective Date which will satisfy the provisions
     of Section 11(a) of the Act. For the purpose of the preceding sentence,
     "Availability Date" means the 45th day after the end of the fourth fiscal
     quarter following the fiscal quarter that includes the Effective Date,
     except that, if such fourth fiscal quarter is the last quarter of the
     Issuers' fiscal year, "Availability Date" means the 90th day after the end
     of such fourth fiscal quarter.

          (e)  The Issuers will furnish to you copies of the Registration 
     Statement, three (3) of which will be signed and will include all exhibits,
     each related preliminary prospectus, the Prospectus and all amendments and
     supplements to such documents, in each case as soon as available and in
     such quantities as you request.

          (f)  The Issuers will arrange for the qualification of the 
     Securities for sale and the determination of their eligibility for
     investment under the state securities or Blue Sky laws of such
     jurisdictions as you designate and will continue such qualifications in
     effect so long as required for the distribution.

          (g)  During the period of five years hereafter, the Company will 
     furnish to you, as soon as practicable after the end of each fiscal year, a
     copy of its annual report to stockholders for such year; and the Issuers
     will furnish to you (i) as soon as available, a copy of each report or
     definitive proxy statement of the Issuers filed with the Commission under
     the Securities Exchange Act of 1934 or mailed to stockholders, and (ii)
     from time to time, such other information concerning the Issuers as you may
     reasonably request.

                                      11
<PAGE>
 
          (h)  Whether or not the transactions contemplated hereby are 
     consummated or this Agreement is terminated, the Issuers will pay and be
     responsible for all costs, expenses, fees and taxes in accordance with or
     incident to (i) the printing, processing, filing, distribution and delivery
     under the Act of the Registration Statement, each preliminary prospectus,
     the Prospectus and all amendments or supplements thereto, (ii) the
     printing, processing, execution, distribution and delivery of this
     Agreement, the Indenture, any memoranda describing state securities or Blue
     Sky laws and all other agreements, memoranda, correspondence and other
     documents printed, distributed and delivered in connection with the
     offering of the Securities, (iii) the registration with the Commission and
     the issuance and delivery of the Securities, (iv) the registration or
     qualification of the Securities for offer and sale under the securities or
     Blue Sky laws of the jurisdictions referred to in paragraph (f) above
     (including, in each case the fees and disbursements of counsel relating to
     such registration or qualification and memoranda relating thereto and any
     filing fees in connection therewith, (v) furnishing such copies of the
     Registration Statement, Prospectus and preliminary prospectus, and all
     amendments and supplements to any of them, as may be reasonably requested
     by you, (vi) filing, registration and clearance with the NASD in connection
     with the offering of the Securities (including the fees and disbursements
     of counsel relating thereto), (vii) the listing of the Securities, if any,
     on a stock exchange or automated quotation system, (viii) the rating or
     tentative rating of the Securities by investment rating agencies, and (ix)
     the performance by the Issuers of their other obligations under this
     Agreement, including (without limitation) the fees of the Trustee and the
     Trustee's counsel, the cost of their personnel and other internal costs,
     the cost of printing and engraving the certificates representing the
     Securities, and all expenses and taxes incident to the sale and delivery of
     the Securities to you.

          (i)  The Company will use the proceeds from the sale of the 
     Securities in the manner described in the Prospectus under the caption "Use
     of Proceeds."

          (j)  The Issuers will not voluntarily claim, and will actively 
     resist any attempts to claim, the benefit of any usury laws against the
     holders of the Securities.

          (k)  The Issuers will use their best efforts to do and perform all 
     things required to be done and performed under this Agreement by them prior
     to or after the Closing Date and to satisfy all conditions precedent on
     their part to the delivery of the Securities.

          (l)  The Issuers will notify you promptly of any material change 
     affecting any of its respective representations, warranties, agreements or
     indemnities herein at any time prior to payment being made to the Issuers
     on the Closing Date and the Issuers will take such steps as you may
     reasonably request to remedy and/or publicize the same.

                                      12
<PAGE>
 
     6.   Conditions of the Obligations of the Underwriters.  The obligations 
of the several Underwriters to purchase and pay for the Securities will be
subject to the accuracy of the representations and warranties on the part of the
Issuers herein, to the accuracy of the statements of Issuers' officers made
pursuant to the provisions hereof, to the performance by the Issuers of their
obligations hereunder and to the following additional conditions precedent:

          (a)  You shall have received a letter, dated the date of delivery 
     thereof (which, if the Effective Time is prior to the execution and
     delivery of this Agreement, shall be on or prior to the date of this
     Agreement, or, if the Effective Time is subsequent to the execution and
     delivery of this Agreement, shall be prior to the filing of the amendment
     or post-effective amendment to the registration statement to be filed
     shortly prior to the Effective Time), of Coopers & Lybrand confirming that
     they are independent public accountants within the meaning of the Act and
     the applicable published Rules and Regulations thereunder and stating in
     effect that:

               (i)     in their opinion the financial statements and schedules, 
          examined by them and included in the Registration Statement comply in
          form in all material respects with the applicable accounting
          requirements of the Act and the related published Rules and
          Regulations;

               (ii)    they have made a review of the unaudited financial 
          statements included in the Registration Statement in accordance with
          standards established by the American Institute of Certified Public
          Accountants;

               (iii)   on the basis of the review referred to in clause (ii) 
          above, a reading of the latest available interim financial statements
          of the Company, inquiries of officials of the Company who have
          responsibility for financial and accounting matters and other
          specified procedures, nothing came to their attention that caused them
          to believe that:

                    (A)   the unaudited financial statements included in the
               Registration Statement do not comply in form in all material 
               respects with the applicable accounting requirements of the Act
               and the related published Rules and Regulations or are not in
               conformity with generally accepted accounting principles applied
               on a basis substantially consistent with that of the audited
               financial statements in the Registration Statement;
               
                    (B)  at the date of the latest available balance sheet 
               read by such accountants, or at a subsequent specified date not
               more than five days prior to the date of this Agreement, there
               was any change in the capital stock or any material increase in
               short-term indebtedness or 

                                      13
<PAGE>
 
               long-term debt of the Company and its Subsidiaries consolidated
               or, at the date of the latest available balance sheet read by
               such accountants, there was any decrease in consolidated net
               current assets or net assets, as compared with amounts shown on
               the latest balance sheet included in the Prospectus; or

                    (C)  for the period from the closing date of the latest 
               income statement included in the Prospectus to the closing date
               of the latest available income statement read by such accountants
               there were any decreases, as compared with the corresponding
               period of the previous year and with the period of corresponding
               length ended the date of the latest income statement included in
               the Prospectus, in consolidated revenues or income from
               operations, or in the ratio of earnings to fixed charges;

          except in all cases set forth in clauses (B) and (C) above for 
          changes, increases or decreases which the Prospectus discloses have
          occurred or may occur or which are described in such letter; and

               (iv) they have compared specified dollar amounts (or percentages
          derived from such dollar amounts) and other financial information
          contained in the Registration Statement (in each case to the extent
          that such dollar amounts, percentages and other financial information
          are derived from the general accounting records of the Company and its
          Subsidiaries subject to the internal controls of the Company's
          accounting system or are derived directly from such records by
          analysis or computation) with the results obtained from inquiries, a
          reading of such general accounting records and other procedures
          specified in such letter and have found such dollar amounts,
          percentages and other financial information to be in agreement with
          such results, except as otherwise specified in such letter.

     For purposes of this subsection, if the Effective Time is subsequent to 
     the execution and delivery of this Agreement, "Registration Statement"
     shall mean the registration statement as proposed to be amended by the
     amendment or post-effective amendment to be filed shortly prior to the
     Effective Time, and "Prospectus" shall mean the prospectus included in the
     Registration Statement. All financial statements and schedules included in
     material incorporated by reference into the Prospectus shall be deemed
     included in the Registration Statement for purposes of this subsection.

          (b)  If the Effective Time is not prior to the execution and 
     delivery of this Agreement, the Effective Time shall have occurred not
     later than 10:00 P.M., Boston time, on the date of this Agreement or such
     later date as shall have been consented to by you. If the Effective Time is
     prior to the execution and delivery of this 

                                      14
<PAGE>
 
     Agreement, the Prospectus shall have been filed with the Commission in
     accordance with the Rules and Regulations and Section 5(a) of this
     Agreement. Prior to the Closing Date, no stop order suspending the
     effectiveness of the Registration Statement shall have been issued and no
     proceedings for that purpose shall have been instituted or, to the
     knowledge of the Issuers or you, shall be contemplated by the Commission.

          (c)  Subsequent to the execution and delivery of this Agreement, 
     there shall not have occurred: (i) any change, or any development involving
     a prospective change, in or affecting particularly the business or
     properties of the Company or its Subsidiaries which, in your judgment,
     materially impairs the investment quality of the Securities; (ii) any
     downgrading in the rating or tentative rating of any debt securities of the
     Company by any "nationally recognized statistical rating organization" (as
     defined for purposes of Rule 436(g) under the Act), or any public
     announcement that any such organization has under surveillance or review
     its rating of any debt securities of the Company (other than an
     announcement with positive implications of a possible upgrading, and no
     implication of a possible downgrading, of such rating); (iii) any
     suspension or limitation of trading in securities generally on the New York
     Stock Exchange, or any setting of minimum prices for trading on such
     exchange, or any suspension of trading of any securities of the Company on
     any exchange or in the over-the-counter market; (iv) any banking moratorium
     declared by Federal or New York authorities; or (v) any outbreak or
     escalation of major hostilities in which the United States is involved, any
     declaration of war by Congress or any other substantial national or
     international calamity or emergency if, in the judgment of a majority in
     interest of the Underwriters including you, the effect of any such
     outbreak, escalation, declaration, calamity or emergency makes it
     impractical or inadvisable to proceed with completion of the sale of and
     payment for the Securities.

          (d)  You shall have received an opinion, dated the Closing Date, of 
     Davis, Malm & D'Agostine, P.C., counsel for the Issuers, to the effect
     that:
              
                 (i)   The Company has been duly incorporated and is an existing
          corporation in good standing under the laws of The Commonwealth of
          Massachusetts with corporate power and authority to own its properties
          and conduct its business as described in the Prospectus; and the
          Company is duly qualified to do business as a foreign corporation in
          good standing in all other jurisdictions in which it owns or leases
          substantial properties or in which the conduct of its business
          requires such qualification, except where failure to be so qualified
          or to be in good standing would not have a Material Adverse Effect and
          would not materially and adversely affect the consummation of this
          Agreement or the transactions contemplated hereby;      

               (ii)    Each of the Subsidiaries has been duly incorporated and
          is an existing corporation in good standing under the laws of its
          jurisdiction of 

                                      15
<PAGE>
 
          incorporation, with corporate power and authority to own its
          properties and conduct its business as described in the Prospectus;
          and each of the Subsidiaries is duly qualified to do business as a
          foreign corporation in good standing in each jurisdiction in which
          such qualification is required, except where failure to be so
          qualified or be in good standing would not have a Material Adverse
          Effect and would not materially and adversely affect the consummation
          of this Agreement or the transactions contemplated hereby. All
          outstanding shares of the capital stock of the Subsidiaries which are
          Guarantors have been duly authorized and validly issued, are fully
          paid and nonassessable and, except for the capital stock of CHTC, are
          wholly owned by the Company free and clear of any mortgage, pledge,
          lien, encumbrance or claims other than any mortgage, pledge, lien,
          encumbrance or claim which secures indebtedness described in the
          Registration Statement or Prospectus. The issued and outstanding
          capital stock of CHTC is currently owned 99% by the Company and 1% by
          the president of CHTC;

               (iii)   The Company has full power and authority to execute, 
          deliver and perform this Agreement and to authorize, issue, sell and
          deliver the Notes as contemplated by this Agreement. Each Guarantor
          has full power and authority to execute, deliver and perform this
          Agreement and to authorize, issue, sell and deliver its Guarantees as
          contemplated by this Agreement;

                (iv)   Each of this Agreement, the Notes and the Indenture 
          have been duly authorized, executed and delivered by the Company, and
          each of this Agreement, the Guarantees and the Indenture have been
          duly authorized, executed and delivered by each Guarantor;

                 (v)   The execution, delivery and performance of the
          Indenture and this Agreement and the issuance and sale of the
          Securities and compliance with the terms and provisions thereof will
          not result in a breach or violation of any of the terms and provisions
          of, or constitute a default under, any statute, any material rule,
          regulation or order of any governmental agency or body or any court
          having jurisdiction over any Issuer or any of their properties, or any
          agreement or instrument known to such counsel to which any Issuer is a
          party or by which any Issuer is bound or to which any of the
          properties of any Issuer is subject, or the charter or by-laws of any
          Issuer;

                (vi)   When authenticated in accordance with the terms of this
          Agreement, (x) the Notes will constitute valid and legally binding 
          obligations of the Company, enforceable in accordance with their terms
          and entitled to the benefits of the Indenture, subject to bankruptcy,
          insolvency, fraudulent transfer, reorganization, moratorium and
          similar laws of general applicability relating to or affecting
          creditors' rights and to general principles of equity, and 

                                      16
<PAGE>
 
          (y) the Guarantees will constitute valid and legally binding
          obligations of each respective Guarantor, enforceable in accordance
          with their terms and entitled to the benefits of the Indenture,
          subject to bankruptcy, insolvency, fraudulent transfer,
          reorganization, moratorium and similar laws of general applicability
          relating to or affecting creditors' rights and to general principles
          of equity;

               (vii)   This Agreement constitutes a valid and legally binding
          obligation of each Issuer, enforceable against each Issuer in
          accordance with its terms except as rights to indemnity or
          contribution hereunder may be limited by applicable federal or state
          securities laws;

               (viii)  The Indenture, assuming due authorization, execution and
          delivery thereof by the Trustee, constitutes a valid and legally
          binding obligation of each Issuer, enforceable against each Issuer in
          accordance with its terms, subject to bankruptcy, insolvency,
          fraudulent transfer, reorganization, moratorium and similar laws of
          general applicability relating to or affecting creditors' rights and
          to general principles of equity;

                (ix)   The Securities and the Indenture conform in all 
          material respects to the descriptions thereof in the Prospectus;

                 (x)   Except as described in the Prospectus, there are no 
          contracts, agreements or understandings known to such counsel between
          the Company and any Person granting such Person the right to require
          the Company to include any securities of the Company owned or to be
          owned by such Person in the securities registered pursuant to the
          Registration Statement;

                (xi)   To the knowledge of such counsel, (A) other than as 
          described in the Prospectus (including materials incorporated therein
          by reference), there are no legal or governmental proceedings pending
          or threatened against any Issuer, or to which any Issuer, or any of
          its property or assets, is subject, which are required to be described
          in the Registration Statement or Prospectus and (B) there are no
          agreements, contracts, indentures, leases or other instruments that
          are required to be described in the Registration Statement or the
          Prospectus or to be filed as an exhibit to the Registration Statement
          that are not described or filed as required, as the case may be;

               (xii)   No consent, approval, authorization or order of, or 
          filing with, any governmental agency or body or any court is required
          for the consummation of the transactions contemplated by this
          Agreement in connection with the issuance or sale of the Securities by
          the Issuers, except such as have been obtained and made under the Act
          and the Trust Indenture 

                                      17
<PAGE>
 
          Act and such as may be required under state securities laws or the
          rules of the NASD;

               (xiii)  The Registration Statement was declared effective under
          the Act as of the date and time specified in such opinion, the
          Prospectus either was filed with the Commission pursuant to the
          subparagraph of Rule 424(b) specified in such opinion on the date
          specified therein or was included in the Registration Statement (as
          the case may be), and, to the knowledge of such counsel, no stop order
          suspending the effectiveness of the Registration Statement or any part
          thereof has been issued and no proceedings for that purpose have been
          instituted or are pending or contemplated under the Act, and the
          Registration Statement and the Prospectus, and each amendment or
          supplement thereto, as of their respective effective or issue dates,
          complied as to form in all material respects with the requirements of
          the Act, the Trust Indenture Act and the Rules and Regulations; such
          counsel have no reason to believe that either the Registration
          Statement or the Prospectus, or any such amendment or supplement, as
          of such respective dates and as of the Closing Date, contained any
          untrue statement of a material fact or omitted to state any material
          fact required to be stated therein or necessary to make the statements
          therein not misleading; the descriptions in the Registration Statement
          and Prospectus of statutes, legal and governmental proceedings and
          contracts and other documents are accurate and fairly present the
          information required to be shown; and such counsel do not know of any
          legal or governmental proceedings required to be described in the
          Registration Statement or Prospectus which are not described as
          required or of any contracts or documents of a character required to
          be described in the Registration Statement or Prospectus or to be
          filed as exhibits to the Registration Statement which are not
          described and filed as required; it being understood that such counsel
          need express no opinion as to the financial statements or other
          financial data contained in the Registration Statement or the
          Prospectus;

               (xiv)   Neither the Company nor any of the Subsidiaries is (a) an
          "investment company" or a company "controlled" by an investment 
          company within the meaning of the Investment Company Act of 1940, as
          amended, or (b) a "holding company" or a "subsidiary company" of a
          holding company, or an "affiliate" thereof within the meaning of the
          Public Utility Holding Company Act of 1935, as amended; and

                (xv)   The  Indenture has been duly qualified under the Trust 
          Indenture Act.

          (e)  You shall have received from Goodwin, Procter & Hoar, counsel for
     the Underwriters, such opinion or opinions, dated the Closing Date, with
     respect to 
     
                                      18
<PAGE>
 
     the incorporation of the Issuers, the validity of the Securities, the
     Registration Statement, the Prospectus and other related matters as you may
     require, and the Issuers shall have furnished to such counsel such
     documents as they may request for the purpose of enabling them to pass upon
     such matters and in order to evidence the accuracy, completeness or
     satisfaction in all material respects of any of the representations,
     warranties or conditions herein contained.

          (f)  You shall have received a certificate, dated the Closing Date, 
     of the President or any Vice-President and a principal financial or
     accounting officer of the Company in which such officers, to the best of
     their knowledge after reasonable investigation, shall state that the
     representations and warranties of the Issuers in this Agreement are true
     and correct, that the Issuers have complied with all agreements and
     satisfied all conditions on their part to be performed or satisfied
     hereunder at or prior to the Closing Date, that no stop order suspending
     the effectiveness of the Registration Statement had been issued and no
     proceedings for that purpose have been instituted or are contemplated by
     the Commission and that, subsequent to the date of the most recent
     financial statements in the Prospectus, there has been no material adverse
     change in the financial position or results of operation of the Company and
     its Subsidiaries except as set forth in or contemplated by the Prospectus
     or as described in such certificate.

          (g)  You shall have received a letter, dated the Closing Date, of 
     Coopers & Lybrand which meets the requirements of subsection (a) of this
     Section, except that the specified date referred to in such subsection will
     be a date not more than five days prior to the Closing Date for the
     purposes of this subsection.

The Issuers will furnish you with such conformed copies of such opinions, 
certificates, letters and documents as you reasonably request.

     7.   Indemnification and Contribution.

          (a)  The Issuers, jointly and severally, will indemnify and hold 
     harmless each Underwriter against any losses, claims, damages or
     liabilities, joint or several, to which such Underwriter may become
     subject, under the Act or otherwise, insofar as such losses, claims,
     damages or liabilities (or actions in respect thereof) arise out of or are
     based upon any untrue statement or alleged untrue statement of any material
     fact contained in the Registration Statement, the Prospectus, or any
     amendment or supplement thereto, or any related preliminary prospectus, or
     arise out of or are based upon the omission or alleged omission to state
     therein a material fact required to be stated therein or necessary to make
     the statements therein not misleading, and will reimburse each Underwriter
     for any legal or other expenses reasonably incurred by such Underwriter in
     connection with investigating or defending any such loss, claim, damage,
     liability or action as such expenses are incurred; provided, however, that
     (i) 

                                      19
<PAGE>
 
     the Issuers will not be liable 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 in or omission or alleged
     omission from any of such documents in reliance upon and in conformity with
     written information furnished to the Issuers by any Underwriter
     specifically for use therein; and (ii) the Company shall not be liable for
     the costs and expenses of more than one law firm representing all of the
     Underwriters.

          (b)  Each Underwriter, severally and not jointly, will indemnify and
     hold harmless the Issuers against any losses, claims, damages or
     liabilities to which the Issuers may become subject, under the Act or
     otherwise, insofar as such losses, claims, damages or liabilities (or
     actions in respect thereof) arise out of or are based upon any untrue
     statement or alleged untrue statement of any material fact contained in the
     Registration Statement, the Prospectus, or any amendment or supplement
     thereto, or any related preliminary prospectus, or arise out of or are
     based upon the omission or the alleged omission to state therein a material
     fact required to be stated therein or necessary to make the statements
     therein not misleading, in each case to the extent, but only to the extent,
     that such untrue statement or alleged untrue statement or omission or
     alleged omission was made in reliance upon and in conformity with written
     information furnished to the Issuers by such Underwriter specifically for
     use therein, and will reimburse any legal or other expenses reasonably
     incurred by the Issuers in connection with investigating or defending any
     such loss, claim, damage, liability or action as such expenses are
     incurred.

          (c)  Promptly after receipt by an indemnified party under this 
     Section of notice of the commencement of any action, such indemnified party
     will, if a claim in respect thereof is to be made against the indemnifying
     party under subsection (a) or (b) above, notify the indemnifying party of
     the commencement thereof; but the omission so to notify the indemnifying
     party will not relieve it from any liability which it may have to any
     indemnified party otherwise than under Subsection (a) or (b) above. In case
     any such action is brought against any indemnified party and it notifies
     the indemnifying party of the commencement thereof, the indemnifying party
     will be entitled to participate therein and, to the extent that it may
     wish, jointly with any other indemnifying party similarly notified, to
     assume the defense thereof, with counsel satisfactory to such indemnified
     party (who shall not, except with the consent of the indemnified party, be
     counsel to the indemnifying party), and after notice from the indemnifying
     party to such indemnified party of its election so to assume the defense
     thereof, the indemnifying party will not be liable to such indemnified
     party under this Section for any legal or other expenses subsequently
     incurred by such indemnified party in connection with the defense thereof
     other than reasonable costs of investigation. No indemnifying party shall,
     without the prior written consent of the indemnified party, effect any
     settlement of any pending or threatened action in respect to which any
     indemnified party is or could have been a party and indemnity could 
     
                                      20
<PAGE>
 
     have been sought hereunder by such indemnified party unless such settlement
     includes an unconditional release of such indemnified party from all
     liability on any claims that are the subject matter of such action.

          (d)  If the indemnification provided for in this Section is 
     unavailable or insufficient to hold harmless an indemnified party under
     subsection (a) or (b) above, then each indemnifying party shall contribute
     to the amount paid or payable by such indemnified party as a result of the
     losses, claims, damages or liabilities referred to in subsection (a) or (b)
     above (i) in such proportion as is appropriate to reflect the relative
     benefits received by the Issuers on the one hand and the Underwriters on
     the other from the offering of the Securities or (ii) if the allocation
     provided by clause (i) above is not permitted by applicable law, in such
     proportion as is appropriate to reflect not only the relative benefits
     referred to in clause (i) above but also the relative fault of the Issuers
     on the one hand and the Underwriters on the other in connection with the
     statements or omissions which resulted in such losses, claims, damages or
     liabilities as well as any other relevant equitable considerations. The
     relative benefits received by the Issuers on the one hand and the
     Underwriters on the other shall be deemed to be in the same proportion as
     the total net proceeds from the offering (before deducting expenses)
     received by the Issuers bear to the total underwriting discounts and
     commissions received by the Underwriters. The relative fault shall be
     determined by reference to, among other things, whether the untrue or
     alleged untrue statement of a material fact or the omission or alleged
     omission to state a material fact relates to information supplied by the
     Issuers or the Underwriters and the parties' relative intent, knowledge,
     access to information and opportunity to correct or prevent such untrue
     statement or omission. The amount paid by an indemnified party as a result
     of the losses, claims, damages or liabilities referred to in the first
     sentence of this subsection (d) shall be deemed to include any legal or
     other expenses reasonably incurred by such indemnified party in connection
     with investigating or defending any action or claim which is the subject of
     this subsection (d). Notwithstanding the provisions of this subsection (d),
     no Underwriter shall be required to contribute any amount in excess of the
     amount by which the total price at which the Securities underwritten by it
     and distributed to the public were offered to the public exceeds the amount
     of any damages which such Underwriter has otherwise been required to pay by
     reason of such untrue or alleged untrue statement or omission or alleged
     omission. No Person guilty of fraudulent misrepresentation (within the
     meaning of Section 11(f) of the Act) shall be entitled to contribution from
     any Person who was not guilty of such fraudulent misrepresentation. The
     Underwriters' obligations in this subsection (d) to contribute are several
     in proportion to their respective underwriting obligations and not joint.

          (e)  The obligations of the Issuers under this Section shall be in 
     addition to any liability which the Issuers may otherwise have and shall
     extend, upon the same terms and conditions, to each person, if any, who
     controls any Underwriter within the 

                                      21
<PAGE>
 
     meaning of the Act; and the obligations of the Underwriters under this
     Section shall be in addition to any liability which the respective
     Underwriters may otherwise have and shall extend, upon the same terms and
     conditions, to each director of the Issuers, to each officer of the Issuers
     who has signed the Registration Statement and to each Person, if any, who
     controls the Issuers within the meaning of the Act.

     8.   Default of Underwriters.  If any Underwriter defaults in its 
     obligations to purchase Securities hereunder and the aggregate principal
amount of the Securities that such defaulting Underwriter agreed but failed to
purchase does not exceed 10% of the total principal amount of the Securities,
you may make arrangements satisfactory to the Issuers for the purchase of such
Securities by other Persons, including the other Underwriter, but if no such
arrangements are made by the Closing Date, the nondefaulting Underwriter shall
be obligated to purchase the Securities that such defaulting Underwriter agreed
but failed to purchase. If any Underwriter so defaults and the aggregate
principal amount of the Securities with respect to which such default occurs
exceeds 10% of the total principal amount of the Securities and arrangements
satisfactory to you and the Issuers for the purchase of such Securities by other
Persons are not made within 36 hours after such default, this Agreement will
terminate without liability on the part of any nondefaulting Underwriter or the
Issuers, except as provided in Section 9. As used in this Agreement, the term
"Underwriter" includes any Person substituted for an Underwriter under this
Section. Nothing herein will relieve a defaulting Underwriter from liability for
its default.

     9.   Survival of Certain Representations and Obligations.  The respective
indemnities, agreements, representations, warranties and other statements of the
Issuers or their officers and of the several Underwriters set forth in or made
pursuant to this Agreement will remain in full force and effect, regardless of
any investigation, or statement as to the results thereof, made by or on behalf
of any Underwriter, the Issuers or any of their respective representatives,
officers or directors or any controlling person, and will survive delivery of
and payment for the Securities. If this Agreement is terminated pursuant to
Section 8 or if for any reason the purchase of the Securities by the
Underwriters is not consummated, the Issuers shall remain responsible for the
expenses to be paid or reimbursed by it pursuant to Section 5 and the respective
obligations of the Issuers and the Underwriters pursuant to Section 7 shall
remain in effect. If the purchase of the Securities by the Underwriters is not
consummated for any reason other than solely because of the termination of this
Agreement pursuant to Section 8 or the occurrence of any event specified in
clause (iii), (iv) or (v) of Section 6(c), the Issuers will reimburse the
Underwriters for all out-of-pocket expenses (including fees and disbursements of
counsel) reasonably incurred by them in connection with the offering of the
Securities.

     10.  Notices.  All communications hereunder will be in writing and, if 
sent to the Underwriters, will be mailed, delivered or telegraphed and confirmed
to you c/o CS First Boston Corporation, Park Avenue Plaza, New York, N.Y. 10055,
Attention: Investment Banking Department Transactions Group, with a copy to
Goodwin, Procter & Hoar, 

                                      22
<PAGE>
 
Exchange Place, Boston, Massachusetts 02109, Attention: Ettore A. Santucci,
P.C., or, if sent to the Issuers, will be mailed, delivered or telegraphed and
confirmed to it at 1200 Crown Colony Drive, Quincy, Massachusetts 02169,
Attention; Mr. James A. Pitts, with a copy to Davis, Malm & D'Agostine, P.C.,
One Boston Place, Boston, Massachusetts 02108, Attention: C. Michael Malm, Esq.;
provided, however, that any notice to an Underwriter pursuant to Section 7 will
be mailed, delivered or telegraphed and confirmed to such Underwriter.

     11.  Successors.  This Agreement will inure to the benefit of and be 
binding upon the parties hereto and their respective successors and the officers
and directors and controlling persons referred to in Section 7, and no other
Person will have any right or obligation hereunder.

     12.  Representation of Underwriters.  You will act for the several 
Underwriters in connection with this financing, and any action under this
Agreement taken by you jointly or by CS First Boston Corporation will be binding
upon all of the Underwriters.

     13.  Counterparts.  This Agreement may be executed in any number of
counterparts, each of which shall be deemed to be an original, but all such
counterparts shall together constitute one and the same Agreement.

     14.  Applicable Law.  This Agreement shall be governed by, and construed in
accordance with, the laws of the state of New York, without regard to the
conflict of law principles thereto.
                                      23
<PAGE>
 
      If the foregoing is in accordance with your understanding of our 
agreement, kindly sign and return to us one of the counterparts hereof,
whereupon it will become a binding agreement between the Issuers and the several
Underwriters in accordance with its terms.

                                   Very truly yours,

                                   CLEAN HARBORS, INC.

                                   By
                                     ---------------------------------------   
                                     James A. Pitts, Executive Vice
                                     President of Finance and Administration
                                     and Chief Financial Officer 


                                   CLEAN HARBORS ENVIRONMENTAL
                                     SERVICES, INC.
                                   CLEAN HARBORS OF NATICK, INC.
                                   CLEAN HARBORS OF BRAINTREE, INC.
                                   CLEAN HARBORS OF CHICAGO, INC.
                                   CLEAN HARBORS OF CLEVELAND, INC.
                                   CLEAN HARBORS OF BALTIMORE, INC.
                                   CLEAN HARBORS OF CONNECTICUT,
                                     INC.
                                   CLEAN HARBORS KINGSTON FACILITY
                                     CORPORATION
                                   MURPHY'S WASTE OIL SERVICE, INC.
                                   CLEAN HARBORS TECHNOLOGY
                                     CORPORATION
                                   MR. FRANK, INC.
                                   SPRING GROVE RESOURCE RECOVERY,
                                     INC.


                                   By:                                        
                                      --------------------------------------  
                                      James A. Pitts
                                      Vice President

                                      24
<PAGE>
 
The foregoing Underwriting Agreement is hereby
  confirmed and accepted as of the date first above
  written.

CS FIRST BOSTON CORPORATION



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


ALEX. BROWN & SONS INCORPORATED



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

                                      25
<PAGE>
 
                                  SCHEDULE A


<TABLE> 
<CAPTION> 
                                                  Principal
                                                   Amount
                                                   ------
     Underwriter
     -----------
<S>                                               <C> 
CS First Boston Corporation. . . . . . . . .      $33,750,000

Alex. Brown & Sons Incorporated. . . . . . .       16,250,000

                                                  -----------
     Total . . . . . . . . . . . . . . . . .      $50,000,000    
                                                  ===========
</TABLE> 

                                      26

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









                              CLEAN HARBORS, INC.
                              
                          12.5% Senior Notes Due 2001      



                            _______________________



                                   INDENTURE

                               
                           Dated as of August 4, 1994      



                            _______________________




                          Shawmut Bank, N.A., Trustee





================================================================================
<PAGE>
 
                             CROSS-REFERENCE TABLE

TIA Section                                                  Indenture Section
- -----------                                                  -----------------
310 (a)(1) ............................................              7.10
    (a)(2) ............................................              7.10
    (a)(3) ............................................              N.A.
    (a)(4) ............................................              N.A.
    (b)    ............................................        7.08; 7.10
    (c)    ............................................              N.A.
311 (a)    ............................................              7.11
    (b)    ............................................              7.11
    (c)    ............................................              N.A.
312 (a)    ............................................              2.05
    (b)    ............................................             11.03
    (c)    ............................................             11.03
313 (a)    ............................................              7.06
    (b)(1) ............................................              N.A.
    (b)(2) ............................................              7.06
    (c)    ............................................             11.02
    (d)    ............................................              7.06
314 (a)    ............................................ 4.02; 4.16; 11.02
    (b)    ............................................              N.A.
    (c)(1) ............................................             11.04
    (c)(2) ............................................             11.04
    (c)(3) ............................................              N.A.
    (d)    ............................................              N.A.
    (e)    ............................................             11.05
    (f)    ............................................              4.18
315 (a)    ............................................              7.01
    (b)    ............................................       7.05; 11.02
    (c)    ............................................              7.01
    (d)    ............................................              7.01
    (e)    ............................................              6.11
316 (a) (last sentence) ...............................             11.06
    (a)(1)(A) .........................................              6.05
    (a)(1)(B) .........................................              6.04
    (a)(2) ............................................              N.A.
    (b)    ............................................              6.07
317 (a)(1) ............................................              6.08
    (a)(2) ............................................              6.09
    (b)    ............................................              2.04
318 (a)    ............................................             11.01

N.A. means Not Applicable

_____________________

Note: This Cross-Reference Table shall not, for any purpose, be deemed to be
      part of the Indenture.
<PAGE>
 
                               TABLE OF CONTENTS

                                                                            Page
                                                                            ----
ARTICLE 1 - Definitions and Incorporation by Reference.....................   1

  SECTION 1.01  Definitions................................................   1
  SECTION 1.02  Other Definitions..........................................  13
  SECTION 1.03  Incorporation by Reference of Trust Indenture Act..........  13
  SECTION 1.04  Rules of Construction......................................  14

ARTICLE 2 - The Securities.................................................  15

  SECTION 2.01  Form and Dating............................................  15
  SECTION 2.02  Execution and Authentication...............................  15
  SECTION 2.03  Registrar and Paying Agent.................................  16
  SECTION 2.04  Paying Agent to Hold Money in Trust........................  16
  SECTION 2.05  Securityholder Lists.......................................  16
  SECTION 2.06  Transfer and Exchange......................................  16
  SECTION 2.07  Replacement Securities.....................................  17
  SECTION 2.08  Outstanding Securities.....................................  18
  SECTION 2.09  Temporary Securities.......................................  18
  SECTION 2.10  Cancellation...............................................  18
  SECTION 2.11  Defaulted Interest.........................................  18
  SECTION 2.12  Payments to Trustee........................................  19

ARTICLE 3 - Redemption.....................................................  19

  SECTION 3.01  Notices to Trustee.........................................  19
  SECTION 3.02  Selection of Securities to be Redeemed.....................  19
  SECTION 3.03  Notice of Redemption.......................................  20
  SECTION 3.04  Effect of Notice of Redemption.............................  21
  SECTION 3.05  Deposit of Redemption Price................................  21
  SECTION 3.06  Securities Redeemed in Part................................  21

ARTICLE 4 - Covenants......................................................  21

  SECTION 4.01  Payment of Securities......................................  21
  SECTION 4.02  SEC Reports................................................  21
  SECTION 4.03  Limitation on Debt.........................................  22
  SECTION 4.04  Limitation on Subsidiary Debt and Preferred Stock..........  24
  SECTION 4.05  Limitation on Liens........................................  25

                                      (i)
<PAGE>
 
                                                                            Page
                                                                            ----
  SECTION 4.06  Limitation on Sale/Leaseback Transactions..................  26
  SECTION 4.07  Limitation on Restricted Payments..........................  26
  SECTION 4.08  Limitation on Issuance and Sale of Capital Stock of
                Subsidiaries...............................................  29
  SECTION 4.09  Limitation on Restrictions on Distributions from
                Subsidiaries...............................................  30
  SECTION 4.10  Limitation on Sales of Assets and Subsidiary Stock.........  31
  SECTION 4.11  Limitation on Transactions with Affiliates.................  34
  SECTION 4.12  Lines of Business..........................................  35
  SECTION 4.13  Compliance Certificate.....................................  35
  SECTION 4.14  Change of Control..........................................  36
  SECTION 4.15  Additional Subsidiary Guarantees...........................  37
  SECTION 4.16  Corporate Existence........................................  37
  SECTION 4.17  Further Instruments and Acts...............................  37

ARTICLE 5 - Successor Company..............................................  37

  SECTION 5.01  When Company May Merge or Transfer Assets..................  37

ARTICLE 6 - Defaults and Remedies..........................................  38

  SECTION 6.01  Events of Default..........................................  38
  SECTION 6.02  Acceleration...............................................  40
  SECTION 6.03  Other Remedies.............................................  41
  SECTION 6.04  Waiver of Past Defaults....................................  41
  SECTION 6.05  Control by Majority........................................  41
  SECTION 6.06  Limitation on Suits........................................  42
  SECTION 6.07  Rights of Holders to Receive Payment.......................  42
  SECTION 6.08  Collection Suit by Trustee.................................  42
  SECTION 6.09  Trustee May File Proofs of Claim...........................  42
  SECTION 6.10  Priorities.................................................  43
  SECTION 6.11  Undertaking for Costs......................................  43
  SECTION 6.12  Waiver of Stay or Extension Laws...........................  43

ARTICLE 7 - Trustee........................................................  44

  SECTION 7.01  Duties of Trustee..........................................  44
  SECTION 7.02  Rights of Trustee..........................................  45
  SECTION 7.03  Individual Rights of Trustee...............................  46
  SECTION 7.04  Trustee's Disclaimer.......................................  46
  SECTION 7.05  Notice of Defaults.........................................  46
  SECTION 7.06  Reports by Trustee to Holders..............................  46
  SECTION 7.07  Compensation and Indemnity.................................  46

                                     (ii)
<PAGE>
 
                                                                            Page
                                                                            ----
  SECTION 7.08  Replacement of Trustee.....................................  47
  SECTION 7.09  Successor Trustee by Merger................................  48
  SECTION 7.10  Eligibility; Disqualification..............................  48
  SECTION 7.11  Preferential Collection of Claims Against Company..........  48

ARTICLE 8 - Discharge of Indenture; Defeasance.............................  49

  SECTION 8.01  Discharge of Liability on Securities; Defeasance...........  49
  SECTION 8.02  Conditions to Defeasance...................................  49
  SECTION 8.03  Application of Trust Money.................................  51
  SECTION 8.04  Repayment to Company.......................................  51
  SECTION 8.05  Indemnity for Government Obligations.......................  51
  SECTION 8.06  Reinstatement..............................................  51

ARTICLE 9 - Amendments.....................................................  52

  SECTION 9.01  Without Consent of Holders.................................  52
  SECTION 9.02  With Consent of Holders....................................  53
  SECTION 9.03  Compliance with Trust Indenture Act........................  54
  SECTION 9.04  Revocation and Effect of Consents and Waivers..............  54
  SECTION 9.05  Notation on or Exchange of Securities......................  54
  SECTION 9.06  Trustee to Sign Amendments.................................  54
  SECTION 9.07  Payment for Consent........................................  55

ARTICLE 10 - Subsidiary Guarantees.........................................  55

  SECTION 10.01 Unconditional Subsidiary Guarantee.........................  55
  SECTION 10.02 Limitation of Guarantor Subsidiary's Liability.............  57
  SECTION 10.03 Execution and Delivery of Subsidiary Guarantees............  57
  SECTION 10.04 Addition of Guarantor Subsidiary...........................  58
  SECTION 10.05 Release of the Subsidiary Guarantees.......................  58

ARTICLE 11 - Miscellaneous.................................................  59

  SECTION 11.01 Trust Indenture Act Controls...............................  59
  SECTION 11.02 Notices....................................................  59
  SECTION 11.03 Communication by Holders with Other Holders................  60
  SECTION 11.04 Certificate and Opinion as to Conditions Precedent.........  60
  SECTION 11.05 Statements Required in Certificate or Opinion..............  60
  SECTION 11.06 When Securities Disregarded................................  60
  SECTION 11.07 Rules by Trustee, Paying Agent and Registrar...............  61
  SECTION 11.08 Legal Holidays.............................................  61

                                     (iii)
<PAGE>
 
                                                                            Page
                                                                            ----
  SECTION 11.09 Governing Law..............................................  61
  SECTION 11.10 No Recourse Against Others.................................  61
  SECTION 11.11 Successors.................................................  61
  SECTION 11.12 Multiple Originals.........................................  61
  SECTION 11.13 Table of Contents; Headings................................  61
  SECTION 11.14 Separability Clause........................................  62
  SECTION 11.15 Benefits of Indenture......................................  62

EXHIBIT A - FORM OF FACE OF SECURITY....................................... A-1

EXHIBIT B - FORM OF SUPPLEMENTAL INDENTURE TO BE DELIVERED BY
                FUTURE GUARANTOR SUBSIDIARIES.............................. B-1

EXHIBIT C - FORM OF NOTATION ON SENIOR NOTE RELATING TO
                SUBSIDIARY GUARANTEE....................................... C-1

                                     (iv)
<PAGE>

     
        INDENTURE dated as of August 4, 1994, between CLEAN HARBORS, INC., a
Massachusetts corporation (the "Company"), the Guarantor Subsidiaries set forth
on the signature pages hereof and Shawmut Bank, N.A., a national banking
association, as trustee (the "Trustee").      
    
        Each party agrees as follows for the benefit of the other parties and
for the equal and ratable benefit of the Holders of the Company's 12 1/2% Senior
Notes Due May 15, 2001 (the "Securities"):      


            ARTICLE 1 - Definitions and Incorporation by Reference
                        ------------------------------------------
        SECTION 1.01    Definitions.
                        -----------

        "Adjusted EBITDA" means for any period (i) EBITDA for such period minus
(ii) for such period, the sum of (A) the net income of CHTC plus (B) taxes, if
any, of CHTC, the total interest expense of CHTC, depreciation expense of CHTC,
amortization expense of CHTC and all other non-cash charges to the extent
included in the calculation of net income of CHTC, in each case determined in
accordance with generally accepted accounting principles.

        "Affiliate" of any specified person means (i) any other person which,
directly or indirectly, is in control of, is controlled by or is under common
control with such specified person or (ii) any other person who is a director or
officer (A) of such specified person, (B) of any subsidiary of such specified
person or (C) of any person described in clause (i) above. For purposes of this
definition, control of a person means the power, direct or indirect, to direct
or cause the direction of the management and policies of such person whether
through the ownership of voting securities, by contract or otherwise; and the
terms "controlling" and "controlled" have meanings correlative to the foregoing.

        "Asset Disposition" means any sale, lease, transfer or other disposition
(or series of related sales, leases, transfers or dispositions), including any
such disposition by means of a merger, consolidation or similar transaction, of
shares of Capital Stock of a Subsidiary (other than directors' qualifying
shares), property or other assets (each referred to for the purposes of this
definition as a "disposition") by the Company or any of its Subsidiaries, but
excluding the following: (i) a disposition by a Subsidiary to the Company or by
the Company or a Subsidiary to a Wholly Owned Subsidiary, (ii) a disposition of
tangible property or assets which have become obsolete or are otherwise not used
or useful, so long as such disposition is at Fair Market Value (as determined by
the Board of Directors of the Company in good faith) in the ordinary course of
business, (iii) a disposition that constitutes a Restricted Payment, a
Sale/Leaseback Transaction, or a public offering, in each case so long as
effected in accordance with all applicable provisions of this Indenture, and
(iv) a disposition of inventory in the ordinary course of business.
<PAGE>
 
        "Attributable Debt" means, in respect of a Sale/Leaseback Transaction,
at the date of determination, the present value (discounted at the lower of the
interest rate of such Sale/Leaseback Transaction and the interest rate borne by
the Bank Revolver at the time, compounded annually) of the total obligations of
the lessee for rental payments during the remaining term of the lease included
in such Sale/Leaseback Transaction (including any period for which such lease
has been extended).

        "Average Life" means, as of the date of determination, with respect to
any Debt or Preferred Stock, the quotient obtained by dividing (i) the sum of
the products of the numbers of years from the date of determination to the dates
of each successive scheduled principal payment of such Debt or redemption or
similar payment with respect to such Preferred Stock multiplied by the amount of
such payment by (ii) the sum of all such payments.

        "Bank Debt" means any and all amounts payable under or in respect of the
Bank Revolver (or if all the obligations under the Bank Revolver shall be
replaced, refinanced or refunded one or more times with obligations under one or
more other agreements and the Trustee shall receive notice thereof from time to
time from the Company designating such other agreements at any given time as the
agreements constituting Bank Debt for purposes of this definition of Bank Debt,
the agreements from time to time so designated), as amended and supplemented
from time to time, including principal, premium (if any), interest (including
interest accruing on or after the filing of any petition in bankruptcy or for
reorganization relating to the Company whether or not a claim for post-filing
interest is allowed in such proceeding), fees, charges, expenses, letters of
credit, reimbursement obligations, Guarantees and all other amounts payable
thereunder or in respect thereof.

        "Bank Obligation" means, for any Subsidiary, the Guarantee by such
Subsidiary of the Bank Debt and any other Debt of any Subsidiary which Debt,
directly or indirectly, Guarantees or secures any Bank Debt or the agreement by
any Subsidiary to act as a co-borrower with respect to any Bank Debt.

        "Bank Revolver" means the Amended and Restated Revolving Credit
Agreement among the Company, certain Subsidiaries of the Company named therein,
and The First National Bank of Boston, Shawmut Bank, N.A., and USTrust, and The
First National Bank of Boston, as agent, as in effect on the date on which the
Securities are originally issued.

        "Board of Directors" means the Board of Directors of the Company or any
committee thereof duly authorized to act on behalf of such Board.

        "Business Day" means each day which is not a Legal Holiday.

        "CHTC" means Clean Harbors Technology Corporation and any successor
thereto.

                                       2
<PAGE>
 
        "Capital Lease Obligations" of a person means any obligation which is
required to be classified and accounted for as a capital lease on the face of a
balance sheet of such person prepared in accordance with generally accepted
accounting principles; the amount of such obligation shall be the capitalized
amount thereof, determined in accordance with generally accepted accounting
principles; and the Stated Maturity thereof shall be the date of the last
payment of rent or any other amount due under such lease prior to the first date
upon which such lease may be terminated by the lessee without payment of a
penalty.

        "Capital Stock" means any and all shares, interests, rights to purchase,
warrants, options, participations or other equivalents of or interests in
(however designated) corporate stock, including any Preferred Stock.

        "Cash Equivalents" means: (i) Investments in U.S. Government Obligations
maturing within 18 months of the date of acquisition thereof; (ii) Investments
in certificates of deposit or Eurodollar deposits maturing within 18 months of
the date of acquisition thereof issued by a bank or trust company which is
organized under the laws of the United States or any state thereof and which has
a combined capital and surplus of at least $100 million and rated at least A3 by
Moody's Investors Service, Inc.; (iii) Investments in repurchase agreements,
involving Investments in U.S. Government Obligations or other Cash Equivalents
entered into with any bank, trust company or investment bank rated at least A-
and A-1 by Standard & Poor's Corporation and at least A3 and P-1 by Moody's
Investors Service, Inc.; (iv) Investments in commercial paper maturing not more
than 270 days from the date of acquisition thereof and rated at least A-1 by
Standard & Poor's Corporation and at least P-1 by Moody's Investors Service,
Inc. issued by a corporation (except the Company or an Affiliate of the Company)
that is organized under the laws of any state of the United States or the
District of Columbia; (v) Investments in debt securities issued or directly and
fully guaranteed by any state of the United States or the District of Columbia
or a municipality thereof maturing not more than 18 months from the date of
acquisition thereof and rated at least A3 by Moody's Investors Service, Inc. and
(vi) Investments in money market accounts or funds substantially all of the
assets of which consist of cash or securities of the types described in clauses
(i) through (v) above.

        "Change of Control" means the occurrence of any of the following events:

                        (i) except to the extent caused by the issuance of
        securities by the Company subsequent to the date on which the Securities
        were originally issued, the Permitted Holders cease, at any time prior
        to the death or disability (as defined in Section 22(e)(3) of the
        Internal Revenue Code) of Alan McKim, to be the "beneficial owners" (as
        defined in Rules 13d-3 and 13d-5 under the Exchange Act, except that a
        person shall be deemed to have "beneficial ownership" of all shares that
        any such person has the right to acquire, whether such right is
        exercisable immediately or only after the passage of time), directly or
        indirectly, of at least 20% in the aggregate of the total voting power
        of the Voting Stock of the Company, whether as a result of any merger,
        consolidation, liquidation or dissolution of the Company, any direct or
        indirect transfer of securities or otherwise (for purposes of

                                       3
<PAGE>
 
        this clause (i) and clause (ii) below, the Permitted Holders shall be
        deemed to beneficially own any Voting Stock of a corporation (the
        "specified corporation") held by any other corporation (the "parent
        corporation") so long as the Permitted Holders beneficially own (as so
        defined), directly or indirectly, in the aggregate a majority of the
        voting power of the Voting Stock of the parent corporation);

                        (ii) any "person" (as such term is used in Sections
        13(d) and 14(d) of the Exchange Act), other than one or more Permitted
        Holders, is or becomes the beneficial owner (as defined in clause (i)
        above), directly or indirectly, of more than 35% of the total voting
        power of the Voting Stock of the Company; provided, however, that the
                                                  --------  -------
        Permitted Holders "beneficially own" (as so defined), directly or
        indirectly, in the aggregate a lesser percentage of the total voting
        power of the Voting Stock of the Company than such other person and do
        not have the right or ability by voting power, contract or otherwise to
        elect or designate for election a majority of the Board of Directors of
        the Company (for the purposes of this clause (ii), such other person
        shall be deemed to beneficially own any Voting Stock of a specified
        corporation held by a parent corporation, if such other person
        "beneficially owns" (as so defined), directly or indirectly, a majority
        of the voting power of the Voting Stock of such parent corporation and
        the Permitted Holders "beneficially own" (as so defined), directly or
        indirectly, in the aggregate a lesser percentage of the voting power of
        the Voting Stock of such parent corporation and do not have the right or
        ability by voting power, contract or otherwise to elect or designate for
        election a majority of the Board of Directors of such parent
        corporation); or

                        (iii) during any period of two consecutive years,
        individuals who at the beginning of such period constituted the Board of
        Directors of the Company (together with any new directors whose election
        by such Board of Directors or whose nomination for election by the
        shareholders of the Company was approved by a vote of at least 66 2/3%
        of the directors of the Company then still in office who were either
        directors at the beginning of such period or whose election or
        nomination for election was previously so approved) cease for any reason
        to constitute a majority of the Board of Directors of the Company then
        in office.

        "Company" means the party named as such in the caption of this Indenture
until a successor replaces it and, thereafter, means the successor and, for
purposes of any provision contained herein and required by the TIA, each other
obligor on the indenture securities.

        "Consolidated EBITDA Coverage Ratio" as of any date of determination
means the ratio of (i) the aggregate amount of EBITDA for the period of the most
recent four consecutive fiscal quarters ending at least 45 days prior to such
determination to (ii) Consolidated Interest Expense for such four fiscal
quarters; provided, however, that (1) if the Company or any Subsidiary has
          --------  -------   
issued any Debt since the beginning of such period that 


                                       4
<PAGE>
 
remains outstanding or if the transaction giving rise to the need to calculate
the Consolidated EBITDA Coverage Ratio is an issuance of Debt, or both, EBITDA
and Consolidated Interest Expense for such period shall be calculated after
giving effect on a pro forma basis to such Debt as if such Debt had been issued
on the first day of such period and the discharge of any other Debt refinanced,
refunded, exchanged or otherwise discharged with the proceeds of such new Debt
as if any such discharge had occurred on the first day of such period, (2) if
since the beginning of such period the Company or any Subsidiary shall have made
any Asset Disposition, EBITDA for such period shall be reduced by an amount
equal to the EBITDA (if positive) directly attributable to the assets which are
the subject of such Asset Disposition for such period, or increased by an amount
equal to the EBITDA (if negative) directly attributable thereto for such period
and Consolidated Interest Expense for such period shall be reduced by an amount
equal to the Consolidated Interest Expense directly attributable to any Debt of
the Company or any Subsidiary refinanced, refunded, exchanged or otherwise
discharged with respect to the Company and its continuing Subsidiaries in
connection with such Asset Dispositions for such period (or if the Capital Stock
of any Subsidiary is sold, the Consolidated Interest Expense for such period
directly attributable to the Debt of such Subsidiary to the extent the Company
and its continuing Subsidiaries are no longer liable for such Debt after such
sale), and (3) if since the beginning of such period the Company or any
Subsidiary (by merger or otherwise) shall have made an Investment in any
Subsidiary (or any person which becomes a Subsidiary) or an acquisition of
assets, including any acquisition of assets occurring in connection with a
transaction causing a calculation to be made hereunder, which constitutes all of
an operating unit of a business, EBITDA and Consolidated Interest Expense for
such period shall be calculated after giving pro forma effect thereto (including
the issuing of any Debt), as if such Investment or acquisition occurred on the
first day of such period. For purposes of this definition, whenever pro forma
effect is to be given to an acquisition of assets, the amount of income or
earnings relating thereto, and the amount of Consolidated Interest Expense
associated with any Debt issued in connection therewith, the pro forma
calculations shall be determined in good faith by a responsible financial or
accounting Officer of the Company. If any Debt bears a floating rate of interest
and is being given pro forma effect, the interest on such Debt shall be
calculated as if the rate in effect on the date of determination had been the
applicable rate for the entire period.

        "Consolidated Interest Expense" means, for any period, the aggregate
total interest expense of the Company and its consolidated Subsidiaries
determined in accordance with generally accepted accounting principles,
including (i) interest expense attributable to capital leases, (ii) amortization
of debt discount and debt issuance cost, (iii) capitalized interest, (iv) non-
cash interest payments, (v) commissions, discounts and other fees and charges
owed with respect to letters of credit and bankers' acceptance financing, (vi)
net costs under Hedging Obligations (including amortization of fees), (vii)
Preferred Stock dividends in respect of all Preferred Stock held by persons
other than the Company or a Wholly Owned Subsidiary, (viii) interest incurred in
connection with investments in discontinued operations,


                                       5
<PAGE>
 
and (ix) interest actually paid by the Company or any of its consolidated
Subsidiaries under any Guarantee of Debt or other obligation of any other
person.

        "Consolidated Net Income" means, for any period, the aggregate net
income of the Company and its consolidated Subsidiaries, determined in
accordance with generally accepted accounting principles; provided, however,
                                                          --------  -------
that there shall not be included in such Consolidated Net Income: (i) any net
income of any person if such person is not a Subsidiary, except that (A) the
Company's equity in the net income of any such person for such period shall be
included in such Consolidated Net Income up to the aggregate amount of cash
actually distributed by such person during such period to the Company or a
Subsidiary as a dividend or other distribution (subject, in the case of a
dividend or other distribution to a Subsidiary, to the limitations contained in
clause (iii) below) and (B) the Company's equity in a net loss of any such
person for such period shall be included in determining such Consolidated Net
Income; (ii) any net income of any person acquired by the Company or a
Subsidiary in a pooling of interest transaction for any period prior to the date
of such acquisition; (iii) any net income of any Subsidiary if such Subsidiary
is subject to restrictions, directly or indirectly, on the payment of dividends
or the making of distributions by such Subsidiary, directly or indirectly, to
the Company, except that (A) the Company's equity in the net income of any such
Subsidiary for such period shall be included in such Consolidated Net Income up
to the aggregate amount of cash actually distributed by such Subsidiary during
such period to the Company or another Subsidiary as a dividend or other
distribution (subject, in the case of a dividend or other distribution to
another Subsidiary, to the limitation contained in this clause) and (B) the
Company's equity in a net loss of any such Subsidiary for such period shall be
included in determining such Consolidated Net Income; (iv) any gain or loss
realized upon the sale or other disposition of any property, plant or equipment
of the Company or its consolidated Subsidiaries (including pursuant to any
Sale/Leaseback Transaction) which is not sold or otherwise disposed of in the
ordinary course of business and any gain or loss realized upon the sale or other
disposition of any Capital Stock of any person; and (v) the cumulative effect of
a change in accounting principles.

        "Consolidated Net Tangible Assets" of any person means the total assets
of such person and its consolidated subsidiaries after deducting therefrom all
intangible assets, current liabilities (excluding any thereof which are by their
terms extendible or renewable at the option of the obligor thereon to a time
more than 12 months after the time as of which the amount thereof is being
computed) and minority interests, if any, in any assets of such person's
subsidiaries.

        "Consolidated Net Worth" of any person means the total of the amounts
shown on the balance sheet of such person and its consolidated subsidiaries,
determined on a consolidated basis in accordance with generally accepted
accounting principles, as of the end of the most recent fiscal quarter of such
person ending at least 45 days prior to the taking of any action

                                       6
<PAGE>
 
for the purpose of which the determination is being made, as (i) the par or
stated value of all outstanding Capital Stock of such person plus (ii) paid-in
capital or capital surplus relating to such Capital Stock plus (iii) any
retained earnings or earned surplus less (A) any accumulated deficit, (B) any
amounts attributable to Redeemable Stock, and (C) any amounts attributable to
Exchangeable Stock.

        "Debt" of any person means, without duplication: (i) the principal of
and premium (if any) in respect of (A) indebtedness of such person for money
borrowed and (B) indebtedness evidenced by notes, debentures, bonds or other
similar instruments for the payment of which such person is responsible or
liable; (ii) all Capital Lease Obligations of such person; (iii) all obligations
of such person issued or assumed as the deferred purchase price of property, all
conditional sale obligations of such person and all obligations of such person
under any title retention agreement (but excluding trade accounts payable
arising in the ordinary course of business); (iv) all obligations of such person
for the reimbursement of any obligor on any letter of credit, banker's
acceptance or similar credit transaction (other than obligations with respect to
letters of credit securing obligations (other than obligations described in (i)
through (iii) above) which are the functional equivalent of commercial surety or
fidelity bonds and not issued in connection with the borrowing of money, or are
entered into in the ordinary course of business of such person to the extent
such letters of credit are not drawn upon or, if and to the extent drawn upon,
such drawing is reimbursed no later than the third Business Day following
receipt by such person of a demand for reimbursement following payment on the
letter of credit); (v) the amount of all obligations of such person with respect
to the redemption, repayment or other repurchase of any Redeemable Stock (but
excluding any accrued dividends); (vi) all obligations of the type referred to
in clauses (i) through (v) of other persons and all dividends of other persons
for the payment of which, in either case, such person is responsible or liable,
directly or indirectly, as obligor, guarantor or otherwise, including by means
of any agreement which has the economic effect of a Guarantee; and (vii) all
obligations of the type referred to in clauses (i) through (vi) of other persons
secured by any Lien on any property or asset of such person (whether or not such
obligation is assumed by such person or is otherwise its legal liability), the
amount of such obligation being deemed to be the lesser of the value of such
property or assets or the amount of the obligation so secured.

        "Default" means any event which is, or after notice or passage of time
or both would be, an Event of Default.

        "EBITDA" for any period means the Consolidated Net Income for such
period, plus the following to the extent included in calculating such
Consolidated Net Income: (i) income tax expense, (ii) Consolidated Interest
Expense, (iii) depreciation expense, (iv) amortization expense, (v) all other
non-cash charges (excluding any non-cash charge which requires an accrual of or
a reserve for cash charges for any future period), and (vi) without duplication,

                                       7
<PAGE>
 
cash and non-cash charges associated with the early extinguishment of debt
incurred in connection with the issuance of the Securities and the application
of the proceeds therefrom.

        "Eligible Accounts Receivable" means all accounts, accounts receivable,
notes, bills, drafts, acceptances, instruments, documents, and all other Debt,
obligations and liabilities in whatever form owing from any person for goods
sold or for services rendered, at any time existing on the books of the Company
which, at the time of determination, are not more than 90 days from the date of
invoice.

        "Exchange Act" means the Securities Exchange Act of 1934, as amended.

        "Exchangeable Stock" means any Capital Stock which is exchangeable or
convertible into another security (other than Capital Stock of the Company which
is neither Exchangeable Stock nor Redeemable Stock).

        "Fair Market Value" means, with respect to any asset or property, the
sale value that would be obtained in an arm's-length transaction between an
informed and willing seller under no compulsion to sell and an informed and
willing buyer under no compulsion to buy.

        "Guarantee" means any obligation, contingent or otherwise, of any person
directly or indirectly guaranteeing any Debt or other obligation of any person
and any obligation, direct or indirect, contingent or otherwise, of such person
(i) to purchase or pay (or advance or supply funds for the purchase or payment
of) such Debt or other obligation of such person (whether arising by virtue of
partnership arrangements, or by agreement to keep-well, to purchase assets,
goods, securities or services, to take-or-pay, or to maintain financial
statement conditions or otherwise) or (ii) entered into for purposes of assuring
in any other manner the obligee of such Debt or other obligation of the payment
thereof or to protect such obligee against loss in respect thereof (in whole or
in part); provided, however, that the term "Guarantee" shall not include
          --------  -------
endorsements for collection or deposit in the ordinary course of business. The
term "Guarantee" used as a verb has a corresponding meaning.

        "Guarantor Subsidiaries" means each of (i) Clean Harbors Environmental
Services, Inc., Clean Harbors of Natick, Inc., Clean Harbors of Braintree, Inc.,
Clean Harbors of Chicago, Inc., Clean Harbors of Cleveland, Inc., Clean Harbors
of Baltimore, Inc., Clean Harbors of Connecticut, Inc., Clean Harbors Kingston
Facility Corporation, Murphy's Waste Oil Service, Inc., Clean Harbors Technology
Corporation, Mr. Frank, Inc. and Spring Grove Resource Recovery, Inc. and (ii)
any other Subsidiary that executes a Subsidiary Guarantee, and their respective
successors and assigns.

        "Hedging Obligations" of any person means the obligations of such person
pursuant to any interest rate swap agreement, foreign currency exchange
agreement, interest rate collar

                                       8
<PAGE>
 
agreement, option or futures contract or other similar agreement or arrangement
designed to protect such person against changes in interest rates or foreign
exchange rates.

        "Holder" or "Securityholder" means the person in whose name a Security
is registered on the Registrar's books.

        "Indenture" means this Indenture as amended or supplemented from time to
time.

        "Investment" in any person means any loan or advance to, any acquisition
of Capital Stock, equity interest, obligation or other security of, or capital
contribution or other investment in, such person.

        "issue" means issue, assume, Guarantee, incur or otherwise become liable
for; provided, however, that any Debt or Capital Stock of a person existing at
the time such person becomes a Subsidiary (whether by merger, consolidation,
acquisition or otherwise) shall be deemed to be issued by such Subsidiary at the
time it becomes a Subsidiary.

        "Legal Holiday" means a Saturday, a Sunday or a day on which banking
institutions are not required to be open in the State of New York or the
principal office of the Trustee.

        "Lien" means any mortgage, pledge, security interest, conditional sale,
encumbrance, charge or adverse claim affecting title or resulting in an
encumbrance against real or personal property, or a security interest of any
kind.

        "Net Available Cash" from an Asset Disposition means cash payments
received (including any cash payments received by way of deferred payment of
principal pursuant to a note or installment receivable or otherwise, but only as
and when received, but excluding any other consideration received in the form of
assumption by the acquiring person of Debt or other obligations relating to such
properties or assets or received in any other non-cash form) therefrom, in each
case net of all legal, title and recording tax expenses, commissions and other
fees and expenses incurred, and all Federal, state, provincial, foreign and
local taxes required to be accrued as a liability under generally accepted
accounting principles, as a consequence of such Asset Disposition, and in each
case net of all payments made on any Debt which is secured by any assets subject
to such Asset Disposition, in accordance with the terms of any Lien upon or
other security agreement of any kind with respect to such assets, or which must
by its terms, or in order to obtain a necessary consent to such Asset
Disposition, or by applicable law be repaid out of the proceeds from such Asset
Disposition, and net of all distributions and other payments required to be made
to minority interest holders in Subsidiaries or joint ventures as a result of
such Asset Disposition.

        "Net Cash Proceeds", with respect to any issuance or sale of Capital
Stock, means the cash proceeds of such issuance or sale net of attorneys' fees,
accountants' fees, underwriters'


                                       9
<PAGE>
 
or placement agents' fees, discounts or commissions and brokerage, consultant
and other fees actually incurred in connection with such issuance or sale and
net of taxes paid or payable as a result thereof.

        "Non-Convertible Capital Stock" means, with respect to any corporation,
any non-convertible Capital Stock of such corporation and any Capital Stock of
such corporation convertible solely into non-convertible common stock of such
corporation; provided, however, that Non-Convertible Capital Stock shall not
             --------  -------
include any Redeemable Stock or Exchangeable Stock.

        "Non-Guarantor Subsidiary" means Northeast Casualty Risk Retention
Group, Inc.

        "Officer" means the Chairman of the Board, the President, any Vice
President, the Treasurer or the Secretary of the Company.

        "Officers' Certificate" means a certificate signed by two Officers.

        "Opinion of Counsel" means a written opinion from legal counsel who is
acceptable to the Trustee. The counsel may be an employee of or counsel to the
Company or the Trustee.

        "Permitted Holders" means (i) Alan McKim, (ii) the trustees of a trust
for the benefit of Alan McKim, which trust is revocable solely by Mr. McKim,
(iii) Mr. McKim's spouse or children, (iv) a trust created for the exclusive
benefit of Mr. McKim's spouse or children or for the exclusive benefit of Mr.
McKim and such persons, and (v) any charitable trust or foundation qualified
under Section 501(c)(3) of the Internal Revenue Code established by Mr. McKim
and for which he serves as a trustee or director.
    
        "Permitted Investments" means: (i) Cash Equivalents; (ii) Investments in
a Wholly Owned Subsidiary (or any person which will become a Wholly Owned
Subsidiary as a result of such Investment); (iii) loans and reasonable advances
to employees of the Company or its Subsidiaries for travel, entertainment and
relocation expenses in the ordinary course of business; and (iv) other
Investments not to exceed $5.0 million at any one time outstanding, provided 
that no Investment under this clause (iv) shall consist of Capital Stock of the 
Company.      

       "Permitted Liens" means, with respect to any person, (i) pledges or
deposits by such person under workers' compensation laws, unemployment insurance
laws or similar legislation, or good faith deposits in connection with bids,
tenders, contracts (other than for the payment of Debt) or leases to which such
person is a party, or deposits to secure public or statutory obligations of such
person or deposits or cash or United States government bonds to secure surety or
appeal bonds to which such person is a party, or deposits as security for
contested taxes or import duties or for the payment of rent, in each case
incurred in the ordinary course of business; (ii) Liens imposed by law, such as
carriers', warehousemen's

                                      10
<PAGE>
 
and mechanics' Liens, in each case for sums not yet due or being contested in
good faith by appropriate proceedings; or other Liens arising out of judgments
or awards against such person with respect to which such person shall then be
proceeding with an appeal or other proceedings for review or time for appeal has
not yet expired; (iii) Liens for property taxes not yet subject to penalties for
non-payment or which are being contested in good faith by appropriate
proceedings; (iv) Liens in favor of issuers of surety bonds or letters of credit
issued pursuant to the request of and for the account of such person in the
ordinary course of its business; provided, however, that such letters of credit
do not constitute Debt; (v) survey exceptions, encumbrances, easements or
reservations of, or rights of others for, licenses, rights of way, sewers,
electric lines, telegraph and telephone lines and other similar purposes, or
zoning or other restrictions as to the use of real properties or Liens
incidental to the conduct of the business of such person or to the ownership of
its properties which were not incurred in connection with Debt and which do not
in the aggregate materially adversely affect the value of said properties or
materially impair their use in the operation of the business of such person;
(vi) Liens securing a Hedging Obligation so long as the related Debt is, and is
permitted to be under this Indenture, secured by a Lien on the same property
securing the Hedging Obligation; and (vii) leases and subleases of real property
which do not interfere with the ordinary conduct of the business of such person
or the ownership of its properties which were not incurred in connection with
Debt and which do not in the aggregate materially adversely affect the value of
said properties or materially impair their use in the operation of the business
of such person, and which are made on customary and usual terms applicable to
similar properties.

        "person" means any individual, corporation, partnership, joint venture,
association, joint-stock company, trust, unincorporated organization, government
or any agency or political subdivision thereof or any other entity.

        "Preferred Stock", as applied to the Capital Stock of any corporation,
means Capital Stock of any class or classes (however designated) which is
preferred as to the payment of dividends, or as to the distribution of assets
upon any voluntary or involuntary liquidation or dissolution of such
corporation, over shares of Capital Stock of any other class of such
corporation.

        "Principal" of a Security means the principal of the Security plus the
premium (if any) payable on the Security which is due or overdue or is to become
due at the relevant time.

        "Redeemable Stock" means any Capital Stock that by its terms or
otherwise is required to be redeemed on or prior to the first anniversary of the
Stated Maturity of the Securities or is redeemable at the option of the holder
thereof at any time on or prior to the first anniversary of the Stated Maturity
of the Securities.

                                      11
<PAGE>
 
        "Sale/Leaseback Transaction" means an arrangement relating to property
now owned or hereafter acquired whereby the Company or a Subsidiary transfers
such property to a person and the Company or a Subsidiary leases it from such
person.

        "SEC" means the Securities and Exchange Commission.

        "Securities" means the Securities issued under this Indenture.

        "Stated Maturity" means, with respect to any security, the date
specified in such security as the fixed date on which the principal of such
security is due and payable, including pursuant to any mandatory redemption
provision (but excluding any provision providing for the repurchase of such
security at the option of the holder thereof upon the happening of any
contingency).

        "Subordinated Obligation" means any Debt of the Company (whether
outstanding on the date hereof or hereafter incurred) which is subordinated or
junior in right of payment to the Securities.

        "Subsidiary" means any corporation, association, partnership or other
business entity of which more than 50% of the total voting power of shares of
Capital Stock or other interests (including partnership interests) entitled
(without regard to the occurrence of any contingency) to vote in the election of
directors, managers or trustees thereof is at the time owned or controlled,
directly or indirectly, by (i) the Company, (ii) the Company and one or more
Subsidiaries, or (iii) one or more Subsidiaries.

        "Subsidiary Guarantee" means the Guarantee by a Guarantor Subsidiary of
the obligations of the Company under the Securities as set forth in Article X
hereof.

        "TIA" means the Trust Indenture Act of 1939 (15 U.S.C. (S)(S)77aaa-
77bbbb) as in effect on the date of this Indenture.

        "Trustee" means the party named as such in the caption of this Indenture
until a successor replaces it and, thereafter, means the successor.

        "Trust Officer" means the Chairman of the Board, the President or any
other officer or assistant officer of the Trustee assigned by the Trustee to
administer its corporate trust matters.

        "Uniform Commercial Code" means the New York Uniform Commercial Code as
in effect from time to time.


                                      12
<PAGE>
 
        "U.S. Government Obligations" means direct obligations (or certificates
representing an ownership interest in such obligations) of the United States of
America (including any agency or instrumentality thereof) for the payment of
which the full faith and credit of the Untied States of America is pledged and
which are not callable at the issuer's option.

        "Voting Stock" of a corporation means all classes of Capital Stock of
such corporation then outstanding and normally entitled to vote in the election
of directors or other governing body of such corporation.

        "Wholly Owned Subsidiary" means a Subsidiary all the Capital Stock of
which (other than directors' qualifying shares) is owned by the Company or
another Wholly Owned Subsidiary.

        SECTION 1.02    Other Definitions.
                        ----------------- 
                                                                 Defined in
Term                                                               Section  
- ----                                                             ----------
"Bankruptcy Law"..............................................       6.01
"Benefitted Party"............................................      10.01
"covenant defeasance option"..................................       8.01
"Change of Control Payment Date"..............................       4.14
"Custodian"...................................................       6.01
"Event of Default"............................................       6.01
"legal defeasance option".....................................       8.01
"Legal Holiday"...............................................      11.08
"Offer".......................................................       4.10
"Offer Amount"................................................       4.10
"Offer Period"................................................       4.10
"Paying Agent"................................................       2.03
"Public Offering".............................................       4.08
"Purchase Date"...............................................       4.10
"Registrar"...................................................       2.03
"Restricted Payment"..........................................       4.07


        SECTION 1.03 Incorporation by Reference of Trust Indenture Act. Whenever
                     -------------------------------------------------
this Indenture refers to a provision of the TIA, the provision is incorporated
by reference in and made a part of this Indenture. The following TIA terms used
in this Indenture have the following meanings:

        "Commission" means the SEC.

                                      13
<PAGE>
 
        "indenture securities" means the Securities.

        "indenture security holder" means a Securityholder.

        "indenture to be qualified" means this Indenture.

        "indenture trustee" or "institutional trustee" means the Trustee.

        "obligor" on the indenture securities means the Company and any other
obligor on the indenture securities.

        All other TIA terms used in this Indenture that are defined by the TIA,
defined by TIA reference to another statute or defined by SEC rule have the
meanings assigned to them by such definitions.

        SECTION 1.04 Rules of Construction. Unless the context otherwise
                     ---------------------
requires:

                (1) a term has the meaning assigned to it;

                (2) an accounting term not otherwise defined has the meaning
        assigned to it in accordance with generally accepted accounting
        principles as in effect on the date of this Indenture;

                (3) "or" is not exclusive;

                (4) "including" means including, without limitation;

                (5) words in the singular include the plural and words in the
        plural include the singular;

                (6) unsecured Debt shall not be deemed to be subordinated or
        junior to secured Debt merely by virtue of its nature as unsecured Debt;

                (7) the principal amount of any noninterest bearing or other
        discount security at any date shall be the principal amount thereof that
        would be shown on a balance sheet of the issuer dated such date prepared
        in accordance with generally accepted accounting principles and
        accretion of principal on such security shall be deemed to be the
        issuance of Debt;

                (8) the principal amount of any Preferred Stock shall be (i) the
        maximum liquidation value of such Preferred Stock or (ii) the maximum
        mandatory

                                      14
<PAGE>
 
        redemption or mandatory repurchase price with respect to such Preferred
        Stock, whichever is greater.


                          ARTICLE 2 - The Securities
                                      --------------

        SECTION 2.01 Form and Dating. The Securities and the Trustee's
                     --------------- 
certificate of authentication shall be substantially in the form of Exhibit A,
which is hereby incorporated in and expressly made a part of this Indenture. The
notation on each Security relating to the Subsidiary Guarantees shall be
substantially in the form set forth on Exhibit C, which is hereby incorporated
in and expressly made a part of this Indenture. The Securities may have
notations, legends or endorsements required by law, stock exchange rules,
agreements to which the Company is subject, if any, or usage (provided that any
such notation, legend or endorsement is in a form acceptable to the Company).
Each Security shall be dated the date of its authentication. The terms of the
Securities set forth in Exhibit A are part of the terms of this Indenture.

        SECTION 2.02 Execution and Authentication. Two Officers shall sign the
                     ----------------------------
Securities for the Company by manual or facsimile signature. The Company's seal
shall be impressed, affixed, imprinted or reproduced on the Securities and may
be in facsi mile form.

        If an Officer whose signature is on a Security no longer holds that
office at the time the Trustee authenticates the Security, the Security shall be
valid nevertheless.

        A Security shall not be valid until an authorized signatory of the
Trustee manually signs the certificate of authentication on the Security. The
signature shall be conclusive evidence that the Security has been authenticated
under this Indenture.
    
        The Trustee shall authenticate and deliver Securities for original issue
in an aggregate principal amount of $50,000,000, upon a written order of the
Company signed by two Officers or by an Officer and either an Assistant
Treasurer or an Assistant Secretary of the Company. Such order shall specify the
amount of the Securities to be authenticated and the date on which the original
issue of Securities is to be authenticated. The aggregate amount of Securities
outstanding at any time may not exceed that amount except as provided in Section
2.07.      

        The Trustee may appoint an authenticating agent reasonably acceptable to
the Company to authenticate the Securities. Unless limited by the terms of such
appointment, an authenticating agent may authenticate Securities whenever the
Trustee may do so. Each reference in this Indenture to authentication by the
Trustee includes authentication by such agent. An authenticating agent has the
same rights as any Registrar, Paying Agent or agent for service of notices and
demands.

                                      15
<PAGE>
 
        SECTION 2.03 Registrar and Paying Agent. The Company may maintain an
                     --------------------------
office or agency where Securities may be presented for registration or transfer
or for exchange (the "Registrar") and an office or agency where Securities may
be presented for payment (the "Paying Agent"). The Registrar shall keep a
register of the Securities and of their transfer and exchange. The Company may
have one or more co-registrars and one or more additional paying agents.

        The Company shall enter into an appropriate agency agreement with any
Registrar, Paying Agent or co-registrar not a party to this Indenture, which
shall incorporate the terms of the TIA. The agreement shall implement the
provisions of this Indenture that relate to such agent. The Company shall notify
the Trustee of the name and address of any such agent. If the Company fails to
maintain a Registrar or Paying Agent, the Trustee shall act as such and shall be
entitled to appropriate compensation therefor pursuant to Section 7.07. The
Company or any of its domestically incorporated Wholly Owned Subsidiaries may
act as Paying Agent, Registrar, co-registrar or transfer agent.

        The Company initially appoints Shawmut Bank, N.A. as Registrar and
Paying Agent in connection with the Securities.

        SECTION 2.04 Paying Agent to Hold Money in Trust. Prior to each due date
                     -----------------------------------
of the principal and interest on any Security, the Company shall deposit with
the Paying Agent a sum sufficient to pay such principal and interest when so
becoming due. The Company shall require each Paying Agent (other than the
Trustee) to agree in writing that the Paying Agent shall hold in trust for the
benefit of Securityholders or the Trustee all money held by the Paying Agent for
the payment of principal of or interest on the Securities and shall notify the
Trustee of any default by the Company in making any such payment. If the Company
or a Subsidiary acts as Paying Agent, it shall segregate the money held by it as
Paying Agent and hold it as a separate trust fund. The Company at any time may
require a Paying Agent to pay all money held by it to the Trustee and to account
for any funds disbursed by the Paying Agent. Upon complying with this Section,
the Paying Agent shall have no further liability for the money delivered to the
Trustee.

        SECTION 2.05 Securityholder Lists. The Trustee shall preserve in as
                     --------------------
current a form as is reasonably practicable the most recent list available to it
of the names and addresses of Securityholders. If the Trustee is not the
Registrar, the Company shall furnish to the Trustee, in writing at least five
Business Days before each interest payment date and at such other times as the
Trustee may request in writing, a list in such form and as of such date as the
Trustee may reasonably require of the names and addresses of Securityholders.

        SECTION 2.06 Transfer and Exchange. The Securities shall be issued in
                     ---------------------
registered form and shall be transferable only upon the surrender of a Security
for registration of transfer. When a Security is presented to the Registrar or a
co-registrar with 

                                      16
<PAGE>
 
a request to register a transfer, the Registrar shall register the transfer as
requested if the requirements of section 8-401(1) of the Uniform Commercial Code
are met. When Securities are presented to the Registrar or a co-registrar with a
request to exchange them for an equal principal amount of Securities of other
denominations, the Registrar shall make the exchange as requested if the same
requirements are met. To permit registration of transfers and exchanges, the
Company shall execute and the Trustee shall authenticate Securities at the
Registrar's or co-registrar's request. The Company may require payment of a sum
sufficient to pay all taxes, assessments or other governmental charges in
connection with any transfer or exchange pursuant to this Section (other than
any such tax assessment or other governmental charges payable upon exchanges
pursuant to Sections 2.09, 3.06 or 9.05, which the Company shall pay). The
Company shall not be required to make and the Registrar need not register
transfers or exchanges of Securities selected for redemption (except, in the
case of Securities to be redeemed in part, the portion thereof not to be
redeemed) or any Securities for a period of 15 days before a selection of
Securities to be redeemed or 15 days before an interest payment date.

        Prior to the due presentation for registration of transfer of any
Security, the Company, the Trustee, the Paying Agent, the Registrar or any co-
registrar may deem and treat the person in whose name a Security is registered
as the absolute owner of such Security for the purpose of receiving payment of
principal of and interest on such Security and for all other purposes
whatsoever, whether or not such Security is overdue, and none of the Company,
the Trustee, the Paying Agent, the Registrar or any co-registrar shall be
affected by notice to the contrary.

        All Securities issued upon any transfer or exchange pursuant to the
terms of this Indenture will evidence the same debt and will be entitled to the
same benefit under this Indenture as the Securities surrendered upon such
transfer or exchange.

        SECTION 2.07 Replacement Securities. If a mutilated Security is
                     ----------------------
surrendered to the Registrar or if the Holder of a Security claims that the
Security has been lost, destroyed or wrongfully taken, the Company shall issue
and the Trustee shall authenticate a replacement Security if the requirements of
Section 8-405 of the Uniform Commercial Code are met and the Holder satisfies
any other reasonable requirements of the Trustee. If required by the Trustee or
the Company, such Holder shall furnish an indemnity bond sufficient in the
judgment of the Company and the Trustee to protect the Company, the Trustee, the
Paying Agent, the Registrar and any co-registrar from any loss which any of them
may suffer if a Security is replaced. The Company and the Trustee may charge the
Holder for their expenses in replacing a Security.

        Every replacement Security is an additional obligation of the Company.

                                      17
<PAGE>
 
        SECTION 2.08 Outstanding Securities. Securities outstanding at any time
                     ----------------------
are all Securities authenticated by the Trustee except for those canceled by it,
those delivered to it for cancellation and those described in this Section as
not outstanding. A Security does not cease to be outstanding because the Company
or an Affiliate of the Company holds the Security.

        If a Security is replaced pursuant to Section 2.07, it ceases to be
outstanding unless the Trustee and the Company receive proof satisfactory to
them that the replaced Security is held by a bona fide purchaser.

        If the Paying Agent segregates and holds in trust, in accordance with
this Indenture, on a redemption date or maturity date money sufficient to pay
all principal and interest payable on that date with respect to the Securities
(or portions thereof) to be redeemed or maturing, as the case may be, and the
Paying Agent is not prohibited from paying such money to the Securityholders on
that date pursuant to the terms of this Indenture, then on and after that date
such Securities (or portions thereof) cease to be outstanding and interest on
them ceases to accrue.

        SECTION 2.09 Temporary Securities. Until definitive Securities are ready
                     --------------------
for delivery, the Company may prepare and the Trustee shall authenticate
temporary Securities. Temporary Securities shall be substantially in the form of
definitive Securities but may have variations that the Company considers
appropriate for temporary Securities. Without unreasonable delay, the Company
shall prepare and the Trustee shall authenticate definitive Securities and
deliver them in exchange for temporary Securities. Until such exchange,
temporary Securities shall be entitled to the same rights, benefits and
privileges as definitive Securities.

        SECTION 2.10 Cancellation. The Company at any time may deliver
                     ------------
Securities to the Trustee for cancellation. The Registrar and the Paying Agent
shall forward to the Trustee any Securities surrendered to them for registration
of transfer, exchange or payment. The Trustee and no one else shall cancel and
destroy (subject to the record retention requirements of the Exchange Act) all
Securities surrendered for registration of transfer, exchange, payment or
cancellation and deliver a certificate of such destruction to the Company unless
the Company directs the Trustee to deliver canceled Securities to the Company.
The Company may not issue new Securities to replace Securities it has redeemed,
paid or delivered to the Trustee for cancellation.

        SECTION 2.11 Defaulted Interest. If the Company defaults in a payment of
                     ------------------
interest on the Securities, the Company shall pay defaulted interest (plus
interest on such defaulted interest to the extent lawful) in any lawful manner.
The Company may pay the defaulted interest to the persons who are
Securityholders on a subsequent special record date, which date shall be at
least five Business Days prior to the payment date. The Company

                                      18
<PAGE>
 
shall fix or cause to be fixed any such special record date and payment date,
and, at least 15 days before any such special record date, the Company shall
mail to each Securityholder a notice that states the special record date, the
payment date and the amount of defaulted interest to be paid.

        SECTION 2.12 Payments to Trustee. Any payments to be made by the Company
                     ------------------- 
to the Trustee hereunder shall be made by no later than 11:00 a.m. Boston time
on the date specified in immediately available funds.


                            ARTICLE 3 - Redemption
                                        ----------

        SECTION 3.01 Notices to Trustee. If the Company elects to redeem
                     ------------------
Securities pursuant to paragraph 5 of the Securities, it shall notify the
Trustee in writing of the redemption date, the principal amount of Securities to
be redeemed and the paragraph of the Securities pursuant to which the redemption
will occur.

        The Company shall give each notice to the Trustee provided for in this
Section at least 60 days before the redemption date unless the Trustee consents
to a shorter period. Such notice shall be accompanied by an Officers'
Certificate and an Opinion of Counsel from the Company to the effect that such
redemption will comply with the conditions herein. If fewer than all the
Securities are to be redeemed, the record date relating to such redemption shall
be selected by the Company and given to the Trustee, which record date shall be
not less than 15 days after the date of notice to the Trustee. If the Trustee is
not the Registrar, the Company shall, concurrently with delivery of its notice
to the Trustee of redemption, cause the Registrar to deliver to the Trustee a
certificate (upon which the Trustee may rely) setting forth the name of, and the
aggregate principal amount of Securities held by each Holder.

        SECTION 3.02 Selection of Securities to be Redeemed. If fewer than all
                     --------------------------------------
the Securities are to be redeemed, the Trustee shall select the Securities to be
redeemed by lot or by a method that complies with applicable legal and
securities exchange requirements, if any, and that the Trustee considers fair
and appropriate and in accordance with methods generally used at the time of
selection by fiduciaries in similar circumstances. The Trustee shall make the
selection from outstanding Securities not previously called for redemption. The
Trustee may select for redemption portions of the principal of Securities that
have denominations larger than $1,000. Securities and portions of them the
Trustee selects shall be in amounts of $1,000 or a whole multiple of $1,000.
Provisions of this Indenture that apply to Securities called for redemption also
apply to portions of Securities called for redemption. The Trustee shall notify
the Company promptly of the Securities or portions of Securities to be redeemed.


                                      19
<PAGE>
 
        SECTION 3.03 Notice of Redemption. At least 30 days but not more than 60
                     --------------------
days before a date for redemption of Securities, the Company shall mail a notice
of redemption by first-class mail to each Holder of Securities to be redeemed.

        The notice shall identify the Securities or portions thereof to be
redeemed and shall state:

                (1) the redemption date;

                (2) the redemption price and the amount of unpaid and accrued
        interest on such Securities as of the date of redemption;

                (3) the name and address of the Paying Agent;

                (4) that Securities called for redemption must be surrendered to
        the Paying Agent to collect the redemption price for and any accrued but
        unpaid interest on such Securities;

                (5) if fewer than all the outstanding Securities are to be
        redeemed, the identification and principal amounts of the particular
        Securities to be redeemed and, that, after the redemption date, upon
        surrender of such Security, a new Security or a Security in principal
        amount of the unredeemed portions will be issued;

                (6) that, unless the Company defaults in making such redemption
        payment or the Paying Agent is prohibited from making such payment
        pursuant to the terms of this Indenture, interest on Securities (or
        portions thereof) called for redemption ceases to accrue on and after
        the redemption date and that the only remaining right of the Holders of
        such Securities is to receive payment of the redemption price upon
        surrender to the Paying Agent of the Securities redeemed;

                (7) the paragraph of the Securities pursuant to which the
        Securities called for redemption are being redeemed; and

                (8) The CUSIP number of the Securities to be redeemed, if any.

        At the Company's request, the Trustee shall give the notice of
redemption in the Company's name and at the Company's expense. In such event,
the Company shall provide the Trustee at least 10 days prior to the date that
notice of the redemption is to be mailed to Holders, an Officer's Certificate
that (i) requests the Trustee to give notice of the redemption to Holders, (ii)
sets forth the information to be provided to Holders in the notice of
redemption, as set forth in the preceding paragraph, and (iii) sets forth the
aggregate principal amount of Securities to be redeemed and the amount of
accrued and unpaid interest 

                                      20
<PAGE>
 
thereon as of the redemption date. If the Trustee is not the Registrar, the
Company shall, concurrently with any such request, cause the Registrar to
deliver to the Trustee a certificate (upon which the Trustee may rely) setting
forth the name of, the address of, and the aggregate principal amount of
Securities held by, each Holder.

        SECTION 3.04 Effect of Notice of Redemption. Once notice of redemption
                     ------------------------------  
is mailed, Securities called for redemption become due and payable on the
redemption date and at the redemption price stated in the notice. Upon surrender
to the Paying Agent, such Securities shall be paid at the redemption price
stated in the notice, plus accrued interest to the redemption date. Failure to
give notice or any defect in the notice to any Holder shall not affect the
validity of the notice to any other Holder.

        SECTION 3.05 Deposit of Redemption Price. Prior to the redemption date,
                     ---------------------------   
the Company shall deposit with the Paying Agent (or, if the Company or a
Subsidiary is the Paying Agent, shall segregate and hold in trust) money
sufficient to pay the redemption price of and accrued interest on all Securities
to be redeemed on that date other than Securities or portions of Securities
called for redemption which have been delivered by the Company to the Trustee
for cancellation.

        SECTION 3.06 Securities Redeemed in Part. Upon surrender of a Security
                     ---------------------------
that is redeemed in part, the Company shall execute and the Trustee shall
authenticate for the Holder (at the Company's request) a new Security equal in
principal amount to the unredeemed portion of the Security surrendered.


                             ARTICLE 4 - Covenants
                                         ---------

        SECTION 4.01 Payment of Securities. The Company shall promptly pay the
                     ---------------------
principal of and interest on the Securities on the dates and in the manner
provided in the Securities and in this Indenture. Principal and interest shall
be considered paid on the date due if on such date the Trustee or the Paying
Agent holds in accordance with this Indenture money sufficient to pay all
principal and interest then due and the Trustee or the Paying Agent, as the case
may be, is not prohibited from paying such money to the Securityholders on that
date pursuant to the terms of this Indenture.

        The Company shall pay interest on overdue principal at the rate
specified therefor in the Securities, and it shall pay interest on overdue
installments of interest (without regard to any applicable grace period) at the
same rate to the extent lawful.

        SECTION 4.02 SEC Reports. Each of the Company and the Guarantor
                     -----------
Subsidiaries shall file with the Trustee and provide Securityholders, within 15
days after it files them with the SEC, copies of its annual report and of the
information, documents and

                                      21
<PAGE>
 
other reports (or copies of such portions of any of the foregoing as the SEC may
by rules and regulations prescribe) which the Company or such Guarantor
Subsidiary is required to file with the SEC pursuant to Section 13 or 15(d) of
the Exchange Act. Notwithstanding that the Company may not be required to remain
subject to the reporting requirements of Section 13 or 15(d) of the Exchange
Act, the Company shall continue to file with the SEC and provide the Trustee and
Securityholders with such annual reports and such information, documents and
other reports (or copies of such portions of any of the foregoing as the SEC may
by rules and regulations prescribe) which are specified in Sections 13 and 15(d)
of the Exchange Act. The Company also shall comply with the other provisions of
TIA (S)314(a).

        SECTION 4.03    Limitation on Debt.
                        ------------------

                (a) The Company shall not issue, directly or indirectly, any
Debt unless immediately after giving effect to the issuance of such Debt and the
receipt and application of the proceeds thereof the Consolidated EBITDA Coverage
Ratio for the period of the most recently completed four fiscal quarters of the
Company ending at least 45 days prior to the date such Debt is issued exceeds
2.5 to 1.0; provided, however, that nothing herein shall limit the ability of
            --------  -------
the Subsidiaries to incur Debt in accordance with Section 4.04.

                (b) Notwithstanding Section 4.03(a), the Company may issue the
following Debt:

                (1) Debt issued pursuant to the Bank Revolver or any other Bank
        Debt in an aggregate principal amount outstanding at any one time not to
        exceed the greater of $35.0 million or 80% of Eligible Accounts
        Receivable; provided, however, that such amount shall be reduced by the
                    --------  -------
        aggregate outstanding principal amount of all Debt issued pursuant to
        clauses (5), (6) and (7) below and clause (3) under Section 4.04 below;

                (2) Debt owed to and held by a Wholly Owned Subsidiary;
        provided, however, that any subsequent issuance or transfer of any
        Capital Stock which results in any such Wholly Owned Subsidiary ceasing
        to be a Wholly Owned Subsidiary or any transfer of such Debt (other than
        to a Wholly Owned Subsidiary) shall be deemed, in each case, to
        constitute the issuance of such Debt by the Company;

                (3) the Securities and Debt issued in exchange for, or the
        proceeds of which are used to refund or refinance, any Debt permitted by
        this clause (3); provided, however, that (i) the principal amount of the
                         --------  -------
        Debt so issued shall not exceed the principal amount of the Debt so
        exchanged, refunded or refinanced and (ii) the Debt so issued (A) shall
        not mature prior to the Stated Maturity of the Debt so exchanged,
        refunded or refinanced and (B) shall have an Average Life equal to or


                                      22
<PAGE>
 
        greater than the remaining Average Life of the Debt so exchanged,
        refunded or refinanced;

                (4) Debt (other than Debt described in clause (1), (2) or (3)
        above) outstanding on the date on which the Securities were originally
        issued and Debt issued in exchange for, or the proceeds of which are
        used to refund or refinance, any Debt permitted by this clause (4) or by
        clause (4) under Section 4.04 below, or any Debt issued as permitted by
        Section 4.03(a); provided, however, that (i) the principal amount of the
                         --------  -------
        Debt so issued shall not exceed the principal amount of the Debt so
        exchanged, refunded or refinanced and (ii) the Debt so issued (A) shall
        not mature prior to the Stated Maturity of the Debt so exchanged,
        refunded or refinanced and (B) shall have an Average Life equal to or
        greater than the remaining Average Life of the Debt so exchanged,
        refunded or refinanced;

                (5) Debt issued with respect to obligations that are tax-exempt
        pursuant to Section 103 of the Internal Revenue Code of 1986, as from
        time to time amended (the "Code"), and that are issued in connection
        with pollution control facilities or other plant and equipment or other
        facilities of the Company or a Subsidiary; provided, however, that the
                                                   --------  -------
        aggregate principal amount of all Debt permitted by this clause (5)
        outstanding at any one time shall not exceed $10.0 million;

                 (6) Debt issued by the Company, whether or not secured by a
        Lien, constituting all or a part of the purchase price of assets or
        property acquired or constructed in the ordinary course of business
        after the date on which the Securities were originally issued and Debt
        issued by the Company in exchange for, or the proceeds of which are used
        to refund or refinance, any then outstanding Debt permitted by this
        clause (6); provided, however, that (i) the principal amount of the Debt
                    --------  -------
        so issued shall not exceed the principal amount of the Debt so
        exchanged, refunded or refinanced, and (ii) the Debt so issued (A) shall
        not mature prior to the Stated Maturity of the Debt so exchanged,
        refunded or refinanced and (B) shall have an Average Life equal to or
        greater than the remaining Average Life of the Debt so exchanged,
        refunded or refinanced; provided further, however, that the aggregate
                                -------- -------  -------
        principal amount of all Debt permitted by this clause (6) outstanding at
        any one time shall not exceed $10.0 million; and

                (7) Debt (other than Debt described in clauses (1) through (6)
        above and in Section 4.03(a)) in an aggregate principal amount
        outstanding at any time not to exceed $10.0 million minus the aggregate
        outstanding principal amount of all Debt of Subsidiaries issued pursuant
        to clause (3) of Section 4.04 below.

                                      23
<PAGE>
 
                (c) Notwithstanding Sections 4.03(a) and 4.03(b), the Company
shall not issue any Debt (i) if the proceeds thereof are used, directly or
indirectly, to repay, prepay, redeem, defease, retire, refund or refinance any
Subordinated Obligations unless such Debt shall be subordinated to the
Securities to at least the same extent as such Subordinated Obligations or (ii)
if such Debt is subordinate or junior in ranking in any respect to any other
indebtedness unless such Debt is expressly subordinated in right of payment to
the Securities.

        SECTION 4.04 Limitation on Subsidiary Debt and Preferred Stock. The
                     ------------------------------------------------- 
Company shall not permit any Subsidiary to issue, directly or indirectly, any
Debt or Preferred Stock except:

                (1) any Subsidiary Guarantee and any Bank Obligation;

                (2) Debt or Preferred Stock issued to and held by the Company or
        a Wholly Owned Subsidiary; provided, however, that (i) any subsequent
                                   --------  -------
        issuance or transfer of any Capital Stock which results in any such
        Wholly Owned Subsidiary ceasing to be a Wholly Owned Subsidiary, or (ii)
        any subsequent transfer of such Debt or Preferred Stock (other than to
        the Company or a Wholly Owned Subsidiary) shall be deemed, in each case,
        to constitute the issuance of such Debt or Preferred Stock by the issuer
        thereof;

                (3) Debt or Preferred Stock of a Subsidiary issued and
        outstanding on or prior to the date on which such Subsidiary was
        acquired by the Company (other than Debt or Preferred Stock issued as
        consideration in, or to provide all or any portion of the funds or
        credit support utilized to consummate, the transaction or series of
        related transactions pursuant to which such Subsidiary became a
        Subsidiary or was acquired by the Company); provided, however, that the
                                                    --------  -------
        aggregate principal amount or liquidation value of such Debt and
        Preferred Stock permitted by this clause (3) outstanding at any one time
        shall not exceed $10.0 million;

                (4) Debt or Preferred Stock (other than Debt or Preferred Stock
        described in clauses (1) through (3) above) outstanding on the date of
        this Indenture; and

                (5) Debt or Preferred Stock issued in exchange for, or the
        proceeds of which are used to refinance, Debt or Preferred Stock
        referred to in the foregoing clause (3) or (4); provided, however, that
                                                        --------  -------
        (i) the principal amount or liquidation value of such Debt or Preferred
        Stock so issued shall not exceed the principal amount or liquidation
        value of the Debt or Preferred Stock so exchanged, refunded or
        refinanced and (ii) the Debt or Preferred Stock so issued (A) shall have
        a Stated Maturity later than the Stated Maturity of the Debt or
        Preferred Stock so exchanged, refunded or 

                                      24
<PAGE>
 
        refinanced and (B) shall have an Average Life equal to or greater than
        the remaining Average Life of the Debt or Preferred Stock so exchanged,
        refunded or refinanced.

        SECTION 4.05 Limitation on Liens. The Company shall not, and shall not
                     -------------------
permit any Subsidiary to, create or permit to exist any Lien upon any of its
property or assets, now owned or hereafter acquired, securing any obligation
unless concurrently with the creation of such Lien effective provision is made
to secure the Securities equally and ratably with such obligation for so long as
such obligation is so secured; provided, however, that if such obligation is a
                               --------  -------
Subordinated Obligation, the Lien securing such obligation shall be subordinated
and junior to the Lien securing the Securities with the same or lesser relative
priority as such Subordinated Obligation shall have with respect to the
Securities. The preceding restriction shall not require the Company or any
Subsidiary to equally and ratably secure the Securities if the Lien consists of
the following:

                (1) Liens created by the Indenture and Liens existing as of the
        date on which the Securities were originally issued;

                (2) Permitted Liens;

                (3) Liens to secure Debt issued by the Company for the purpose
        of financing all or a part of the purchase price of assets or property
        acquired or constructed in the ordinary course of business after the
        date on which the Securities were originally issued; provided, however,
                                                             --------  -------
        that (i) the aggregate principal amount (or accreted value in the case
        of Debt issued at a discount) of Debt so issued shall not exceed the
        lesser of cost or Fair Market Value, as determined in good faith by the
        Board of Directors of the Company, of the assets or property so acquired
        or constructed, (ii) the Debt secured by such Liens shall have been
        permitted to be issued under Section 4.03(b)(6) and (iii) such Liens
        shall not encumber any other assets or property of the Company or any of
        its Subsidiaries other than such assets or property or any improvement
        on such assets or property and shall attach to such assets or property
        within 90 days of the construction or acquisition of such assets or
        property;

                (4) Liens on the assets or property of a Subsidiary existing at
        the time such Subsidiary became a Subsidiary and not issued as a result
        of (or in connection with or in anticipation of) such Subsidiary
        becoming a Subsidiary; provided, however, that (i) the Debt secured by
                               --------  -------
        such Liens shall have been permitted to be issued under clause (3) of
        Section 4.04 above and (ii) such Liens do not extend to or cover any
        other property or assets of the Company or any of its other
        Subsidiaries;


                                      25
<PAGE>
 
                (5) Liens on the assets of the Company or any Subsidiary that is
        a guarantor thereof or which acts as a co-borrower thereunder securing
        Debt under the Bank Revolver or other revolving credit agreement
        permitted under Section 4.03(b)(1) above;

                (6) Liens securing industrial revenue or pollution control bonds
        issued by the Company; provided, however, that (i) the aggregate
                               --------  -------  
        principal amount of Debt secured by such Liens shall not exceed the
        lesser of cost or Fair Market Value, as determined in good faith by the
        Board of Directors of the Company, of the assets or property so
        financed, (ii) the Debt secured by such Liens shall have been permitted
        to be issued under clause (5) of Section 4.03 above, and (iii) such
        Liens do not extend to or cover any other property or assets of the
        Company; or

                (7) Liens securing Debt issued to refinance Debt which has been
        secured by a Lien permitted under this Indenture and is permitted to be
        refinanced under this Indenture; provided, however, that such Liens do
                                         --------  -------
        not extend to or cover any property or assets of the Company or any of
        its Subsidiaries not securing the Debt so refinanced, and the principal
        amount (or accreted value) of the Debt so secured is not increased
        except as otherwise permitted pursuant to this Indenture.

        SECTION 4.06 Limitation on Sale/Leaseback Transactions. The Company
                     -----------------------------------------
shall not, and shall not permit any Subsidiary to, enter into, Guarantee or
otherwise become liable with respect to any Sale/Leaseback Transaction unless at
least one of the following conditions is satisfied:

                (1) The Company or such Subsidiary, pursuant to Sections 4.05(2)
        through (7) could create a Lien on the property to secure Debt in an
        amount at least equal to the Attributable Debt in respect of such
        Sale/Leaseback Transaction and the Company or such Subsidiary, as the
        case may be, receives consideration at least equal to the Fair Market
        Value, as determined in good faith by the Board of Directors of the
        Company, of the property transferred; or

                (2) the Sale/Leaseback Transaction is treated as an Asset
        Disposition and all the conditions of Section 4.10 are satisfied with
        respect to such Sale/Leaseback Transaction (without giving effect to the
        exceptions for Net Available Cash, as set forth in Section 4.10(a)).

        SECTION 4.07    Limitation on Restricted Payments.
                        ---------------------------------

                (a) The Company shall not, and shall not permit any Subsidiary,
directly or indirectly, to (i) declare or pay any dividend or make any
distribution on or in respect of its Capital Stock (including any payment in
connection with any merger or consolidation

                                      26
<PAGE>
 
involving the Company) or to the direct or indirect holders of its Capital Stock
(except dividends or distributions payable solely in its Non-Convertible Capital
Stock or in options, warrants or other rights to purchase its Non-Convertible
Capital Stock and except dividends or distributions payable to the Company or a
Wholly Owned Subsidiary), (ii) purchase, redeem or otherwise acquire or retire
for value any of its Capital Stock (except Capital Stock of a Wholly Owned
Subsidiary), (iii) purchase, repurchase, redeem, defease or otherwise acquire or
retire for value, prior to scheduled maturity, scheduled repayment or scheduled
sinking fund payment, any Subordinated Obligations (other than the purchase,
repurchase or other acquisition of Subordinated Obligations purchased in
anticipation of satisfying a sinking fund obligation, principal installment or
final maturity, in each case due within one year of the date of acquisition) or
(iv) make any Investment other than Permitted Investments (any such dividend,
distribution, purchase, redemption, repurchase, defeasance, other acquisition,
retirement or Investment being herein referred to as a "Restricted Payment"), if
at the time the Company or such Subsidiary makes such Restricted Payment:

                (1) a Default shall have occurred and be continuing (or would
        result therefrom); or

                (2) upon giving effect to such Restricted Payment, the Company
        is not able to incur an additional $1.00 of Debt pursuant to the
        Consolidated EBITDA Coverage Ratio as set forth in Section 4.03(a); or

                (3) upon giving effect to such Restricted Payment, the aggregate
        amount of such Restricted Payment and all other Restricted Payments
        since the date on which the Securities were originally issued would
        exceed the sum of:

                    (a) 50% of the Consolidated Net Income accrued during the
            period (treated as one accounting period) from the first day of the
            first month of the fiscal quarter in which Securities were
            originally issued through the last full fiscal quarter for which
            quarterly or annual financial statements are available prior to the
            date of such Restricted Payment (or, in case such Consolidated Net
            Income shall be a deficit, minus 100% of such deficit); provided,
                                                                    --------  
            however, that if a Public Offering as described in Section 4.08
            -------
            below has been consummated, Consolidated Net Income for the purposes
            of this clause (iv)(3)(a) shall be reduced by an amount equal to the
            net income of CHTC from the date of the original issuance of the
            Securities to the date of the closing of the Public Offering;

                    (b) the aggregate Net Cash Proceeds received by the Company
            from the issue or sale of its Capital Stock (other than Redeemable
            Stock or Exchangeable Stock) subsequent to the date on which the
            Securities


                                      27
<PAGE>
 
            were originally issued (other than an issuance or sale to a
            Subsidiary or an employee stock ownership plan or similar trust);

                    (c) the aggregate Net Cash Proceeds received by the Company
            from the issue or sale of its Capital Stock (other than Redeemable
            Stock or Exchangeable Stock) to an employee stock ownership plan
            subsequent to the date on which the Securities were originally
            issued, but (if such employee stock ownership plan incurs any Debt)
            only to the extent that any such proceeds are equal to any increase
            in the Consolidated Net Worth of the Company resulting from
            principal repayments made by such employee stock ownership plan with
            respect to indebtedness incurred by it to finance the purchase of
            such Capital Stock; and

                    (d) the amount by which consolidated Debt of the Company is
            reduced on the Company's balance sheet upon the conversion or
            exchange (other than by a Subsidiary) subsequent to the date on
            which the Securities were originally issued, of any Debt of the
            Company convertible or exchangeable for Capital Stock (other than
            Redeemable Stock or Exchangeable Stock) of the Company (less the
            amount of any cash, or other property, distributed by the Company
            upon such conversion or exchange).

            (b) So long as no Default shall have occurred and be continuing (or
would result therefrom) the provisions of Section 4.07(a) shall not prohibit:

                        (i) any purchase or redemption of Capital Stock or
        Subordinated Obligations of the Company made by exchange for, or out of
        the proceeds of the substantially concurrent sale of, Capital Stock of
        the Company (other than Redeemable Stock or Exchangeable Stock and other
        than Capital Stock issued or sold to a Subsidiary or an employee stock
        ownership plan); provided, however, that (A) such purchase or redemption
                         --------  ------- 
        shall be excluded in the calculation of the amount of Restricted
        Payments and (B) the Net Cash Proceeds from such sale shall be excluded
        from clauses (3)(b) and (3)(c) of Section 4.07(a);

                        (ii) any purchase or redemption of Subordinated
        Obligations of the Company made by exchange for, or out of the proceeds
        of the substantially concurrent sale of, Debt of the Company other than
        to a Subsidiary; provided, however, that such Debt (A) shall be
                         --------  -------
        subordinated to the Securities to at least the same extent as the
        Subordinated Obligations so exchanged, purchased or redeemed, (B) shall
        have a Stated Maturity later than the Stated Maturity of the Securities
        and (C) shall have an Average Life greater than the remaining Average
        Life of the Securities; provided further, however, that such purchase or
                                -------- -------  -------
        redemption shall be excluded in the calculation of the amount of
        Restricted Payments;


                                      28
<PAGE>
 
                        (iii) any purchase or redemption of Subordinated
        Obligations from Net Available Cash to the extent permitted by Section
        4.10; provided, however, that such purchase or redemption shall be
              --------  -------
        excluded in the calculation of the amount of Restricted Payments; or

                        (iv) dividends paid within 60 days after the date of
        declaration thereof if at such date of declaration such dividend would
        have complied with this Section; provided, however, that at the time of
                                         --------  -------
        payment of such dividend, no other Default shall have occurred and be
        continuing (or result therefrom); provided further, however, that such
                                          -------- -------  -------
        dividend shall be included in the calculation of the amount of
        Restricted Payments.

        SECTION 4.08 Limitation on Issuance and Sale of Capital Stock of
                     ---------------------------------------------------
Subsidiaries. The Company shall not permit any Subsidiary to issue or sell any
- ------------ 
Capital Stock to any person, or permit any person in either case, other than the
Company and its Wholly Owned Subsidiaries, to own or hold an interest, other
than any Lien permitted by Section 4.05 or any interest or right to receive any
interest owned or held on the date on which the Securities were originally
issued by a person other than the Company and its Wholly Owned Subsidiaries, in
any Capital Stock of any Subsidiary; provided, however, that the foregoing
                                     --------  -------
limitation shall not apply to (i) the sale of all but not less than all of the
Capital Stock of any Subsidiary made in accordance with Section 4.10 hereof, and
(ii) the issuance and sale of Capital Stock of Clean Harbors Technology
Corporation ("CHTC") pursuant to one or more firm commitment underwritten public
offerings by CHTC (each a "Public Offering"); provided, however, that (1)
                                              --------  -------
following each Public Offering the Company shall continue to own at least 75% of
the outstanding Capital Stock of CHTC, (2) the net proceeds from each Public
Offering shall be invested by CHTC in the business of CHTC, (3) CHTC may not
within 18 months after the closing of the Public Offering (A) declare or pay any
dividend or make any distribution on or in respect of its Capital Stock
(including any payment in connection with any merger or consolidation involving
CHTC) or to the direct or indirect holders of its Capital Stock (except
dividends or distributions payable solely in its Non-Convertible Capital Stock
or in options, warrants or other rights to purchase its Non-Convertible Capital
Stock) or (B) purchase, redeem or otherwise acquire or retire for value any
Capital Stock of CHTC, and (4) as of the date of commencement of each Public
Offering the Adjusted EBITDA for the period of the most recently completed four
fiscal quarters of the Company ending at least 45 days prior to such date
exceeds 95% of EBITDA for such period, provided, however, that (A) if the
Company or any Subsidiary has issued any Debt since the beginning of such period
that remains outstanding, EBITDA and Adjusted EBITDA for such period shall be
calculated after giving effect on a pro forma basis to such Debt as if such Debt
had been issued on the first day of such period and the discharge of any other
Debt refinanced, refunded, exchanged or otherwise discharged with the proceeds
of such new Debt as if any such discharge had occurred on the first day of such
period, (B) if since the beginning of such period the Company or any Subsidiary
shall have made any Asset 

                                      29
<PAGE>
 
Disposition, EBITDA and Adjusted EBITDA for such period shall be reduced by an
amount equal to the EBITDA (if positive) directly attributable to the assets
which are the subject of such Asset Disposition for such period, or increased by
an amount equal to the EBITDA (if negative) directly attributable thereto for
such period, and (C) if since the beginning of such period the Company or any
Subsidiary (by merger or otherwise) shall have made an Investment in any
Subsidiary (or any person which becomes a Subsidiary) or an acquisition of
assets, including any acquisition of assets occurring in connection with a
transaction causing a calculation to be made hereunder, which constitutes all of
an operating unit of a business, EBITDA and Adjusted EBITDA for such period
shall be calculated after giving pro forma effect thereto (including the
issuance of any Debt), as if such Investment or acquisition occurred on the
first day of such period. For purposes of this calculation, whenever pro forma
effect is to be given to an acquisition of assets, the amount of income or
earnings relating thereto, and the amount of Consolidated Interest Expense
associated with any Debt issued in connection therewith, the pro forma
calculations shall be determined in good faith by a responsible financial or
accounting Officer of the Company. If any Debt bears a floating rate of interest
and is being given pro forma effect, the interest on such Debt shall be
calculated as if the rate in effect on the date of determination had been the
applicable rate for the entire period.

        SECTION 4.09 Limitation on Restrictions on Distributions from
                     ------------------------------------------------
Subsidiaries. The Company shall not, and shall not permit any Subsidiary to,
- ------------ 
create or otherwise cause or permit to exist or become effective any consensual
encumbrance or restriction on the ability of any Subsidiary to (i) pay dividends
or make any other distributions on its Capital Stock or pay any Debt or other
obligation owed to the Company or any Subsidiary, (ii) make any loans or
advances to the Company or any Subsidiary, or (iii) transfer any of its property
or assets to the Company or any Subsidiary. Notwithstanding the foregoing, the
Company may, and may permit any Subsidiary to, suffer to exist:

                (1) any encumbrance or restriction pursuant to an agreement in
        effect at or entered into on or prior to the date on which the
        Securities were originally issued;

                (2) any encumbrance or restriction with respect to a Subsidiary
        pursuant to an agreement relating to any Debt issued by such Subsidiary
        on or prior to the date on which such Subsidiary became a Subsidiary of
        the Company (other than Debt issued as consideration in, or to provide
        all or any portion of the funds utilized to consummate, the transaction
        or series of related transactions pursuant to which such Subsidiary
        became a Subsidiary or was acquired by the Company) and outstanding on
        such date;

                (3) any encumbrance or restriction pursuant to an agreement
        effecting a refinancing or extension of Debt issued pursuant to an
        agreement referred


                                      30
<PAGE>
 
        to in clause (1) or (2) of this Section or contained in any amendment to
        an agreement referred to in clause (1) or (2) of this Section; provided,
                                                                       --------
        however, that the encumbrances and restrictions contained in any such
        -------
        refinancing or extension agreement or amendment are not materially less
        favorable to the Securityholders than encumbrances and restrictions
        contained in such agreements referred to in clause (1) or (2) above;

                (4) any encumbrance or restriction consisting of customary
        nonassignment provisions in leases governing leasehold interests to the
        extent such provisions restrict the transfer of the lease;

                (5) in the case of clause (iii) above, restrictions contained in
        security agreements securing Debt of a Subsidiary otherwise permitted by
        this Indenture to the extent such restrictions restrict the transfer of
        the property subject to such security agreements; and

                (6) restrictions imposed pursuant to clause (ii) of Section 4.08
        above.

        SECTION 4.10    Limitation on Sales of Assets and Subsidiary Stock.
                        --------------------------------------------------

                (a) The Company shall not, and shall not permit any Subsidiary
to, make any Asset Disposition unless: (i) the Company or such Subsidiary
receives consideration at the time of such Asset Disposition at least equal to
the Fair Market Value, as determined in good faith, with or without independent
appraisal, by the Board of Directors of the Company (including as to the value
of all non-cash consideration), of the shares and assets subject to such Asset
Disposition and at least 85% of the consideration thereof received by the
Company or such Subsidiary is in the form of cash or Cash Equivalents; and (ii)
an amount equal to 100% of the Net Available Cash from such Asset Disposition is
applied by the Company (or such Subsidiary, as the case may be) (A) first, to
the extent the Company is required by the terms of any Debt to prepay, repay or
purchase Debt (other than any Redeemable Stock) of the Company, such Subsidiary
or any Wholly Owned Subsidiary (in each case other than Debt owed to the Company
or an Affiliate of the Company) within 60 days from the later of the date of
such Asset Disposition or the receipt of such Net Available Cash; (B) second, to
the extent of the balance of such Net Available Cash after application in
accordance with clause (A), at the Company's election to the investment by the
Company, such Subsidiary or any Wholly Owned Subsidiary in assets to replace the
assets that were the subject of such Asset Disposition or in assets that (as
determined by the Board of Directors) will be used in the businesses of the
Company and its Wholly Owned Subsidiaries existing on the date on which the
Securities were originally issued or in businesses reasonably related thereto,
in all cases within the later of one year from the date of such Asset
Disposition or the receipt of such Net Available Cash; (C) third, to the extent
of the balance of such Net 

                                      31
<PAGE>
 
Available Cash after application in accordance with clauses (A) and (B) above,
to make an offer pursuant to and subject to this Indenture, to the holders of
the Securities to purchase Securities at a purchase price of 100% of the
principal amount thereof plus accrued and unpaid interest; and (D) fourth, to
the extent of the balance of such Net Available Cash after application in
accordance with clauses (A), (B) and (C) above, to the prepayment, repayment or
purchase of Debt (other than any Redeemable Stock) of the Company (other than
Debt owed to an Affiliate of the Company) or Debt of any Subsidiary (other than
Debt owed to the Company or an Affiliate of the Company), in each case within
one year from the later of the receipt of such Net Available Cash and, if
applicable, the date the offer described in the next paragraph below is
consummated; provided, however, that in connection with any prepayment,
             --------  -------
repayment or purchase of Debt pursuant to clause (A) or clause (D) above, the
Company shall cause the related loan commitment (if any) to be permanently
reduced in an amount equal to the principal amount so prepaid, repaid or
purchased; and provided, further, however, that in connection with an offer
pursuant to clause (C) above, if the principal amount of such Securities,
together with accrued and unpaid interest, tendered for acceptance pursuant to
such offer exceeds the balance of Net Available Cash, then the Company will
accept for purchase the Securities of each such tendering holder on a pro rata
basis in accordance with the principal amount so tendered.

        Notwithstanding the provisions of clause (ii) above, in the event that
the Net Available Cash resulting from any Asset Disposition is less than $2.5
million, the application of an amount equal to such Net Available Cash in
accordance with such clause (ii) may be deferred until such time as such Net
Available Cash from any prior or subsequent Asset Dispositions not otherwise
applied in accordance with such clause (ii), is at least equal to $2.5 million.
In the event that the Net Available Cash resulting from any Asset Disposition,
after giving effect to clauses (A) and (B) above, is less than $2.5 million, the
application of such amount equal to such Net Available Cash to make an offer to
purchase Securities in accordance with clause (C) above may be deferred until
such time as such Net Available Cash, together with Net Available Cash from any
prior or subsequent Asset Dispositions not otherwise applied in accordance with
this provision, is at least equal to $2.5 million. Pending application of Net
Available Cash pursuant to this Section 4.10, such Net Available Cash shall be
invested in Cash Equivalents. To the extent any portion of the amount of Net
Available Cash remains after compliance with this Section 4.10 and provided that
all holders of Securities have been given the opportunity to tender their
Securities for repurchase as provided in subsection (a)(ii)(C) above, the
Company may use such remaining amount for general corporate purposes.

                (b) In the event of an Asset Disposition that requires the
purchase of Securities pursuant to Section 4.10(a)(ii)(C), the Company will be
required to purchase Securities tendered pursuant to an offer by the Company for
the Securities (the "Offer") at a purchase price set forth in Section 4.10(a) in
accordance with the procedures (including prorationing in the event of
oversubscription) set forth in Section 4.10(c).

                                      32
<PAGE>
 
                (c) (1) Promptly, and in any event within 5 days after the date
by which the Company must have applied Net Available Cash pursuant to Section
4.10(a)(ii)(B), the Company shall be obligated to deliver to the Trustee and
send, by first-class mail to each Holder, a written notice stating that the
Holder may elect to have his Securities purchased by the Company either in whole
or in part (subject to prorationing as hereinafter described in the event the
Offer is oversubscribed) in integral multiples of $1,000 of principal amount, at
the applicable purchase price. The notice shall specify a purchase date not less
than 30 days nor more than 60 days after the date of such notice (the "Purchase
Date") and shall contain information concerning the business of the Company
which the Company in good faith believes will enable such Holders to make an
informed decision (which at a minimum will include (i) the most recently filed
Annual Report on Form 10-K (including audited consolidated financial statements)
of the Company, the most recent subsequently filed Quarterly Report on Form 10-Q
and any Current Report on Form 8-K of the Company filed subsequent to such
Quarterly Report, other than Current Reports describing Asset Dispositions
otherwise described in the offering materials (or corresponding successor
reports), (ii) a description of material developments in the Company's business
subsequent to the date of the latest of such Reports, and (iii) if material,
appropriate pro forma financial information and all instructions and materials
necessary to tender Securities pursuant to the Offer, together with the
information contained in subsection (c)(3) below.

                    (2) Not later than the date upon which written notice of an
Offer is delivered to the Trustee as provided in subsection (c)(1) above, the
Company shall deliver to the Trustee an Officers' Certificate as to (i) the
amount of the Offer (the "Offer Amount"), (ii) the allocation of the Net
Available Cash from the Asset Dispositions pursuant to which such Offer is being
made and (iii) the compliance of such allocation with the provisions of Section
4.10. On such date, the Company shall irrevocably deposit with the Trustee or
with a paying agent (or, if the Company or a Subsidiary is acting as its own
paying agent, segregate and hold in trust) in immediately available funds an
amount equal to the Offer Amount to be held for payment in accordance with the
provisions of this Section 4.10. The amount so deposited, at the option of, and
pursuant to the specific written direction of, the Company, may be invested in
Cash Equivalents the maturity date of which is not later than the Purchase Date.
The Company shall be entitled to any interest or dividends accrued, earned or
paid on such Cash Equivalents. Upon the expiration of the period for which the
Offer remains open (the "Offer Period"), the Company shall deliver to the
Trustee the Securities or portions thereof which have been properly tendered to
and are to be accepted by the Company. The Trustee shall, on the Purchase Date,
mail or deliver payment to each tendering Holder in the amount of the purchase
price. In the event that the aggregate purchase price of the Securities
delivered by the Company to the Trustee is less than the Offer Amount, the
Trustee shall deliver the excess to the Company immediately after the expiration
of the Offer Period.


                                      33
<PAGE>
 
                    (3) Holders electing to have a Security purchased will be
required to surrender the Security, with an appropriate form duly completed, to
the Company at the address specified in the notice at least 10 Business Days
prior to the Purchase Date. Holders will be entitled to withdraw their election
if the Trustee or the Company receives not later than three Business Days prior
to the Purchase Date, a telegram, telex, facsimile transmission or letter
setting forth the name of the Holder, the principal amount of the Security which
was delivered for purchase by the Holder and a statement that such Holder is
withdrawing its election to have such Security purchased. If at the expiration
of the Offer Period the purchase price of Securities surrendered by Holders
exceeds the Offer Amount, the Company shall select the Securities and such other
Senior Subordinated Debt to be purchased on a pro rata basis (with such
adjustments as may be deemed appropriate by the Company so that only Securities
in denominations of $1,000, or integral multiples thereof, shall be purchased).
Holders whose Securities are purchased only in part will be issued new
Securities equal in principal amount to the unpurchased portion of the
Securities surrendered. The Company shall promptly execute, and the Guarantor
Subsidiaries shall promptly execute their Subsidiary Guarantees to be endorsed
thereon and thereafter the Trustee shall promptly authenticate and mail or
deliver to such Holders a new Security equal in principal amount to any
unpurchased portion of the Security surrendered. Any Security not accepted for
payment shall be promptly mailed or delivered by the Company to the Holder
thereof. The Company shall publicly announce the results of the Offer on or as
soon as practicable after the Purchase Date.

                    (4) At the time the Company delivers Securities to the
Trustee which are to be accepted for purchase, the Company will also deliver an
Officers' Certificate stating that such Securities are to be accepted by the
Company pursuant to and in accordance with the terms of this Section. A Security
shall be deemed to have been accepted for purchase at the time the Trustee,
directly or through an agent, mails or delivers payment therefor to the
surrendering Holder.

                (d) The Company shall comply, to the extent applicable, with the
requirements of Section 14(e) of the Exchange Act and any other securities laws
or regulations in connection with the repurchase of Securities pursuant to this
Section. To the extent that the provisions of any securities laws or regulations
conflict with provisions of this Indenture, the Company shall comply with the
applicable securities laws and regulations and shall not be deemed to have
breached its obligations under this Indenture by virtue thereof.

        SECTION 4.11 Limitation on Transactions with Affiliates. The Company
                     ------------------------------------------
shall not, and shall not permit any Subsidiary to, conduct any business or enter
into any transaction or series of similar transactions (including the purchase,
sale, lease or exchange of any property or the rendering of any service) with
any Affiliate of the Company or any legal or beneficial owner of 5% or more of
any class of Capital Stock of the Company or with any Affiliate of any such
owner (other than (i) a Wholly Owned Subsidiary or (ii) an

                                      34
<PAGE>
 
employee stock ownership plan for the benefit of the Company's or a Subsidiary's
employees), unless the terms of such business, transaction or series of
transactions are (A) set forth in writing, (B) as favorable to the Company or
such Subsidiary as terms that would be obtainable at the time for a comparable
transaction or series of similar transactions in arm's-length dealings with an
unrelated third person and (C) if such business or transaction or series of
transactions involves in excess of $1.0 million, (x) the Board of Directors of
the Company has, by resolution approved by a majority of the disinterested
directors, determined in good faith that such business or transaction or series
of transactions meets the criteria set forth in clause (B) above, and (y) the
Company has obtained an opinion of a nationally recognized expert with
experience in appraising the terms and conditions of the type of business or
transaction or series of transactions stating that such business or transaction
or series of transactions is fair (from a financial point of view) to the
Company or such Subsidiary, as the case may be. This Section, however, will not
prohibit (1) any transactions between the Company or a Subsidiary and its own
employee stock ownership plan, (2) Restricted Payments permitted under Section
4.07 or (3) management compensation arrangements approved by the disinterested
members of the Board of Directors.

         SECTION 4.12 Lines of Business. The Company shall not, and shall not
                      -----------------
permit any of its Subsidiaries to, enter into any business, either directly or
through any Subsidiary, except for those businesses in which the Company and its
Subsidiaries were engaged on the date on which the Securities were originally
issued or businesses reasonably related thereto.

        SECTION 4.13 Compliance Certificate.
                     ---------------------- 

                (a) The Company and the Guarantor Subsidiaries shall deliver to
the Trustee, within 120 days after the end of each fiscal year, an Officers'
Certificate, one of the signers of which shall be the principal executive
officer, principal financial officer or principal accounting officer, stating
whether or not to the best knowledge of the signers thereof the Company or the
Guarantor Subsidiaries, as the case may be, have fulfilled all their obligations
hereunder, are not in default in the performance and observance of any of the
terms, and if the Company or the Guarantor Subsidiaries, as the case may be,
shall be in default, specifying all such defaults and the nature and status
thereof of which they may have knowledge. For purposes of this Section 4.13,
such compliance or default shall be determined without regard to any period of
grace or requirement of notice provided under this Indenture.

                (b) The Company and each Guarantor Subsidiary shall deliver to
the Trustee, as soon as possible and in any event within 30 days after the
Company or any Guarantor Subsidiary becomes aware or should reasonably become
aware of the occurrence of an Event of Default or an event which, with notice or
the lapse of time or both, would constitute an Event of Default, an Officers'
Certificate setting forth the details of such Event

                                      35
<PAGE>
 
of Default or default, and the action which the Company or any Guarantor
Subsidiary proposes to take with respect thereto.

        SECTION 4.14    Change of Control.
                        -----------------

                (a) Upon the occurrence of a Change of Control, each Holder
shall have the right to require that the Company repurchase such Holder's
Securities at a purchase price in cash equal to 101% of the principal amount
thereof plus accrued and unpaid interest, if any, to the date of repurchase, in
accordance with the terms contemplated in this Section 4.14.

                (b) Within 30 days following any Change of Control, the Company
shall send by first-class mail, postage prepaid a notice to each Holder at his
address appearing in the Security register, with a copy to the Trustee stating:

                    (1) that a Change of Control has occurred and that such
            Holder has the right to require the Company to purchase such
            Holder's Securities at a repurchase price in cash equal to 101% of
            the principal amount thereof plus accrued and unpaid interest, if
            any, to the date of repurchase;

                    (2) the circumstances and relevant facts regarding such
            Change of Control (including information with respect to pro forma
            historical income, cash flow and capitalization after giving effect
            to such Change of Control);

                    (3) the repurchase date (the "Change of Control Payment
            Date") which shall be no earlier than 30 days nor later than 60 days
            from the date such notice is mailed; and

                   (4) the instructions determined by the Company, consistent
            with this Section, that a Holder must follow in order to have its
            Securities purchased.

                (c) Holders electing to have a Security purchased will be
required to surrender the Security, with an appropriate form duly completed, to
the Company at the address specified in the notice at least three Business Days
prior to the purchase date. Holders will be entitled to withdraw their election
if the Trustee or the Company receives not later than three Business Days prior
to the purchase date, a telegram, telex, facsimile transmission or letter
setting forth the name of the Holder, the principal amount of the Securities
which were delivered for repurchase by the Holder as to which its election is to
be withdrawn and a statement that such Holder is withdrawing its election to
have such Securities repurchased. Holders whose Securities are repurchased only
in part will be issued new Securities equal in principal amount to the
unpurchased portion of the Securities surrendered.


                                      36
<PAGE>
 
                (d) On the Change in Control Payment Date, the Company shall (i)
accept for payment Securities or portions thereof tendered pursuant to the
Change in Control Offer, (ii) deposit with the Paying Agent money sufficient to
pay the purchase price of all Securities or portions thereof so tendered, and
(iii) deliver to the Trustee Securities so accepted together with an Officers'
Certificate stating the Securities or portions thereof tendered to the Company.
The Paying Agent shall promptly mail to the Holder of Securities so accepted
payment in an amount equal to the purchase price, and the Trustee shall promptly
authenticate and mail to such Holders a new Security equal in principal amount
to any unpurchased portion of the Security surrendered.

                (e) The Company shall comply, to the extent applicable, with the
requirements of Section 14(e) of the Exchange Act and any other securities laws
or regulations in connection with the repurchase of Securities pursuant to a
Change of Control.

        SECTION 4.15 Additional Subsidiary Guarantees. If the Company or any of
                     --------------------------------
its Subsidiaries shall, after the date of this Indenture, create or acquire any
Subsidiary, then such newly created or acquired Subsidiary shall and the Company
shall cause such Subsidiary to, promptly, but in no event later than 15 days
following the date any Person shall become a Subsidiary, execute and deliver to
the Trustee a supplemental indenture substantially in the form of Exhibit B
hereof, pursuant to which such Subsidiary shall Guarantee all of the Obligations
of the Company with respect to the Securities as provided in Article 10 hereof,
together with an Opinion of Counsel, all as set forth in Section 10.04 hereof.

        SECTION 4.16 Corporate Existence. Subject to Article 5 hereof, the
                     -------------------
Company will do or cause to be done all things necessary to preserve and keep in
full force and effect the corporate existence, rights (charter and statutory),
licenses and franchises of the Company and each Guarantor Subsidiary.

        SECTION 4.17 Further Instruments and Acts. Upon request of the Trustee,
                     ----------------------------
the Company and each Guarantor Subsidiary will execute and deliver such further
instruments and do such further acts as may be reasonably necessary or proper to
carry out more effectively the purpose of this Indenture.


                         ARTICLE 5 - Successor Company
                                     -----------------

        SECTION 5.01 When Company May Merge or Transfer Assets. The Company
                     -----------------------------------------
shall not consolidate with or merge with or into, or convey, transfer or lease
all or substantially all its assets to, any person, unless:

                        (i) the resulting, surviving or transferee person (if
        not the Company) shall be a person organized and existing under the laws
        of the United

                                      37
<PAGE>
 
        States of America, any State thereof or the District of Columbia and
        such person shall expressly assume, by an indenture supplemental hereto,
        executed and delivered to the Trustee, in form satisfactory to the
        Trustee, all the obligations of the Company under the Securities and
        this Indenture;

                        (ii) immediately after giving effect to such transaction
        (and treating any Debt which becomes an obligation of the resulting,
        surviving or transferee person or any Subsidiary as a result of such
        transaction as having been issued by such person or such Subsidiary at
        the time of such transaction), no Default shall have occurred and be
        continuing;

                        (iii) immediately after giving effect to such
        transaction, on a pro forma basis, the resulting, surviving or
        transferee person would be able to issue at least an additional $1.00 of
        Debt pursuant to Section 4.03(a) hereof;

                        (iv) immediately after giving effect to such
        transaction, on a pro forma basis, the resulting, surviving or
        transferee person shall have Consolidated Net Worth in an amount which
        is not less than the Consolidated Net Worth of the Company immediately
        prior to such transaction; and

                        (v) the Company shall have delivered to the Trustee an
        Officers' Certificate and an Opinion of Counsel, each stating that such
        consolidation, merger or transfer and such supplemental indenture (if
        any) comply with this Indenture.

        The resulting, surviving or transferee person shall be the successor
Company and shall succeed to, and be substituted for, and may exercise every
right and power of, the Company under this Indenture, but the predecessor
Company in the case of a conveyance, transfer or lease shall not be released
from the obligation to pay the principal of and interest on the Securities.

                       ARTICLE 6 - Defaults and Remedies
                                   ---------------------

        SECTION 6.01 Events of Default. Wherever used herein, "Event of Default"
                     -----------------
means any one of the following events (whatever the reason for such Event of
Default and whether it shall be voluntary or involuntary or be effected by
operation of law or pursuant to any judgment, decree or order of any court or
any order, rule or regulation of any administrative agency or governmental
body):

                (1) a default in any payment of interest on the Securities when
        due, continued for 30 days;


                                      38
<PAGE>
 
                (2) a default in the payment of principal of any Security when
        due at its Stated Maturity, upon redemption, upon acceleration or
        otherwise, or the failure to redeem or purchase the Securities when
        required pursuant to the Indenture or the Securities;

                (3) the failure by the Company to comply with its obligations
        under Section 5.01 hereof, to make or consummate an Offer in accordance
        with the provisions of Section 4.10 hereof or to make or consummate a
        Change of Control Offer in accordance with the provisions of Section
        4.14 hereof;

                (4) the failure by the Company to observe or comply with any of
        the agreements in the Securities or this Indenture (other than those
        referred to in clauses (1), (2) or (3) above), which continues for 60
        days after there has been given to the Company by the Trustee or to the
        Company and the Trustee by the Holders of at least 25% in principal
        amount of the then outstanding Securities a written notice specifying
        such failure;

                (5) Debt of the Company or any Subsidiary is not paid within any
        applicable grace period after final maturity or is accelerated by the
        holders thereof because of a default and the total amount of such Debt
        unpaid or accelerated exceeds $5.0 million;

                (6) any judgment or decree for the payment of money in excess of
        $5.0 million is rendered and entered against the Company or a Subsidiary
        and is not discharged and either (A) an enforcement proceeding has been
        commenced by any creditor upon such judgment or decree or (B) there is a
        period of 60 days following such judgment or decree during which such
        judgment or decree is not discharged, waived or the execution thereof
        stayed; or

                (7) any Subsidiary Guarantee issued by any Guarantor Subsidiary
        ceases to be in full force and effect other than in accordance with its
        terms, or any Guarantor Subsidiary shall deny or disaffirm its
        obligations under its Subsidiary Guarantee; or

                (8) the Company or any Subsidiary pursuant to or within the
        meaning of any Bankruptcy Law:

                    (A) commences a voluntary case;

                    (B) consents to the entry of an order for relief against it
            in an involuntary case;


                                      39
<PAGE>
 
                    (C) consents to the appointment of a Custodian of it or for
            any substantial part of its property;

                    (D) makes a general assignment for the benefit of its
            creditors; or

                    (E) admits in writing its inability to pay any debts as the
            same become due; or

                (9) a court of competent jurisdiction enters an order or decree
        under any Bankruptcy Law that:

                    (A) is for relief against the Company or any Subsidiary in
            an involuntary case;

                    (B) appoints a Custodian of the Company or any Subsidiary or
            for all or any substantial part of its property; or

                    (C) orders the winding up or liquidation of the Company or
            any Subsidiary;

and the order or decree remains unstayed and in effect for 60 days.

        The term "Bankruptcy Law" means Title 11, United States Code, or any
                                                  ------------------
similar Federal or state law for the relief of debtors. The term "Custodian"
means any receiver, trustee, assignee, liquidator, custodian or similar official
under any Bankruptcy Law.

        The Company shall deliver to the Trustee, within 30 days after the
Company learns of the existence thereof, written notice in the form of an
Officers' Certificate of any event which with the giving of notice and the lapse
of time would become an Event of Default under clause (4), (5), (6) or (9) of
this Section 6.01, its status and what action the Company is taking or proposes
to take with respect thereto.

        SECTION 6.02 Acceleration. If an Event of Default (other than an Event
                     ------------
of Default specified in Section 6.01(8) or (9) with respect to the Company)
occurs and is continuing, the Trustee by notice to the Company, or the Holders
of at least 25% in principal amount of the Securities by notice to the Company
and the Trustee, may declare the principal of and accrued interest on all the
Securities to be due and payable. Upon such a declaration, such principal and
interest shall be due and payable immediately. If an Event of Default specified
in Section 6.01(8) or (9) with respect to the Company occurs, the principal of
and interest on all the Securities shall ipso facto become and be immediately
                                         ---- -----
due and payable without any declaration or other act on the part of the Trustee
or any Securityholders. The

                                      40
<PAGE>
 
Holders of a majority in principal amount of the Securities by notice to the
Trustee may rescind an acceleration and its consequences if the rescission would
not conflict with any judgment or decree and if all existing Events of Default
have been cured or waived except nonpayment of principal or interest that has
become due solely because of acceleration. No such rescission shall affect any
subsequent Default or impair any right consequent thereto.

        SECTION 6.03 Other Remedies. If an Event of Default occurs and is
                     --------------
continuing, the Trustee may pursue any available remedy to collect the payment
of principal of or interest on the Securities or to enforce the performance of
any provisions of the Securities or this Indenture.

        The Trustee may maintain a proceeding even if it does not possess any of
the Securities or does not produce any of them in the proceeding. Any custodian,
receiver, assignee, trustee, liquidator, or sequestrator (or other similar
official) in any such proceeding is hereby authorized by each Holder to make
such payments to the Trustee, and in the event that the Trustee shall consent to
the making of such payments directly to the Holders, to pay to the Trustee any
amount due to it for the reasonable compensation, expenses, disbursements and
advances of the Trustee and any predecessor Trustee, their agents and counsel,
and any other amounts due the Trustee or any predecessor Trustee under Section
7.07. A delay or omission by the Trustee or any Securityholder in exercising any
right or remedy accruing upon an Event of Default shall not impair the right or
remedy or constitute a waiver of or acquiescence in the Event of Default. No
remedy is exclusive of any other remedy. All available remedies are cumulative.

        SECTION 6.04 Waiver of Past Defaults. The Holders of a majority in
                     -----------------------
principal amount of the Securities by notice to the Trustee may waive an
existing Default or Event of Default and its consequences except (i) a Default
or Event of Default in the payment of the principal of or interest on a Security
or (ii) a Default or Event of Default in respect of a provision that under
Section 9.02 cannot be amended without the consent of each Securityholder
affected. When a Default is waived, it is deemed cured, but no such waiver shall
extend to any subsequent or other Default or impair any consequent right.

        SECTION 6.05 Control by Majority. The Holders of a majority in principal
                     ------------------- 
amount of the Securities may direct the time, method and place of conducting any
proceeding for any remedy available to the Trustee or of exercising any trust or
power conferred on the Trustee. However, the Trustee may refuse to follow any
direction that conflicts with law or this Indenture or, subject to Section 7.01,
that the Trustee determines is unduly prejudicial to the rights of other
Securityholders or would involve the Trustee in personal liability; provided,
                                                                    --------
however, that the Trustee may take any other action deemed proper by the Trustee
- -------
that is not inconsistent with such direction. Prior to taking any action
hereunder, the Trustee shall be entitled to indemnification satisfactory to it
in its sole discretion against all losses and expenses caused by taking or not
taking such action.

                                      41
<PAGE>
 
        SECTION 6.06 Limitation on Suits. A Securityholder may not pursue any
                     -------------------
remedy with respect to this Indenture or the Securities unless:

                (1) the Holder shall have previously given to the Trustee
        written notice stating that an Event of Default is continuing;

                (2) the Holders of at least 25% in principal amount of the
        Securities make a written request to the Trustee to pursue the remedy;

                (3) such Holder or Holders offer to the Trustee reasonable
        security or indemnity against any loss, liability or expense;

                (4) the Trustee shall have failed to comply with the request
        within 60 days after receipt of the request and the offer of security or
        indemnity; and

                (5) the Holders of a majority in principal amount of the
        Securities do not give the Trustee a direction inconsistent with the
        request during such 60-day period.

        A Securityholder may not use this Indenture to prejudice the rights of
another Securityholder or to obtain a preference or priority over another
Securityholder.

        SECTION 6.07 Rights of Holders to Receive Payment. Notwithstanding any
                     ------------------------------------
other provision of this Indenture, the right of any Holder to receive payment of
principal of, premium (if any) and interest on the Securities held by such
Holder, on or after the respective due dates expressed in the Securities, or to
bring suit for the enforcement of any such payment on or after such respective
dates, shall not be impaired or affected without the consent of such Holder.

        SECTION 6.08 Collection Suit by Trustee. If an Event of Default in
                     --------------------------
payment of interest or principal specified in Section 6.01(1) or (2) occurs and
is continuing, the Trustee may recover judgment in its own name and as trustee
of an express trust against the Company for the whole amount of principal and
interest remaining unpaid (together with interest on such unpaid interest to the
extent lawful) and the amounts provided for in Section 7.07.

        SECTION 6.09 Trustee May File Proofs of Claim. The Trustee may file such
                     --------------------------------
proofs of claim and other papers or documents as may be necessary or advisable
in order to have the claims of the Trustee and the Securityholders allowed in
any judicial proceedings relative to the Company, its creditors or its property
and, unless prohibited by law or applicable regulations, may vote on behalf of
the Holders in any election of a trustee in bankruptcy or other person
performing similar functions, and any Custodian in any such 

                                      42
<PAGE>
 
judicial proceeding is hereby authorized by each Holder to make payments to the
Trustee and, in the event that the Trustee shall consent to the making of such
payments directly to the Holders, to pay to the Trustee any amount due it for
the reasonable compensation, expenses, disbursements and advances of the
Trustee, its agents and its counsel, and any other amounts due the Trustee under
Section 7.07.

        SECTION 6.10 Priorities. If the Trustee collects any money or property
                     ----------
pursuant to this Article 6, it shall pay out the money or property in the
following order:

            FIRST: to the Trustee for amounts due under Section 7.07;

            SECOND: to Securityholders for amounts due and unpaid on the
        Securities for principal and interest, ratably, without preference or
        priority of any kind, according to the amounts due and payable on the
        Securities for principal and interest, respectively; and

            THIRD: to the Company.

        The Trustee may fix a record date and payment date for any payment to
Securityholders pursuant to this Section. At least 15 days before such record
date, the Company shall mail to each Securityholder and the Trustee a notice
that states the record date, the payment date and amount to be paid.

        SECTION 6.11 Undertaking for Costs. In any suit for the enforcement of
                     ---------------------
any right or remedy under this Indenture or in any suit against the Trustee for
any action taken or omitted by it as Trustee, a court in its discretion may
require the filing by the party litigant in the suit of an undertaking to pay
the costs of the suit, and the court in its discretion may assess reasonable
costs, including reasonable attorneys' fees, against any party litigant in the
suit, having due regard to the merits and good faith of the claims or defenses
made by the party litigant. This Section does not apply to a suit by the
Trustee, a suit by a Holder pursuant to Section 6.07 or a suit by Holders of
more than 50% in principal amount of the Securities.

        SECTION 6.12 Waiver of Stay or Extension Laws. The Company (to the
                     --------------------------------
extent it may lawfully do so) shall not at any time insist upon, or plead, or in
any manner whatsoever claim or take the benefit or advantage of, any stay or
extension law wherever enacted, now or at any time hereafter in force, which may
affect the covenants or the performance of this Indenture; and the Company (to
the extent that it may lawfully do so) hereby expressly waives all benefit or
advantage of any such law, and shall not hinder, delay or impede the execution
of any power herein granted to the Trustee, but shall suffer and permit the
execution of every such power as though no such law had been enacted.


                                      43
<PAGE>
 
                              ARTICLE 7 - Trustee
                                          -------

        SECTION 7.01    Duties of Trustee.
                        -----------------

                (a) If an Event of Default has occurred and is continuing, the
Trustee shall exercise the rights and powers vested in it by this Indenture and
use the same degree of care and skill in their exercise as a prudent person
would exercise or use under the circumstances in the conduct of such person's
own affairs.

                (b) Except during the continuance of an Event of Default:

                    (1) the Trustee undertakes to perform such duties and only
        such duties as are specifically set forth in this Indenture and no
        implied covenants or obligations shall be read into this Indenture
        against the Trustee; and

                    (2) in the absence of bad faith on its part, the Trustee may
        conclusively rely, as to the truth of the statements and the correctness
        of the opinions expressed therein, upon certificates or opinions
        furnished to the Trustee and conforming to the requirements of this
        Indenture. However, the Trustee shall examine the certificates and
        opinions to determine whether or not they conform to the requirements of
        this Indenture.

                (c) The Trustee may not be relieved from liability for its own
negligent action, its own negligent failure to act or its own wilful misconduct,
except that:

                    (1) this subsection (c) does not limit the effect of
        paragraph (b) of this Section;

                    (2) the Trustee shall not be liable for any error of
        judgment made in good faith by a Trust Officer unless it is proved that
        the Trustee was negligent in ascertaining the pertinent facts; and

                    (3) the Trustee shall not be liable with respect to any
        action it takes or omits to take in good faith in accordance with a
        direction received by it pursuant to Section 6.05.

                (d) Every provision of this Indenture that in any way relates to
the Trustee is subject to paragraphs (a), (b) and (c) of this Section 7.01.

                (e) The Trustee shall not be liable for interest on any money
received by it except as the Trustee may agree in writing with the Company.


                                      44
<PAGE>
 
                (f) Money held in trust by the Trustee need not be segregated
from other funds except to the extent required by law.

                (g) No provision of this Indenture shall require the Trustee to
expend or risk its own funds or otherwise incur financial liability in the
performance of any of its duties hereunder or in the exercise of any of its
rights or powers, if it shall have reasonable grounds to believe that repayment
of such funds or adequate indemnity against such risk or liability is not
reasonably assured to it.

                (h) The Trustee shall not be bound to make any investigation
into the facts or matters stated in any resolution, certificate, statement,
instrument, opinion, report, notice, request, direction, consent, order, bond,
debenture, note, coupon or other paper or document, but the Trustee, in its
discretion, may make such further inquiry or investigation into such facts or
matters as it may see fit, and, if the Trustee shall determine to make such
further inquiry or investigation, it shall be entitled to examine the books,
records and premises of the Company, personally or by agent or attorney.

        SECTION 7.02    Rights of Trustee.
                        -----------------

                (a) The Trustee may rely on any document believed by it to be
genuine and to have been signed or presented by the proper person. The Trustee
need not investigate any fact or matter stated in the document.

                (b) Before the Trustee acts or refrains from acting, it may
require an Officers' Certificate or an Opinion of Counsel. The Trustee shall not
be liable for any action it takes or omits to take in good faith in reliance on
the Officers' Certificate or Opinion of Counsel.

                (c) The Trustee may act through agents and shall not be
responsible for the misconduct or negligence of any agent appointed with due
care.

                (d) The Trustee shall not be liable for any action it takes or
omits to take in good faith which it believes to be authorized or within its
rights or powers; provided, however, that the Trustee's conduct does not
                  --------  -------
constitute wilful misconduct, negligence or bad faith.

                (e) The Trustee may consult with counsel, and the advice or
opinion of counsel with respect to legal matters relating to this Indenture and
the Securities shall be full and complete authorization and protection from
liability in respect to any action taken, omitted or suffered by it hereunder in
good faith and in accordance with the advice or opinion of such counsel.

                                      45
<PAGE>
 
        SECTION 7.03 Individual Rights of Trustee. The Trustee in its individual
                     ----------------------------
or any other capacity may become the owner or pledgee of Securities and may
otherwise deal with the Company or its Affiliates with the same rights it would
have if it were not Trustee. Any Paying Agent, Registrar, co-registrar or co-
paying agent may do the same with like rights. However, the Trustee must comply
with Sections 7.10 and 7.11.

        SECTION 7.04 Trustee's Disclaimer. The Trustee shall not be responsible
                     -------------------- 
for and makes no representation as to the validity or adequacy of this Indenture
or the Securities, it shall not be accountable for the Company's use of the
proceeds from the Securities, and it shall not be responsible for any statement
of the Company in the Indenture or in any prospectus, registration statement or
other document issued in connection with the sale of the Securities or in the
Securities other than the Trustee's certificate of authentication.

        SECTION 7.05 Notice of Defaults. If a Default occurs and is continuing
                     ------------------
and if it is known to the Trustee, the Trustee shall mail to each Securityholder
and to the Company notice of the Default within 90 days after it occurs. Except
in the case of a Default in payment of principal of or interest on any Security,
the Trustee may withhold the notice if and so long as a committee of its Trust
Officers in good faith determines that withholding the notice is in the interest
of Securityholders.

        SECTION 7.06 Reports by Trustee to Holders. As promptly as practicable
                     -----------------------------
after each February 15 beginning with February 15 following the date of this
Indenture, and in any event prior to April 15 in each year, the Trustee shall
mail to each Securityholder a brief report dated as of such February 15 that
complies with TIA (S)313(a). The Trustee also shall comply with TIA (S)313(b).

        A copy of each report at the time of its mailing to Securityholders
shall be filed with the SEC and each stock exchange (if any) on which the
Securities are listed. The Company agrees to notify promptly the Trustee
whenever the Securities become listed on any stock exchange and of any delisting
thereof.

        SECTION 7.07 Compensation and Indemnity. The Company shall pay to the
                     --------------------------
Trustee from time to time reasonable compensation for its services. The
Trustee's compensation shall not be limited by any law on compensation of a
trustee of an express trust. The Company shall reimburse the Trustee upon
request for all reasonable out-of-pocket expenses incurred or made by it,
including costs of collection, in addition to the compensation for its services.
Such expenses shall include the reasonable compensation and expenses,
disbursements and advances of the Trustee's agents, counsel, accountants and
experts. The Company shall indemnify the Trustee against any and all loss,
liability or reasonable expense (including attorneys' fees) incurred by it in
connection with the administration of this trust and the performance of its
duties hereunder. The Trustee shall notify the Company promptly of any claim for
which it may seek indemnity. Failure by the

                                      46
<PAGE>
 
Trustee to so notify the Company shall not relieve the Company of its
obligations hereunder. The Company shall defend the claim and the Trustee may
have separate counsel and the Company shall pay the fees and expenses of such
counsel. The Company need not reimburse any expense or indemnify against any
loss, liability or expense incurred by the Trustee through the Trustee's own
wilful misconduct, negligence or bad faith.

        To secure the Company's payment obligations in this Section, the Trustee
shall have a Lien prior to the Securities on all money or property held or
collected by the Trustee other than money or property held in trust to pay
principal of and interest on particular Securities.

        The Company's payment obligations pursuant to this Section shall survive
the discharge of this Indenture. When the Trustee incurs expenses (including the
reasonable charges and expenses of its counsel) after the occurrence of a
Default specified in Section 6.01(8) or (9) with respect to the Company, the
expenses are intended to constitute expenses of administration under the
Bankruptcy Law.

        SECTION 7.08 Replacement of Trustee. The Trustee may resign at any time
                     ----------------------
by so notifying the Company. The Holders of a majority in principal amount of
the Securities may remove the Trustee by so notifying the Trustee and may
appoint a successor Trustee. The Company shall remove the Trustee if:

                (1) the Trustee fails to comply with Section 7.10;

                (2) the Trustee is adjudged bankrupt or insolvent;

                (3) a receiver or other public officer takes charge of the
        Trustee or its property; or

                (4) the Trustee otherwise becomes incapable of acting.

        If the Trustee resigns or is removed or if a vacancy exists in the
office of Trustee for any reason (the Trustee in such event being referred to
herein as the retiring Trustee), the Company shall promptly appoint a successor
Trustee.

        A successor Trustee shall deliver a written acceptance of its
appointment to the retiring Trustee and to the Company. Thereupon the
resignation or removal of the retiring Trustee shall become effective, and the
successor Trustee shall have all the rights, powers and duties of the Trustee
under this Indenture. The successor Trustee shall mail a notice of its
succession to Securityholders. The retiring Trustee shall promptly transfer all
property held by it as Trustee to the successor Trustee, subject to the Lien
provided for in Section 7.07.


                                      47
<PAGE>
 
        If a successor Trustee does not take office within 60 days after the
retiring Trustee resigns or is removed, the retiring Trustee, the Company or the
Holders of a majority in principal amount of the Securities may petition any
court of competent jurisdiction for the appointment of a successor Trustee.

        If the Trustee fails to comply with Section 7.10, any Securityholder may
petition any court of competent jurisdiction for the removal of the Trustee and
the appointment of a successor Trustee.

        Notwithstanding the replacement of the Trustee pursuant to this Section,
the Company's obligations under Section 7.07 shall continue for the benefit of
the retiring Trustee.

        SECTION 7.09 Successor Trustee by Merger. If the Trustee consolidates
                     ---------------------------
with, mergers or converts into, or transfers all or substantially all its
corporate trust business or assets to another corporation or banking
association, the resulting, surviving or transferee corporation without any
further act shall be the successor Trustee.

        In case at the time such successor or successors by merger, conversion
or consolidation to the Trustee shall succeed to the trusts created by this
Indenture any of the Securities shall have been authenticated but not delivered,
any such successor to the Trustee may adopt the certificate of authentication of
any predecessor Trustee, and deliver such Securities so authenticated; and in
case at that time any of the Securities shall not have been authenticated, any
successor to the Trustee may authenticate such Securities either in the name of
any predecessor hereunder or in the name of the successor to the Trustee; and in
all such cases such certificates shall have the full force which it is anywhere
in the Securities or in this Indenture provided that the certificate of the
Trustee shall have.

        SECTION 7.10 Eligibility; Disqualification. The Trustee shall at all
                     -----------------------------
times satisfy the requirements of TIA (S)310(a). The Trustee shall have a
combined capital and surplus of at least $50,000,000 as set forth in its most
recent published annual report of condition. The Trustee shall comply with TIA
(S)310(b), including the optional provision permitted by the second sentence of
TIA (S)310(b)(9); provided, however, that there shall be excluded from the
operation of TIA (S)310(b)(1) any indenture or indentures under which other
securities or certificates of interest or participation in other securities of
the Company are outstanding if the requirements for such exclusion set forth in
TIA (S)310(b)(1) are met.

        SECTION 7.11 Preferential Collection of Claims Against Company. The
                     -------------------------------------------------
Trustee shall comply with TIA (S)311(a), excluding any creditor relationship
listed in TIA (S)311(b). A Trustee who has resigned or been removed shall be
subject to TIA (S)311(a) to the extent indicated.


                                      48
<PAGE>
 
                ARTICLE 8 - Discharge of Indenture; Defeasance
                            ----------------------------------
        SECTION 8.01    Discharge of Liability on Securities; Defeasance.
                        ------------------------------------------------

                (a) When (i) the Company delivers to the Trustee all outstanding
Securities (other than Securities replaced pursuant to Section 2.07) for
cancellation or (ii) all outstanding Securities have become due and payable and
the Company irrevocably deposits with the Trustee funds sufficient to pay at
maturity all outstanding Securities, including interest thereon (other than
Securities replaced pursuant to Section 2.07), and if in either case the Company
pays all other sums payable hereunder by the Company, then this Indenture shall,
subject to Sections 8.01(c) and 8.06, cease to be of further effect. The Trustee
shall acknowledge satisfaction and discharge of this Indenture on demand of the
Company accompanied by an Officers' Certificate and an Opinion of Counsel and at
the cost and expense of the Company.

                (b) Subject to Sections 8.01(c), 8.02 and 8.06, the Company at
any time may terminate (i) all its obligations under the Securities and this
Indenture ("legal defeasance option") or (ii) its obligations under Sections
4.02, 4.03, 4.04, 4.05, 4.06, 4.07, 4.08, 4.09 and 4.10 and the operation of
Section 6.01(3) and Section 6.01(4) (with respect to the aforementioned Sections
only) ("covenant defeasance option"). The Company may exercise its legal
defeasance option notwithstanding its prior exercise of its covenant defeasance
option.

        If the Company exercises its legal defeasance option, payment of the
Securities may not be accelerated because of an Event of Default. If the Company
exercises its covenant defeasance option, payment of the Securities may not be
accelerated because of an Event of Default specified in Section 6.01(3) or
6.01(4) (with respect to compliance with the aforementioned Sections).

        Upon satisfaction of the conditions set forth herein and upon request of
the Company, the Trustee shall acknowledge in writing the discharge of those
obligations that the Company terminates.

                (c) Notwithstanding clauses (a) and (b) above, the Company's
obligations in Sections 2.03, 2.04, 2.05, 2.06, 2.07, 7.07, 7.08, 8.04, 8.05 and
8.06 shall survive until the Securities have been paid in full. Thereafter, the
Company's obligations in Sections 7.07, 8.04 and 8.05 shall survive.

        SECTION 8.02 Conditions to Defeasance. The Company may exercise its
                     ------------------------
legal defeasance option or its covenant defeasance option only if:

                                      49
<PAGE>
 
                (1) the Company irrevocably deposits in trust with the Trustee
sufficient money or U.S. Government Obligations which, together with the payment
of interest when due (and without reinvestment) to be received on such U.S.
Government Obligations to the date of redemption or maturity of the Securities,
as the case may be, will fully provide for the payment of principal, premium (if
any) and interest on the Securities to maturity or redemption, as the case may
be;

                (2) the Company delivers to the Trustee a certificate from a
nationally recognized firm of independent accountants expressing its opinion
that the payments of principal and interest when due (and without reinvestment)
to be received on the deposited U.S. Government Obligations plus any deposited
money without investment will provide cash at such times and in such amounts
(but, in the case of the legal defeasance option only, not more than such
amounts) as will be sufficient to pay principal, premium (if any) and interest
when due on all the Securities to maturity or redemption, as the case may be;

                (3) 123 days pass after the deposit is made and during the 123-
day period no Default specified in Section 6.01(8) or (9) with respect to the
Company occurs which is continuing at the end of the period;

                (4) no Default has occurred and is continuing on the date of
such deposit and after giving effect thereto;

                (5) the deposit does not constitute a default under any other
agreement binding on the Company;

                (6) the Company delivers to the Trustee an Opinion of Counsel to
the effect that the trust resulting from the deposit does not constitute, or is
qualified as, a regulated investment company under the Investment Company Act of
1940;

                (7) in the case of the legal defeasance option, the Company
shall have delivered to the Trustee an Opinion of Counsel stating that (i) the
Company has received from, or there has been published by, the Internal Revenue
Service a ruling, or (ii) since the date of this Indenture there has been a
change in the applicable Federal income tax law, in either case to the effect
that, and based thereon such Opinion of Counsel shall confirm that, the
Securityholders will not recognize income, gain or loss for Federal income tax
purposes as a result of such defeasance and will be subject to Federal income
tax on the same amounts, in the same manner and at the same times as would have
been the case if such deposit and defeasance had not occurred;

                                      50
<PAGE>
 
                (8) in the case of the covenant defeasance option, the Company
shall have delivered to the Trustee an Opinion of Counsel to the effect that the
Securityholders will not recognize income, gain or loss for Federal income tax
purposes as a result of such covenant defeasance and will be subject to Federal
income tax on the same amounts, in the same manner and at the same time as would
have been the case if such covenant defeasance had not occurred; and

                (9) the Company delivers to the Trustee an Officers' Certificate
and an Opinion of Counsel, each stating that all conditions precedent to the
defeasance and discharge of the Securities as contemplated by this Article 8
have been complied with.

        Before or after a deposit, the Company may make arrangements
satisfactory to the Trustee for the redemption of Securities at a future date in
accordance with Article 3.

        SECTION 8.03 Application of Trust Money. The Trustee shall hold in trust
                     --------------------------
money or U.S. Government Obligations deposited with it pursuant to this Article
8. It shall apply the deposited money and the money from U.S. Government
Obligations through the Paying Agent and in accordance with this Indenture to
the payment of principal of and interest on the Securities.

        SECTION 8.04 Repayment to Company. The Trustee and the Paying Agent
                     --------------------
shall promptly turn over to the Company upon request any excess money or
securities held by them at any time.

        Subject to any applicable abandoned property law, the Trustee and the
Paying Agent shall pay to the Company upon request any money held by them for
the payment of principal or interest that remains unclaimed for two years, and,
thereafter, Securityholders entitled to the money must look to the Company for
payment as general creditors.

        SECTION 8.05 Indemnity for Government Obligations. The Company shall pay
                     ------------------------------------
and shall indemnify the Trustee against any tax, fee or other charge imposed on
or assessed against deposited U.S. Government Obligations or the principal and
interest received on such U.S. Government Obligations.

        SECTION 8.06 Reinstatement. If the Trustee or Paying Agent is unable to
                     -------------
apply any money or U.S. Government Obligations in accordance with this Article 8
by reason of any legal proceeding or by reason of any order or judgment of any
court or governmental authority enjoining, restraining or otherwise prohibiting
such application, the Company's obligations under this Indenture and the
Securities shall be revived and reinstated as though no deposit had occurred
pursuant to this Article 8 until such time as the Trustee or Paying Agent is
permitted to apply all such money or U.S. Government Obligations in

                                      51
<PAGE>
 
accordance with this Article 8; provided, however, that, if the Company has made
any payment of interest on or principal of any Securities because of the
reinstatement of its obligations, the Company shall be subrogated to the rights
of the Holders or such Securities to receive such payment from the money or U.S.
Government Obligations held by the Trustee or Paying Agent.


                            ARTICLE 9 - Amendments
                                        ----------

        SECTION 9.01    Without Consent of Holders.  The Company and the Trustee
                        --------------------------
may amend this Indenture or the Securities without notice to or consent of any
Securityholder:

                (1) to cure any ambiguity, omission, defect or inconsistency;

                (2) to comply with Article 5;

                (3) to provide for uncertificated Securities in addition to or
        in place of certificated Securities; provided, however, that the
                                             --------  -------
        uncertificated Securities are issued in registered form for purposes of
        Section 163(f) of the Internal Revenue Code of 1986, as amended, or in a
        manner such that the uncertificated Securities are described in Section
        163(f)(2)(B) of the Internal Revenue Code of 1986, as amended;

                (4) to add Guarantees with respect to the Securities;

                (5) to add to the covenants of the Company or the Guarantor
        Subsidiaries for the benefit of the Holders or to surrender any right or
        power herein conferred upon the Company;

                (6) to reflect the release of any Guarantor Subsidiary from its
        Subsidiary Guarantee, or the addition of any Subsidiary of the Company
        as a Guarantor Subsidiary, in the manner provided by this Indenture;

                (7) to comply with any requirements of the SEC in connection
        with qualifying this Indenture under the TIA; or

                (8) to make any change that does not adversely affect the rights
        of any Securityholder.

        After an amendment under this Section becomes effective, the Company
shall mail to Securityholders a notice briefly describing such amendment. The
failure to give such notice

                                      52
<PAGE>
 
to all Securityholders, or any defect therein, shall not impair or affect the
validity of an amendment under this Section.

        SECTION 9.02 With Consent of Holders. The Company and the Trustee may
                     -----------------------
amend this Indenture or the Securities without notice to any Securityholder but
with the written consent of the Holders of a majority in principal amount of the
then outstanding Securities. However, without the consent of each Securityholder
affected, an amendment may not:

                (1) reduce the amount of Securities whose Holders must consent
        to an amendment;

                (2) reduce the rate of or extend the time for payment of
        interest on any Security;

                (3) reduce the principal of or extend the Stated Maturity of any
        Security;

                (4) reduce the premium payable upon the redemption of any
        Security or change the time at which any Security may be redeemed in
        accordance with Article 3;

                (5) make any Security payable in money other than that stated in
        the Security;

                (6) make any change in the provisions concerning waiver of
        Defaults by Holders of Securities or the rights of Holders to receive
        payments of principal and interest in Section 6.04 or 6.07 or the second
        sentence of this Section;

                (7) make any change in Section 4.14 hereof or the definition
        "Change of Control";

                (8) make any change adversely affecting the rights of any
        holder; or

                (9) make any change in this Section 9.02.

        It shall not be necessary for the consent of the Holders under this
Section to approve the particular form of any proposed amendment, but it shall
be sufficient if such consent approves the substance thereof.

        After an amendment under this Section becomes effective, the Company
shall mail to Securityholders a notice briefly describing such amendment. The
failure to give such notice

                                      53
<PAGE>
 
to all Securityholders, or any defect therein, shall not impair or affect the
validity of an amendment under this Section.

        SECTION 9.03 Compliance with Trust Indenture Act. Every amendment to
                     -----------------------------------
this Indenture or the Securities shall comply with the TIA as than in effect.

        SECTION 9.04 Revocation and Effect of Consents and Waivers. A consent to
                     ---------------------------------------------
an amendment or a waiver by a Holder of a Security shall bind the Holder and
every subsequent Holder of that Security or portion of the Security that
evidences the same debt as the consenting Holder's Security, even if notation of
the consent or waiver is not made on the Security. However, any such Holder or
subsequent Holder may revoke the consent or waiver as to such Holder's Security
or portion of the Security if the Trustee receives the notice of revocation
before the date the amendment or waiver becomes effective. After an amendment or
waiver becomes effective, it shall bind every Securityholder.

        The Company may, but shall not be obligated to, fix a record date for
the purpose of determining the Securityholders entitled to give their consent or
take any other action described above or required or permitted to be taken
pursuant to this Indenture. If a record date is fixed, then notwithstanding the
immediately preceding paragraph, those persons who were Securityholders at such
record date (or their duly designated proxies), and only those persons, shall be
entitled to give such consent or to revoke any consent previously given or to
take any such action, whether or not such persons continue to be the Holders
after such record date. No such consent shall be valid or effective for more
than 120 days after such record date.

        SECTION 9.05 Notation on or Exchange of Securities. If an amendment
                     -------------------------------------
changes the terms of a Security, the Trustee may require the Holder of the
Security to deliver it to the Trustee. The Trustee may place an appropriate
notation on the Security regarding the changed terms and return it to the
Holder. Alternatively, if the Company or the Trustee so determines, the Company
in exchange for the Security shall issue and the Trustee shall authenticate a
new Security that reflects the changed terms. Failure to make the appropriate
notation or to issue a new Security shall not affect the validity of such
amendment.

        SECTION 9.06 Trustee to Sign Amendments. The Trustee shall sign any
                     --------------------------
amendment authorized pursuant to this Article 9 if the amendment does not
adversely affect the rights, duties, liabilities or immunities of the Trustee.
If it does, the Trustee may but need not sign it. In signing such amendment the
Trustee shall be entitled to receive indemnity reasonably satisfactory to it and
to receive, and (subject to Section 7.01) shall be fully protected in relying
upon, an Officers' Certificate and an Opinion of Counsel stating that such
amendment is authorized or permitted by this Indenture.

                                      54
<PAGE>
 
        SECTION 9.07 Payment for Consent. Neither the Company, any Affiliate of
                     -------------------
the Company nor any Subsidiary shall, directly or indirectly, pay or cause to be
paid any consideration, whether by way of interest, fee or otherwise, to any
Holder for or as an inducement to any consent, waiver or amendment of any of the
terms or provisions of this Indenture or the Securities unless such
consideration is offered to be paid or agreed to be paid to all Holders which so
consent, waive or agree to amend in the time frame set forth in solicitation
documents relating to such consent, waiver or agreement.


                      ARTICLE 10 - Subsidiary Guarantees
                                   ---------------------

        SECTION 10.01   Unconditional Subsidiary Guarantee.
                        ----------------------------------

                (a) Each Guarantor Subsidiary set forth on the signature pages
hereof and each Guarantor Subsidiary of the Company which in accordance with
Section 4.15 hereof is required to Guarantee the obligations of the Company
under the Securities, upon execution of a counterpart of this Indenture, hereby
jointly and severally unconditionally Guarantees to each Holder of a Security
authenticated and delivered by the Trustee irrespective of the validity or
enforceability of this Indenture, the Securities or the obligations of the
Company under this Indenture or the Securities, that: (i) the principal of and
interest on the Securities will be paid in full when due, whether at maturity or
interest payment, by acceleration, call for redemption or otherwise, and
interest on the overdue principal of and interest, if any, on the Securities and
all other obligations of the Company to the Holders or the Trustee under this
Indenture or the Securities will be promptly paid in full or performed, all in
accordance with the terms of this Indenture and the Securities; and (ii) in the
case of any extension of time or payment or renewal of any Securities or any of
such other obligations, they will be paid in full when due or performed in
accordance with the terms of the extension or renewal, whether at maturity, by
acceleration or otherwise. Failing payment when due of any amount so Guaranteed
for whatever reason, each Guarantor Subsidiary will be obligated to pay the same
whether or not such failure to pay has become an Event of Default which could
cause acceleration pursuant to Section 6.02 hereof. Each Guarantor Subsidiary
agrees that this is a Guarantee of payment, not a Guarantee of collection.

                (b) Each Guarantor Subsidiary hereby jointly and severally
agrees that its obligations with regard to this Subsidiary Guarantee shall be
joint and several, unconditional, irrespective of the validity or enforceability
of the Securities or the obligations of the Company under this Indenture, the
absence of any action to enforce the same, the recovery of any judgment against
the Company or any other obligor with respect to this Indenture, the Securities
or the obligations of the Company under this Indenture or the Securities, any
action to enforce the same or any other circumstances (other than complete
performance) which might otherwise constitute a legal or equitable discharge or
defense of a Guarantor Subsidiary. Each Guarantor Subsidiary further waives and
relinquishes all claims, rights and

                                      55
<PAGE>
 
remedies accorded by applicable law to guarantors and agrees not to assert or
take advantage of any such claims, right or remedies, including but not limited
to: (a) any right to require the Trustee, the Holders or the Company (each, a
"Benefitted Party") to proceed against the Company or any other person or to
proceed against or exhaust any security held by a Benefitted Party at any time
or to pursue any other remedy in any Benefitted Party's power before proceeding
against such Guarantor Subsidiary; (b) the defense of the statute of limitations
in any action hereunder or in any action for the collection of any indebtedness
or the performance of any obligation hereby Guaranteed; (c) any defense that may
arise by reason of the incapacity, lack of authority, death or disability of any
other person or the failure of a Benefitted Party to file or enforce a claim
against the estate (in administration, bankruptcy or any other proceeding) of
any other person; (d) demand, protest and notice of any kind including but not
limited to notice of the existence, creation or incurring of any new or
additional indebtedness or obligation or of any action or non-action on the part
of such Guarantor Subsidiary, the Company, any Benefitted Party, any creditor of
such Guarantor Subsidiary, the Company or on the part of any other person
whomsoever in connection with any indebtedness or obligations hereby Guaranteed;
(e) any defense based upon an election of remedies by a Benefitted Party,
including but not limited to an election to proceed against such Guarantor
Subsidiary for reimbursement; (f) any defense based upon any statute or rule of
law which provides that the obligation of a surety must be neither larger in
amount nor in other respects more burdensome than that of the principal; (g) any
defense arising because of a Benefitted Party's election, in any proceeding
instituted under the Federal Bankruptcy Code, of the application of Section
1111(b)(2) of the Federal Bankruptcy Code; or (h) any defense based on any
borrowing or grant of a security interest under Section 364 of the Federal
Bankruptcy Code. Each Guarantor Subsidiary hereby covenants that its Subsidiary
Guarantee will not be discharged except by complete performance of the
obligations contained in its Subsidiary Guarantee and this Indenture.

        Each Guarantor Subsidiary agrees that if, after the occurrence and
during the continuance of an Event of Default, the Trustee or any of the Holders
are prevented by applicable law from exercising their respective rights to
accelerate the maturity of the Securities, to collect interest on the
Securities, or to enforce or exercise any other right or remedy with respect to
the Securities, such Guarantor Subsidiary agrees to pay to the Trustee for the
account of the Holders, upon demand therefor, the amount that would otherwise
have been due and payable had such rights and remedies been permitted to be
exercised by the Trustee or any of the Holders.

                (c) Each Guarantor Subsidiary shall be subrogated to all rights
of the Holders of the Securities upon which its Subsidiary Guarantee is endorsed
against the Company in respect of any amounts paid by such Guarantor Subsidiary
on account of such Security pursuant to the provisions of its Subsidiary
Guarantee or this Indenture; provided, however, that no Guarantor Subsidiary
                             --------  -------
shall be entitled to enforce or to receive any payments

                                      56
<PAGE>
 
arising out of, or based upon, such right of subrogation until the principal of
(and premium, if any) and interest on all Securities issued hereunder shall have
been paid in full.

                (d) Each Subsidiary Guarantee shall remain in full force and
effect and continue to be effective should any petition be filed by or against
the Company for liquidation or reorganization, should the Company become
insolvent or make an assignment for the benefit of creditors or should a
receiver or trustee be appointed for all or any significant party of the
Company's assets, and shall, to the fullest extent permitted by law, continue to
be effective or be reinstated, as the case may be, if at any time payment and
performance of the Securities, is, pursuant to applicable law, rescinded or
reduced in amount, or must otherwise be restored or returned by an obligee on
the Securities, whether as a "voidable preference," "fraudulent transfer," or
otherwise, all as though such payment or performance had not been made. In the
event that any payment, or any part thereof, is rescinded, reduced, restored or
returned, the Securities shall, to the fullest extent permitted by law, be
reinstated and deemed reduced only by such amount paid and not so rescinded,
reduced, restored or returned.

                (e) Each Guarantor Subsidiary shall have the right to seek
contribution from any non-paying Guarantor Subsidiary so long as the exercise of
such right does not impair the rights of the Holders under the Subsidiary
Guarantees.

        SECTION 10.02 Limitation of Guarantor Subsidiary's Liability. Each
                      ----------------------------------------------
Guarantor Subsidiary and by its acceptance hereof, each Holder, hereby confirms
that it is its intention that the Subsidiary Guarantee by such Guarantor
Subsidiary not constitute a fraudulent transfer or conveyance for purposes of
any federal or state law to the extent applicable to any Subsidiary Guarantees.
To effectuate the foregoing intention, each such person hereby irrevocably
agrees that the obligation of such Guarantor Subsidiary under its Subsidiary
Guarantee under this Article 10 shall be limited to the maximum amount as will,
after giving effect to such maximum amount and all other (contingent or
otherwise) liabilities of such Guarantor Subsidiary that are relevant under such
laws, and after giving effect to any collections from, rights to receive
contribution from or payments made by or on behalf of any other Guarantor
Subsidiary in respect of the obligations of such other Guarantor Subsidiary
under this Article 10, result in the obligations of such Guarantor Subsidiary in
respect of such maximum amount not constituting a fraudulent conveyance.

        SECTION 10.03 Execution and Delivery of Subsidiary Guarantees. To
                      -----------------------------------------------
further evidence the Subsidiary Guarantees set forth in Section 10.1 hereof,
each Guarantor Subsidiary and the Company hereby agree that a notation relating
to such Subsidiary Guarantees substantially in the form of Exhibit C hereto
shall be endorsed on each Security authenticated and delivery by the Trustee and
executed by either manual or facsimile signature of an Officer of each Guarantor
Subsidiary.

                                      57
<PAGE>
 
        A Subsidiary Guarantee bearing the manual or facsimile signature of
individuals who were at any time the Officers of a Guarantor Subsidiary shall
bind such Guarantor Subsidiary, notwithstanding that such individuals or any of
them have ceased to hold such offices prior to the authentication and delivery
of the Security on which such Subsidiary Guarantee is endorsed or did not hold
such offices at the date of such Subsidiary Guarantee.

        The delivery of any Security by the Trustee, after the authentication
thereof hereunder, shall constitute due delivery of the Subsidiary Guarantee
endorsed thereon on behalf of the Guarantor Subsidiary. Each Guarantor
Subsidiary hereby jointly and severally agrees that its Subsidiary Guarantee set
forth in Section 10.1 hereof shall remain in full force and effect
notwithstanding any failure to endorse a Subsidiary Guarantee on any Security.

        SECTION 10.04   Addition of Guarantor Subsidiary.
                        --------------------------------

                For as long as any Subsidiary Guarantees are required to remain
in effect pursuant to the terms of this Indenture, promptly but in no event
later than 15 days following the date any person shall become a Subsidiary
(other than the Non-Guarantor Subsidiary) after the date of this Indenture, the
Company shall cause such Subsidiary to become a Guarantor Subsidiary with
respect to the Securities by executing and delivering to the Trustee (i) a
supplemental indenture, a form of which is attached hereto as Exhibit B, in form
and substance satisfactory to the Trustee, which subjects such person to the
provisions (including the representations and warranties) of this Indenture as a
Guarantor Subsidiary and (ii) an Opinion of Counsel to the effect that such
supplemental indenture has been duly authorized and executed by such person and
constitutes the legal, valid, binding and enforceable obligation of such person
(subject to such customary exceptions concerning creditors' rights and equitable
principles as maybe acceptable to the Trustee in its discretion).

        SECTION 10.05   Release of the Subsidiary Guarantees.
                        ------------------------------------

                (a) Concurrently with any sale or other disposition by way of
merger, consolidation or otherwise of all or substantially all the assets of a
Guarantor Subsidiary or all the capital stock of a Guarantor Subsidiary
permitted by and in accordance with the terms of this Indenture, and upon
delivery by the Company to the Trustee of an Officers' Certificate and an
Opinion of Counsel to the effect that such sale or other disposition was made by
the Company in accordance with the provisions of this Indenture, the Trustee
shall execute any documents reasonably required and reasonably acceptable in
form and substance to the Trustee to evidence the release of such Guarantor
Subsidiary from the obligations under its Subsidiary Guarantee. Any Guarantor
Subsidiary not released from its obligations under its Subsidiary Guarantee
endorsed on the Securities and under this Article 10 shall remain liable for the
obligations under its Subsidiary Guarantee endorsed on the Securities and under
this Article 10.

                                      58
<PAGE>
 
                (c) Concurrently with the defeasance of the Securities or the
covenant defeasance of the Securities under Article 8 hereof, the Guarantor
Subsidiaries shall be released from all of their obligations under their
Subsidiary Guarantees endorsed on the Securities and under this Article 10,
without any action on the part of the Trustee or any Holder of Securities.


                          ARTICLE 11 - Miscellaneous

        SECTION 11.01 Trust Indenture Act Controls. If any provision of this
                      ----------------------------
Indenture limits, qualifies or conflicts with another provision which is
required to be included in this Indenture by the TIA, the required provision
shall control.

        SECTION 11.02 Notices. Any notice or communication shall be in writing
                      -------
and delivered in person or mailed by first-class mail addressed as follows:

                if to the Company:      Clean Harbors, Inc.
                                        1200 Crown Colony Drive
                                        Quincy, Massachusetts 02169

                Attention of:           Chief Financial Officer

                if to the Trustee:      Shawmut Bank, N.A.
                                        Corporate Trust Department
                                        One Federal Street
                                        Boston, Massachusetts  02211

                Attention of:           Robert L. Bice, Assistant Vice President

        The Company or the Trustee by notice to the other may designate
additional or different addresses for subsequent notices or communications.

        Any notice or communication mailed to a Securityholder shall be mailed
to the Securityholder at the Securityholder's address as it appears on the
registration books of the Registrar and shall be sufficiently given if so mailed
within the time prescribed.

        Failure to mail a notice or communication to a Securityholder or any
defect in it shall not affect its sufficiency with respect to other
Securityholders. If a notice or communication is mailed in the manner provided
above, it is duly given, whether or not the addressee receives it.

                                      59
<PAGE>
 
        SECTION 11.03 Communication by Holders with Other Holders.
                      -------------------------------------------
Securityholders may communicate pursuant to TIA (S)312(b) with other
Securityholders with respect to their rights under this Indenture or the
Securities. The Company, the Trustee, the Registrar and anyone else shall have
the protection of TIA (S)312(c).

        SECTION 11.04 Certificate and Opinion as to Conditions Precedent. Upon
                      --------------------------------------------------
any request or application by the Company to the Trustee to take or refrain from
taking any action under this Indenture, the Company shall furnish to the
Trustee:

                (1) an Officers' Certificate in form and substance reasonably
        satisfactory to the Trustee stating that, in the opinion of the signers,
        all conditions precedent, if any, provided for in this Indenture
        relating to the proposed action have been complied with; and

                (2) an Opinion of Counsel in form and substance reasonably
        satisfactory to the Trustee stating that, in the opinion of such
        counsel, all such conditions precedent have been complied with.

        SECTION 11.05 Statements Required in Certificate or Opinion. Each
                      ---------------------------------------------
        certificate or opinion with respect to compliance with a covenant or
        condition provided for in this Indenture shall include:

                (1) a statement that the person making such certificate or
        opinion has read such covenant or condition;

                (2) a brief statement as to the nature and scope of the
        examination or investigation upon which the statements or opinions
        contained in such certificate or opinions are based;

                (3) a statement that, in the opinion of such person, he has made
        such examination or investigation as is necessary to enable him to
        express an informed opinion as to whether or not such covenant or
        condition has been complied with; and

                (4) a statement as to whether or not, in the opinion of such
        person, such covenant or condition has been complied with.

        SECTION 11.06 When Securities Disregarded. In determining whether the
                      ---------------------------
Holders of the required principal amount of Securities have concurred in any
direction, waiver or consent, Securities owned by the Company or by any person
directly or indirectly controlling or controlled by or under direct or indirect
common control with the Company shall be disregarded and deemed not to be
outstanding, except that, for the purpose of

                                      60
<PAGE>
 
determining whether the Trustee shall be protected in relying on any such
direction, waiver or consent, only Securities which the Trustee knows are so
owned shall be so disregarded. Also, subject to the foregoing, only Securities
outstanding at the time shall be considered in any such determination.

        SECTION 11.07 Rules by Trustee, Paying Agent and Registrar. The Trustee
                      --------------------------------------------
may make reasonable rules for action by or a meeting of Securityholders. The
Registrar and the Paying Agent may make reasonable rules for their functions.

        SECTION 11.08 Legal Holidays. A "Legal Holiday" is a Saturday, a Sunday
                      --------------
or a day on which banking institutions are not required to be open in the State
of New York or the principal office of the Trustee. If a payment date is a Legal
Holiday, payment shall be made on the next succeeding day that is not a Legal
Holiday, and no interest shall accrue for the intervening period. If a regular
record date is a Legal Holiday, the record date shall not be affected.

        SECTION 11.09 Governing Law. This Indenture, the Securities and the
                      -------------
Subsidiary Guarantees shall be governed by, and construed in accordance with,
the laws of the State of New York but without giving effect to applicable
principles of conflicts of law to the extent that the application of the laws of
another jurisdiction would be required thereby.

        SECTION 11.10 No Recourse Against Others. A director, officer, employee
                      --------------------------
or stockholder, as such, of the Company or any Guarantor Subsidiary shall not
have any liability for any obligations of the Company or any Guarantor
Subsidiary under the Securities, the Subsidiary Guarantees or this Indenture or
for any claim based on, in respect of or by reason of such obligations or their
creation. By accepting a Security and the related Subsidiary Guarantees, each
Securityholder shall waive and release all such liability. The waiver and
release shall be part of the consideration for the issue of the Securities.

        SECTION 11.11 Successors. All agreements of the Company in this
                      ----------
Indenture and the Securities shall bind their respective successors. All
agreements of the Trustee in this Indenture shall bind its successors.

        SECTION 11.12 Multiple Originals. The parties may sign any number of
                      ------------------
copies of this Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement. One signed copy is enough to prove this
Indenture.

        SECTION 11.13 Table of Contents; Headings. The table of contents, cross-
                      ---------------------------
reference sheet and headings of the Articles and Sections of this Indenture have
been inserted for convenience of reference only, are not intended to be
considered a part hereof and shall not modify or restrict any of the terms or
provisions hereof.

                                      61
<PAGE>
 
        SECTION 11.14 Separability Clause. In case any provision in this
                      -------------------
Indenture or in the Securities shall be invalid, illegal or unenforceable, the
validity, legality and enforceability of the remaining provisions shall not in
any way be affected or impaired thereby.

        SECTION 11.15 Benefits of Indenture. Nothing in this Indenture or in the
                      ---------------------
Securities, express or implied, shall give to any person, other than the parties
hereto and their successors hereunder and the Holders, any benefit or any legal
or equitable right, remedy or claim under this Indenture.

                                      62
<PAGE>
 
        IN WITNESS WHEREOF, the parties have caused this Indenture to be duly
executed as of the date first written above.

Attest:                                    CLEAN HARBORS, INC.



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


Attest:                                    CLEAN HARBORS ENVIRONMENTAL  
                                              SERVICES, INC.
                                           CLEAN HARBORS OF NATICK, INC.
                                           CLEAN HARBORS OF BRAINTREE, INC.
                                           CLEAN HARBORS OF CHICAGO, INC.
                                           CLEAN HARBORS OF CLEVELAND, INC.
                                           CLEAN HARBORS OF BALTIMORE, INC.
                                           CLEAN HARBORS OF CONNECTICUT, INC.
                                           CLEAN HARBORS KINGSTON FACILITY 
                                              CORPORATION
                                           MURPHY'S WASTE OIL SERVICE, INC.
                                           CLEAN HARBORS TECHNOLOGY 
                                              CORPORATION
                                           MR. FRANK, INC.
                                           SPRING GROVE RESOURCE RECOVERY, 
                                              INC.


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

        

Attest:                                    SHAWMUT BANK, N.A., as Trustee



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

                                      63
<PAGE>
 
                     EXHIBIT A - FORM OF FACE OF SECURITY

No._______                                                      $__________

                              CLEAN HARBORS, INC.
                         
                     12.5% Senior Note Due May 15, 2001      

        GUARANTEED AS TO PAYMENT OF PRINCIPAL, PREMIUM, IF ANY, AND INTEREST, BY
CLEAN HARBORS ENVIRONMENTAL SERVICES, INC., CLEAN HARBORS OF NATICK, INC., CLEAN
HARBORS OF BRAINTREE, INC., CLEAN HARBORS OF CHICAGO, INC., CLEAN HARBORS OF
CLEVELAND, INC., CLEAN HARBORS OF BALTIMORE, INC., CLEAN HARBORS OF CONNECTICUT,
INC., CLEAN HARBORS KINGSTON FACILITY CORPORATION, MURPHY'S WASTE OIL SERVICE,
INC., CLEAN HARBORS TECHNOLOGY CORPORATION, MR. FRANK, INC., SPRING GROVE
RESOURCE RECOVERY, INC. AND ANY OTHER SUBSIDIARY THAT EXECUTES A SUBSIDIARY
GUARANTEE (THE "GUARANTOR SUBSIDIARIES").
    
        Clean Harbors, Inc., a Massachusetts corporation, promises to pay to
_______________, or registered assigns, the principal sum of ____________ 
Dollars on May 15, 2001.      
                   
               Interest Payment Dates:  May 15 and November 15.      
                         
                     Record Dates:  May 1 and November 1.       

        Additional provisions of this Security are set forth on the other side
of this Security.

Dated:

                                           CLEAN HARBORS, INC.


                                           By:             
                                                ------------------------------
                                                President


                                                ------------------------------
                                                Treasurer


TRUSTEE'S CERTIFICATE OF AUTHENTICATION

Shawmut Bank, N.A.

as Trustee, certifies that this is one of                               [Seal]
the Securities referred to in the Indenture.


By: 
     ------------------------------
     Authorized Signatory

                                      A-1
<PAGE>
 
                      [FORM OF REVERSE SIDE OF SECURITY]

                              CLEAN HARBORS, INC.
                           
                      12.5% Senior Note Due May 15, 2001      

        1.      Interest
                --------
    
        Clean Harbors, Inc., a Massachusetts corporation (such corporation, and
its successors and assigns under the Indenture hereinafter referred to, being
herein called the "Company"), promises to pay interest on the principal amount
of this Security at the rate per annum shown above. The Company will pay
interest semiannually on May 15 and November 15 of each year. Interest on the
Securities will accrue from the most recent date to which interest has been paid
or, if no interest has been paid, from August 4, 1994. Interest will be
computed on the basis of a 360-day year of twelve 30-day months. The Company
shall pay interest on overdue principal at the rate borne by the Securities plus
1% per annum, and it shall pay interest on overdue installments of interest at
the same rate to the extent lawful.      

        2.      Method of Payment
                -----------------  
    
        The Company will pay interest on the Securities (except defaulted
interest) to the persons who are registered holders of Securities at the close
of business on the May 1 or November 1 next preceding the interest payment date
even if Securities are canceled after the record date and on or before the
interest payment date. Holders must surrender Securities to a Paying Agent to
collect principal payments. The Company will pay principal and interest in money
of the United States that at the time of payment is legal tender for payment of
public and private debts. However, the Company may pay principal and interest by
check payable in such money. It may mail an interest check to a Holder's
registered address.      

        3.      Paying Agent and Registrar
                --------------------------

        Initially, Shawmut Bank, N.A., a national banking association (the
"Trustee"), will act as Paying Agent and Registrar. The Company may appoint and
change any Paying Agent, Registrar or co-registrar without notice. The Company
or any of its domestically incorporated Wholly Owned Subsidiaries may act as
Paying Agent, Registrar or co-registrar.

        4.      Indenture
                ---------
    
        The Company issued the Securities under an Indenture dated as of 
August 4, 1994 (the "Indenture"), between the Company, each of the Guarantor 
Subsidiaries listed on the face of this Security and the Trustee. The terms of
the Securities include those stated in the      

                                      A-2
<PAGE>
 
Indenture and those made part of the Indenture by reference to the Trust
Indenture Act of 1939, as amended, (15 U.S.C. (S)(S)77aaa-77bbbb) as in effect
on the date of the Indenture (the "Act"). Capitalized terms used herein and not
defined herein have the meanings ascribed thereto in the Indenture. The
Securities are subject to all such terms, and Securityholders are referred to
the Indenture and the Act for a statement of those terms.
    
        The Securities are general unsecured obligations of the Company limited
to $50,000,000 aggregate principal amount (subject to Section 2.07 of the
Indenture). The Indenture imposes certain limitations on, among other things,
the issuance of additional Debt by the Company, the issuance of Debt and
Preferred Stock by any Subsidiary, the incurrence of Liens on the assets of the
Company and its Subsidiaries, the payment of dividends on, and redemption of
capital stock of the Company and its Subsidiaries and the redemption of certain
subordinated obligations of the Company and the making of Investments by the
Company or its Subsidiaries, the issuance and sale of equity interests of the
Subsidiaries, sales of assets, including Subsidiary Capital Stock, transactions
with Affiliates, and consolidations, mergers and transfers of all or
substantially all of the Company's assets. The Indenture also prohibits certain
restrictions on distributions from Subsidiaries and the incurrence by the
Company or the Subsidiaries of indebtedness that is senior in any respect in
right of payment to the Securities or the Subsidiary Guarantees. In addition,
the Indenture requires the Company, under certain circumstances, to offer to
purchase Securities in the event of a Change of Control.      

        5.      Optional Redemption
                -------------------
    
        Except as set forth in the next paragraph, the Securities may not be
redeemed prior to May 15, 1999. On and after that date, the Company may redeem
the Securities in whole at any time or in part at the following redemption
prices (expressed in percentages of principal amount), plus accrued interest to
the redemption date:      
    
        If redeemed during the 12-month period beginning May 15 of the years
indicated:      

<TABLE> 
<CAPTION> 
        Year                                                      Percentage
        <S>                                                       <C> 
        1999..............................................         106.25%
        2000 and thereafter...............................         100.00% 
</TABLE> 

        6.      Notice of Redemption
                -------------------- 

        Notice of redemption will be mailed by first class mail at least 30 days
but not more than 60 days before the redemption date to each Holder of
Securities to be redeemed at its registered address. Securities in denominations
larger than $1,000 may be redeemed in part

                                      A-3
<PAGE>
 
but only in whole multiples of $1,000. If money sufficient to pay the redemption
price of and accrued interest on all Securities (or portions thereof) to be
redeemed on the redemption date is deposited with the Paying Agent on or before
the redemption date and certain other conditions are satisfied, on and after
such date interest ceases to accrue on such Securities (or such portions
thereof) called for redemption.

        7.      Put Provisions
                --------------

        Upon a Change of Control, any Holder of Securities will have the right
to cause the Company to repurchase all or any part of the Securities of such
Holder at a repurchase price equal to 101% of the principal amount of the
Securities to be repurchased plus accrued interest to the date of repurchase as
provided in, and subject to the terms of, the Indenture.

        8.      Subsidiary Guarantees
                ---------------------

        As provided in the Indenture and subject to certain limitations therein
set forth, the obligations of the Company under the Indenture and this Security
are Guaranteed on a senior basis pursuant to Subsidiary Guarantees endorsed
hereon by each Guarantor Subsidiary. The Indenture provides that a Guarantor
Subsidiary shall be released from its Subsidiary Guarantee and that the Holder
shall have no further claim against such Guarantor Subsidiary upon compliance
with certain conditions.

        9.      Denominations; Transfer; Exchange
                ---------------------------------

        The Securities are in registered form without coupons in denominations
of $1,000 and whole multiples of $1,000. A Holder may transfer or exchange
Securities in accordance with the Indenture. The Registrar may require a Holder,
among other things, to furnish appropriate endorsements or transfer documents
and to pay any taxes and fees required by law or permitted by the Indenture. The
Registrar need not register the transfer of or exchange any Securities selected
for redemption (except, in the case of a Security to be redeemed in part, the
portion of the Security not to be redeemed) or any Securities for a period of 15
days before a selection of Securities to be redeemed or 15 days before an
interest payment date.

        10.     Persons Deemed Owners
                ---------------------

        The registered Holder of this Security may be treated as the owner of it
for all purposes.

        11.     Unclaimed Money
                ---------------

        If money for the payment of principal or interest remains unclaimed for
two years, the Trustee or Paying Agent shall pay the money back to the Company
at its request unless

                                      A-4
<PAGE>
 
an abandonment property law designates another person. After any such payment,
Holders entitled to the money must look only to the Company and not to the
Trustee for payment.

        12.     Defeasance
                ----------

        Subject to certain conditions, the Company at any time may terminate
some or all of its obligations under the Securities and the Indenture if the
Company deposits with the Trustee money or U.S. Government Obligations for the
payment of principal and interest on the Securities to redemption or maturity,
as the case may be.

        13.     Amendment, Waiver
                -----------------

        Subject to certain exceptions set forth in the Indenture, (i) the
Indenture or the Securities may be amended with the written consent of the
Holders of at least a majority in principal amount outstanding of the Securities
and (ii) any default or noncompliance with any provision may be waived with the
written consent of the Holders of a majority in principal amount outstanding of
the Securities. Subject to certain exceptions set forth in the Indenture,
without the consent of any Securityholder, the Company and the Trustee may amend
the Indenture or the Securities to cure any ambiguity, omission, defect or
inconsistency, or to comply with Article 5 of the Indenture, or to provide for
uncertificated Securities in addition to or in place of certificated Securities,
or to add Guarantees with respect to the Securities, or to add to the covenants
of the Company or the Guarantor Subsidiaries for the benefit of the Holders or
surrender any right or power conferred upon the Company, or to reflect either
the release of any Guarantor Subsidiary from its Subsidiary Guarantee or the
addition of any Subsidiary as a Guarantor Subsidiary to the extent permitted by
the Indenture, or to comply with any requirements of the SEC in connection with
qualifying the Indenture under the Act, or to make any change that does not
adversely affect the rights of any Securityholder.

        14.     Defaults and Remedies
                ---------------------

        Under the Indenture, Events of Default include (a) default in any
payment of interest on any Security when the same becomes due and payable, and
such default continues for a period of 30 days, (b) default in the payment of
the principal of any Security when the same becomes due and payable at its
Stated Maturity, upon redemption, upon acceleration or otherwise, or failure to
redeem or purchase Securities when required pursuant to the Indenture and the
Securities, (c) failure to (i) comply with the covenant described under Section
5.01 of the Indenture, (ii) make or consummate an Offer in accordance with the
provisions of Section 4.10 of the Indenture or (iii) make or consummate a Change
in Control Offer in accordance with the provisions of Section 4.14 of the
Indenture, (d) failure to comply with any of the agreements in the Securities or
the Indenture (other than those referred to in subsection (a), (b) or (c)
above), which continues for 60 days after there has been given to the Company by
the Trustee or to the Company and the Trustee by the Holders of at least 25% in
principal amount of Securities then outstanding a written notice specifying

                                      A-5
<PAGE>
 
such failure, (e) Debt of the Company or any Subsidiary is not paid within any
applicable grace period after final maturity or is accelerated by the holder
thereof because of a default, and the total amount of such Debt unpaid or
accelerated exceeds $5.0 million, (f) any judgment or decree for the payment of
money in excess of $5.0 million is rendered against the Company or a Subsidiary
and is not discharged and either (i) an enforcement proceeding has been
commenced by any creditor upon such judgment or decree or (ii) there is a period
of 60 days following such judgement during which such judgment or decree is not
discharged, waived or the execution thereof stayed, (g) any Subsidiary Guarantee
issued by any Guarantor Subsidiary ceases to be in full force and effect other
than in accordance with its terms, or any Guarantor Subsidiary shall deny or
disaffirm its obligations under its Subsidiary Guarantee, and (h) certain events
in bankruptcy, insolvency or reorganization with respect to the Company or any
Subsidiary.

        If an Event of Default occurs and is continuing, the Trustee or the
Holders of at least 25% in principal amount of the Securities may declare all
the Securities to be due and payable immediately. Certain events of bankruptcy
or insolvency with respect to the Company or any Subsidiary are Events of
Default which will result in the Securities being due and payable immediately
upon the occurrence of such Events of Default.

        Securityholders may not enforce the Indenture or the Securities except
as provided in the Indenture. The Trustee may refuse to enforce the Indenture or
the Securities unless it receives reasonable indemnity or security. Subject to
certain limitations, Holders of a majority in principal amount of the Securities
may direct the Trustee in its exercise of any trust or power. The Trustee may
withhold from Securityholders notice of any continuing default (except a Default
in payment of principal or interest) if it determines that withholding notice is
in their interest.

        15.     Trustee Dealings with the Company
                ---------------------------------

        Subject to certain limitations imposed by the Act, the Trustee under the
Indenture, in its individual or any other capacity, may become the owner or
pledgee of Securities and may otherwise deal with and collect obligations owed
to it by the Company or its affiliates and may otherwise deal with the Company
or its affiliates with the same rights it would have if it were not Trustee.

        16.     No Recourse Against Others
                --------------------------

        A director, officer, employee or stockholder, as such, of the Company,
any Guarantor Subsidiary or the Trustee shall not have any liability for any
obligations of the Company or any Guarantor Subsidiary under the Securities or
the Indenture or for any claim based on, in respect of or by reason of such
obligations or their creation. By accepting a Security, each Securityholder
waives and releases all such liability. The waiver and release are part of the
consideration of the issue of the Securities.

                                      A-6
<PAGE>
 
        17.     Authentication
                --------------

        This Security shall not be valid until an authorized signatory of the
Trustee (or an authenticating agent) manually signs the certificate of
authentication on the other side of this Security.

        18.     Abbreviations
                -------------

        Customarily abbreviations may be used in the name of a Securityholder or
an assignee, such as TEN COM (=tenants in common), TEN ENT (=tenants by the
entireties), JT TEN (=joint tenants with rights of survivorship and not as
tenants in common), CUST (=custodian), and U/G/M/A (=Uniform Gift to Minors
Act).

        19.     CUSIP Numbers
                -------------

        Pursuant to a recommendation promulgated by the Committee on Uniform
Security Identification Procedures the Company has caused CUSIP numbers to be
printed on the Securities and has directed the Trustee to use CUSIP numbers in
notices of redemption as a convenience to Securityholders. No representation is
made as to the accuracy of such numbers either as printed on the Securities or
as contained in any notice of redemption and reliance may be placed only on the
other identification numbers place thereon.

        The Company will furnish to any Securityholder upon written request and
without charge to the Securityholder a copy of the Indenture which has in it the
text of this Security in larger type. Requests may be made to:

        Clean Harbors, Inc.
        1200 Crown Colony Drive
        Quincy, Massachusetts  02169

        Attention:  Chief Financial Officer

                                      A-7
<PAGE>
 
- --------------------------------------------------------------------------------

                                ASSIGNMENT FORM

        To assign this Security, fill in the form below:

        I or we assign and transfer this Security to

                (Print or type assignee's name, address and zip code)

                (Insert assignee's soc. sec. or tax I.D. No.)

        and irrevocably appoint __________________________ agent to transfer
this Security on the books of the Company. The agent may substitute another to
act for him.


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


Date:________________ Your Signature:___________________________________________


- --------------------------------------------------------------------------------
Sign exactly as your name appears on the other side of this Security.


Signature Guarantee:                       ________________________________
                                           (The signature must be guaranteed by
                                           an officer of a participant in a
                                           recognized signature guarantee
                                           medallion program. Notarized or
                                           witnessed signatures are not
                                           acceptable.)


                                      A-8
<PAGE>
 
                      OPTION OF HOLDER TO ELECT PURCHASE


        If you want to elect to have this Security purchased by the Company
pursuant to Section 4.10 or 4.14 of the Indenture, check the box: [ ]

        If you want to elect to have only part of this Security purchased by the
Company pursuant to Section 4.10 or 4.14 of the Indenture, state the amount:
$_____________


Date:________________   Your Signature:________________________________________
                        (sign exactly as your name appears on the other side 
                        of the Security)


Signature Guarantee:____________________________________________________________
                    (Signature must be guaranteed by an officer of a participant
                    in a recognized signature guarantee medallion program.
                    Notarized or witnessed signatures are not acceptable)


Taxpayer Identification Number:_____________________________


                                      A-9
<PAGE>
 
               EXHIBIT B - FORM OF SUPPLEMENTAL INDENTURE TO BE
                  DELIVERED BY FUTURE GUARANTOR SUBSIDIARIES


        Supplemental Indenture (the "Supplemental Indenture"), dated as of
_______________, between _______________ (the "Guarantor Subsidiary"), a
subsidiary of [Clean Harbors, Inc. (or its successor), a Massachusetts
corporation (the "Company")], [Applicable subsidiary] and _____________________,
a national banking association, as trustee under the indenture referred to below
(the "Trustee").

                              W I T N E S S E T H
    
        WHEREAS, Clean Harbors Inc., a Massachusetts corporation has heretofore
executed and delivered to the Trustee an indenture (the "Indenture"), dated as
of August 4, 1994, providing for the issuance of an aggregate principal amount
of $50,000,000 of 12.5% Senior Notes due May 15, 2001 (the "Securities");     

        WHEREAS, Section 4.15 of the Indenture provides that under certain
circumstances the Company is required to cause any Guarantor Subsidiary to
execute and deliver to the Trustee a supplemental indenture pursuant to which
the Guarantor Subsidiary shall unconditionally Guarantee all of the Company's
obligations under the Securities pursuant to a Subsidiary Guarantee on the terms
and conditions set forth herein; and

        WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

        NOW, THEREFORE, in consideration of the foregoing and for other good an
valuable consideration, the receipt of which is hereby acknowledged, the
Guarantor Subsidiary and the Trustee mutually covenant and agree for the equal
and ratable benefit of the Holders of the Securities as follows:

        1. Capitalized Terms. Capitalized terms used herein without definition
           -----------------
shall have the meanings assigned to them in the Indenture.

        2. Agreement to Guarantee. The Guarantor Subsidiary hereby agrees that
           ----------------------
its obligations to the Holder and the Trustee pursuant to this Subsidiary
Guarantee shall be as expressly set forth in Article 10 of the Indenture and in
such other provisions of the Indenture as are applicable to Guarantor
Subsidiaries, and reference is made to the Indenture for the precise terms of
this Supplemental Indenture. The terms of Article 10 of the Indenture and such
other provisions of the Indenture as are applicable to Guarantor Subsidiaries
are incorporated herein by reference.

                                      B-1
<PAGE>
 
        3.      Execution and Delivery of Subsidiary Guarantees.
                -----------------------------------------------

                (a) To evidence its Subsidiary Guarantee set forth in this
        Supplemental Indenture, the Guarantor Subsidiary hereby agrees that a
        notation of such Subsidiary Guarantee substantially in the form of
        Exhibit C to the Indenture shall be endorsed by an Officer of such
        Guarantor Subsidiary on each Security authenticated and delivered by the
        Trustee after the date hereof.

                (b) Notwithstanding the foregoing, the Guarantor Subsidiary
        hereby agrees that its Subsidiary Guarantee set forth herein shall
        remain in full force and effect notwithstanding any failure to endorse
        on each Security a notation of such Subsidiary Guarantee.

                (c) If an Officer whose signature is on this Supplemental
        Indenture or on the Subsidiary Guarantee no longer holds that office at
        the time the Trustee authenticates the Security on which a Subsidiary
        Guarantee is endorsed, the Subsidiary Guarantee shall be valid
        nevertheless.

                (d) The delivery of any Security by the Trustee, after the
        authentication thereof under the Indenture, shall constitute due
        delivery of the Subsidiary Guarantee set forth in this Supplemental
        Indenture on behalf of the Guarantor Subsidiary.

        6. No Recourse Against Others. No past, present or future director,
           --------------------------
officer, employee, incorporator, or stockholder of the Guarantor Subsidiary, as
such, shall have any liability for any obligations of the Company or any
Guarantor Subsidiary, as such, under the Securities, any Subsidiary Guarantees,
the Indenture or this Supplemental Indenture or for any claim based on, in
respect of, or by reason of, such obligations or their creation. Each Holder of
the Securities by accepting a Security waives and releases all such liability.
The waiver and releases are part of the consideration for issuance of the
Securities.

        7. New York Law to Govern. The internal law of the State of New York
           ----------------------
shall govern and be used to construe this Supplemental Indenture and the
Subsidiary Guarantee.

        8. Counterparts. The parties may sign any number of copies of this
           ------------
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

        9. Effect of Headings. The Section headings herein are for convenience
           ------------------
only and shall not affect the construction hereof.

        IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

                                      B-2
<PAGE>
 
Dated:                             [Guarantor Subsidiary ]  
      -------------------------

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

Dated:          
      -------------------------     -----------------------------------------   
                                    as Trustee



                                         By:     
                                             --------------------------------
                                             Name:
                                             Title:
 
                                      B-3
<PAGE>
 
                        EXHIBIT C - FORM OF NOTATION ON
                 SENIOR NOTE RELATING TO SUBSIDIARY GUARANTEE

        Each Guarantor Subsidiary set forth below and each Subsidiary of the
Company which in accordance with Section 4.15 of the Indenture is required to
Guarantee the obligations of the Company under the Securities upon execution of
a counterpart of the Indenture, has jointly and severally, unconditionally and
absolutely Guaranteed (i) the due and punctual payment of the principal of and
interest on the Securities, whether at the maturity or interest payment or
mandatory redemption date, by acceleration, call for redemption or otherwise,
and of interest on the overdue principal of and interest, if any, on the
Securities and all other obligations of the Company to the Holders or the
Trustee under the Indenture or the Securities and (ii) in case of any extension
of time of payment or renewal of any Securities or any of such other
obligations, that the same will be promptly paid in full when due or performed
in accordance with the terms of the extension or renewal, whether at maturity,
by acceleration or otherwise.

        The obligations of each Guarantor Subsidiary to the Holder and to the
Trustee pursuant to this Subsidiary Guarantee and the Indenture are as expressly
set forth in Article 10 of the Indenture and in such other provisions of the
Indenture as are applicable to Guarantor Subsidiaries, and reference is hereby
made to such Indenture for the precise terms of this Subsidiary Guarantee. The
terms of Article 10 of the Indenture and such other provisions of the Indenture
as are applicable to Guarantor Subsidiaries are incorporated herein by
reference.

        This is a continuing Guarantee and shall remain in full force and effect
and shall be binding upon each Guarantor Subsidiary and its successors and
assigns until full and final payment of all of the Company's obligations under
the Securities and the Indenture and shall inure to the benefit of the
successors and assigns of the Trustee and the Holders and, in the event of any
transfer or assignment of rights by any Holder or the Trustee, rights and
privileges herein conferred upon that party shall automatically extend to and be
vested in such transferee or assignee, all subject to the terms and conditions
hereof. This is a Guarantee of payment, not a Guarantee of collection.

        This Subsidiary Guarantee shall not be valid or obligatory for any
purpose until the certificates of authentication on the Security upon which this
Subsidiary Guarantee is

                                      C-1
<PAGE>
 
noted shall have been executed by the Trustee under the Indenture by the manual
signature of one of its authorized officers.


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


84044.c6
7/25/94 9:40 pm


                                      C-2

<PAGE>
 
                         Davis, Malm & D'Agostine, P.C.
                                One Boston Place
                          Boston, Massachusetts  02108
                            Telephone (617) 367-2500
                               Fax (617) 523-6215



                                             July 28, 1994

Clean Harbors, Inc.
1200 Crown Colony Drive
Quincy, Massachusetts  02169

Gentlemen:

       You are seeking to offer and sell $50,000,000 of the 12 1/2% Senior Notes
due 2001 (the "Senior Notes") of Clean Harbors, Inc. (the "Company") through a
public offering made in accordance with the Securities Act of 1933, as amended.
The Senior Notes will be unconditionally guaranteed by guarantees (the
"Subsidiary Guarantees") provided by each of the Company's direct subsidiaries
(the "Guarantor Subsidiaries"). You have requested that we furnish to you an
opinion as to the legality of these securities, which opinion is to be filed as
Exhibit 5 to your Registration Statement, as amended, with respect to such
securities (the "Registration Statement").

       We have examined the charters and by-laws of each of the Company and the
Guarantor Subsidiaries, as amended to date, copies of votes of the Board of
Directors of the Company and the Guarantor Subsidiaries, the Registration
Statement as filed (or, in the case of Amendment No. 3 thereto, to be filed)
with the Securities and Exchange Commission (the "Commission") with respect to
the offering of such securities, and such other documents as we have deemed
pertinent. We have also made such examination of law as we have felt necessary
in order to render this opinion.

       We are of the opinion that, upon the issuance of an appropriate order by
the Commission allowing the Registration Statement to become effective, the due
execution of the Note Indenture, and the execution, issuance, authentication,
sale and delivery of the Senior Notes and the Subsidiary Guarantees as described
in the Registration Statement, the Senior Notes and the Subsidiary Guarantees
will be duly authorized and validly issued.
 
       This opinion does not pass on the application of the "Blue Sky" or 
securities laws of the various states.

       We hereby consent that this opinion may be filed as an exhibit to the 
Registration Statement.  We further consent to the use of our name and to all 
references to us included in or made a part of the Registration Statement.

                                             Yours very truly,

                                             DAVIS, MALM & D'AGOSTINE, P.C.



                                             By: /s/ C. Michael Malm
                                                -----------------------
                                                  C. Michael Malm,
                                                  Managing Director


CMM/JDC/mrw

<PAGE>
 
                          CONSENT OF COOPERS & LYBRAND
 
  We consent to the inclusion in or the incorporation by reference in the
registration statement of Clean Harbors, Inc. on Form S-2 of our reports dated
February 1, 1994 on our audits of the consolidated financial statements and
financial statement schedules of Clean Harbors, Inc. as of December 31, 1993
and 1992 and for the years ended December 31, 1993, 1992 and 1991, which
reports are included in the Clean Harbors, Inc. Annual Report on Form 10-K, for
the year ended December 31, 1993. We also consent to the reference to our Firm
under the caption "Experts."
 
                                          Coopers & Lybrand
 
Boston, Massachusetts
   
July 27, 1994     


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