EMCON
10-Q, 1997-05-14
ENGINEERING SERVICES
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                UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                    FORM 10-Q

(Mark One)

[ X ]    QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                  For the quarterly period ended March 31, 1997

                                       OR

[    ]   TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                         Commission file number 0-16225

                                      EMCON

             (Exact name of Registrant as specified in its charter)


             California                                       94-1738964
 ----------------------------------                      ----------------------
(State or other jurisdiction of                          (I.R.S.Employer
incorporation or organization)                           Identification No.)

400 South El Camino Real, Suite 1200
San Mateo, California                                           94402
- ---------------------------------------                     -------------
(Address of  principal executive offices)                    (Zip Code)


       Registrant's telephone number, including area code: (415) 375-1522

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the  preceding 12 months (or for such  shorter  period that the  registrant  was
required  to file  such  reports),  and  (2) has  been  subject  to such  filing
requirements for the past 90 days. Yes [ X ] No [ ]

8,535,372 shares of Common Stock Issued and Outstanding as of May 13, 1997.



                                       1
<PAGE>




                                      EMCON
                                      INDEX
                               REPORT ON FORM 10-Q
                      FOR THE QUARTER ENDED MARCH 31, 1997




                                                                         Page
                                                                        Number

FACING SHEET..........................................................     1

TABLE OF CONTENTS.....................................................     2

PART I.   FINANCIAL INFORMATION

    Item 1.      Financial Statements

                 Consolidated Balance Sheets -
                 March 31, 1997 and December 31, 1996.................     3

                 Consolidated Statements of Income -
                 Three months ended March 31, 1997 and 1996...........     4

                 Consolidated Statements of Cash Flows -
                 Three months ended March 31, 1997 and 1996...........     5 

                 Notes to Consolidated Financial Statements...........     6

   Item 2.       Management's Discussion and Analysis of
                     Financial Condition and Results of Operations....     9

PART II.   OTHER INFORMATION..........................................     12

Signatures............................................................     13

Index to Exhibits.....................................................     14


                             2
<PAGE>


<TABLE>
<CAPTION>

                                      EMCON
                           CONSOLIDATED BALANCE SHEETS
- ----------------------------------------------------------------------------------------------------------------------------------
                                                                                                         March 31,      December 31,
                                                                                                           1997             1996
(In thousands, except share amounts)                                                                    (Unaudited)      (Audited)
- -----------------------------------------------------------------------------------------------------------------------------------
<S>                                                                                                       <C>                 <C>
ASSETS                   
Current Assets:
Cash and cash equivalents ....................................................................            $ 7,901            $ 5,331
Accounts receivable, net of allowance for doubtful accounts of $1,226
     and $951 at March 31, 1997 and December 31, 1996, respectively ..........................             34,615             32,860
Costs and estimated earnings in excess of billings on
     uncompleted contracts ...................................................................              1,250                904
Prepaid expenses and other current assets ....................................................              4,965              4,425
Assets held for sale .........................................................................               --                9,382
                                                                                                          -------            -------

    Total Current Assets .....................................................................             48,731             52,902

Net property and equipment, at cost ..........................................................             14,552             14,722

Other assets .................................................................................              7,811              4,800
Deferred tax assets ..........................................................................              4,818              4,818
Goodwill, net of amortization ................................................................             12,596             12,716
Other intangible assets, net of amortization .................................................                905                954
                                                                                                          -------            -------

    Total Assets .............................................................................            $89,413            $90,912
                                                                                                          =======            =======

LIABILITIES AND SHAREHOLDERS' EQUITY
Current Liabilities:
Accounts payable .............................................................................            $ 4,527            $ 5,483
Accrued payroll and related benefits .........................................................              3,671              6,020
Other accrued liabilities ....................................................................              5,333              4,454
Billings in excess of costs and estimated earnings
     on uncompleted contracts ................................................................              1,283                 94
Long-term obligations due within one year ....................................................              2,226              2,250
                                                                                                          -------            -------

    Total Current Liabilities ................................................................             17,040             18,301

Long-term debt ...............................................................................             14,023             14,667
 Other noncurrent obligations ................................................................              1,810              2,132

Commitments and contingencies ................................................................               --                 --

Shareholders' Equity:
Preferred stock, no par value, 5,000,000 shares authorized;
     no shares issued or outstanding .........................................................               --                 --
Common stock, no par value, 15,000,000 shares authorized;
    8,535,372 and 8,512,688 shares issued and outstanding at
    March 31, 1997 and December 31, 1996, respectively .......................................             42,059             42,001
Retained earnings ............................................................................             14,481             13,811
                                                                                                          -------            -------

    Total Shareholders' Equity ...............................................................             56,540             55,812
                                                                                                          -------            -------

    Total Liabilities and Shareholders' Equity ...............................................            $89,413            $90,912
                                                                                                          =======            =======
</TABLE>

See accompanying notes

                             3
<PAGE>

                                      EMCON

                        CONSOLIDATED STATEMENTS OF INCOME
                                   (Unaudited)
<TABLE>
<CAPTION>

- -------------------------------------------------------------------------------
                                                           Three months ended
                                                                March 31,
                                                           ------------------
(In thousands, except per share amounts)                   1997          1996
                                                        
- -------------------------------------------------------------------------------
<S>                                                       <C>           <C> 
Gross revenue ....................................      $ 31,363       $ 28,564
Outside services, at cost ........................         3,782          3,957
                                                        --------       --------

   Net revenue ...................................        27,581         24,607

Costs and expenses:
   Direct expenses ...............................        12,606          9,689
   Indirect expenses .............................        14,226         14,799
   Restructuring .................................           (75)          --
   Loss on disposition of laboratory .............           333           --
   Gain on sale of assets ........................          (826)          --
                                                        --------       --------

   Income from operations ........................         1,317            119

Interest income (expense), net ...................          (237)           (22)
Equity in gain (loss) of affiliates ..............            18            (22)
Minority interest ................................           (35)           (22)
                                                        --------       --------

Income before provision for income taxes .........         1,063             53

Provision for income taxes .......................           372             19
                                                        --------       --------

Net income .......................................      $    691       $     34
                                                        ========       ========

Income per share .................................      $   0.08       $   0.01
                                                        ========       ========




</TABLE>

See accompanying notes


                              4
<PAGE>


                                      EMCON

                      CONSOLIDATED STATEMENTS OF CASH FLOWS
                                   (Unaudited)
<TABLE>
<CAPTION>

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

                                                                                                              Three months ended
                                                                                                                    March 31,
                                                                                                              -------------------
Increase (decrease) in cash and cash equivalents (in thousands)                                               1997           1996
- -----------------------------------------------------------------------------------------------------------------------------------
<S>                                                                                                             <C>           <C>

Cash flow from operating activities:
   Net income ......................................................................................        $   691         $    34
   Adjustments to reconcile net income to net cash
     used for operating activities:
     Depreciation and amortization .................................................................          1,044           1,463
     Gain (loss) on sale/disposal of property and equipment ........................................           (142)             29
     Loss on disposition of laboratories ...........................................................            333            --
     Gain on disposition of assets .................................................................           (826)           --
     Increase in salary continuation plan ..........................................................             17              11
     Changes in operating assets and liabilities:
       Accounts receivable .........................................................................         (1,755)             (8)
       Prepaid expenses and other current assets ...................................................           (450)           (902)
       Other assets ................................................................................           (147)           (384)
       Accounts payable ............................................................................           (416)           (472)
       Accrued payroll and related benefits ........................................................         (1,247)           (241)
       Other accrued liabilities ...................................................................          1,793             272
- -----------------------------------------------------------------------------------------------------------------------------------
   Net cash used for operating activities ..........................................................         (1,105)           (198)
- -----------------------------------------------------------------------------------------------------------------------------------
Cash flow from investing activities:
   Additions to property and equipment .............................................................         (1,157)           (621)
   Maturities of available for sale securities .....................................................           --               514
   Acquisitions,  net of cash acquired .............................................................           --            (4,007)
   Net cash on disposition of laboratory ...........................................................          3,794            --
   Net cash from disposition of assets .............................................................            840            --
   Proceeds from sale of property and equipment ....................................................            512               6
- -----------------------------------------------------------------------------------------------------------------------------------
   Net cash provided by (used for) investing activities ............................................          3,989          (4,108)
- -----------------------------------------------------------------------------------------------------------------------------------
Cash flow from financing activities:
   Dividend payments ...............................................................................            (21)           --
   Payment of current and noncurrent obligations ...................................................           (619)           (152)
   Issuance of common stock for cash ...............................................................             76             527
   Proceeds of new debt obligation .................................................................            250            --
- -----------------------------------------------------------------------------------------------------------------------------------
   Net cash provided by (used for) financing activities ............................................           (314)            375
- -----------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) in cash and cash equivalents ...................................................          2,570          (3,931)
Cash and cash equivalents, beginning of year .......................................................          5,331           9,451
- -----------------------------------------------------------------------------------------------------------------------------------
Cash and cash equivalents, end of period ...........................................................        $ 7,901         $ 5,520
- -----------------------------------------------------------------------------------------------------------------------------------

</TABLE>

See accompanying notes


                             5
<PAGE>


                                      EMCON

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                                   (Unaudited)


1.   Basis of Presentation

     The accompanying  consolidated financial statements include the accounts of
     the Company and its  wholly-owned  subsidiaries  after  elimination  of all
     significant intercompany accounts and transactions.

     While the financial information is unaudited, the statements in this report
     reflect all adjustments, which are normal and recurring, that are necessary
     for a fair  presentation  of the  results  of  operations  for the  interim
     periods covered and of the financial  condition of the Company at the dates
     of the balance  sheets.  The  operating  results  for the  interim  periods
     presented  are not  necessarily  indicative of  performance  for the entire
     year.

     These financial statements and notes should be read in conjunction with the
     Company's  consolidated  financial  statements  for the  fiscal  year ended
     December 31, 1996.

2.   Restructuring Charges

     In the fourth  quarter of 1996,  senior  management  reviewed the Company's
     operational  and  administrative  functions  for  the  purpose  of  further
     improving the Company's competitiveness and overall profitability. Based on
     this  review,  the  Company's  Board  of  Directors  approved  a  strategic
     restructuring  plan to  reposition  the  Company to fully  exploit its core
     strengths in engineering, design, construction, operations and maintenance.
     The  plan  included  closure  or  downsizing  of  underperforming  offices,
     write-off  of  employment   contracts   for  former   employees  no  longer
     participating in the Company's affairs and employee  severance.  During the
     quarter ended March 31, 1997,  $98,000 relating to the  restructuring  were
     incurred and charged  against the established  reserve.  At March 31, 1997,
     $940,000 of accrued  restructuring costs, net of a $75,000 reduction due to
     earlier than anticipated  subleasing of abandonded  office space,  remained
     and were  included  in other  accrued  liabilities.  To-date,  $217,000  of
     restructuring costs related to these actions have been incurred.

    In December 1994, as a result of changes in senior management, the Company's
    Board of Directors  approved a corporate  restructuring  plan which included
    the write off of  employment  contracts  with no  current  or future  value,
    termination of personnel,  and the  elimination or abandonment of excess and
    underperforming  assets and  facilities.  During the quarter ended March 31,
    1997,  $27,000  of cash  charges  related  to the  1994  restructuring  were
    incurred and charged against the established  reserve,  bringing the reserve
    to a zero balance.  To-date,  $1,169,000 of  restructuring  costs related to
    these actions have been incurred.



                             6
<PAGE>



3.   Acquisition

     On February 29, 1996,  EMCON acquired all of the outstanding  capital stock
     of  Organic  Waste   Technologies,   Inc.   ("OWT"),   a  Cleveland   based
     construction,   equipment  and  operations  and  maintenance  company  with
     significant expertise in solid waste management.

     The following  summarizes  the unaudited pro forma net revenue,  net income
     (loss) and net income  (loss) per share for the  combined  company  for the
     three  month  periods  ended  March 31,  1997 and 1996 had the  acquisition
     occurred at the beginning of each period presented.

                                                    (unaudited)
                                             Three months ended March 31,
                                             ----------------------------
       (in thousands)                        1997                 1996
       ----------------------------------------------------------------------
       Net revenue                         $27,581              $27,506
       Net income (loss)                       691                 (282)
       Income (loss) per share             $  0.08             $ (0.03)
       -------------------------------------------------------------------

4.   Credit Agreement

     In  conjunction  with the  acquisition  of OWT, the Company  entered into a
     $20,000,000  secured credit  agreement with its existing  commercial  bank,
     replacing its previous $10,000,000  unsecured line of credit. Under the new
     agreement,  the Company  borrowed  $10,000,000 on a long term basis with an
     interest  rate not to exceed the prime rate.  Principal  is to be amortized
     over seven  years,  but with any unpaid  amount  finally due and payable on
     June 30, 2001.  The  remaining  $10,000,000  under the credit  agreement is
     available on a line of credit basis for working  capital  purposes (with up
     to $5,000,000  available for  non-working  capital  purposes).  The line of
     credit component of the credit agreement expires on May 31, 1997.

5.   Litigation

    As a professional  services firm engaged in  environmental-related  matters,
    the Company encounters potential liability, including claims for significant
    environmental damage in the normal course of business.  The Company is party
    to lawsuits and is aware of potential  exposure  related to certain  claims,
    but in the opinion of  management  the  resolution of these matters will not
    have a material adverse effect on the Company's financial position,  results
    of operations or cash flows.

6.   Income Per Share

    Income per share for the three  months  ended March 31, 1997 is based on the
    weighted common and dilutive common equivalent shares  outstanding using the
    treasury stock method.  Common  equivalent  shares  include shares  issuable
    under the Company's stock option plans.  Primary and fully diluted  earnings
    per share are substantially the same.

                             7
<PAGE>

    Income per share for the three  months  ended March 31, 1996 is based on the
    weighted  average  number of common and dilutive  common  equivalent  shares
    outstanding using the modified treasury stock method.

    In February 1997, the Financial  Accounting Standards Board issued Statement
    No. 128,  "Earnings  per Share," which is required to be adopted on December
    31,  1997.  At that time,  the Company will be required to change the method
    currently  used to  compute  earnings  per  share and to  restate  all prior
    periods.  Under the new  requirements  for calculating  primary earnings per
    share, the dilutive effect of stock options will be excluded.  The impact is
    expected  to result in no change to the primary  earnings  per share for the
    first  quarter  ended  March 31,  1997 and a $0.01  decrease  to the primary
    earnings per share for the first quarter ended March 31, 1996. The impact of
    Statement 128 on the  calculation  of fully  diluted  earnings per share for
    these quarters is not expected to be material.

7.   Other

    In 1994, the Company converted to a  fifty-two/fifty-three  week fiscal year
    which will result in a fifty-two  week year in 1997.  The Company's year end
    falls  on the  Friday  closest  to the last day of the  calendar  year.  The
    Company also follows a five-four-four week quarterly cycle. For convenience,
    the accompanying  financial statements have been shown as ending on the last
    day of the calendar period.



                             8
<PAGE>


                                      EMCON

ITEM 2.       Management's Discussion and Analysis of Financial Condition and 
              Results Of Operations.

RESULTS OF OPERATIONS

NET REVENUE. Net revenue for the first quarter of 1997 totalled  $27,581,000,  a
12.1% increase from  $24,607,000  for the first quarter of 1996. The increase in
net revenue is due in part to the  inclusion of OWT for all of the first quarter
of 1997,  as compared to only one month of the first  quarter of 1996  following
its acquisition on February 29, 1996.  Excluding the net revenue contribution of
OWT  ($6,417,000  and  $1,675,000 in the quarters ended March 31, 1997 and 1996,
respectively), net revenue for the quarter totalled $21,164,000; a 7.7% decrease
from net revenue of  $22,932,000  in the first quarter of 1996.  The decrease in
net  revenue  is  primarily  attributable  to  lower  demand  for the  Company's
professional  services in the Company's  South and Southwest areas combined with
the planned reduction in headcount  companywide  throughout 1996, offset in part
by stronger demand for such services in the Company's North and Northwest areas.

DIRECT  EXPENSES.  Direct expenses  include  compensation for billable hours for
technical and  professional  staff and other project related expenses as well as
direct labor and  materials  for in-house  laboratory  testing and  construction
activities.  Direct expenses for the first quarter of 1997 totalled $12,606,000,
a 30.1% increase from the $9,689,000 for the same period in 1996.  Excluding the
impact of OWT,  direct  expenses  for the quarter  totalled  $8,105,000,  a 5.1%
decrease compared to direct expenses of $8,544,000 in the first quarter of 1996.
Excluding  the  impact  of OWT,  direct  expenses  as a percent  of net  revenue
increased to 38.3% in the first  quarter of 1997  compared to 37.3% in the first
quarter of 1996.

INDIRECT EXPENSES. Indirect expenses include salary compensation for nonbillable
hours  for  professional,   technical  and  administrative  staff,  and  general
administrative expenses such as rent, bonuses,  benefits,  insurance,  legal and
depreciation.   Indirect  expenses  for  the  first  quarter  of  1997  totalled
$14,226,000,  a 3.9% decrease from indirect expenses of $14,799,000 in the first
quarter of 1996.  Excluding the impact of OWT, indirect expenses for the quarter
totalled  $12,648,000,  a  12.5%  decrease  compared  to  indirect  expenses  of
$14,459,000 in the first quarter of 1996.

Excluding  the impact of OWT,  indirect  expenses  as a percent  of net  revenue
decreased to 59.7% in the first  quarter of 1997  compared to 63.1% in the first
quarter of 1996.  The  decrease  was  attributable  to improved  utilization  of
technical  and  professional  staff  as  well  as the  positive  impact  of cost
containment and restructuring measures put in place at the end of 1996.

ADJUSTMENT  OF  RESTRUCTURING  ACCRUAL.  During the first  quarter of 1997,  the
Company reversed an accrual of $75,000 made as part of the restructuring actions
taken in the fourth quarter of 1996. The year end accrual was revised to reflect
lower than  anticipated  costs  associated  with the  abandonment and subsequent
sublease of certain office space.

                                       9
<PAGE>

LOSS ON DISPOSITION OF LABORATORY. During the first quarter of 1997, the Company
completed the sale of its laboratory  subsidiary,  Columbia Analytical Services,
Inc.  ("CAS"),  to the employees of CAS for  $4,000,000 in cash,  CAS promissory
notes for $3,219,000 and a continuing  preferred stock interest in CAS valued at
$500,000.  The  Company  paid to CAS  $206,000  in  cash  for  retired  employee
contracts  and for  accelerated  vesting of stock  options  and other non vested
stock rights.  In  anticipation  of completing the sale, the Company  recognized
impairment  in the value of its  investment  in CAS of  $3,327,000 at the end of
1996. As a result of several pre closing adjustments,  the Company recognized an
additional loss on disposition of CAS in the first quarter of $333,000.

GAIN ON SALE OF ASSETS.  During the quarter  ended March 31,  1997,  the Company
completed the sale of one of its landfill gas-to-energy projects,  including the
related leasehold production rights and associated machinery and equipment.  The
Company recognized a gain on disposition of the project of $826,000.

INCOME FROM OPERATIONS. Income from operations for the first quarter of 1997 was
$1,317,000 compared to $119,000 during the comparable period last year.

INTEREST INCOME (EXPENSES) NET. The Company recorded  interest  expense,  net of
interest  income of $237,000 in the first quarter of 1997 compared to $22,000 in
the comparable quarter last year. The increase was due primarily to increases in
long term debt  incurred  for purposes of financing  the  acquisition  of OWT in
February  of  1996  and  the  subsequent  expansion  of  one of  OWT's  landfill
gas-to-energy projects.

LIQUIDITY AND CAPITAL RESOURCES

During  the  first  quarter  of  1997,  the  Company   financed  its  operations
principally from cash and marketable securities on hand, cash generated from the
disposition  of assets,  and from the  return on  investment  on its cash,  cash
equivalents and marketable  securities.  Net cash used for operating  activities
during the first quarter of 1997 was $1,105,000.  At March 31, 1997, the Company
had cash and cash equivalents of $7,901,000.

In  conjunction  with  the  acquisition  of  OWT,  the  Company  entered  into a
$20,000,000   secured  credit  agreement  with  its  existing  commercial  bank,
replacing  its  previous  $10,000,000  unsecured  line of credit.  Under the new
agreement,  the Company borrowed  $10,000,000 on a term loan basis with interest
at a managed  rate not to exceed the prime rate.  Principal  is to be  amortized
over seven years, but with any unpaid amount finally due and payable on June 30,
2001.  In April 1997,  following  the infusion of cash upon the sale of CAS, the
Company  prepaid,  on an accelerated  basis,  $3,000,000 of the then outstanding
principal  balance of the term loan. The remaining  $10,000,000 under the Credit
Agreement is available for working capital  purposes (with up to $5,000,000 also
being available for non-working capital purposes).  The line of credit component


                                       10
<PAGE>

of the Credit  Agreement  expires on May 31, 1997. The Company  expects to renew
the line of credit  component of the Credit  Agreement  prior to its expiration.
The  Credit  Agreement  contains  provisions  with  respect  to the  payment  of
dividends and the level of capital  expenditures and requires the maintenance of
specific levels of working capital,  tangible net worth and continued  quarterly
profitability.

The Company  invested  $1,157,000  in the first  quarter of 1997 in additions to
property and equipment;  mainly computers,  field equipment and the expansion of
its equipment fabrication facilities.

The Company  believes that its cash on hand and cash generated from  operations,
together  with its  available  bank  financing  will be  sufficient  to meet the
Company's capital needs for at least the next twelve months.


                                       11
<PAGE>




                                      EMCON

                            PART II OTHER INFORMATION

Items 1. - 4.     Not applicable.

Item 5.           Other Information

       On April  30,  1997,  EMCON  acquired  all of the  outstanding  equity of
       National  Earth  Products,  Inc.  ("NEP")  for cash of  $860,780  and the
       issuance  of  EMCON's  convertible  promissory  notes  in  the  aggregate
       principal amount of $800,000.  Approximately 50% of the convertible notes
       are  due on  May 1,  2000  with  the  balance  due  on May 1,  2002.  The
       indebtedness  bears  interest  at  the  rate  of  8%  per  annum  and  is
       convertible  into EMCON Common  Stock at a conversion  price of $6.50 per
       share.  The  former  shareholders  of NEP are also  eligible  to  receive
       additional  earn out payments in each of the three  twelve month  periods
       immediately  following the acquisition;  which earn out payments are tied
       to the financial  performance of NEP. NEP is a  Pennsylvania-based  solid
       waste  construction  company with  specialized  expertise in securing and
       processing  natural landfill cover and liner materials,  such as dirt and
       clay.

Item 6.           Exhibits and Reports

(a)   Exhibits - See Index to Exhibits on Page 14

(b)   Reports  on Form  8-K - No  reports  on  Form  8-K  were  filed  with  the
      Securities  and  Exchange  Commission  during the quarter  ended March 31,
      1997.


                                       12
<PAGE>


                                      EMCON


                                   SIGNATURES

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



Date:   May 14, 1997                 EMCON


                                       R. Michael Momboisse
                                       -------------------------------------
                                       R. MICHAEL MOMBOISSE
                                       Chief Financial Officer,
                                       Vice President - Legal, and Secretary
                                       (Duly authorized and principal
                                        financial and accounting officer)

                                       13
<PAGE>


                                                                   Sequentially
Exhibit                                                               Numbered
Number            INDEX TO EXHIBITS                                     Page
- ---------        ----------------------------                          ------

2.1       Stock Purchase  Agreement  dated January 30, 1996,               *
          among Organic Waste  Technologies,  Inc.  ("OWT"),
          Registrant and the selling shareholders and option
          holders of OWT,  incorporated  by  reference  from
          Exhibit  2.1 of the  Current  Report  on Form  8-K
          dated  March 14,  1996,  (the  "March  1996 8-K").

2.2       Asset  Purchase   Agreement  between  Yolo  Energy               *
          Partners,  Inc.,  Yolo  Landfill Gas  Corporation,
          EMCON,  Yolo Neo LLC,  and  Minnesota  Methane LLC
          dated December 31, 1996, incorporated by reference
          from  Exhibit  10.20 of the Annual  Report on Form
          10-K for the fiscal year ended  December  31, 1996
          (the "1996 10-K").

2.3       Acquisition Agreement between EMCON and its wholly               *
          owned    subsidiary,    Monterey    Landfill   Gas
          Corporation,  and Biomass Energy Partners V, L.P.,
          dated  March 6, 1997,  incorporated  by  reference
          from Exhibit 10.22 of the 1996 10-K.

 2.4      Stock Purchase Agreement dated April 4, 1997 among               18
          Registrant,  Columbia  Analytical  Services,  Inc.
          (`CAS"),  Northwest  Trust as  trustee  of the CAS
          Employee Stock  Ownership Trust and certain senior
          management employees of CAS.

 2.5      Stock  Purchase  Agreement  dated  April 30,  1997               43
          among  Registrant,  OWT,  National Earth Products,
          Inc. ("NEP") and the selling stockholders of NEP.

 3.1      Articles    of    Incorporation,    as    amended,               *
          incorporated  by referenc  from Exhibit 3.1 of the
          Registrant's  Registration  Statement  on Form S-1
          (File No. 33-16337)  effective  September 16, 1987
          (the "Form S-1 Registration Statement").

3.2       Certificate  of Amendment of Restated  Articles of               *
          Incorporation   as   filed   on  May   24,   1988,
          incorporated  by reference from Exhibit 3.2 of the
          Annual  Report  on Form 10-K for the  fiscal  year
          ended December 31, 1988 (the "1988 10-K").

3.3       Certificate  of Amendment of Restated  Articles of               *
          Incorporation   as   filed   on  June   4,   1991,
          incorporated  by reference from Exhibit 4.1 of the
          Quarterly  Report  on Form  10-Q  for  the  fiscal
          quarter  ended  June  30,  1991  (the  "June  1991
          10-Q").

3.4       Bylaws, as amended, incorporated by reference from               *
          Exhibit 4.2 of the June 1991 10-Q.


                             14
<PAGE>

                                                                  Sequentially
Exhibit                                                               Numbered
Number        INDEX TO EXHIBITS (Continued)                              Page
- --------- --------------------------------------------                  ------

10.1      EMCON  1986   Incentive   Stock  Option  Plan  and               *(1)
          Amendment,  incorporated by reference from Exhibit
          10.15 of the Form S-1 Registration Statement.

10.2      Form of Agreement pursuant to Salary  Continuation               *(1)
          Plan, incorporated by reference from Exhibit 10.17
          of the Form S-1 Registration Statement.

10.3      Schedule identifying Agreements pursuant to Salary               81(1)
          Continuation  Plan between  Registrant and certain
          employees.

10.4      Form of Indemnity Agreement between the Registrant               *
          and  each  of  the   Registrant's   officers   and
          directors,  incorporated by reference from Exhibit
          10.20 of the  Registrant's  Annual  Report on Form
          10-K for the fiscal year ended  December  31, 1988
          (the "1988 10-K").

10.5      EMCON  1988   Stock   Option   Plan,   amended  by               *(1)
          shareholder  approval  on May  25,1994,  including
          form  of  Nonqualified   Stock  Option   Agreement
          (Outside  Directors),  incorporated  by  reference
          from Exhibit 10.9 of Registrant's Quarterly Report
          on Form 10-Q for the fiscal quarter ended June 30,
          1994 (the "June 30, 1994 10-Q").

10.6      EMCON Employee Stock Purchase Plan incorporated by               *(1)
          reference  from Exhibit 10.10 of the  Registrant's
          Quarterly  Report  on Form  10-Q  for  the  fiscal
          quarter ended June 30, 1995.

10.7      EMCON  Restricted   Stock  Plan   incorporated  by               *(1)
          reference  from Exhibit 10.15 of the Annual Report
          on Form 10-K for the fiscal  year  ended  December
          31, 1990.

10.8      EMCON Deferred Compensation Plan effective January               *(1)
          1, 1994,  incorporated  by reference  from Exhibit
          10.12 of the  Registrant's  Annual  Report on Form
          10-K for the fiscal year ended  December  31, 1993
          (the "1993 10-K").

10.9      Trust    Agreement   for   the   EMCON    Deferred               *(1)
          Compensation  Plan and  Salary  Continuation  Plan
          Trust dated February 19, 1994,  between Registrant
          and  Wells  Fargo  Bank,   N.A.   incorporated  by
          reference  from  Exhibit  10.13 of the 1993  10-K.
         
10.10     Agreement  between Eugene M. Herson and Registrant               *(1)
          dated November 30, 1995, incorporated by reference
          from Exhibit 10.21 of  Registrant's  Annual Report
          on Form 10-K for the fiscal  year  ended  December
          31, 1995 (the "1995 10-K").


                             14
<PAGE>

                                                                   Sequentially 
Exhibit                                                               Numbered
Number          INDEX TO EXHIBITS (Continued)                           Page
- ------         --------------------------------                         ------

 10.12    Credit  Agreement  between The Bank of California,               *
          N.A.  and  Registrant  dated  February  29,  1996,
          incorporated by reference from Exhibit 10.2 of the
          March 1996 8-K.

10.13     Security Agreement between The Bank of California,               *
          N.A.  and  Registrant  dated  February  29,  1996,
          incorporated by reference from Exhibit 10.3 of the
          March 1996 8-K.

10.14     Pledge  Agreement  between The Bank of California,               *
          N.A.  and  Registrant  dated  February  29,  1996,
          incorporated by reference from Exhibit 10.4 of the
          March 1996 8-K.

10.15     Eurodollar Rate Option Agreement  between The Bank               *
          of California,  N.A. and Registrant dated February
          29, 1996,  incorporated  by reference from Exhibit
          10.5 of the March 1996 8-K.

10.16     Fixed Rate  Amortization  Option Agreement between               *
          The Bank of California,  N.A. and Registrant dated
          February 29, 1996,  incorporated by reference from
          Exhibit 10.6 of the March 1996 8-K.

10.17     Note  Agreement  among the  Registrant,  OWT,  and               *
          certain   employees  of  OWT  ,   incorporated  by
          reference from Exhibit 10.1 of the March 1996 8-K.

10.18     Rescission   and   Reformation   Agreement   dated               *
          effective  November 1, 1996 among EMCON,  OWT, and
          certain   employees   of  OWT,   incorporated   by
          reference from Exhibit 10.18 of the 1996 10-K.

10.19     New Note  Agreement  dated  effective  November 1,               *
          1996 among  EMCON,  OWT and certain  employees  of
          OWT,  incorporated by reference from Exhibit 10.19
          of the 1996 10-K.*

10.20     Second   Amendment  to  Credit   Agreement   dated               *
          effective  January  27, 1997 among EMCON and Union
          Bank of California,  N.A.  (formerly  known as The
          Bank  of  California,   N.A.),   incorporated   by
          reference from Exhibit 10.21 of the 1996 10-K.
  
10.21     Third   Amendment   to  Credit   Agreement   dated               *
          effective  March 27,  1997  among  EMCON and Union
          Bank of California,  N.A.  (formerly  known as The
          Bank  of  California,   N.A.),   incorporated   by
          reference from Exhibit 10.23 of the 1996 10-K.

10.22     Convertible  Notes  dated April 30, 1997 issued by               82
          EMCON to Dennis Grimm and Charles  Gearhart in the
          principal  amounts of $400,798.40 and $399,201.60,
          respectively.


                             15
<PAGE>

                                                                   Sequentially
Exhibit                                                                Numbered
Number          INDEX TO EXHIBITS (Continued)                            Page
- --------- --------------------------------------------                  ------


10.23     Lease Agreement dated April 4, 1997, between EMCON               96
          and Columbia Analytical Services, Inc.

11.1      Computation of Income (Loss) Per Share.                          127

27        Financial Data Schedule, included herein.                        128

*   Incorporated by reference
(1) Management contract or compensatory plan or arrangement required to be filed
    as an exhibit to this form  pursuant  to Item 14(c) of the  instructions  to
    Form 10-K.

                             16

<PAGE>


                                  EXHIBIT 2.4

                            STOCK PURCHASE AGREEMENT


         THIS STOCK  PURCHASE  AGREEMENT  ("Agreement")  dated  April 4, 1997,
1997,  among EMCON,  a California  corporation  ("Seller" or "EMCON"),  COLUMBIA
ANALYTICAL SERVICES,  INC., a Washington corporation ("CAS"), the members of the
senior  management  employee  group of CAS listed on the  signature  page hereto
("Management Purchasers") and NORTHWESTERN TRUST, as the trustee (the "Trustee")
of the COLUMBIA ANALYTICAL SERVICES, INC., EMPLOYEE STOCK OWNERSHIP TRUST ("ESOT
Purchaser").

                                R E C I T A L S:

         Pursuant  to a  Plan  of  Recapitalization  ("Recapitalization")  under
Section  368(a)(1)(E) of the Internal Revenue Code of 1986, as amended ("Code"),
a copy of which is attached  hereto as Exhibit A, the Seller owns the  following
shares  of stock in CAS:  1,250,000  shares  of  Class A Common  Stock  ("Common
Stock"),  4,000,000 shares of Class A Super Common Stock ("Super Common Stock"),
and 500,000 shares of Class A Preferred Stock  ("Preferred  Stock").  The Seller
desires to sell to ESOT  Purchaser and CAS certain of these shares in accordance
with the terms of this Agreement.

         NOW,  THEREFORE,  in consideration of the mutual covenants  hereinafter
contained, the parties hereby agree as follows:

                                   ARTICLE 1.
                           Purchase and Sale of Stock

     1.1 Purchase by ESOT Purchaser. Subject to the terms and conditions of this
Agreement, at the Closing, the Seller shall sell to the ESOT Purchaser,  and the
ESOT Purchaser shall purchase from the Seller,  4,000,000 shares of Super Common
Stock ("Super Common Shares") for a total purchase price of $5,000,000.

     1.2 Purchase by CAS. Subject to the terms and conditions of this Agreement,
at the Closing,  the Seller shall sell to CAS, and CAS shall  purchase  from the
Seller,  1,250,000 shares of Common Stock ("Common Shares") for a total purchase
price of $500,000.

     1.3 Stock  Retained by Seller.  Seller shall  retain the 500,000  shares of
Preferred Stock.

     1.4 Sale of Stock By CAS.  Subject  to the  terms  and  conditions  of this
Agreement,  within five (5) business days following  Closing,  CAS shall sell to
the Management Purchasers, and the Management Purchasers shall purchase from CAS
a total  of  461,538  shares  of  Common  Stock  for a total  purchase  price of
$300,000.  The shares of Common Stock shall be distributed  among the Management
Purchasers as shown on Schedule 1.4.

                                       18
<PAGE>

     1.5 Options to Management  Purchasers.  At Closing, CAS shall grant options
to the  Management  Purchasers  to purchase the number of shares of Common Stock
shown on Schedule 1.5 hereof.  The Stock  Option  shall be in the form  attached
hereto as Exhibit 1.5.

                                   ARTICLE 2.
                            ESOT Purchaser Financing

         The  obligation of the ESOT  Purchaser to purchase the shares of Seller
as provided in Section 1.1 is  conditioned  upon ESOT  Purchaser  obtaining  the
necessary financing. ESOT Purchaser intends such financing to be as follows:

     2.1 Bank  Financing.  CAS will undertake to obtain a $3,500,000 loan from a
financial institution.  Upon receipt of the proceeds of that loan, CAS will then
loan $3,500,000 to ESOT Purchaser upon the same terms and conditions as the loan
from the financial  institution  and which shall be in the form of the ESOT Loan
and Pledge  Agreement  attached as Exhibit 2.1. The ESOT Purchaser shall use the
loan proceeds to pay part of the purchase price referred to in Section 1.1.

     2.2 Seller  Financing.  Seller  agrees to loan to CAS the sum of $1,500,000
upon the terms and  conditions  of the  Subordinated  Promissory  Note  attached
hereto as  Exhibit  2.2.  CAS  agrees to loan to the ESOT the sum of  $1,500,000
which  shall be in the form of the ESOT Loan and Pledge  Agreement  attached  as
Exhibit 2.1. The ESOT  Purchaser  shall use the loan proceeds to pay part of the
purchase price referred to in Section 1.1.

     2.3 Contributions.  CAS shall make cash contributions to the ESOT Purchaser
in such amounts and at such times which,  together with any cash  dividends that
may be declared by CAS with  respect to the Class A Super  Common  Shares,  will
enable  the  ESOT  Purchaser  to pay  when  due all  amounts  owing  by the ESOT
Purchaser  under the Notes to CAS described in Section 2.1 and 2.2,  whether for
principal  or  interest.  A  contribution  or  dividend  by the CAS to the  ESOT
Purchaser to enable the ESOT  Purchaser to make any given  payment shall be made
sufficiently  prior  to the date  such  payment  is due to  provide  for  timely
payment.

                                   ARTICLE 3.
                                    Closing

     3.1 Time and Place.  The  exchange of items  described in Section 3.2 below
("the Closing") shall be held at the offices of CAS,  located at 1317 South 13th
Avenue, Kelso, Washington,  at 10 a.m., local time, on April 4, 1997, or at such
other time and place as shall be mutually  agreed upon by the parties.  The date
of the Closing is sometimes referred to herein as the "Closing Date."

     3.2  Deliveries.  On the Closing Date (a) CAS and the ESOT Purchaser  shall
execute and exchange  counterparts of the ESOT Loan and Pledge  Agreement in the
form  attached  hereto as  Exhibit  2.1;  (b) the ESOT  Purchaser  and CAS shall
deliver to the Seller  payment by federal  wire  transfer  or  cashier's  checks
representing  the purchase  price in accordance  with Section 1.1 and 1.2 above;
(c) the  Seller  shall  deliver  to the  ESOT  Purchaser  and  CAS  certificates


                                       19
<PAGE>

representing  the Super  Common  Shares and Common  Shares,  respectively,  duly
endorsed to the ESOT  Purchaser and CAS or  accompanied  by duly executed  stock
powers,  in transferable form with all requisite stock transfer stamps attached;
and (d) the parties shall deliver all other documents or agreements  required by
this Agreement.

                                   ARTICLE 4.
                          Other Transactions at Closing

     4.1  Subordinated  Promissory  Note.  CAS and Seller  acknowledge  that CAS
currently  owes  to  Seller  the sum of  $1,718,615.64.  As a  condition  to the
purchase of the shares by the ESOT  Purchaser,  Seller has agreed that this debt
shall be  represented  by a  Subordinated  Promissory  Note from CAS in the form
attached hereto as Exhibit 4.1.

     4.2 Terms of Subordination.  The two Subordinated Promissory Notes referred
to in Section  2.2 and 4.1 ("EMCON  Notes")  shall be  subordinated  to the bank
financing referred to in Section 2.1 and an operating line of credit for CAS not
to exceed  $1,200,000.  The  operating  line of credit  may  increase,  with the
approval of Seller, in its sole discretion, at the rate of $1.00 for every $2.00
in principal reduction under the EMCON Notes.

     4.3 Security for EMCON Notes.  The obligations of CAS under the EMCON Notes
shall be secured by an assignment by CAS of the Stock Pledge  Agreement  between
CAS and the ESOT. The form of assignment is attached hereto as Exhibit 4.3.

     4.4 Purchase of Seller's  Shares.  At Closing,  Seller will pay to CAS, via
wire  transfer,  a total of Two  Hundred Six  Thousand  Four  Hundred  Fifty-six
Dollars and Forty-three cents  ($206,456.43).  Four Hundred Eighty-seven Dollars
and Forty-three cents ($487.43) of such sum represents reimbursement of the cost
incurred by CAS pursuant to Section 4.6 below for the policy of title  insurance
on the property. CAS will promptly distribute the balance of such monies (net of
applicable  withholding)  to those persons and in the amounts listed on Schedule
4.4 in final  satisfaction  of  Seller's  agreements  to (a)  cancel  its Salary
Continuation  Agreements  with  Steve  Vincent;  (b) buy  back  shares  of EMCON
restricted  stock held by CAS  employees;  and (c) cash out  options to purchase
EMCON common stock held by CAS  employees.  Following the Closing,  CAS shall be
responsible  for  the  payment  of  all  income  tax,  withholding,   and  other
payroll-related taxes on all the payments described in this Section 4.4.

     4.5  State/Federal  Taxes.  The  following  amounts  shall  be  treated  as
additional  contributions  to  capital to CAS by  Seller:  (a) All  intercompany
payable amounts owed by Seller to Purchaser for past years accrued local, state,
and/or  federal  income taxes up through April 4, 1997; and (b) all debt owed by
CAS to  Seller  relating  to  Columbia  Aquatics.  Seller  agrees  to be  solely
responsible for the payment of these liabilities.

     4.6 Kelso Property.  The land and real property improvements for the Kelso,
Washington,  real estate legally  described on Schedule 4.6 hereof  ("Property")
shall be distributed to Seller by CAS as a dividend.  At the Closing,  CAS shall
convey to Seller by warranty deed  ("Deed") the fee title to the  Property.  The
form of the Deed shall be subject to the reasonable  approval of Seller and CAS.


                                       20
<PAGE>

The Property  shall be conveyed to Seller  subject only to  non-delinquent  real
property taxes and assessments  and those certain  exceptions to title set forth
in that certain  preliminary report issued as order No. 111643 by Cowlitz County
Title Company (the "Title Company") and dated March 3, 1997  (collectively,  the
"Approved Exceptions to Title"). At the Closing, the Title Company shall issue a
standard  ALTA  Owner's  Policy  of Title  Insurance  to EMCON in the  amount of
$300,000,  subject only to the Approved Exceptions to Title. At the Closing, CAS
and Seller shall also execute a Lease  Agreement in the form attached  hereto as
Exhibit  4.6 (the  "Lease  Agreement"),  pursuant  to which CAS shall  lease the
Property from Seller for a period of ten (10) years. Subject to reimbursement by
Seller  pursuant  to Section  4.4  above,  CAS shall pay for the policy of title
insurance  issued  in  connection  with the  foregoing.  CAS  shall  pay for all
transfer taxes, escrow fees, and other closing charges in connection therewith.

     Prior to Closing,  CAS will deposit the duly  executed and  notarized  Deed
into escrow for  recordation at the Closing upon telephone  confirmation by both
parties that the Closing has occurred  with respect to the transfer of the Super
Common Shares and the Common  Shares.  Both parties shall deposit with the Title
Company  their  respective  portions  of the  closing  costs  hereunder,  escrow
instructions  sufficient to close escrow and cause  issuance of the Title Policy
at the Closing, and such other documents as may be reasonably necessary to close
the escrow.

                                   ARTICLE 5.
                     Seller's Representations and Warranties

     Subject to the limitations  set forth in Article 10, the Seller  represents
and warrants to the ESOT Purchaser,  as follows, and, subject to the limitations
set forth in  Article 10  hereof,  Seller  represents  and  warrants  to CAS the
statements  set forth in Sections  5.1,  5.2,  5.3, 5.5, 5.6, 5.7, 5.8, 5.9, and
5.10:

     5.1 Title to Stock.  The Seller is the record and beneficial  owners of the
Shares, which, as of closing,  shall be free and clear of any security interest,
claim, lien, pledge,  option,  encumbrance or restriction (on transferability or
otherwise)  whatsoever  in law or in equity.  The  delivery  to CAS and the ESOT
Purchaser on the Closing Date of  certificates  for the Common  Shares and Super
Common Shares will convey to CAS and the ESOT Purchaser  respectively lawful and
valid title  thereto,  free and clear of any  security  interest,  claim,  lien,
pledge, option,  encumbrance or restriction whatsoever,  except those created by
the ESOT Loan Agreement and the EMCON Notes.

     5.2  Necessary  Authority;   Enforceability.   The  Seller  has  the  legal
competence and full power to enter into,  deliver and perform this Agreement and
to consummate the transactions contemplated herein. This Agreement has been duly
executed  and  delivered by the Seller,  and  constitutes  the legal,  valid and
binding  obligations of the Seller enforceable  against the Seller in accordance
with its terms,  except as the same may be limited  by  bankruptcy,  insolvency,
reorganization  or other laws  affecting the  enforcement  of creditors'  rights
generally  now or  hereafter  in  effect,  and  subject to the  availability  of
equitable remedies.

     5.3 No  Conflicts.  Except for the consents  listed on Schedule 5.3, all of
which  consents  have been or are being  delivered  concurrently  herewith,  the
execution,  delivery  and  performance  of this  Agreement by the Seller and the
Seller's  consummation of the transactions  contemplated hereby, do not and will
not  (i)  require  the  consent,   approval,   authorization,   order,   filing,
registration or  qualification of or with any court,  governmental  authority or
third  person,  (ii)  conflict  with or result in any  material  violation of or


                                       21
<PAGE>

default  under any  provision of any mortgage,  indenture,  lease,  agreement or
other instrument,  permit, concession,  grant, franchise or license to which the
Seller is party or by which it may be bound,  (iii)  conflict  with or result in
any violation of or default under any provision of the Articles of Incorporation
or the By-Laws of the Seller, (iv) violate any law, ordinance, rule, regulation,
judgment,  order or  decree  applicable  to the  Seller,  or (v)  result  in the
creation of any security  interest,  claim, lien, charge or encumbrance upon any
of the Common  Shares and Super  Common  Shares  except as set forth in the ESOT
Loan Agreement and the EMCON Notes.

     5.4 Authorized and Outstanding Stock

        (a) Prior to  implementation  of the  Recapitalization,  the  authorized
stock of CAS consisted of 100,000 shares of common stock, of which 10,000 shares
were issued and outstanding in the name of Seller.  After the  Recapitalization,
the capitalization of CAS is as follows:  3,500,000 authorized shares of Class A
Common Stock, of which 1,250,000 shares are issued and  outstanding;  10,000,000
authorized  shares of Class A Super Common Stock, of which 4,000,000  shares are
issued and  outstanding;  and  500,000  authorized  shares of Class A  Preferred
Stock, of which 500,000 shares are issued and outstanding.  All of the foregoing
outstanding shares are owned by Seller. To Seller's  knowledge,  all outstanding
shares  have  been  duly  authorized  and  are  validly   issued,   fully  paid,
nonassessable  and issued in full compliance  with the preemptive  rights of any
existing  shareholders  and in full compliance  with all applicable  federal and
state  securities  laws.  Except  as set  forth in  Schedule  5.4,  to  Seller's
knowledge, no shares of the capital stock of CAS have been reserved for issuance
for any purposes, and there are no outstanding rights, subscriptions,  warrants,
options, conversion rights, commitments or agreements of any kind outstanding to
purchase  or  otherwise  acquire  from CAS, or to cause CAS to issue or sell any
shares  of its  authorized  stock  or  securities  or  obligations  of any  kind
convertible into, exchangeable for or evidencing the right to acquire any shares
of its authorized stock.

        (b) To Seller's actual  knowledge,  there are no other shares or classes
of shares of authorized or outstanding capital stock of CAS. Notwithstanding the
fact that Stephen  Vincent or any other  executive  officer of CAS may have been
deemed to be an executive officer of Seller under the Securities Exchange Act of
1934  or any  other  law or  regulation.  Seller  shall  not be  deemed  to have
possessed  knowledge  of any  facts or  circumstances  solely  by  virtue of Mr.
Vincent's  or  such  other  executive  officer's  knowledge  of  such  facts  or
circumstances for the purposes of the  representation  set forth in this Section
5.4(b).

     5.5 Taxes. Seller has duly filed all consolidated federal, state, local and
foreign  income tax returns  necessary to be filed by it (all such returns being
true and  correct  in all  material  respects)  and Seller has duly paid or made
provisions  for the payment of all taxes  (including  any interest or penalties)
which are due or payable  pursuant to such returns or pursuant to any assessment
with  respect to  federal,  state,  and local  income  taxes,  whether or not in
conjunction with such returns, through the date of Closing.

     Except as set forth on Schedule 5.5 attached hereto, to Seller's knowledge,
there are no pending or  threatened  examinations  or audits of the  returns and
reports  of Seller for CAS's  operations  or any  claims  asserted  for taxes or
assessments of Seller for CAS operations nor are there outstanding agreements or
waivers  extending  the  statutory  period  of  limitations  applicable  to  any
consolidated income tax return of Seller for any period. Seller has not prepared
and filed a  consolidated  income tax return for the year  ending  December  31,



                                       22
<PAGE>

1996. Taxes will be due on account of the filing of said returns. Seller has and
will have  obligations to pay all local,  state and federal income taxes for CAS
operations with respect to periods up to April 4, 1997.

     5.6 Undisclosed  Liabilities.  Except as set forth on Schedule 5.6 attached
hereto,  Seller has not obligated  CAS nor caused CAS to incur any  liabilities,
whether absolute, accrued, contingent or otherwise, whether due or to become due
other than such liabilities Seller shall continue to be solely responsible for.

     5.7 Benefit Plan.  Except as set forth on Schedule 5.7, Seller has no plans
of the following  types which may result in any liability to CAS or its officers
or  directors:  pension,  profit-sharing,  stock  bonus,  or other plan which is
"qualified," or is intended to be "qualified"  under Section 401(a) of the Code,
or any bonus,  deferred  compensation,  hospitalization  or other  medical stock
purchase, life or other insurance, golden parachute agreements or other employee
benefit plan or arrangement.

     5.8  Financial  Statements.  Attached  hereto as Schedule  5.8 are true and
complete copies of Seller's  auditors  workpapers  showing the balance sheets of
CAS at December 31,  1994,  December 31,  1995,  and the related  statements  of
income,  stockholders'  equity and cash  flows for the  fiscal  years then ended
(collectively,  the "Annual Financial Statements"), and an audited balance sheet
and related  statement  of income of EMCON for the year ended  December 31, 1996
(collectively,  the Balance Sheet and the Statements may hereinafter be referred
to as the "Financial Statements").

        (a) To Seller's knowledge,  the Annual Financial  Statements  (including
the notes  thereto)  present  fairly  the  financial  condition  and  results of
operations  of CAS at and for the periods  indicated,  and have been prepared in
accordance with generally accepted accounting principles applied on a consistent
basis.

        (b) To  Seller's  knowledge,  CAS  has no  liabilities,  commitments  or
obligations  of any nature,  whether  absolute,  accrued,  contingent,  known or
unknown, due or to become due or otherwise,  which, in accordance with generally
accepted accounting  principles are required to be set forth on a balance sheet,
except (i) as reflected in its December 31, 1996, balance sheet included as part
of the Financial Statements and not heretofore discharged, (ii) as incurred as a
result of the normal and ordinary  course of its business since the date of such
balance sheet, none of which is materially adverse.

     5.9 No Liens and  Encumbrances.  Except as set forth on Schedule 5.9, or as
otherwise contemplated by this Agreement,  Seller has not placed or caused to be
placed any lien,  security  interest,  or other  encumbrance  upon the  personal
property of CAS.

     5.10 Representations  Complete.  None of the representations and warranties
made by the Seller herein,  nor any statement  made in any Schedule,  Exhibit or
certificate  furnished pursuant to this Agreement,  contains or will contain any
untrue statement of a material fact, or omit to state any material fact required
to be stated  therein,  or necessary in order to make the  statements  made, not
misleading.

                                       23
<PAGE>

                                   ARTICLE 6.
       Sellers' and Management Purchasers' Representations and Warranties

     The Management  Purchasers  jointly and severally  represent and warrant to
the ESOT  Purchaser as follows,  and,  subject to the  limitations  set forth in
Article 10 hereof, the Seller represents and warrants to the ESOT Purchaser,  to
Seller's knowledge, as follows:

     6.1  Subsidiaries.  Schedule  6.1 attached  hereto lists all  subsidiaries,
partnerships and other entities which CAS has organized or in which it has owned
an interest (other than publicly traded corporations or entities in which it has
held a de minimis  interest  for  investment  purposes)  and the status of CAS's
ownership in such  entitles on the date hereof.  Except as disclosed in Schedule
6.1,  immediately  after the Closing,  there will be no  corporation  which is a
member of the same  "controlled  group of  corporations"  as CAS, as  determined
under Section 1563(a) of the Code.

     6.2 Litigation and Contracts.  Schedule 6.2 attached hereto contains a true
and  complete  list  of  all  actions,  suits,   proceedings,   arbitrations  or
investigations  pending  or  threatened  against  CAS (or any of its  respective
officers or directors in  connection  with the business or affairs of CAS or the
transactions contemplated hereby), before any court or governmental body, United
States or foreign ("Proceeding" or "Proceedings"). The status of each Proceeding
is set forth on Schedule  6.2. As of the date  hereof,  except as  described  in
Schedule  6.2,  the  claims  which are the  subject of each  Proceeding  and the
defense  thereof is covered by  insurance  as  described  on  Schedule  6.2 or a
sufficient  cash  reserve  has been set  aside by CAS with the  result  that the
Proceedings,  in the aggregate, will not require any currently unfunded material
payments  by CAS or any  other  commitments,  other  than the time  expended  by
officers and employees in connection  with testimony or other  participation  in
the defense of the Proceedings. CAS is not in default in any material respect on
any of its contracts,  agreements or evidences of indebtedness,  and no party to
any  contract  or  agreement  with CAS which is material to the conduct of CAS's
business,  is in default in any  material  respect  under any such  contract  or
agreement.

                                   ARTICLE 7.
          CAS and Management Purchasers Representations and Warranties

     CAS and the  Management  Purchasers  jointly and  severally  represent  and
warrant to Seller and the ESOT Purchaser as follows:

     7.1 Necessary  Power and Authority;  Enforceability.  CAS has all requisite
power and  authority to enter into,  deliver and perform this  Agreement  and to
consummate the transactions  contemplated  herein.  The execution,  delivery and
performance  of  the  Agreement  and  the   consummation  of  the   transactions
contemplated  herein,  have been duly authorized by all necessary  action on the
part of CAS's Board of Directors and shareholders.  This Agreement has been duly
executed and delivered on behalf of CAS by the authorized corporate officers and
constitutes CAS's valid and legally binding obligation,  enforceable against CAS
in accordance  with its terms,  except as the same may be limited by bankruptcy,
insolvency, reorganization or other laws affecting the enforcement of creditors'
rights generally now or hereafter in effect,  and subject to the availability of
equitable remedies.

                                       24
<PAGE>

     7.2 No  Conflicts.  Except for the consents  listed on Schedule 7.2, all of
which  consents  have been or are being  delivered  concurrently  herewith,  the
execution,  delivery  and  performance  of  this  Agreement  by  CAS  and  CAS's
consummation of the transactions  contemplated  hereby,  do not and will not (i)
require the consent,  approval,  authorization,  order, filing,  registration or
qualification of or with any court, governmental authority or third person, (ii)
conflict  with or result in any  violation of or default  under any provision of
any  mortgage,   indenture,  lease,  agreement  or  other  instrument,   permit,
concession, grant, franchise or license to which CAS is party or by which any of
its outstanding Shares are or may be bound, (iii) conflict with or result in any
violation of or default under any provision of the Articles of  Incorporation or
the By-Laws of CAS, (iv) violate any law, ordinance, rule, regulation, judgment,
order or decree applicable to CAS, or (v) result in the creation of any security
interest,  claim, lien, charge or encumbrance upon any of the outstanding Shares
of CAS, except as set forth in the ESOT Loan Agreement and EMCON Notes.

        Authorized  and  Outstanding  Stock.  Prior  to  implementation  of  the
Recapitalization,  the  authorized  stock of CAS consisted of 100,000  shares of
common stock,  of which 10,000 shares were issued and outstanding in the name of
Seller.  After the  Recapitalization,  the  capitalization of CAS is as follows:
3,500,000  authorized  shares of Class A Common Stock, of which 1,250,000 shares
are issued and outstanding; 10,000,000 authorized shares of Class A Super Common
Stock,  of which  4,000,000  shares  are  issued and  outstanding;  and  500,000
authorized shares of Class A Preferred Stock of CAS, of which 500,000 shares are
issued and  outstanding.  All of the foregoing  outstanding  shares are owned by
Seller.  There  are no other  shares or  classes  of  shares  of  authorized  or
outstanding  capital  stock  of CAS.  All  outstanding  shares  have  been  duly
authorized and are validly issued, fully paid,  nonassessable and issued in full
compliance with the preemptive  rights of any existing  shareholders and in full
compliance with all applicable federal and state securities laws.

        Except as set forth in Schedule  7.3, no shares of the capital  stock of
CAS  have  been  reserved  for  issuance  for any  purposes,  and  there  are no
outstanding  rights,   subscriptions,   warrants,  options,  conversion  rights,
commitments  or  agreements  of any kind  outstanding  to purchase or  otherwise
acquire  from  CAS,  or to cause  CAS to issue or  purchase,  any  shares of its
authorized  stock or securities or  obligations  of any kind  convertible  into,
exchangeable  for or  evidencing  the right to acquire any shares of  authorized
stock.

     7.4 Litigation and Contracts.  Schedule 7.4 attached hereto contains a true
and  complete  list  of  all  actions,  suits,   proceedings,   arbitrations  or
investigations  pending  or  threatened  against  CAS (or any of its  respective
officers or directors in  connection  with the business or affairs of CAS or the
transactions  contemplated  herewith),  before any court or  governmental  body,
United States or foreign  ("Proceeding"  or  "Proceedings").  The status of each
Proceeding  is set  forth on  Schedule  7.4.  As of the date  hereof,  except as
described in Schedule  7.4, the claims which are the subject of each  Proceeding
and the defense  thereof is covered by insurance as described on Schedule 7.4 or
a  sufficient  cash  reserve  has been set aside by CAS with the result that the
Proceedings,  in the aggregate, will not require any currently unfunded material
payments  by CAS or any  other  commitments,  other  than the time  expended  by
officers and employees in connection  with testimony or other  participation  in
the defense of the Proceedings. CAS is not in default in any material respect on
any of its contracts,  agreements or evidences of indebtedness,  and no party to
any  contract  or  agreement  with CAS which is material to the conduct of CAS's
business,  is in default in any  material  respect  under any such  contract  or
agreement.

                                       25
<PAGE>

     7.5 Corporate  Organization  and Good Standing of CAS. CAS is a corporation
duly incorporated and organized, validly existing and in good standing under the
laws of the  State of  Washington  and has all  requisite  power  and  authority
(corporate  and other) to own,  operate and lease its properties and to carry on
its business as such business is now being  conducted.  CAS is duly qualified or
licensed to transact  business as a foreign  corporation and is in good standing
in all jurisdictions where its present activities require it to be so qualified,
licensed or in good standing.  Schedule 7.5 attached  hereto  contains a list of
all  jurisdictions in which CAS is qualified or licensed to transact business as
a foreign  corporation.  CAS has not  received  any written  notice or assertion
within the last three years from the Secretary of State or  comparable  official
of any  jurisdiction  to the effect  that CAS is  required  to be  qualified  or
otherwise  authorized to do business therein,  in which CAS has not qualified or
obtained such authorization.

     7.6 Employee  Benefit  Plans.  Except as set forth on Schedule 7.6 attached
hereto,  CAS  maintains  no pension,  profit-sharing,  stock bonus or other plan
which is "qualified,"  or is intended to be "qualified"  under Section 401(a) of
the Code.  Schedule 7.6  contains an accurate  and complete  list of each bonus,
deferred compensation, hospitalization or other medical, stock purchase, life or
other  insurance,  and each other  employee  benefit plan or  arrangement of CAS
(collectively,  the "Plans"). CAS has heretofore delivered to the ESOT Purchaser
true and complete copies of the documents  governing all such Plans as in effect
on the  date  hereof.  Each of the  Plans  has  been  administered  in  material
compliance  with its  terms  and all  filing,  reporting,  disclosure  and other
requirements of the Employee  Retirement Income Security Act of 1974, as amended
"ERISA"). CAS has no plan or commitment,  whether formal or informal and whether
legally  binding or not, to create any additional  such Plan or modify or change
any existing plan or arrangement. The trustee has been duly appointed.

     7.7 Personnel.

        (a) Schedule 7.7 attached hereto lists the names and current salaries of
all directors  and officers of CAS and the amount of all bonuses  accrued and to
be paid by CAS to all directors and officers of CAS for services rendered to CAS
through December 31, 1996.

        (b) Except as contained on Schedule 7.7 attached hereto,  CAS is not, or
will not be,  by  reason of  anything  done  hereafter  in  connection  with the
execution of this Agreement or the consummation of the transactions contemplated
hereby,  liable to any  employees of CAS for any amount of severance  pay or for
any other similar payments.

        (c) There is no unfair  labor  practice  pending  against CAS before the
National Labor Relations Board. There is no labor strike,  slowdown or stoppage,
or any union organizing campaign, actually pending or to the knowledge of CAS of
the Management  Purchasers,  threatened  against or involving CAS. No collective
bargaining agreement is currently being negotiated by CAS.

        (d) Except as set forth on Schedule  7.7,  CAS has not entered  into any
employment agreements or similar arrangements related to the compensation of its
officers.

                                       26
<PAGE>

     7.8 Sales and Use Taxes.  CAS has duly filed all sales and use tax  returns
necessary  to be filed by it, and CAS has duly paid or made  provisions  for the
payment of all such taxes,  (including any interest or penalties)  which are due
and payable to such returns or pursuant to any  assessments  with respect to all
such taxes, whether or not in conjunction with such returns, through the date of
closing.

        Except  as set  forth on  Schedule  7.8  attached  hereto,  there are no
pending or threatened  examinations  or audits of the returns or reports of CAS,
or claims  asserted for sales or use taxes or assessments  (other than as listed
by CAS on  Schedule  7.8  attached  hereto)  for CAS  operations,  nor are there
outstanding waivers or agreements  extending the statutory period of limitations
applicable to any tax return or report for any period.

     7.9  Corporate  Documents.  Complete and correct  copies of the Articles of
Incorporation of CAS ("Articles") and all amendments  thereto,  certified by the
Secretary  of  State of  Washington,  and of the  By-Laws  of CAS,  as  amended,
certified by the Secretary of CAS, have been furnished to the ESOT Purchaser and
no  amendments  to the Articles or the By-Laws have been adopted  subsequent  to
said  furnishing.  CAS is not in  default  in the  performance,  observation  or
fulfillment of its Articles or By-Laws.

     7.10 Liabilities.  There are no material transactions in which CAS has been
involved  or in  which  CAS has  participated  in the last  five  years or which
represents  a  current  or  contingent  commitment  or  liability  which are not
reflected on Schedule 7.10 attached hereto,  in the Annual Financial  Statements
(defined in Section  6.8) or in  resolutions,  or minutes,  certified  copies of
which have been delivered to all parties.

     7.11 Environmental  Matters.  Except as set forth on Schedule 7.11 attached
hereto, to the best of Management Purchasers' knowledge,  no condition exists at
any facility of, or real  property  owned by, CAS with respect to the storage or
discharge  into  the  earth  or its  atmosphere  of  effluents,  waste  or other
materials,  solid, liquid or gaseous,  nor has any waste been disposed of in any
way or manner,  in  violation  of law.  CAS has not received any notice from any
governmental  body  claiming  any material  violation  of any zoning,  building,
health or safety law or  ordinance,  or requiring  any material  work,  repairs,
construction,  alterations,  noise reduction,  cleanup or installation which has
not been fully complied with.

     7.12 No Violation.  Except as disclosed on Schedule  7.12 attached  hereto,
CAS is not in violation  of, or is under  investigation  with respect to, or has
been charged  with or given  notice of any  violation  of, any  applicable  law,
statute, order, rule, regulation,  policy or guideline promulgated,  or judgment
entered, by any federal, state, local or foreign court or governmental authority
relating to or affecting  CAS, or any of its  properties,  where such  violation
could have a  material  adverse  effect on CAS.  Neither  CAS nor any  director,
officer,  agent, employee or other person associated with or acting on behalf of
any of them in  connection  with the business of CAS, has (i) used any corporate
funds for unlawful contributions,  payments,  gifts or entertainment or made any
unlawful  expenditures  relating to  political  activity,  or made any direct or
indirect unlawful  payments to government  officials or others, or (ii) accepted
or received any unlawful contributions, payments, gifts or expenditures.

                                       27
<PAGE>

     7.13 Licenses, Patents, Trademarks.  Schedule 7.13 attached hereto contains
a list and rief description of all domestic and foreign letters patent, patents,
patent  applications,  patent and  know-how  licenses,  trade  names,  trademark
registrations   and   applications,   common  law   trademarks,   and  copyright
registrations and applications (collectively, the "Intangibles"),  owned by CAS.
The  business  of CAS is being  carried  on  without  conflict  with  registered
patents, licenses, trademarks,  copyrights, and trade names or other proprietary
rights of others. CAS has not received notice that it infringed or is infringing
on any Intangible,  invention,  technology,  process,  design, computer program,
know-how or formulae of another.  Except as described in Schedule  7.13, CAS has
not  assigned  any rights in, or granted any  security  interest  in, any of its
trade secrets, trademarks or copyrights and no current or previous key employees
or consultants of CAS have any rights in any  inventions,  software  programs or
designs  or  other   proprietary   concepts,   whether  or  not   patentable  or
copyrightable, which relate in any material respect to the business of CAS.

     7.14  Title to and  Condition  of Assets.  Schedule  7.14  attached  hereto
contains a list and brief  description  of each parcel of real property owned by
CAS or under  which  CAS is a  lessee,  true  copies  of any  applicable  leases
(including  all  amendments  thereof  and  modifications  thereto)  having  been
delivered to the ESOT Purchaser prior to the date hereof.

        (a) Except as set forth on Schedule  7.14,  CAS has good and valid title
to all of its  personal  property and  leasehold  interests,  including  but not
limited to the property and assets reflected on its balance sheet as of December
31, 1996,  included in the Financial  Statements (other than property and assets
disposed of in the ordinary  course of business  since such date) free and clear
of all material title defects and all liens, pledges, claims, charges,  security
interests, and other encumbrances. Except as set forth in Schedule 7.14, CAS has
not received notice of any existing claims adverse or challenges to the title or
ownership of any personal property of CAS.

        (b) All  personal  property  material  to the  condition  (financial  or
otherwise),  operations,  business  or  prospects  of CAS,  and  all  buildings,
structures  and  fixtures  used  by CAS  in the  conduct  of its  business  are,
considering their ages and uses, in satisfactory operating condition (subject to
normal  maintenance  and repair).  CAS has not received  notice of any violation
(which has not been cured) of any  building,  zoning or other law,  ordinance or
regulation  in respect of any notice that it has failed to comply in any respect
with such obligations.

     7.15 No Material  Change.  Since December 31, 1996,  except as disclosed in
Schedule 7.15 attached  hereto,  there has not been: (i) any materially  adverse
change  (whether or not in the  ordinary  and usual  course of  business) in the
financial condition,  net worth, assets,  liabilities,  personnel,  business, or
results of operations of CAS, (ii) any damage,  destruction  or loss (whether or
not covered by insurance)  materially  affecting the business of CAS,  (iii) any
material increase in the compensation payable or to become payable by CAS to its
officers or key employees,  pursuant to any agreement, bonus, insurance, pension
or other  beneficial plan or arrangement  made to or for the benefit of any such
officers or key employees,  other than in a manner  consistent  with  historical
practice,  (iv) any loans to or  borrowing  by CAS,  any mortgage or pledge with
respect  to any of their  properties  or  assets or any  assumption,  guarantee,
endorsement  or other  agreement to become  liable  (directly,  contingently  or
otherwise)  for any  loans  to any  other  person  or  entity,  (v) any  sale or
disposition  (or  agreement  to sell or  dispose)  of any  assets,  tangible  or


                                       28
<PAGE>

intangible,  of CAS,  except  in the  ordinary  course  of  business,  (vi)  any
cancellation  (or  agreement to cancel) of more than $10,000 in the aggregate of
any debts owed to or claims of CAS, except in the ordinary course of business or
(vii) any  amendment  or  termination  of any  material  contract,  agreement or
license to which CAS is a party, (viii) any amendment to the Articles or By-Laws
of, or any merger or consolidation of, CAS.

     7.16  Accounts  Receivable.  Schedule  7.16  attached  hereto sets forth an
accurate,  correct and  complete  aging of all  outstanding  accounts  and notes
receivable  as  of  December  31,  1996.  All  outstanding  accounts  and  notes
receivable reflected on the Financial Statements delivered to the ESOT Purchaser
are due and valid claims against account debtors for goods or services delivered
or  rendered.  All  receivables  arose in the ordinary  course of  business.  No
receivables are subject to prior assignment, claim, lien or security interest.

     7.17  Contracts.  Schedule 7.17  attached  hereto sets forth a complete and
accurate list of all outstanding  contracts to which CAS is a party,  other than
purchase orders and any contract which involves an aggregate  expenditure  after
the date of this  Agreement  of not more than  $10,000  and which is not already
reflected  in  the  Annual  or  Interim  Financial  Statements.   Schedule  7.17
identifies all contracts of CAS with its officers,  directors,  shareholders  or
any other person, firm or corporation affiliated with such persons.

     7.18  Insurance.  Schedule  7.18  attached  hereto sets forth an  accurate,
correct and complete  list and summary  description  (including  the name of the
insurer,  coverage,  premium and  expiration  date) of all binders,  policies of
insurance, sell insurance programs or fidelity bonds ("Insurance") maintained by
CAS or in which CAS is a named  insured.  Except as set forth on Schedule  7.18,
since  December 31,  1996,  there have been no claims or events which could form
the basis of a claim  against any  Insurance  as to which any insurer has denied
liability,  and there are no claims filed after  December  31,  1996,  under any
Insurance  that  have  been  disallowed  or  improperly   filed.  No  notice  of
cancellation  or non-renewal  with respect to any insurance has been received by
CAS.

                                   ARTICLE 8.
             Representations and Warranties Concerning the Property

     In connection with the conveyance of the Property to Seller, CAS represents
and warrants to Seller as follows:

     8.1  Compliance.  To the best of CAS's  actual  knowledge,  and  except  as
otherwise  disclosed to Seller by CAS,  CAS has not received any written  notice
that the current use and  operation  of the Property is not in  compliance  with
actual building codes, local, state, and federal laws and regulations.

     8.2  Procedures.  CAS has not  received  any  notice  of any  condemnation,
environmental,  zoning, or any other land use regulations or proceedings  either
instituted or, to CAS's actual knowledge, threatened or planned to be instituted
which would materially affect the use and operation of the Property.

     8.3  Litigation.  There is no  litigation  pending,  or,  to  CAS's  actual
knowledge,  threatened  against CAS arising out of the  ownership  or use of the
Property.

                                       29
<PAGE>

     8.4  Ownership.  CAS is the  sole  owner of the  Property  and has the full
right, power, and authority to convey the Property to Seller.

     8.5 Hazardous Materials. To CAS's knowledge, except to the extent set forth
in this Agreement, CAS has not received any written notice from any governmental
agency and has no actual knowledge that there exists any hazardous  materials in
or under the Property in  violation  of  applicable  laws,  rules,  regulations,
ordinances, or orders.

     For  purposes of this  Section 8.5,  the term  "hazardous  material"  shall
include  any  substance,  chemical,  compound,  or  mixture  which is (or  which
contains any substance, chemical compound, or mixture which is:

        (a) a "Hazardous Substance," "Hazardous Material," "Hazardous Waste," or
"Toxic Substance" under the Comprehensive  Environmental Response,  Compensation
and Liability Act of 1980, 42 U.S.C.  ss. 9601, et seq., the Hazardous  Material
Transportation  Act, 49 U.S.C.  ss. 1801, et seq., or the Resource  Conservation
and Recovery Act, 42 U.S.C. ss. 6901, et seq.;

        (b)  an  "Extremely   Hazardous  Waste,"  a  "Hazardous   Waste,"  or  a
"Restricted  Hazardous  Waste," under Section  25115,  25117,  or 25112.7 of the
California Health and Safety Code, or is listed pursuant to Section 25140 of the
California Health and Safety Code;

        (c) a "Hazardous Material," "Hazardous  Substance," or "Hazardous Waste"
under Section 25281, 25316, or 25501 of the California Health and Safety Code;

        (d) "Oil" or a "Hazardous  Substance"  under  Section 311 of the Federal
Water  Pollution  Control  Act,  33  U.S.C.  ss.  1321  as  well  as  any  other
hydrocarbonic substance or by-product.

        (e)  listed  under  any  law,  rules,  or  regulations  of the  State of
Washington as hazardous or toxic;

        (f) a material which, due to its characteristics or interaction with one
or more other substances,  chemical compounds, or mixtures, damages or threatens
to damage  health,  safety,  or the  environment,  or is  required by any law or
public agency to be remediated,  including  remediation which such law or public
agency requires in order for the property to be put to any lawful purpose; or

        (g) any  material  the  presence  of  which  would  require  remediation
pursuant  to the  guidelines  set  forth  in the  State  of  California  Leaking
Underground Fuel Tank Field Manual, whether or not the presence of such material
resulted from a leaking underground fuel tank.

     8.6  No  Encumbrances.  The  Property  is  free  and  clear  of  liens  and
encumbrances other than as described or referenced in Section 4.6 hereof.

                                       30
<PAGE>

     8.7 Condition of  Structures.  To CAS's  knowledge,  (i) no building on the
Property is in need of repairs to any structural  components,  including but not
limited to the foundation,  floor slabs, load-bearing walls, roof structure, and
roof  membrane;  and (ii) the parking  areas and related  paved areas within the
Property are in good condition and are not in need of repair or repaving.

                                   ARTICLE 9.
              Representations and Warranties of the ESOT Purchaser

         The  Trustee,  in its  capacity  as  such  and on  behalf  of the  ESOT
Purchaser, represents and warrants to the Seller and the CAS as follows:

     9.1 Necessary Authority. The Trustee has full power and authority under the
ESOT to execute and deliver this  Agreement on behalf of the ESOT  Purchaser and
to consummate the transactions contemplated hereby. This Agreement has been duly
authorized,  executed  and  delivered  by the  Trustee  on  behalf  of the  ESOT
Purchaser and  constitutes the legal,  valid and binding  obligation of the ESOT
Purchaser,  enforceable against the ESOT Purchaser in accordance with its terms,
except  as  the  same  may  be   limited  by  ERISA,   bankruptcy,   insolvency,
reorganization  or other laws  affecting the  enforcement  of creditors'  rights
generally  now or  hereafter  in  effect,  and  subject to the  availability  of
equitable remedies.

     9.2 No Conflicts. The execution, delivery and performance of this Agreement
by the Trustee,  in its capacity as such and on behalf of the ESOT Purchaser and
the consummation of the transactions  contemplated herein do not (a) require the
consent or approval  of, or filing  with,  any person or public  authority;  (b)
constitute  or result in the breach of any provision of, or constitute a default
under, the Columbia  Analytical  Services,  Inc.,  Employee Stock Ownership Plan
("ESOP"),  the ESOT Loan and Pledge  Agreement,  or any agreement,  indenture or
other instrument  known to the Trustee to which the Trustee,  in its capacity as
such,  or the ESOT  Purchaser  is a party or by  which it or its  assets  may be
bound;  or (c) violate any law,  regulation,  judgment or order binding upon the
Trustee,  in its  capacity as such,  or the ESOT  Purchaser  or give rise to any
liability  to the ESOT  Purchaser  under Title I of ERISA or Section 4975 of the
Code.

     9.3 Qualification. The ESOP is, in form, an "employee stock ownership plan"
within the meaning of Section  4975(e)(7)  of the Code and,  in form,  qualifies
under Section 401(a) of the Code.  The ESOT Purchaser has been duly  constituted
in accordance with valid and binding trust instruments, is validly existing and,
in form, qualifies under Section 501(a) of the Code.

                                   ARTICLE 10.
            Seller and Management Purchasers Obligations to Indemnify

     10.1 Seller.  Subject to Section  10.10,  Seller shall  indemnify  and hold
harmless  CAS,  Management  Purchasers,   the  ESOT  Purchaser,   and  the  ESOT
Purchaser's  authorized agents and  representatives,  against any and all costs,
losses,  claims  (including  claims  by  third  parties),   liabilities,  fines,
penalties,  damages,  and expenses  (including  interest which may be imposed in
connection  therewith,  court costs and  reasonable  fees and  disbursements  of
counsel)  suffered by any of them in connection  with:  (a) any inaccuracy in or
breach of any representations or warranties of the Seller made in Articles 5 and


                                       31
<PAGE>

6 hereof or in any document,  certificate, or exhibit delivered by the Seller in
accordance with the provisions of this  Agreement;  (b) any breach by the Seller
of this Agreement;  or (c) all past and present liabilities relative to Seller's
operations,  excluding any  operations  related to the operations of CAS and for
all of Seller's  other  operations,  including any such  operations no longer in
existence.

     10.2   Management   Purchasers.   Subject  to  Section  10.10,   Management
Purchasers,  jointly and severally,  shall  indemnify and hold harmless CAS, the
ESOT Purchaser and the ESOT Purchaser's  authorized agents and  representatives,
against any and all costs,  losses,  claims (including claims by third parties),
liabilities,  fines,  penalties,  damages and expenses (including interest which
may be imposed in  connection  therewith,  court costs and  reasonable  fees and
disbursements  of  counsel)  suffered  by any of them  in  connection  with  any
inaccuracy in or breach of any  representations  or warranties of the Management
Purchasers set forth in Article 6 hereof.

     10.3 CAS and  Management  Purchasers.  CAS and the  Management  Purchasers,
jointly and  severally,  shall  indemnify  and hold  harmless  Seller,  the ESOT
Purchaser  and the  ESOT  Purchaser's  authorized  agents  and  representatives,
against any and all costs,  losses,  claims (including claims by third parties),
liabilities,  fines,  penalties,  damages and expenses (including interest which
may be imposed in  connection  therewith,  court costs and  reasonable  fees and
disbursements  of  counsel)  suffered  by any of them  in  connection  with  any
inaccuracy  in or  breach  of any  representations  or  warranties  of  CAS  and
Management Purchasers set forth in Article 7 hereof.

     10.4 CAS. CAS will indemnify and hold harmless  Seller from and against any
and all costs, losses, claims (including claims by third parties),  liabilities,
fines, penalties,  damages and expenses (including interest which may be imposed
in connection  therewith,  court costs, and reasonable fees and disbursements of
counsel)  suffered by Seller in connection  with (a) any inaccuracy in or breach
of  any  representation  or  warranties  of  CAS  herein  or  in  any  document,
certificate,  or exhibit delivered by CAS or any officer of CAS pursuant to this
Agreement; and (b) relative to CAS's past, present, and future operations.

     10.5  Environmental  Indemnity.  From and after the Closing,  CAS agrees to
indemnify,  defend,  and  hold  Seller  harmless  from and  against  any and all
Environmental  Claims (as defined below) that may arise in connection with or in
any way related to the  handling,  storage,  existence,  or release of Hazardous
Materials (as defined in Section 8.5 hereof) at, beneath, to, from, or above (a)
the  Property,  (b) in  connection  with  any CAS  operations  conducted  at the
Bothell,  Washington facility occupied by CAS ("Bothell  Facility") during CAS's
occupation  of  such  facility,  or  (c) in  connection  with  CAS's  operations
conducted at the laboratory facility on Ringwood Avenue in San Jose,  California
during CAS's occupation of such facility.  CAS shall defend Seller in connection
with  the  foregoing   indemnity   obligations  with  legal  counsel  reasonably
acceptable to Seller. As used herein, the term "Environmental  Claims" means any
and all actual,  threatened, or potential claims,  proceedings,  suits, actions,
causes  of  actions,  demands,  losses,   obligations,   orders,   requirements,
restrictions,  or  directives  of any  governmental  agency  or  entity,  liens,
penalties,  fines, charges,  deaths,  damages, costs, and expenses of every kind
and nature whether now known or unknown,  whether  foreseeable or unforeseeable,


                                       32
<PAGE>

whether under any foreign,  federal,  or state or local law (both  statutory and
nonstatutory)  and whether  asserted or demanded by a third party against Seller
or incurred  directly or indirectly by Seller.  The provisions of this indemnity
shall survive the Closing and  recordation of the warranty deed and shall run to
the benefit of Seller's successors and assigns.

     10.6 Limitation of Seller's Liability; Offset of Notes.

        (a)  Seller's  liability  under  Section  10.1  shall be  limited to the
aggregate amount of Six Million Dollars ($6,000,000.00).

        (b)  Should  Seller  become  obligated  to  indemnify  CAS or  the  ESOT
Purchaser prior to such time as the Notes have been repaid in full, Seller shall
be entitled to offset any portion of its  liability  against the amounts owed to
Seller  under the Notes,  regardless  whether  such  amounts have become due and
payable.

     10.7 Survival. All representations, warranties, indemnities, covenants, and
agreements made by the Seller,  Management Purchasers,  and CAS herein or in any
other document executed by Seller,  Management Purchasers,  or CAS in connection
herewith shall survive the Closing.

     10.8  Limitations.  Notwithstanding  the foregoing or anything else in this
Agreement   to  the   contrary,   an   indemnitee   shall  not  be  entitled  to
indemnification  for losses  arising out of matters  referred to in this Article
10,  unless each such entity shall have given written  notice to the  indemnitor
and,  each other,  setting  forth its claim for  indemnification  in  reasonable
detail.

     10.9  Defense.  Indemnitee  shall  promptly  give  written  notice  to  the
indemnitor  and each  other  after  such  entity  has  knowledge  that any legal
proceeding  has been brought or any claim has been  asserted in respect of which
indemnification  may be sought under the  provisions  of this Article 10. If the
indemnitor,  within 10 days  after such  notice  has been given (or within  such
shorter period of time as an answer or other responsive motion may be required),
shall have  acknowledged  in writing the  indemnitor's  obligation to indemnify,
then the indemnitor shall have the right to control the defense of such claim or
proceeding,  and the  indemnitee  shall not settle or  compromise  such claim or
proceeding  without the written consent of the  indemnitor,  which consent shall
not  unreasonably  be  withheld  or  delayed.  The  indemnitee  may in any event
participate in any such defense with its own counsel and at its own expense.

     10.10 Seller's Reliance on CAS Management

        (a) The Management  Purchasers,  CAS and the ESOT Purchaser  acknowledge
that, in making the representations and warranties set forth in paragraph (a) of
Section 5.4, paragraphs (a) and (b) of Section 5.8, and Article 6 hereof, Seller
has  relied  exclusively  upon  (i)  the  truthfulness  of  statements  made  by
management  of CAS  from  time  to  time  and  the  statements  set  forth  in a
certificate of Stephen W. Vincent in the form attached hereto as Exhibit "10.10"
(the "CAS Officer's  Certificate");  (ii) the opinion letter of Alan L. Engstrom
delivered  at the Closing  pursuant  to Section  11.3(f)  hereof  (the  "Opinion
Letter");  and (iii) the  assumption  that,  during  such time as CAS has been a
subsidiary of Seller,  CAS's Board of Directors and management have at all times
acted in the best  interests of CAS and Seller.  Seller has made no  independent
investigation of the matters discussed in such  representations  and warranties.
Seller  shall have no liability to the  Management  Purchasers,  CAS or the ESOT


                                       33
<PAGE>

Purchaser in connection with any breach of such  representations  and warranties
to  the  extend  such  breach  is  related  to any of  the  following  facts  or
circumstances,  unless such facts or circumstances were known to Seller prior to
the Closing:

           (1) any facts or circumstances  that are inaccurately or incompletely
described in the CAS Officer's Certificate;

           (2) any inaccurate legal opinion  contained in the Opinion Letter, or
any inaccurate statement of fact upon which the Opinion Letter has relied;

           (3) a breach by CAS's Board of  Directors,  or any of its officers of
his/her or its fiduciary duties to CAS or Seller; and

           (4) a failure of CAS's Board of Directors to follow the  instructions
of Seller,  or the failure of CAS's  management  to follow the  instructions  of
Seller or the Board of Directors of CAS.

        (b) Notwithstanding the fact that Stephen Vincent or any other executive
officer of CAS may have been deemed to be an  executive  officer of Seller under
the Securities Exchange Act of 1934 or any other law or regulation, Seller shall
not be deemed to have possessed  knowledge of any facts or circumstances  solely
by virtue of Mr. Vincent's or such other executive  officer's  knowledge of such
facts or circumstances.

                                   ARTICLE 11.
                              Conditions to Closing

     11.1 Conditions to Each Party's Obligations at the Closing.  The respective
obligations  of each party to this  Agreement to effect the purchase and sale of
the  Common  Shares  and  the  Super  Common  Shares  shall  be  subject  to the
satisfaction at or prior to the Closing of the following conditions:

        (a) At the  time of the  Closing,  the  purchase  of the  Common  Shares
hereunder by CAS, the purchase of the Super Common Shares  hereunder by the ESOT
Purchaser,  and the  purchase  of the shares of Common  Stock by the  Management
Purchasers  from CAS shall be legally  permitted by all laws and  regulations to
which CAS and the Seller are subject.

        (b) All third party  consents  required in connection  with the purchase
and sale of the Common  Shares and the Super  Common  Shares  hereunder  and the
conveyance of the Property shall have been obtained.

        (c) No temporary restraining order, preliminary or permanent injunction,
or other order issued by any court of competent  jurisdiction  or other legal or
regulatory restraint of prohibition  preventing the consummation of the purchase
and sale of the Common  Shares or the Super Common  Shares or the  conveyance of
Property  shall  have  been  issued,  nor shall any  proceeding  brought  by any
governmental agency seeking any of the foregoing be pending; nor shall there, by


                                       34
<PAGE>

any action taken, or any statute, rule, regulation,  or order enacted,  entered,
enforced,  or deemed applicable to the purchase and sale of the Common Shares or
the Super  Common  Shares or the  conveyance  of the  Property  which  makes the
consummation of any of such transactions illegal.

        (d) The Recapitalization shall have been completed.

       11.2 Additional  Conditions to Obligations of CAS and the ESOT Purchaser.
In addition to the conditions set forth in Section 11.1, the  obligations of CAS
and the ESOT  Purchaser to purchase the Common  Shares and Super Common  Shares,
respectively,  and to convey  the  Property  to Seller  shall be  subject to the
satisfaction at or prior to the Closing of the following conditions:

        (a) All of the  representations  and  warranties  made by Seller  herein
shall be true and correct in all  material  respects as of the Closing Date with
the same force and effect as if such  representations  and  warranties  had been
made as of the Closing Date, except as expressly contemplated herein and CAS and
the ESOT  Purchaser  shall have received a certificate  to such effect signed on
behalf of Seller by the Chief Executive  Officer or Chief  Financial  Officer of
Seller.

        (b) Seller shall have performed in all material respects all obligations
required to be performed  by it under this  Agreement on or prior to the Closing
Date and CAS and the ESOT  Purchaser  shall have received a certificate  to such
effect  signed on behalf of  Seller  by the  Chief  Executive  Officer  or Chief
Financial Officer of Seller.

        (c) CAS shall have obtained financing for the ESOT Loan from a qualified
financial institution and shall have loaned such amount to ESOT Purchaser.

        (d) The ESOT Purchaser  shall have received a fairness  opinion from its
financial  advisor to the effect that the portion of the Purchase  Price payable
by the ESOT does not exceed the fair market value of the Super Common Shares and
that  the  purchase  of the  Super  Common  Shares  is fair to the  ESOT  from a
financial point of view.

        (e) Seller shall have executed and delivered a Master Services Agreement
in substantially the form attached as Exhibit 11.2(e) hereto (the "MSA").

        (f) Seller shall have executed and  delivered the Lease  Agreement and a
sublease for the Bothell Facility in the form of Exhibit 11.2(f) attached hereto
(the "Sublease").

        (g) EMCON shall have executed and delivered a Right of First Refusal and
Stock Option Agreement in the form attached hereto as Exhibit 11.2(g);

        (h) The ESOT  Purchaser and CAS shall have received a legal opinion from
R.  Michael  Momboisse,  Chief  Financial  Officer and  Vice-President-Legal  of
Seller, in substantially the form of Exhibit 11.2(h) attached hereto.

        (i) The ESOT  Purchaser  shall have  received a legal  opinion from Alan
Engstrom,  counsel to CAS, in substantially the form of Exhibit 11.2(i) attached
hereto.

                                       35
<PAGE>

        (j) All other  agreements  and  documents  required  to be  executed  or
delivered  by Seller or  Management  Purchasers  shall  have been  executed  and
delivered by them as contemplated hereby.

     11.3  Additional  Conditions  to Seller's  Obligations.  In addition to the
conditions  set forth in Section 11.1,  Seller's  obligations to sell the Common
Shares and the Super Common Shares to CAS and the ESOT Purchaser,  respectively,
shall be subject to the satisfaction at or prior to the Closing of the following
conditions:

        (a)  All  of  the  representations  and  warranties  made  by  the  ESOT
Purchaser,  Management  Purchasers,  and CAS herein shall be true and correct in
all  material  respects as of the Closing Date with the same force and effect as
if such  representations  and  warranties  had been made as of the Closing Date,
except  as  expressly  contemplated  herein,  and  Seller  shall  have  received
certificates  to such  effect  signed  by the  Trustee  on  behalf  of the  ESOT
Purchaser and signed by Stephen W. Vincent,  as Chief  Executive  Officer of CAS
and on behalf of the  Management  Purchasers,  each of whom hereby  appoints Mr.
Vincent to act as his or her representative for such purpose.

        (b) The ESOT  Purchasers,  CAS,  and  Management  Purchaser  shall  have
performed in all material  respects all obligations  required to be performed by
them under this Agreement on or prior to the Closing Date, and Seller shall have
received certificates to such effect signed by the Trustee on behalf of the ESOT
Purchaser and signed by Stephen W. Vincent,  as Chief  Executive  Officer of CAS
and on behalf of the  Management  Purchasers,  each of whom hereby  appoints Mr.
Vincent to act as his or her representative for such purpose.

        (c) CAS shall have executed and delivered the EMCON Notes and Assignment
of Stock Pledge Agreement.

        (d) CAS shall have executed and delivered the MSA.

        (e) CAS shall have executed and  delivered  the Lease  Agreement and the
Sublease.

        (f) Seller  shall  have  received a legal  opinion  from Alan  Engstrom,
counsel to CAS, in substantially the form of Exhibit 11.3(f) attached hereto.

        (g) Seller shall have  received a legal opinion from  McDermott,  Will &
Emery,  counsel  to the  ESOT,  in  substantially  the form of  Exhibit  11.3(g)
attached hereto.

        (h) The CAS  Officer's  Certificate  shall be executed and  delivered to
Seller.

        (i) Seller shall have received a letter from  Houlihan,  Lokey,  Howard,
and Zukin ("Houlihan")  stating in substance that, in its opinion,  the approach
taken by Williamette Management Associates,  Inc. with respect to the evaluation
of CAS,  and its  conclusion  regarding  the  purchase  price  paid by the  ESOT
Purchaser for the Super Common Shares are  reasonable  based on the  information
reviewed by Houlihan in connection with its engagement by Seller.

                                       36
<PAGE>

        (j) All  other  agreements  or  documents  required  to be  executed  or
delivered by CAS, the ESOT  Purchaser,  or Management  Purchaser shall have been
executed and delivered by them as contemplated hereby.

     11.4  Additional  Conditions to  Obligations of Management  Purchasers.  In
addition to the conditions set forth in Section 11.1, the Management Purchasers'
obligations  to purchase the shares of Common Stock from CAS shall be subject to
the  satisfaction  of all the  conditions  set  forth in  Sections  11.2 and the
additional  condition  that CAS shall have  executed  and  delivered  employment
agreements with members of senior  management  listed on Schedule 11.4 hereto in
the form attached hereto as Exhibit 11.4

                                   ARTICLE 12.
              Pre-Closing and Post-Closing Covenants of the Parties

     12.1 Plan  Operation.  CAS shall submit the Columbia  Analytical  Services,
Inc.,  Employee Stock  Ownership Plan ("ESOP") to the Internal  Revenue  Service
("IRS") for a  favorable  determination  letter  within the  remedial  amendment
period  set forth in Section  401(b) of the Code and shall make such  changes to
the  ESOP  as  the  IRS  requires  as  a  condition  to  the  issuance  of  such
determination  letter.  Further,  CAS shall  cause the ESOP to be  operated  and
administered  as a qualified  plan under  Sections  401(a) and 4975(e)(7) of the
Code and in material  compliance  with all applicable  requirements of ERISA and
regulations  thereunder  as from time to time in effect  and  applicable  to the
ESOP.

     12.2 401(k) Plan  Rollover.  Seller  shall  provide  pre- and  post-closing
assistance  to CAS in the  transfer  of CAS  Employees'  401(k)  Plan  accounts,
including converting 401(k) loan assets to a new 401(k) plan administrator.  All
CAS employees  participating  in the Seller's  401(k) Plan shall be deemed fully
vested in such plan as of Closing and  entitled to rollover of their  vested and
unvested account balances  conditioned upon  satisfaction of all remaining ERISA
requirements.

     12.3 Purchase of Stock by Management  Purchasers.  Following  Closing,  the
Management  Purchasers  shall  purchase  the stock from CAS as  contemplated  by
Section 1.4.

     12.4  Reimbursement of Long Distance.  Seller currently has a contract with
MCI for long  distance  service.  Seller and CAS agree that CAS will continue to
use MCI under the terms of this contract until such time as the parties mutually
agree  otherwise.  Seller shall invoice CAS monthly for its actual charges under
the MCI  contract  and CAS shall  timely pay such invoice as is customary in the
industry.

     12.5  Expenses.  CAS shall pay its  expenses  and the  expenses of the ESOT
Purchaser, incurred in connection with the authorization, preparation, execution
and performance of this Agreement.

     12.6 Further  Assurance.  Consistent with the terms and conditions  hereof,
each party hereto shall execute and deliver such instruments and take such other
action as the other parties hereto may reasonably  require in order to carry out
this Agreement and the transactions contemplated hereby.

                                       37
<PAGE>

     12.7 Confidentiality.  All written and unwritten information made available
to the ESOT  Purchaser  and its  representatives  and all copies,  excerpts  and
summaries  thereof  shall be treated and held by them in  confidence,  excepting
only that such data may be disclosed in confidence to advisors and agents of the
ESOT  Purchaser and  potential  lenders for the sole purpose of carrying out the
terms of this Agreement.

     12.8 Cooperation in Financial  Reporting and Tax. After the Closing CAS and
the Management Purchasers agree to cooperate,  and to cause CAS's accountants to
cooperate, with Seller and its accountants in:

        (a) the preparation or auditing of any consolidated financial statements
of Seller and any reports required to be filed by Seller with the Securities and
Exchange Commission;

        (b) the  preparation of any tax return or compliance with any tax audit;
or

        (c) any matter of a similar  nature;  with respect to any period  during
which CAS was a subsidiary of Seller.

     12.9  Continued  Coverage  Under Seller Group Plans.  From the Closing Date
through April 30, 1997,  Seller agrees to maintain  coverage  under its standard
life, accidental death and dismemberment, long-term disability, and supplemental
life  insurance  plans for the benefit of each person who was an employee of CAS
on the  Closing  Date to the same  extent as any such  employee  would have been
eligible  for  coverage  under  such  plans  were CAS to  remain a  wholly-owned
subsidiary  of Seller.  CAS agrees to reimburse  Seller for all premiums paid by
Seller on behalf of such employees for coverage on or after the Closing Date, as
well as any  additional  costs  incurred  by  Seller  in  connection  with  such
coverage.

     12.10 Issuances of Additional Equity Security. After the date hereof, until
such time as the ESOT  Notes have been  repaid in full,  CAS shall not issue any
equity  securities  (including  instruments  or  securities  exercisable  for or
convertible into equity securities) without the written consent of EMCON and the
ESOT Purchaser, other than:

        (i) the  shares  of  Common  Stock  to be  purchased  by the  Management
Purchasers pursuant to Section 1.4 hereof; and

        (ii) the  options  granted  to the  Management  Purchasers  pursuant  to
Section  1.5 hereof  and up to  1,516,666  shares of Common  Stock  issued  upon
exercise of such options.

                                   ARTICLE 13.
                                     General

     13.1 Execution of  Counterparts.  For the convenience of the parties,  this
Agreement  may be executed in one or more  counterparts,  each of which shall be
deemed an original,  but all of which together shall constitute one and the same
document.

                                       38
<PAGE>

     13.2 Notices.  All notices  which are required or may be given  pursuant to
the terms of this  Agreement  shall be in writing and shall be sufficient in all
respects if delivered  personally,  by  registered  or certified  mail,  postage
prepaid, overnight courier, or by facsimile, as follows:

                  If to the Seller:
                  EMCON
                  Attention:  R. Michael Momboisse, CFO
                  400 South El Camino Real, Suite 1200
                  San Mateo, CA 94402-1708
                  Facsimile:  (415) 375-0763

                  If to the Management Purchasers:
                  Columbia Analytical Services, Inc.
                  Attention:  Stephen W. Vincent
                  1317 S. 13th Ave.
                  P.O. Box 479
                  Kelso, WA  98626
                  Facsimile: (360) 425-9096

                  If to the ESOT Purchaser:
                  CAS Employee Stock Ownership Trust.
                  c/o Columbia Analytical Services, Inc.
                  1317 S. 13th Ave.
                  P.O. Box 479
                  Kelso, WA 98626
                  Facsimile:  (360) 425-9096

                  If to CAS to:
                  Columbia Analytical Services, Inc.
                  Attention: Stephen W. Vincent, President
                  1317 S. 13th Ave.
                  P.O. Box 479
                  Kelso, WA 98626
                  Facsimile:  (360) 425-9096

or to such  other  address or  facsimile  number as shall be  furnished  in like
manner by any party to the others.  Any such notice shall be deemed to have been
given,  received and become effective for all purposes at the time it shall have
been (a)  delivered to the  addressee  as  indicated  by the return  receipt (if
transmitted  by mail) or the  affidavit  of the  messenger  (if  transmitted  by
personal   delivery)  or  the   confirmation  of  receipt  (if  transmitted  via
facsimile);  or (b)  presented  for  delivery to the  addressee  as so indicated
during normal  business  hours, if such delivery shall have been refused for any
reason.

     13.3  Assignment,  Successors and. This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their  respective  successors and
assigns.  No party  shall  assign  any of its  rights or  obligations  hereunder


                                       39
<PAGE>

without the prior  written  consent of the other  parties  other than to a party
that acquired  substantially all of the transferor's  assets through a merger or
asset purchase.

     13.4 Governing Law. This Agreement shall be governed by, and interpreted in
accordance  with, the  substantive  laws of the State of  Washington,  except as
preempted by ERISA or required by the Code.  Venue and jurisdiction for any suit
or proceeding with respect to the interpretation or enforcement of any provision
hereof shall be in the County of Cowlitz, State of Washington.

     13.5 Entire  Agreement.  This  Agreement,  together  with the schedules and
exhibits  attached  hereto,  constitutes the entire  agreement among the parties
hereto, and no party hereto shall be bound by any communications between them on
the subject matter hereof unless such  communications  are in writing and bear a
date  contemporaneous  with or subsequent to the date hereof.  Any prior written
agreements or letters of intent among the parties  shall,  upon the execution of
this Agreement, be null and void.

     13.6 Headings.  The headings in the sections of this Agreement are inserted
for  convenience  only and  shall not  constitute  a part  hereof or affect  the
meaning or interpretation hereof.

     13.7  Representations  as to Compliance with Law. Whenever a representation
or  warranty  is made  herein  with  respect to  compliance  with any law,  that
representation  means  the  applicable  subject  matter  is in  compliance  with
applicable  statutes,  regulations  and  ordinances  as in existence on the date
hereof  and on the  Closing  Date and  does  not  extend  to any  amendments  or
revisions of such laws adopted subsequent to such dates.

     13.8 Severability.  The invalidity or  unenforceability of any provision of
this  Agreement  shall not affect the  validity or  enforceability  of any other
provision hereunder.

     13.9  Facsimile  Signatures.  Delivery  of  an  executed  counterpart  of a
signature page to this Agreement by facsimile  shall be effective as delivery of
a manually executed counterpart of this Agreement.

     13.10  ERISA  Construction.  Whenever  possible,  each  provision  of  this
Agreement  shall be construed and  interpreted in such manner as to be effective
and valid under ERISA and the Code, and regulations  issued  thereunder,  but if
any  provision  of  this  Agreement  shall  be  prohibited  by,  or  invalid  or
unenforceable  under,  such statutes or  regulations,  such  provision  shall be
ineffective and  unenforceable  to the extent of such prohibition or invalidity,
without invalidating the remainder of such provision or the remaining provisions
of this Agreement.

     13.11  Waiver,   Discharge,  etc.  This  Agreement  may  not  be  released,
discharged or modified  except by an  instrument in writing  signed on behalf of
each of the parties  hereto.  The failure of a party to enforce any provision of
this Agreement shall not be deemed a waiver by such party of any other provision
or subsequent breach of the same or any other obligation hereunder.

     13.12 Action Taken as Trustee.  This  document was executed by the Trustee,
not in its individual or corporate capacity, but solely as Trustee of the Trust.
The  performance  of this  Agreement  by the  Trustee  and  any and all  duties,


                                       40
<PAGE>

obligations  and  liabilities of the Trustee  hereunder  shall be effected by it
only as Trustee. The Trustee does not undertake nor shall it have any individual
or corporate  liability or obligation of any nature  whatsoever by virtue of the
execution and delivery of this Agreement,  or the representations,  covenants or
warranties contained herein.

     13.13  Consents  or  Waivers by  Management  Purchasers.  The  holders of a
majority  of the  shares  of  Common  Stock  sold to the  Management  Purchasers
pursuant to paragraph  1.4 hereof shall have the power and  authority to execute
any waiver,  consent, or amendment of or pursuant to this Agreement on behalf of
all of the Management  Purchasers;  provided,  however, that any such instrument
that  materially and adversely  affects the rights of any  Management  Purchaser
relative to the rights of the other Management Purchasers shall not be effective
against such Management Purchaser unless signed by him/her.

     IN WITNESS WHEREOF, the parties have signed this Agreement the day and year
first above written.

EMCON, a California corporation          __/s/________________________________
                                         STEPHEN W VINCENT

By  /s/R. Michael Momboisse              _/s/_________________________________
   ------------------------------------  GENE BENNETT
        Its  CFO & VP Legal
             --------------------------   

"Seller"
COLUMBIA ANALYTICAL SERVICES, INC.,
a Washington corporation                 ____/s/______________________________
                                         DAVID L. EDELMAN, JR.

By /s/Stephen W. Vincent
   ------------------------------------
         Its President                   _______/s/___________________________
             --------------------------  JEFF CHRISTIAN
"CAS"
NORTHWESTERN TRUST, Trustee of the
COLUMBIA ANALYTICAL SERVICES, INC.,
EMPLOYEE STOCK OWNERSHIP TRUST           _____/s/_____________________________
                                         JUDIE A. SCHOLES
By /s/Stephen W. Vincent
   -----------------------------------
    Its President
        -------------------------------

                  "ESOT Purchaser"       ___/s/_______________________________
                                         JOHN S. TAI

                                         ___/s/_______________________________
                                         ERIC H. GRINDELAND

                                      
                                         By____/s/____________________________
                                           STEPHEN W. VINCENT, Attorney-in-Fact

                                       41
<PAGE>
                                         _____/s/_____________________________
                                         MICHAEL SHELTON
                                         

                                         By_______/s/_________________________
                                           STEPHEN W. VINCENT, Attorney-in-Fact

                                                         "Management Purchasers"


                                       42

                                   EXHIBIT 2.5









                            STOCK PURCHASE AGREEMENT

                                      among

                                     EMCON,
                            a California corporation
                                   ("EMCON"),

                        Organic Waste Technologies, Inc.
                             a Delaware corporation
                                   ("Buyer"),

                          NATIONAL EARTH PRODUCTS, INC.
                           a Pennsylvania corporation
                                (the "Company"),

                                       and

                       CERTAIN STOCKHOLDERS OF THE COMPANY
                                   ("Sellers")


                              Dated April 30, 1997





                                       43
<PAGE>






                                TABLE OF CONTENTS

Page
1.       Definitions........................................................  1
         "Agreement"........................................................  1
         "Best Efforts".....................................................  1
         "Breach"...........................................................  2
         "Buyer"............................................................  2
         "Buyer's Disclosure Statement" ....................................  2
         "CERCLA"...........................................................  2
         "Closing"..........................................................  2
         "Closing Date".....................................................  2
         "Code"............................................................   2
         "Common Shares"....................................................  2
         "Company"..........................................................  2
         "Company Financial Statements".....................................  2
         "Consent"..........................................................  2
         "Contemplated Transactions"........................................  3
         "Damages"..........................................................  3
         "Employee Plans"...................................................  3
         "Employment Agreements"............................................  3
         "ERISA"............................................................  3
         "Exchange Act".....................................................  3
         "Family"...........................................................  3
         "GAAP".............................................................  4
         "Governmental Authorization".......................................  4
         "Governmental Body"................................................  4
         "Hazardous Substances".............................................  4
         "IRS"..............................................................  4
         "Knowledge"........................................................  4
         "Knowledge of the Company".........................................  4
         "Legal Requirement"................................................  5
         "Material Contracts"...............................................  5
         "Material Interest.................................................  5
         "Notes"............................................................  5
         "Order"............................................................  5
         "Ordinary Course of Business"......................................  5
         "Person"...........................................................  5
         "Proceeding".......................................................  5
         "Purchase Price"...................................................  5
         "Related Person"...................................................  5
         "Representative"...................................................  6
         "Securities Act"...................................................  6
         "Sellers"..........................................................  6
         "Sellers' Disclosure Schedule".....................................  7

                                       44
<PAGE>

2.       Sale, Transfer and Exchange of Shares and Options; Closing.......  7
         2.1      Sale and Exchange.......................................  7
         2.2      Purchase Price..........................................  7
         2.3      Closing.................................................  8
         2.4      Closing Obligations.....................................  8
         2.5      Employment Agreement.................................... 10
         2.6      Employment Agreement.....................................10

3.       Representations and Warranties of the Company.................... 10
         3.1      Corporation Organization................................ 10
         3.2      Capitalization.......................................... 11
         3.3      Corporate Authority..................................... 11
         3.4      Dissolution; Forfeiture................................. 12
         3.5      The Company Financial Statements........................ 12
         3.6      Absence of Unaccrued or Undisclosed Liabilities......... 12
         3.7      Absence of Certain Changes.............................. 13
         3.8      Taxes................................................... 13
         3.9      Title to Properties; Accounts Receivable................ 14
         3.10     Proprietary Rights...................................... 15
         3.11     Customer Lists.......................................... 16
         3.12     Benefit Plans and Arrangements.......................... 16
         3.13     Compliance with Laws; Legal Proceedings................. 17
         3.14     Contracts and Obligations .............................. 18
         3.15     Employee Relations...................................... 19
         3.16     Insurance............................................... 19
         3.17     Environmental Compliance................................ 19
         3.18     Advances; Related Party Transactions.................... 20
         3.19     Powers of Attorney...................................... 21
         3.20     No Brokers.............................................. 21
         3.21     Other Agreements to Sell the Company.................... 21
         3.22     Banking Relationships................................... 21
         3.23     Ownership of Shares and Options......................... 22
         3.24     Execution, Delivery and Enforceability of Agreement; 
                  No Violation............................................ 22
         3.25     Information Supplied.................................... 23
         3.26     Residence and Domicile.................................. 23

4.       [Reserved]

5.       Representations and Warranties of Buyer and EMCON................ 23
         5.1      Organization and Good Standing.......................... 23
         5.2      Execution, Delivery and Enforceability of Agreement;
                  No Violation............................................ 23
         5.3      Investment Intent....................................... 24
         5.4      Certain Proceedings..................................... 24
         5.5      Brokers or Finders...................................... 24
         5.6      Information Supplied.................................... 24


                                       45
<PAGE>

         5.7      No Material Change..................................... 24

6.       Covenants of the Sellers Prior to Closing Date.................. 24
         6.1      Conduct of Business Pending Closing.................... 24
         6.2      Advice of Changes...................................... 26
         6.3      Access and Information................................. 26
         6.4      Reasonable Efforts..................................... 27
         6.5      Supplements to Company Disclosure Schedule............. 27

7.       Covenants of Buyer Prior to Closing Date........................ 27
         7.1      Access to Information.................................. 27
         7.2      Approvals of Governmental Bodies....................... 27
         7.3      Supplements to Schedules............................... 28
         7.4      Best Efforts........................................... 28
         7.5      Advice of Changes...................................... 28

8.       Conditions Precedent to Buyer's Obligation to Close............. 28
         8.1      Accuracy of Representations............................ 28
         8.2      Material Changes....................................... 29
         8.3      Sellers' and the Company's Performance................. 29
         8.4      Consents............................................... 29
         8.5      Additional Documents................................... 29
         8.6      No Proceedings......................................... 30
         8.7      Sellers Disclosure Schedule............................ 30
         8.8      Execution by Sellers................................... 30
         8.9      Employment Agreement................................... 30
         8.10     Notes.................................................. 30
         8.11     Release of Suretyship Agreement.........................30

9.       Conditions Precedent to Sellers' Obligation to Close............... 30
         9.1      Accuracy of Representations............................... 31
         9.2      Approval of this Agreement by Board of Directors.......... 31
         9.3      Buyer's Performance....................................... 31
         9.4      Consents.................................................. 31
         9.5      No Material Adverse Change................................ 31
         9.6      Buyer's Disclosure Schedule............................... 31
         9.7      Additional Documents...................................... 31
         9.8      No Proceedings............................................ 32
         9.9      Execution................................................. 32
         9.10     Employment Agreements..................................... 32
         9.11     Indebtedness of the Company............................... 32

10.      Covenants After the Closing Date................................... 32
         10.1     Litigation Support........................................ 32
         10.2     NEP Sand & Gravel Receivable.............................. 32
         10.3     Mining License............................................ 32


                                       46
<PAGE>

         10.4     S Corporation Matters................................... 32

11.      Termination...................................................... 33
         11.1     Termination Events...................................... 33
         11.2     Effect of Termination................................... 34

12.      Survival Remedies................................................ 35
         12.1     Survival................................................ 35
         12.2     Limitation of Liability..................................35

13.      General Provisions............................................... 39
         13.1     Expenses................................................ 39
         13.2     Public Announcements.................................... 39
         13.3     Confidentiality......................................... 39
         13.4     Notices................................................. 40
         13.5     Binding Arbitration; Service of Process................. 41
         13.6     Further Assurances...................................... 42
         13.7     Waiver.................................................. 42
         13.8     Entire Agreement and Modification....................... 42
         13.9     Sellers' Disclosure Schedule............................ 43
         13.10    Assignments, Successors, and No Third Party Rights...... 43
         13.11    Severability............................................ 43
         13.12    Section Headings, Construction.......................... 43
         13.13    Interpretation of Agreement..............................43
         13.14    Time of Essence......................................... 44
         13.15    Governing Law........................................... 44
         13.16    Counterparts............................................ 44


Exhibit No.                Document

A                          List of Management Stakeholders

B-1                        Convertible Promissory Note to Dennis Grimm
B-2                        Convertible Promissory Note to Charles Gearhart

C-1                        Employment Agreement of Dennis Grimm
C-2                        Employment Agreement of Charles Gearhart

D                          Certain Pre-Closing Employee Bonuses


                                       47
<PAGE>






                            STOCK PURCHASE AGREEMENT


         THIS STOCK PURCHASE AGREEMENT (the "Agreement") is made as of April 30,
1997  among  EMCON,   a  California   corporation   ("EMCON"),   ORGANIC   WASTE
TECHNOLOGIES,  INC.,  a  Delaware  corporation  ("Buyer"),  and  a  wholly-owned
subsidiary of EMCON; NATIONAL EARTH PRODUCTS,  INC., a Pennsylvania  corporation
(the "Company"),  and the undersigned  selling  shareholders of the Company (the
"Sellers").


                                    RECITALS

     A. The  Sellers  desire to sell and Buyer  desires to buy all of the Common
Shares of the  Company,  held by the  Sellers  and set forth on Exhibit A hereto
(such Common Shares  representing all of the equity interest in the Company) for
the consideration and on the terms set forth in this Agreement.

                                    AGREEMENT

     The parties, intending to be legally bound, agree as follows:

     1.  Definitions.  For the purposes of this  Agreement,  the following terms
have the meanings specified or referred to in this Section 1:

                  "Agreement" -- as defined in the first paragraph hereof.

                  "Best Efforts" -- the efforts that a prudent  Person  desirous
of achieving a result  would use in similar  circumstances  to maximize,  to the
extent reasonably practicable, the prospects that a result will occur; provided,
however,  that an obligation to use Best Efforts under this  Agreement  does not
require that the Person subject to such  obligation take such actions that would
result in a  material  adverse  change to the  benefits  to such  Person of this
Agreement and the Contemplated Transactions.

                  "Breach"  --  a  "Breach"  of  a   representation,   warranty,
covenant,  obligation  or other  provision of this  Agreement or any  instrument
delivered pursuant to this Agreement will be deemed to have occurred if there is
or has been any material  inaccuracy in or breach of, or any material failure to
perform or comply with, such representation,  warranty,  covenant or obligation,
and the term "Breach" means any such inaccuracy, breach or failure.

                  "Buyer" -- as defined in the first paragraph hereof.

                  "Buyer's  Disclosure  Schedule"  --  the  disclosure  schedule
delivered by the Buyer to the Company  prior to the Closing and attached  hereto
and made a part hereof, as required by Section 5, below.

                  "CERCLA" -- as defined in Section 3.17.


                                       48
<PAGE>

                  "Closing" -- as defined in Section 2.4.

                  "Closing  Date" -- the date and time as of which  the  Closing
actually takes place.

                  "Code" -- the Internal  Revenue Code of 1986,  as amended,  or
any successor  law, and  regulations  issued by the IRS pursuant to the Internal
Revenue Code or any successor law.

     "Common  Shares" -- the issued or issuable  shares of the Company's  common
stock.

                  "Company" --  as defined in the first paragraph hereof.

                  "Company Financial Statements" -- as defined in Section 3.5.

                  "Consent" -- any approval,  consent,  ratification,  waiver or
other authorization (including any Governmental Authorization).

     "Contemplated Transactions" -- all of the transactions contemplated by this
Agreement, including:

     (a) the sale to Buyers of the Common Shares held by the Sellers;

     (b) the execution,  delivery and performance of the Employment  Agreements,
the Escrow Agreement, the Note Agreement and the Notes; and

     (c) the performance by Buyer,  the Company and Sellers of their  respective
covenants and obligations under this Agreement.

     "Damages" -- as defined in Section 12.2.

     "Employee Plans" -- as defined in Section 3.12.

     "Employment Agreements" -- as defined in Sections 2.5 and 2.6.

                  "ERISA" -- the Employee Retirement Income Security Act of 1974
or any successor law, and  regulations  and rules issued pursuant to that Act or
any successor law.

                  "Exchange Act" -- the  Securities  Exchange Act of 1934 or any
successor law, and the  regulations or rules issued  pursuant to such Act or any
successor law.

     "Family" -- as defined in the definition of "Related Person."

                  "GAAP"  --  generally   accepted   United  States   accounting
principles,  applied on a basis consistent with the basis on which the financial
statements referred to in Section 3.5 were prepared.


                                       49
<PAGE>

                  "Governmental   Authorization"   --  any  approval,   consent,
license,  permit,  waiver  or  other  authorization  issued,  granted,  given or
otherwise made available by or under the authority of any  Governmental  Body or
pursuant to any Legal Requirement.

                  "Governmental Body"  --  any

     (a)  nation,  state,  county,  city,  town,  village,   district  or  other
governmental jurisdiction of any nature;

     (b) federal, state, local, municipal, foreign or other government;

     (c) governmental or  quasi-governmental  authority of any nature (including
any governmental agency, branch, department, official or entity and any court or
other tribunal);

     (d) multi-national organization or body; or

     (e)  body  exercising,   or  entitled  to  exercise,   any  administrative,
executive,  judicial,  legislative,  police,  regulatory or taxing  authority or
power of any nature.

                  "Hazardous Substances" -- as defined in Section 3.17.

                  "IRS" -- the United  States  Internal  Revenue  Service or any
successor agency,  and, to the extent relevant,  the United States Department of
the Treasury.

     "Knowledge" -- a Person will be deemed to have  "Knowledge" of a particular
fact or other matter if:

     (a) such individual is actually aware of such fact or other matter; or

     (b) a prudent  individual could be expected to discover or otherwise become
aware of such fact in carrying out such individual's duties for the Company.

     "Knowledge  of the  Company"  -- shall  mean  Knowledge  of any  officer or
director of the Company about the affairs of the Company.

     "Legal  Requirement"  -- any federal,  state,  local,  municipal,  foreign,
international, multinational or other constitution, law, ordinance, principle of
common law, regulation, statute or treaty.

     "Material Contracts" -- as defined in Section 3.14.

     "Material Interest" -- as defined in the definition of "Related Person."

                  "Notes" -- as defined in Section 2.2(b).


                                       50
<PAGE>

                  "Order" -- any award, decision,  injunction,  judgment, order,
directive, ruling, decree, subpoena or verdict entered, issued, made or rendered
by any  court,  administrative  agency,  or  other  Governmental  Body or by any
arbitrator.

                  "Ordinary  Course of  Business" -- an action taken by a Person
will be deemed to have been taken in the "Ordinary  Course of Business"  only if
such action is consistent with the past practices of such Person and is taken in
the ordinary course of the normal day-to-day operations of such Person.

                  "Person"  --  any  individual,   corporation   (including  any
non-profit  corporation),  general or  limited  partnership,  limited  liability
company, joint venture, estate, trust, association, organization or other entity
or Governmental Body.

                  "Proceeding"  --  any  action,  arbitration,  audit,  hearing,
investigation,  litigation or suit  (whether  civil,  criminal,  administrative,
investigative or informal) commenced,  brought, conducted or heard by or before,
or otherwise involving, any Governmental Body or arbitrator.

     "Purchase Price" -- as defined in Section 2.2.

     "Related Person" -- with respect to a particular individual:

     (a) each other member of such individual's Family;

     (b) any Person that is directly or indirectly controlled by any one or more
members of such individual's Family;

     (c)  any  Person  in  which  members  of  such  individual's   Family  hold
(individually or in the aggregate) a Material Interest; and

     (d)  any  Person  with  respect  to  which  one or  more  members  of  such
Individual's Family serves as a director,  officer, partner, executor or trustee
(or in a similar capacity).

With respect to a specified Person other than an individual:

     (a) any Person  that  directly  or  indirectly  controls,  is  directly  or
indirectly controlled by, or is directly or indirectly under common control with
such specified Person;

     (b) any Person that holds a Material Interest in such specified Person;

     (c) each Person that serves as a director,  officer, partner,  executor, or
trustee of such specified Person (or in a similar capacity);

     (d) any Person in which such  specified  Person holds a Material  Interest;
and

                                       51
<PAGE>

     (e) any Person  with  respect to which such  specified  Person  serves as a
general partner or a trustee (or in a similar capacity).

For purposes of this definition,  (a) the "Family" of an individual includes (i)
the individual, (ii) the individual's spouse, (iii) any other natural person who
is related to the individual or the individual's  spouse within the first degree
and (iv) any other  natural  person who resides  with such  individual,  and (b)
"Material Interest" means direct or indirect beneficial ownership (as defined in
Rule 13d-3 under the  Securities  Exchange Act of 1934) of voting  securities or
other  voting  interests   representing  at  least  ten  percent  (10%)  of  the
outstanding  voting  power of a Person  or  equity  securities  or other  equity
interests  representing  at least ten percent  (10%) of the  outstanding  equity
securities or equity interests in a Person.

                  "Representative"  -- with respect to a particular  Person, any
director, officer, employee, agent, consultant, advisor, or other representative
of such Person, including legal counsel, accountants, and financial advisors.

                  "Securities  Act"  --  the  Securities  Act  of  1933  or  any
successor  law, and  regulations  and rules  issued  pursuant to that Act or any
successor law.

                  "Sellers"  --  as defined in the first paragraph hereof.

                  "Sellers  Disclosure  Schedule"  --  the  disclosure  schedule
delivered by the Sellers to Buyer prior to the Closing and  attached  hereto and
made a part hereof as required by Section 3 below.

                  2.       Sale, Transfer and Exchange of Shares; Closing.

                           2.1      Sale and Exchange.

     (a) At the Closing,  the Sellers shall sell and transfer to Buyer and Buyer
shall purchase from the Sellers,  the Common Shares held by such Sellers and set
forth opposite their names on Exhibit A hereto.

     2.2  Purchase  Price.  The  purchase  price  for the  Common  Shares  being
purchased shall be paid as follows:

     (a) At the  Closing,  Buyer  shall pay the  Sellers  cash in the  aggregate
amount of  $860,789.81  by wire  transfer  ($431,253.98  to Dennis M.  Grimm and
$429,535.83 to Charels H. Gearhart).

     (b) At the Closing, Buyer shall deliver to Sellers EMCON's promissory notes
in the forms attached  hereto as Exhibit B-1 and B-2 in the aggregate  principal
amount of $800,000 (the "EMCON  Notes").  The EMCON Notes shall bear interest at
the rate of 8% per annum, simple interest, payable quarterly, with all principal
and any unpaid  interest  due and payable in full at maturity  (May 1, 2000 with
respect to the EMCON Note held by Dennis  Grimm and May 1, 2002 with  respect to
the EMCON Note held by Charles  Gearhart).  The  principal  balance of the EMCON
Notes shall be  convertible,  in part or in full, into EMCON Common Stock at the
election of the holders at a conversion rate of $6.50 per share.


                                       52
<PAGE>

     (c) The Sellers shall be entitled to receive an earn out from Buyer tied to
the  financial  performance  of the  Company in each of the three  twelve  month
periods  immediately  following  the Closing (the "Annual Earn Out") as follows:
The aggregate Annual Earn out shall equal 50% of Company's pre-tax profit earned
above the  following  base amounts for each twelve month period from May 1, 1997
through April 30, 2000:

                  Twelve Month Period                Pre-Tax Profit

                  05/01/97 - 04/30/98                   $500,000
                  05/01/98 - 04/30/99                   $550,000
                  05/01/99 - 04/30/00                   $600,000

     (i)   Calculation  of  the  Company's   pre-tax  profits  for  purposes  of
calculating  the Annual Earn Out shall be based on the  application of Generally
Accepted  Accounting  Principles,  consistently  applied,  including  the use of
accrual  accounting.  Until April 30, 2000,  without the consent of the Sellers:
(A)  neither  EMCON nor OWT  shall  allocate  any  portion  of their  respective
corporate overhead to the Company for purposes of the above earnout calculation.
(that  notwithstanding,  to the extent either EMCON or OWT incurs expenses (e.g.
insurance,  outside legal,  etc.) directly for the benefit of the Company,  such
amounts shall be charged to the Company for purposes of such  calculation),  (B)
EMCON and Buyer shall  operate the Company in the  ordinary  course of business,
consistent  with the  Company's  past  practices,  (C) EMCON and Buyer shall not
cause or permit the Company to engage in any  fundamental  transaction,  such as
merger,  consolidation,  sale of substantially  all of the Company's  assets, or
sale of stock,  (D) for  purposes  of the earnout  calculation,  EMCON and Buyer
shall not allocate any acquisition costs or expenses related to the transactions
contemplated  by this  Agreement to the Company  (including  without  limitation
interest  expense on funds used to acquire the Common Shares),  (E) for purposes
of the earnout  calculation,  EMCON and Buyer shall not  allocate  any  goodwill
amortization,   where  such  goodwill   arose   pursuant  to  the   transactions
contemplated by this Agreement, (F) for purposes of the earnout calculation, any
tax-sharing  payments made by the Company to EMCON, Buyer or a Related Person of
EMCON and Buyer shall be considered  tax payments (and not deducted from pre-tax
profits) even though such payments are made to EMCON,  Buyer or a Related Person
of EMCON and Buyer and (G) for purposes of the earnout calculation, the interest
cost of any funds loaned to NEP by EMCON  and/or OWT for any purpose,  including
but not limited to paying off the existing NEP bank lines,  shall be included as
an expense of NEP.

     2.3 Closing. The closing of the purchase, sale and exchange (the "Closing")
provided for in this Agreement will take place at the offices of Kegel, Chesters
& Miller, LLP, 24 North Lime Street, Lancaster, Pennsylvania effective the close
of business on April 30, 1997, or at such other date and time as may be approved
in writing by the parties hereto.

      2.4 Closing Obligations. At the Closing:

                                       53
<PAGE>

     (a) The Sellers, will deliver to Buyer:

     (i) certificates  representing the Common Shares held by the Sellers , duly
endorsed (or accompanied by duly executed stock powers), for transfer to Buyer;

     (ii) a  certificate  executed  by  each  of the  Sellers  representing  and
warranting to Buyer that each of the  representations  and warranties by him, or
it in this  Agreement  was accurate in all  material  respects as of the date of
this Agreements and is accurate in all material  respects as of the Closing Date
as if made on the Closing  Date (giving  full effect to any  supplements  to the
Sellers'  Disclosure  Schedule that were delivered by the Company to Buyer prior
to the Closing Date in accordance with Section 6.5); and

     (iii) such other  documents  as are  required  to be  provided  pursuant to
Section 8; and

     (b) Buyer will deliver to each Seller:

     (i) the  amount to be paid to each  Sellers at the  Closing  as  determined
pursuant  to Section 2.2 above.  Such  amounts  shall be paid by bank  cashier's
check payable to each Seller.

     (ii) a certificate  executed by Buyer  representing  and warranting to each
Seller that each of Buyer's representations and warranties in this Agreement was
accurate  in all  material  respects  as of the  date of this  Agreement  and is
accurate  in all  material  respects  as of the  Closing  Date as if made on the
Closing Date (giving full effect to any  supplements  to any schedules that were
delivered,  pursuant  to this  Agreement,  by the  Buyer to the  Sellers  or the
Company prior to the Closing Date in accordance with Section 7.3);

     (iii) such other  documents  as are  required  to be  provided  pursuant to
Section 9;

     2.5 Grimm Employment Agreement.  Concurrently herewith,  Dennis Grimm shall
execute and deliver an  employment  agreement  with the Company and EMCON in the
form  attached  hereto  as  Exhibit  C-1  (the  "Grimm  Employment  Agreement"),
including the commitment of EMCON to grant an incentive stock option to purchase
10,000 shares of EMCON Common Stock at an exercise  price per share equal to the
closing sales price of EMCON's Common Stock on the Closing Date.

     2.6 Gearhart Employment Agreement.  Concurrently herewith, Charles Gearhart
shall execute and deliver an employment  agreement with the Company and EMCON in
the form attached hereto as Exhibit C-2. (the "Gearhart  Employment  Agreement")
"),  including  the  commitment  of EMCON to grant an incentive  stock option to
purchase  10,000  shares of EMCON  Common  Stock at an exercise  price per share
equal to the closing sales price of EMCON's Common Stock on the Closing Date.

                                       54
<PAGE>

     3. Representations and Warranties of the Sellers. The Sellers each, jointly
and  severally  represent  and warrant to Buyer,  as of the Closing  Date,  that
except as set forth on the Sellers' Disclosure Schedule:

     3.1 Corporation Organization.

     (a) The Company is a corporation,  duly incorporated,  validly existing and
in good standing  under the laws of the State of  Pennsylvania.  The Company has
all requisite  corporate  power to own,  operate and lease its properties and to
conduct its business as now being  conducted.  The Company is duly  qualified or
licensed to do business,  and is in good standing as a foreign  corporation,  in
each state or other  jurisdiction in which it owns or leases properties or where
the  nature  of its  business  or  operations  requires  such  qualification  or
licensing,  unless the failure to do so would not have a material adverse effect
on the  Company's  assets,  business,  operations  or financial  condition.  The
Company  has  obtained  all  approvals,   authorizations,   consents,  licenses,
clearances and orders of, and has currently  effective all  registrations  with,
all governmental and regulatory authorities that are necessary to the conduct of
its business or operations as now being  conducted,  except where the failure to
do so would not have a material adverse effect on the Company.

     3.2 Capitalization.

     (a) The authorized  capital stock of the Company  consists solely of 10,000
shares of common stock, no par value. There are currently issued and outstanding
501  shares of common  stock;  all of which are held by the  Sellers  and listed
beside  their  names  on  Exhibit  A  attached  hereto.  All of the  issued  and
outstanding  shares of the Company are duly  authorized,  validly issued,  fully
paid and  nonassessable  except where failure to be so would not have a material
adverse effect on the business,  financial  position or operating results of the
Company.  All such  shares  have been  issued in  accordance  with  federal  and
applicable  state  securities  laws  concerning the issuance of securities.  The
rights,  preferences and privileges of the Company's capital stock are as stated
in the Company's Articles of Incorporation and Bylaws as heretofore amended.

     (b) Except as otherwise set forth in the Sellers' Disclosure  Schedule,  no
options,  warrants,  conversion  privileges,  preemptive rights, rights to first
refusal or other rights, agreements or commitments (written or otherwise) by the
Company are currently  outstanding  to purchase or otherwise  receive any of the
capital stock of the Company.

     (c) The Sellers have delivered to the Buyer complete and accurate copies of
the Articles of Incorporation and Bylaws  (including all amendments  thereto) of
the Company.  The Company has  delivered to the Buyer copies of the minute books
of the Company  containing  minutes for all  meetings  of, and written  consents
issued by the Company and  executed  by, the  Company's  stockholders,  Board of
Directors and all committees of such Board since the date of organization of the
Company.

 
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<PAGE>

     3.3 Corporate Authority.  The Company has all requisite corporate authority
and power to  execute  and  deliver  this  Agreement  and the  other  agreements
referenced  herein and to perform  all of its  obligations  with  respect to the
Contemplated  Transactions.  The  execution,  delivery and  performance  of this
Agreement and the other agreements referenced herein and the consummation of the
transactions contemplated hereby and thereby have been duly authorized, or prior
to the Closing will be duly authorized, by the Company's Board of Directors and,
if required, by its stockholders.

     3.4  Dissolution;  Forfeiture.  No action  at law or in  equity  and to the
Knowledge of the Sellers,  no  investigation  or  proceeding,  whatsoever is now
pending or threatened to: (a) liquidate, dissolve or disincorporate the Company,
(b) declare any of the corporate rights, powers or privileges of the Company, to
be null and void or  otherwise  than in full force and effect,  (c) declare that
the Company,  or the Boards of Directors  or any of their  respective  officers,
agents or employees has exceeded or violated any of their  respective  corporate
rights, powers or privileges, or (d) obtain any decree, order, judgment or other
judicial  determination  or  administrative  or other ruling that would or might
impede or detract from any of the corporate  rights,  powers or  privileges  now
vested in or claimed by the Company.

     3.5 The Company Financial Statements. The consolidated financial statements
of the Company for the fiscal years ended  September  30, 1995 and September 30,
1996 and the six (6) month period ended March 31, 1997 (the  "Company  Financial
Statements")  have been prepared in accordance with GAAP and fairly present,  in
all material respects,  the financial position of the Company in accordance with
GAAP as at the dates thereof.

     3.6 Absence of Unaccrued  or  Undisclosed  Liabilities.  Except for claims,
liabilities or  obligations  as provided for in the following,  the Company does
not  have  any  material  liabilities  whether  absolute,   accrued,  unaccrued,
contingent or otherwise whether due or to become due:

     (a) which were  properly  reflected or adequately  reserved  against in the
balance sheet included as part of the Financial Statements;

     (b) which were incurred in the Ordinary Course of Business since March
31, 1997;

     (c) which are listed on the Sellers' Disclosure Schedule; or

     (d) which are less than $10,000 in any single case;

     Except as set forth in paragraphs  (a) through (d) of this Section 3.6, the
Sellers do not have  Knowledge of and have no reasonable  grounds to know of any
basis for any assertion against the Company of any material claims,  liabilities
or  obligations  of any nature  required by GAAP to be  reflected in a corporate
balance  sheet which have not been fully  reflected  or reserved  against in the
Financial  Statements;  provided,  however, that no limitation set forth in this
Section  3.6  shall in any way  affect  any  other  representation  or  warranty
contained in this Agreement.

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<PAGE>

     3.7  Absence of Certain  Changes.  Since  March 31, 1997 there has not been
any:  (a)  material  adverse  change in the  business,  financial  condition  or
operations of the Company,  (b)  recapitalization,  amendment to the Articles of
Incorporation or Bylaws or any change in, authorization,  creation,  issuance or
agreement for issuance of, the capital stock or any securities convertible into,
or options, warrants or other rights to subscribe to any shares of capital stock
of the Company,  or any declaration  setting aside or payment of any dividend or
distribution  (whether in cash,  securities or property)  with respect  thereto,
except as  contemplated  hereby,  (c)  increase in the  compensation,  direct or
indirect,  payable to any of the officers or employees of the Company, including
adoption  of or  increase  in any bonus,  insurance,  pension or other  employee
benefit plan, payment or arrangement, or any other agreement or arrangement with
its officers,  employees or  stockholders,  except as contemplated  hereby,  (d)
unwaived default in respect of any Material Contracts, except for such defaults,
if any, which do not have a material  adverse effect on the financial  position,
business or operating results of the Company, (e) material change in the methods
and  procedures  employed in keeping the books and records of the Company or (f)
strike or labor dispute.

     3.8 Taxes.  All tax  returns of the  Company  required  by law  (including,
without   limitation,   all   income,   unemployment   compensation,    worker's
compensation,  Social Security,  excise, privilege and franchise tax laws of the
United States or any state or municipal subdivision thereof) to be filed through
the Closing Date (true and complete  copies of which have been  delivered to the
Buyer) have been or will be duly and timely filed,  and all taxes,  assessments,
contributions,  fees  and  governmental  charges  or  impositions  shown on said
returns or reports (other than those not yet due and payable or payable  without
penalty or interest) have been paid,  except where any failure to so file or pay
would,  individually or in the aggregate,  have a material adverse effect on the
Company, taken as a whole. The Company has not received any notice of assessment
of any  federal,  state,  municipal  or other tax upon or measured by its income
and, to the Sellers' knowledge,  there is no basis for an additional  assessment
of any such tax, except for those for which the Company has established adequate
reserves.  The Company has not knowingly waived any law or regulation fixing, or
consented to the extension of, any period of time for the  assessment of any tax
or other  governmental  imposition,  or become  committed so to do. There are no
audits of the Company pending and there are no matters under discussion with any
federal,  state, local or foreign  authorities with regard to the payment of any
taxes by the  Company.  There are no issues  that have been raised by the IRS or
other taxing  authority in connection  with an examination or otherwise which by
application of similar  principles  could  reasonably be expected to result in a
proposed deficiency for any period not examined.

     3.9 Title to Properties; Accounts Receivable.

     (a) Except for  property and assets that the Company has disposed of in the
Ordinary Course of Business, the Company has, and will have at the Closing Date,
good and  marketable  title to all properties and assets shown or represented on
the  balance  sheet  included  as part of the Company  Financial  Statements  or
acquired since March 31, 1997, free and clear of all mortgages,  pledges, liens,
defects in title, conditional sale agreements and other encumbrances, except for


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<PAGE>

liens, encumbrances and defects in title in respect of property or assets of the
Company which: (i) are incidental to the conduct of the Company's business; (ii)
have  arisen in the  Company's  Ordinary  Course  of  Business;  (iii)  were not
incurred in connection  with the borrowing of money or the obtaining of advances
or credit (other than credit arrangements  related to purchase money liens); and
(iv) do not in the aggregate  materially detract from the property and assets of
the  Company.  The  Company has  performed  all the  obligations  required to be
performed by it with respect to all assets leased by it through the date hereof,
except where the failure to perform would not have a material  adverse effect on
the business or financial condition of the Company.  The Company enjoys peaceful
and undisturbed possession of all of its offices, warehouses,  buildings and all
other real property and related  facilities,  whether owned,  leased or operated
(collectively,  the  "Facilities"),  and,  except as otherwise  set forth in the
Sellers'  Disclosure  Schedule,  such  Facilities are not subject to any claims,
liens, pledges, options, charges, easements, security interests,  rights-of-way,
encumbrances   or  other  rights,   or  any   encroachments,   building  or  use
restrictions,  exceptions,  reservations  or  limitations  which in any material
respect  interfere  with or impair the present and  continued use thereof in the
usual and normal  conduct of its  business.  There are no pending or to Sellers'
Knowledge threatened condemnation proceedings relating to any of the Facilities.
The  Facilities  and  the  real  property   improvements   (including  leasehold
improvements),  equipment and other tangible assets owned or used by the Company
at the Facilities are insured in amounts  believed by the Sellers to be adequate
and, are structurally sound with no material defects. Said items are not subject
to any commitment or other  arrangement  for their sale by the Company or use by
third  parties  other  than  commitments  or  arrangements  entered  into in the
Ordinary Course of Business. The assets are valued at or below the lower of fair
market value or actual cost less an adequate and proper depreciation charge. For
tax purposes,  the Company has not  depreciated  any of the assets in any manner
inconsistent with applicable IRS guidelines, if any.

     (b) All  tangible  property,  real and  personal,  owned or  leased  by the
Company is in reasonable  operating  condition  and repair,  except for ordinary
wear and tear and any  defects  the cost of  repairing  which,  singly or in the
aggregate,  would not be material  or are  accrued for on the Company  Financial
Statements.  The Company has  operated  such  property  in  conformity  with all
applicable laws, ordinances,  orders, regulations,  rules and other requirements
(including applicable zoning, environmental,  motor vehicle safety or standards,
occupational  safety and health laws and  regulations)  currently  in effect and
relating thereto,  except where the failure to conform would not have a material
adverse  effect  on the  business,  operations  or  financial  condition  of the
Company.

     (c) All accounts  receivable of the Company shown on the Company  Financial
Statements are valid,  genuine and  subsisting,  arose in the Ordinary Course of
Business,  and the  aggregate  amount  thereof  less the  reserve  for  doubtful
accounts  with respect  thereto set forth in the Company  Financial  Statements,
are, to the Knowledge of the Sellers,  current and collectible  within customary
payment terms.

     (d) The Company did not perform a title search or purchase title  insurance
on the three properties on which it has license  agreements,  namely,  the Moll,
Hinton  and  Baker  Refractories  properties.  As a  consequence,  Sellers  take
exception for title defects in the respective  owner's title to such  properties
for those title  defects of record or visible on the  property;  provided  that,
Sellers  represent  that  they  have no actual  knowledge,  without  independent
investigation,  of any such  defects  which have  adversely  affected,  or could
adversely affect, the Company's operations on such properties.


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<PAGE>

                           3.10     Proprietary Rights.

     (a) The Company owns the rights to use all trademarks, trade secrets, trade
names, copyrights,  processes, designs, formulas, know-how, inventions, licenses
and  intellectual  property  rights used in connection with its business and the
same are believed by the Sellers to be sufficient to conduct such business as it
is now or heretofore has been conducted with no known or asserted  conflict with
or infringement of the asserted or actual rights of others.  The Sellers have no
Knowledge of any  infringement  by any third party in connection with any of the
foregoing  and  neither the Sellers nor the Company has taken or omitted to take
any action  which would have the effect of waiving any of the  Company's  rights
thereunder, in each case except where such infringement or waiver would not have
a material adverse effect on the business,  prospects,  condition  (financial or
otherwise)  or results of  operations  of the Company.  To the  Knowledge of the
Sellers, no third party has filed or been issued or granted any applications for
patents,  trademarks,  trade  names or  registered  copyrights  relating  to the
Company's assets.

     (b)  The  Sellers'   Disclosure   Schedule   lists  all   patents,   patent
applications,  trademarks,  trade names and registered  copyrights  owned by the
Company. Except as set forth in the Sellers' Disclosure Schedule, the Company is
not required to pay any royalty,  license fee or similar type of compensation in
connection  with the conduct of its business as it is now or heretofore has been
conducted.

     (c) The Company has obtained  written  agreements from all required parties
and entities  assigning to the Company any material  proprietary rights relating
to the Company's  assets.  Such agreements are currently valid and in full force
and effect and except as set forth in the Sellers' Disclosure  Schedule,  do not
contain any provisions or restrictions  with regard to the rights granted to the
Buyer  under this  Agreement  All  material  trade  secrets of the  Company  are
currently  protectable  and are not part of the public  knowledge or literature,
nor have they been used,  divulged,  or appropriated for the benefit of any past
or present employees or other persons, or to the detriment of, the Company.

     3.11  Customer  Lists.  The Company has  provided  the Buyer a complete and
accurate  list  of  each  of  the  material   customers  of  the  Company.   The
relationships between the Company and its active customers and suppliers are, in
the aggregate,  in good standing, and since March 31, 1997, no material customer
or supplier has canceled or  terminated,  or, to the  Knowledge of the Sellers,,
threatened to cancel,  terminate or change its relationship  with the Company in
any manner adverse to the Company.

                           3.12     Benefit Plans and Arrangements.

     (a)  Except  as  set  forth  in the  Sellers'  Disclosure  Schedule,  or as
otherwise  contemplated by this Agreement,  the consummation of the Contemplated
Transactions  will not  result  in any  payment  (whether  of  severance  pay or
otherwise)  becoming due from the Company to any  employee,  consultant or other
third party.


                                       59
<PAGE>

     (b) The Sellers' Disclosure Schedule lists all pension,  retirement,  stock
purchase,  stock option, stock bonus, savings or profit sharing plan, individual
employment  agreement,  bonus  or  incentive  compensation  programs,   deferred
compensation  agreements,  severance  pay  plans,  consultant,  bonus,  or group
insurance  contracts,  or any other  material  incentive,  welfare  or  employee
benefit  plan,  or  similar  arrangement,  understanding  or course of  dealing,
including  all employee  benefit  plans and employee  pension  benefit  plans as
defined in Section 3(3) of ERISA (the "Employee Plans").

     (c) With respect to the Employee  Plans,  the Company has delivered or made
available to the Buyer copies of any: (1) plans and related trust  documents and
amendments thereto;  (ii) the most recent summary plan descriptions and the most
recent annual report; (iii) annual reports on Form 5500 which were filed in each
of the most recent  three (3) plan years,  including,  without  limitation,  all
schedules  thereto  and all  financial  statements  with  attached  opinions  of
independent  accountants;  (iv) Form PBGC-1  which was filed in each of the most
recent three (3) plan years; (v) the most recent actuarial  valuation;  and (vi)
the most recent  determination  letter  received  from the IRS.  Such  financial
statements  fairly  present the  financial  condition of each  Employee  Plan in
accordance with United States generally accepted  accounting  principles applied
on a consistent  basis. All Employee Plans have been administered in substantial
compliance  with  their  terms,  ERISA  to the  extent  applicable,  and,  where
applicable, Section 401 of the Code.

     (d) No event of the type set forth in Section 4043(b) of ERISA has occurred
and is continuing with respect to Employee Plans except insofar as such an event
may arise as a result of the  consummation of the  Contemplated  Transactions or
would not have a material adverse effect upon the Company's business,  financial
position or operating results.  There exists no material violation of ERISA with
respect to the filing of reports,  documents, and notices regarding the Employee
Plan participants or beneficiaries.  No action,  suit, or proceeding is pending,
nor, to the  Knowledge  of the Company,  is any  threatened  or  imminent,  with
respect  to the  assets  of any of the  trusts  under  any  Employee  Plan.  All
amendments required to bring an Employee Plan into conformity, in all applicable
and material respects, with ERISA have been made. Any bonding with respect to an
Employee Plan required under ERISA is in full force and effect.  The Company has
not incurred any liability,  pursuant to Subtitle A of Title IV of ERISA, to the
Pension Benefit Guaranty Corporation.

     (e) No breach of fiduciary  responsibility has occurred with respect to any
of the  Employee  Plans other than such breach,  if any,  which would not have a
material  adverse  effect  on the  Company's  business,  financial  position  or
operating  results.  There is no suit,  litigation  or claim (other than routine
benefit claims) pending or, to the Knowledge of the Sellers,  threatened against
the Company or any fiduciary of any Employee Plan involving any Employee Plan or
against  any such plan or its  assets by any  employee  or former  employee  (or
beneficiary thereof) of the Company which individually or in the aggregate would
adversely affect the financial condition of any such Employee Plan.

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<PAGE>

                           3.13     Compliance with Laws; Legal Proceedings.

     (a) The Company is not in violation  of, or in default with respect to, any
term or provision of (i) its Articles of  Incorporation  or Bylaws,  or (ii) any
judgment,  writ,  order,  injunction,  or decree of any court or of any federal,
state,  or municipal  agency or authority  in any case or  proceeding  expressly
naming the Company.

     (b) The  Company  and its  operations  are in  compliance  with  applicable
statutes,  ordinances,  regulations,  requirements  and  orders  of the  federal
government and of all states,  municipalities,  and agencies thereof, and of all
other  authorities  having  jurisdiction  in  respect  of any of its  assets  or
operations (including any applicable foreign government or agency or subdivision
thereof),  except  where the failure to do so would not have a material  adverse
effect on the Company.

     (c) The  Company  has  not  been  threatened  with,  nor is it a party  to,
directly or indirectly,  nor, to the Knowledge of the Sellers,  is there any set
of facts that is likely to give rise to, any material legal action, governmental
investigation,   or  other  proceeding  (governmental  or  private),   including
investigations,  inquiries, citations, complaints, orders or stipulations by any
federal, state or local agency or governmental unit, and there are no judgments,
orders,  restrictions or decrees of a continuing nature outstanding  against the
Company.  The Company has not been threatened with, nor, to the Knowledge of the
Sellers  is there  any set of facts  that is likely to give rise to, a charge of
any material  violation of any provision of any federal,  state,  local or other
law  (including  common law), or  administrative  regulations  in respect of its
business or property.

     3.14 Contracts and Obligations. The Sellers' Disclosure Schedule sets forth
a true and complete list of the following  agreements  and  instruments to which
the Company is a party: (a) all executory contracts,  agreements and instruments
having  a total  contract  price  in  excess  of  $25,000;  (b)  all  contracts,
agreements or instruments which are in the nature of teaming  agreements,  joint
venture agreements,  non-compete  agreements,  franchise  agreements,  exclusive
license  agreements  or  other  similar  agreements  restricting  access  to any
business   opportunity  of  the  Company;  (c)  all  loan  or  debt  agreements,
guarantees,  indemnities and bonding commitments;  (d) all license or technology
transfer agreements;  (e) all leases,  subleases and equipment leases,  having a
total  contract  price in excess of  $25,000;  (f) all  agreements  between  the
Company,  on the one hand, and any of the officers,  directors or  stockholders;
(g) all material  agreements between the Company, on the one hand, and any other
employees of the Company on the other hand; (h) all material licenses or permits
issued by any government agency or authority for the benefit of the Company; (i)
any  management  or  consultation  agreement  not  terminable  at  will  without
liability;  (j) any  contracts or  agreements  requiring  the payment of fees or
commissions  in  connection  with  any sale of all or  substantially  all of the
Company's stock or assets or any sale of a substantial  interest in the Company;
and (k) any other agreement  which  materially  affects the Company's  business,
financial  position or operating results or which was entered into other than in
the Ordinary Course of Business  (collectively,  the "Material Contracts").  The
Company  has  delivered  to the Buyer  true and  complete  copies of each of the
Material  Contracts.  The Company is not in material violation of, or in default

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<PAGE>

with respect to, any Material  Contract  and the Material  Contracts  are valid,
binding and enforceable,  subject only to applicable bankruptcy,  insolvency and
similar  laws  affecting   creditors  rights   generally  and  subject,   as  to
enforceability,  to general principles of equity. The relationships  between the
Company  and the other  parties  to each of the  Material  Contacts  are in good
standing,  and no such other  contract  party has  canceled  or  terminated,  or
threatened to cancel,  terminate or change in any manner  adverse to the Company
such relationship or the terms of any Material Contract.

                           3.15     Employee Relations.

     (a) The  Company  has no  union or  collective  bargaining  agreement,  any
contract or other agreement with any labor  organization or with any employee or
consultant  which is not terminable at will by the Company,  without  liability,
and no such  contract or  agreement is under  discussion  by  management  of the
Company with any employee or consultant.  There are no pending or threatened (i)
strikes,  work  stoppages,  slowdowns or picketing  respecting  employees of the
Company,  (ii) unfair labor practice  complaints  against the Company,  or (iii)
statutes, contracts or agreements,  domestic or foreign, which will obligate the
Company to make any severance payments as a consequence of the execution of this
Agreement or the consummation of the Contemplated Transactions.

     (b) The Company has not received  notice that there is any key employee who
intends to leave the Company's  employ as a result of, or at the  conclusion of,
the Contemplated Transactions. The Company's relationship with its employees, on
the whole, is consistent within industry norms.

     3.16  Insurance.  The  properties  and risks of the  Company are covered by
valid and currently effective insurance policies issued in favor of the Company,
which  policies  are set  forth on the  Sellers'  Disclosure  Schedule,  and the
Company is included as an insured party under such policies, with full rights as
loss  payee.  The  Sellers'  Disclosure  Schedule  contains  a  list  and  brief
description  of each  insurance  policy  (copies of which  have been  previously
provided  to the  Buyer)  maintained  with  respect  to  the  Company  (or  such
corporation's  assets or operations),  which provides  continuing coverage as of
the date hereof. The Sellers' Disclosure Schedule also includes a list and brief
description of individual claims in excess of $10,000 now pending or made during
the 36-month period immediately  preceding the date of this Agreement,  by or on
behalf of the Company under any insurance policies.

                           3.17     Environmental Compliance.

     (a) The Company has all material permits, licenses and other authorizations
required under applicable laws and regulations relating to pollution control and
protection of the environment necessary for the operation of its Facilities. The
Company is not in material  violation of any of the terms or  conditions  of any
such permits, licenses, leases, or authorizations.  The Company has not acted or
failed to act in violation of any law or regulation,  order or other requirement
of  governmental  authorities  with respect to the pollution of the  atmosphere,
surface water,  groundwater and noise,  the handling of toxic or hazardous waste
material or other matters related to the  environment.  There are no pending or,
to the Knowledge of the Sellers,  threatened civil or criminal actions,  notices
of violations or  administrative  proceedings  relating to pollution  control or
protection of the environment  that would have a material  adverse effect on the
business or financial condition of the Company.

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<PAGE>

     (b) There are no material conditions, circumstances, activities, practices,
incidents,  actions or plans which would be reasonably  likely to interfere with
or  prevent  compliance  or  continued   compliance  by  the  Company  with  any
environmental  laws  currently in force or with any existing  regulation,  code,
order, decree,  judgment,  injunction,  notice or demand letter issued, entered,
promulgated or approved thereunder,  or which may give rise to any common law or
other  legal  liability,  including  without  limitation,  liability  under  the
Comprehensive Environmental Response,  Compensation and Liability Act ("CERCLA")
or similar  state,  foreign or local laws,  or  otherwise  form the basis of any
claim, action, demand, suit, proceeding,  hearing, notice of violation, study or
investigation of or against the Company, based on or related to the manufacture,
processing,  distribution,  use,  treatment,  storage,  disposal,  transport  or
handling,  or the emission,  discharge,  release or threatened  release into the
workplace or the environment by the Company, or to the Company's  Knowledge,  by
any other third party, of any pollutant,  contaminant,  chemical, or industrial,
toxic or  hazardous  material,  substance  or waste on any  properties  owned or
leased  by, or under the direct  control  of,  the  Company.  Without in any way
limiting the foregoing, no release,  emission or discharge to the environment of
any hazardous substance (as that term is currently defined under CERCLA or under
any applicable analogous state law ("Hazardous Substance") by the Company, or to
the Company's  Knowledge,  by any other third party has occurred or is currently
occurring  in  connection  with any action or  failure to act on any  properties
owned or leased by, or under the direct  control  of, the  Company  which has or
could give rise to any liability of the Company.

                           3.18     Advances; Related Party Transactions.

     (a)  There  are no  receivables  of the  Company  owing  by any  directors,
officers,  employees or  consultants  of the Company or to any  affiliate of any
such  Company  person or  entity,  other  than  advances  by the  Company in the
ordinary course of business to officers and employees for reimbursable  business
expenses.

     (b) No stockholder,  officer,  director or employee of the Company, nor any
member of the Family of any such  stockholder,  officer,  director  or  employee
owns, or has owned, directly or indirectly,  any interest exceeding five percent
(5%) in (a) any  business,  corporate or other,  which is material  party to any
material  business  arrangement with the Company or (b) any material property or
rights,  tangible  or  intangible,  used  in the  business  of the  Company.  No
stockholder,  officer, or director of the Company, owns, directly or indirectly,
any  interest in, or is an officer or director  of, any  business,  corporate or
other (other than as a stockholder of a public company), which competes with the
Company.

     3.19  Powers of  Attorney.  The  Sellers'  Disclosure  Schedule  contains a
complete   list  of  all  powers  of  attorney   (or  similar   instruments   or
authorizations)  granted by the Company to any person or entity. All such powers
of  attorney  (or  similar   instruments  or  authorizations)   are  subject  to
termination  or  revocation  by the Company at any time,  without  notice to any
other person or entity and without penalty.

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     3.20 No Brokers.  Neither  the Company nor the Sellers has entered  into or
will enter into any contract,  agreement or understanding with any Person, which
may result in the  obligation  of the  Company or the Buyer to pay any  finder's
fee, brokerage commission or similar payment in connection with the Contemplated
Transactions

     3.21 Other Agreements to Sell the Company.  Except as set forth herein, the
Company has no legal obligation,  absolute or contingent,  to any person or firm
to sell any capital stock of the Company or to effect any merger,  consolidation
or other reorganization,  or disposition of all or substantially all the assets,
of the Company.

     3.22 Banking Relationships.  The Sellers' Disclosure Schedule correctly and
completely  lists all banks and  accounts in such banks,  with which the Company
has deposits,  indicating  the names of those  authorized to sign documents with
respect to such  accounts as of the date of the most recently  approved  banking
resolution with respect to each.

     3.23  Ownership of Shares and Options.  Except as set forth in the Sellers'
Disclosure  Schedule,  the Sellers own of record and  beneficially the number of
Common Shares indicated opposite each such Seller's name in Exhibit A hereto, as
applicable,  with full right and authority to sell or exchange,  as  applicable,
such securities  hereunder,  and upon delivery of such Common Shares  hereunder,
the Buyer will  receive  good title  thereto,  free and clear of all  mortgages,
pledges  or  security   interests   and  not  subject  to  any   agreements   or
understandings  among any Persons with respect to the voting or transfer of such
securities other than those arising under agreements to which Buyer is a party

     3.24 Execution,  Delivery and  Enforceability  of Agreement;  No Violation.
This  Agreement  has been duly  executed  and  delivered  by or on behalf of the
Company  and each  Seller,  and at the  Closing  any  other  documents  required
hereunder to be executed  and  delivered by or on behalf of the Company and each
Seller will have been duly executed and delivered.  This  Agreement  constitutes
the  legal,  valid  and  binding  obligation  of the  Company  and each  Seller,
enforceable  against the Company and each Seller in  accordance  with its terms,
except as  enforcement  may be limited  by  applicable  bankruptcy,  insolvency,
reorganization,  fraudulent  conveyance,  moratorium  or  other  laws  affecting
creditor's  rights  generally.   Any  other  agreements  or  documents  required
hereunder to be executed and delivered by the Company and each Seller at Closing
will constitute the legal,  valid and binding agreements of the Company and each
Seller  executing the same,  enforceable  against the Company and each Seller in
accordance with their respective terms,  except as enforcement may be limited by
applicable  bankruptcy,  insolvency,   reorganization,   fraudulent  conveyance,
moratorium or other laws  affecting  creditor's  rights  generally.  Neither the
execution  of  this  Agreement  nor  the   consummation   of  the   Contemplated
Transactions  by the  Company  and each Seller will  violate,  or  constitute  a
default under,  or permit the  acceleration of maturity of, except to the extent
waived, any indentures,  mortgages, promissory notes, contracts or agreements to
which the  Company and each Seller is a party or by which the Company and Seller
or the Company and each Seller's properties are bound.

     3.25 Information  Supplied.  To the Knowledge of the Sellers,  neither this
Agreement,  the Company Financial Statements,  the Sellers' Disclosure Schedule,
the Exhibits  attached to this Agreement,  nor any other certificate or document
furnished or to be furnished by the Company or the Sellers pursuant to the terms
of this Agreement,  contains or will contain any untrue  statement of a material
fact  known  to the  Sellers  or omits or will  omit to  state a  material  fact
necessary to make the statements contained in such information not misleading in
light of the circumstances under which such statements were made.

 
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<PAGE>

     3.26  Residence and  Domicile.  The Sellers are residents of, and domiciled
in,  the  States  indicated  on Exhibit A hereto,  as  applicable,  as being the
residence of each such Seller.

                  4.       [Reserved]

                  5.  Representations  and Warranties of Buyer and EMCON.  Buyer
and EMCON  jointly  and  severally  represent  and  warrant to  Sellers  and the
Company, as of the date hereof and except as set forth in the Buyer's Disclosure
Schedule, as follows:

     5.1 Organization and Good Standing.  Buyer and EMCON are corporations  duly
organized,  validly existing,  and in good standing under the laws of the States
of Delaware and California, respectfully.

     5.2 Execution, Delivery and Enforceability of Agreement; No Violation. This
Agreement  has been duly executed and delivered by or on behalf of the Buyer and
EMCON, and at the Closing any other documents  required hereunder to be executed
and  delivered  by or on  behalf  of the  Buyer  and  EMCON  will have been duly
executed and delivered.  This Agreement constitutes the legal, valid and binding
obligation  of the  Buyer  and  EMCON,  enforceable  against  Buyer and EMCON in
accordance  with its terms,  except as enforcement  may be limited by applicable
bankruptcy,  insolvency,  reorganization,  fraudulent conveyance,  moratorium or
other laws affecting creditor's rights generally.  Any other agreements required
hereunder  to be executed  and  delivered by the Buyer and EMCON at Closing will
constitute  the  legal,  valid and  binding  agreements  of the Buyer and EMCON,
enforceable against the Buyer and EMCON in accordance with its respective terms,
except as  enforcement  may be limited  by  applicable  bankruptcy,  insolvency,
reorganization,  fraudulent  conveyance,  moratorium  or  other  laws  affecting
creditor's  rights  generally.  Neither the execution of this  Agreement nor the
consummation of the transactions provided for herein by the Buyer and EMCON will
violate,  or constitute a default under, or permit the  acceleration of maturity
of, except to the extent waived,  any indentures,  mortgages,  promissory notes,
contracts or  agreements to which such  respective  party is a party or by which
such  respective  party or its properties are bound.  Except as set forth in the
Buyer's Disclosure Schedule, Buyer and EMCON are not and will not be required to
obtain any Consent from any Person in connection with the execution and delivery
of this Agreement or the  consummation or performance of any of the Contemplated
Transactions.

     5.3  Investment  Intent.  Buyer is  acquiring  the Common  Shares  from the
Sellers for its own account and not with a view to their distribution within the
meaning of Section 2.11 of the Securities Act. Buyer is a sophisticated business
entity,  experienced  in the business of the Company and is able to evaluate the
merits and risks of acquiring the Common Shares.

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<PAGE>

     5.4  Certain  Proceedings.  There is no  pending  Proceeding  that has been
commenced  against  Buyer or EMCON  that  challenges,  or may have the effect of
preventing,  delaying, making illegal, or otherwise interfering with, any of the
Contemplated  Transactions.  To Buyer's  Knowledge,  no such Proceeding has been
threatened.

     5.5 Brokers or Finders.  Buyer and its officers and agents have incurred no
obligation or liability, contingent or otherwise, for brokerage or finders' fees
or  agents'  commissions  or other  similar  payment  in  connection  with  this
Agreement.

     5.6  Information  Supplied.  The EMCON  Annual  Report on Form 10-K for the
fiscal year ending December 31, 1996, does not contain any untrue statement of a
material fact or omits to state a material fact necessary to make the statements
contained therein not misleading in light of the circumstances  under which such
statements were made.

     5.7 No Material Change. Since December 31, 1996, there has been no material
adverse  change in the  business,  financial  position or operations or Buyer or
EMCON.

                  6.       Covenants of the Sellers Prior to Closing Date.

     6.1 Conduct of Business  Pending  Closing.  Except as  contemplated by this
Agreement or otherwise agreed to by the Buyer in writing,  prior to Closing, the
Sellers hereby covenant and agree as follows:

     (a) The  Company  will  carry on its  business  in the  Ordinary  Course of
Business and,  without  limiting the generality of the foregoing,  (i) not sell,
assign, lease, pledge,  mortgage,  encumber or otherwise dispose of or grant any
preferential  rights in any of its assets,  or incur or become obligated to pay,
any  liabilities,  except in the Ordinary  Course of  Business,  (ii) not pay or
prepay  any  obligation  or  liability  (fixed,  contingent  or  otherwise),  or
discharge or satisfy any lien or  encumbrance,  or settle any liability,  claim,
dispute,  proceeding, suit or appeal, pending or threatened against it or any of
its assets or  properties,  except for the pay off of all long term debt owed to
William  Holbrook in the approximate  amount of $79,000 and current  liabilities
included in the Company Financial  Statements and current  liabilities  incurred
since March 31, 1997 in the Ordinary Course of Business or current  non-material
liabilities,  (iii) except for individual  expenditures  and commitments made in
the Ordinary Course of Business and involving amounts not exceeding $10,000, not
make any expenditure or commitment for the purchase,  acquisition,  construction
or  improvement  of a capital  asset,  (iv) use its Best  Efforts to continue in
effect all  existing  policies of  insurance  (or  comparable  insurance)  of or
relating to the Company,  (v) keep proper books of record and account  necessary
to prepare  financial  statements in accordance  with GAAP and (vi) not amend or
terminate any Material  Contract in a manner that would have a material  adverse
effect on the business,  financial  position or operating results of the Company
or amend  any  contract,  agreement  or  license  to which it is a party,  which
amendment  would make it a Material  Contract,  unless such amendment  would not
have a material adverse effect on the business, financial condition or operating
results of the Company and would not extend the term of such contract, agreement
or license by more than one year.


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<PAGE>

     (b) No change  will be made in the  authorized  or issued  and  outstanding
capital stock of the Company, and the Company shall not issue or commit to issue
any option, warrant, note, bond or other security convertible into shares of the
Company's capital stock.

     (c)  Except  as set forth on  Exhibit  D, no  increase  will be made in the
compensation  payable  or to  become  payable  by  the  Company  to  any  of its
directors,  officers, employees, agents, consultants or stockholders,  including
any stock options, bonus payments or other benefits.

     (d) The  Company  will not  effect  or agree to  effect  any  amendment  or
supplement to, or extension of, any Employee Plan.

     (e) The Company will not acquire any equity  securities or similar interest
in any other  corporation,  association,  joint venture,  partnership,  business
trust or other business  entity,  or acquire the assets or liabilities of any of
the  foregoing,  or  merge,  consolidate  or  otherwise  combine  with any other
corporation or other business entity, or enter into any agreement  providing for
any of the foregoing.

     (f) The  Company  will not  enter  into or agree  to enter  into any  other
contracts,  licenses or other  transactions other than in the Ordinary Course of
Business and, without  limiting the generality of the foregoing,  not enter into
or agree to enter into any contracts, agreements or instruments which are in the
nature  of  joint  venture   agreements,   non-compete   agreements,   franchise
agreements, exclusive license agreements, or other similar agreements.

     (g) Except as required by currently existing  agreements,  the Company will
not  declare or pay any  dividend  on the  outstanding  shares of the  Company's
capital  stock in cash,  stock or property or redeem,  repurchase  or  otherwise
acquire any shares of the  Company's  capital  stock or enter into any agreement
providing for any of the foregoing.

     (h) The Company and the Sellers  will not solicit or initiate  proposals or
offers  from any  person  relating  to any  acquisition  or  purchase  of all or
substantially  all of the assets of, or any equity interest in, the Company,  or
any merger, consolidation,  business combination or similar transaction with the
Company, or participate in any negotiations  regarding,  or furnish to any other
person any confidential  information with respect to, or otherwise  cooperate in
any way with, or participate in, facilitate or encourage,  any effort or attempt
by any  other  person  to do or seek any of the  foregoing.  The  Company  shall
promptly  notify  the Buyer if any such  proposal  or offer,  or any  inquiry or
contact with any person with respect thereto, is made.

     (i) No change  will be made with  respect to the  banking  or safe  deposit
arrangements of the Company:

     (j) The Company will use its Best  Efforts to keep intact the  organization
of the  Company;  to  keep  available  the  services  of the  Company's  present
employees;  and to preserve the goodwill of its suppliers,  customers and others
having business relations with the Company; and

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<PAGE>

     (k) The  Company  will timely file all  required  material  tax returns and
promptly  pay all  federal,  state and local tax  assessments  and  governmental
charges lawfully levied or assessed upon it or upon its properties,  or upon any
part thereof,  which have become due and payable,  and the Company will withhold
from its  employee's  wages and pay over all federal and state taxes required to
be withheld and paid over.

     6.2 Advice of Changes. Prior to the Closing Date, the Company will promptly
advise the Buyer in writing of (i) any known event  occurring  subsequent to the
date of this Agreement which would render any  representation or warranty of the
Company contained in this Agreement, if made on and as of the date of such event
or the Closing Date, untrue or inaccurate in any material respect (other than an
event so affecting a representation  or warranty which is expressly limited to a
state of facts  existing at a time prior to the  occurrence of such event),  and
(ii)  any  material  adverse  change  in the  business,  financial  position  or
operating  results  of the  Company  occurring  subsequent  to the  date of this
Agreement.

     6.3 Access and Information. The Company will, at all reasonable times prior
to the Closing  Date and upon  reasonable  notice from Buyer,  open its offices,
books,  accounts and  records,  including  policies,  claims of  creditors,  and
obligations of the Company, and will, upon reasonable notice from Buyer, provide
free  access to the  Company's  management  to discuss  the  Company's  business
operations,  assets,  liabilities,  actual or potential  litigation  and claims,
properties  and  prospects,   to  working  papers,  files  and  records  of  its
accountants,  each for full and  unrestricted  examination and inspection by the
Buyer, its officers, attorneys or accountants.

     6.4  Reasonable  Efforts.  Subject  to  the  terms  and  conditions  herein
provided,  the Company and each Seller shall use his, her or its Best Efforts to
(a) cause to be fulfilled and satisfied all of the  conditions to the Closing to
be fulfilled  and  satisfied by him, her or it and (b) cause to be performed all
of the matters required of him, her or it at the Closing.

     6.5  Supplements to Sellers'  Disclosure  Schedule.  Sellers shall have the
right, from time to time, on or prior to the Closing, to supplement the material
set forth in the Sellers' Disclosure Schedule initially delivered by the Sellers
to Buyer. Any references to the Sellers'  Disclosure  Schedule in this Agreement
or in any other document  entered into in connection  with this Agreement  shall
mean the Sellers'  Disclosure  Schedule as fully amended and  supplemented on or
prior to the Closing Date.

                  7.       Covenants of Buyer Prior to Closing Date.

     7.1  Access to  Information.  Between  the date of this  Agreement  and the
Closing Date, Buyer will afford Sellers and their  Representatives full and free
access,  upon the request of Sellers,  to copies of EMCON's public filings under
the Securities Act, the Exchange Act, and other information as Sellers and their
Representatives shall reasonably request.

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<PAGE>

     7.2 Approvals of Governmental  Bodies. As promptly as practicable after the
date of this  Agreement,  Buyer will, and will cause each of its Related Persons
to,  make  all  filings  required  by Legal  Requirements  to be made by them to
consummate the Contemplated Transactions. Between the date of this Agreement and
the  Closing  Date,  Buyer  will,  and will  cause  each  Related  Person to (a)
cooperate  with Sellers with respect to all filings that Sellers are required by
Legal Requirements to make in connection with the Contemplated Transactions, and
(b) cooperate with Sellers in obtaining all consents  identified in the Sellers'
Disclosure Schedule.

     7.3  Supplements  to  Schedules.  Buyer shall have the right,  from time to
time, on or prior to the Closing,  to  supplement  the material set forth in any
schedule  initially  delivered  to the Company or the  Sellers  pursuant to this
Agreement.  Any references to the Buyer Disclosure Schedule in this Agreement or
in any other document  entered into in connection with this Agreement shall mean
such  schedules  as fully  amended and  supplemented  on or prior to the Closing
Date.

     7.4 Best Efforts.  Subject to the terms and conditions herein provided, the
Buyer and EMCON shall use their Best  Efforts to (a) cause to be  fulfilled  and
satisfied  by it  all of  the  conditions  to the  Closing  to be  fulfilled  or
satisfied by it and (b) cause to be performed all of the matters  required of it
at Closing.

     7.5 Advice of Changes.  Prior to the Closing Date,  the Buyer will promptly
advise all of the other  parties  hereto in  writing of (i) any event  occurring
subsequent to the date of this Agreement  which would render any  representation
or warranty of the Buyer and EMCON contained in this  Agreement,  if made on and
as of the date of such event or the Closing  Date,  untrue or  inaccurate in any
material respect (other than an event so affecting a representation  or warranty
which is expressly  limited to a state of facts  existing at a time prior to the
occurrence of such event),  and (ii) any material adverse change in the business
affairs of the Buyer occurring subsequent to the date of this Agreement.

     8. Conditions  Precedent to Buyer's Obligation to Close. Buyer's obligation
to purchase  the Common  Shares  from the Sellers and to take the other  actions
required to be taken by Buyer at the Closing is subject to the satisfaction,  at
or prior to the Closing,  of each of the following  conditions (any of which may
be waived by Buyer, in whole or in part):

     8.1 Accuracy of Representations. Each of the representations and warranties
in Section 3 of this Agreement, must have been accurate in all material respects
as of the date of this  Agreement and must be accurate in all material  respects
as of the Closing Date as if made on the Closing Date.

     8.2 Material  Changes.  There shall be no material  adverse  changes to the
business, financial condition or operating results of the Company since the date
of this Agreement.

     8.3 Sellers' and the Company's Performance.

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<PAGE>

     (a) All of the covenants and  obligations  that the Sellers and the Company
are required to perform or to comply with pursuant to this Agreement at or prior
to the  Closing  (considered  collectively),  and  each of these  covenants  and
obligations  (considered  individually),  must  have  been  duly  performed  and
complied with in all material respects.

     (b) Each Seller or the  Company,  as the case may be,  must have  delivered
each of the documents  required to be delivered by such Seller  pursuant  hereto
and each of the other  covenants and  obligations in required to be performed by
Seller or the Company must have been performed and complied with in all material
respects.

     8.4  Consents.  Each of the Consents  required to be obtained to consummate
the Contemplated  Transactions must have been obtained and must be in full force
and effect.

     8.5 Additional  Document.  Sellers must have caused the following documents
to be delivered to Buyer:

     (a)  resolution of the Boards of Directors of the Company  authorizing  the
Contemplated Transactions, certified by the Secretary of the Company;

     (b) certificates of good standing from the state of  incorporation  for the
Company as of a date no more than ten (10) days prior to the Closing Date.

     8.6 No Proceedings.  Since the date of this Agreement,  there must not have
been commenced or threatened in writing against Buyer or the Company, or against
any Person  affiliated  with Buyer or the Company,  any Proceeding (a) involving
any material  challenge to, or seeking material damages or injunctive  relief in
connection with, any of the Contemplated Transactions,  or (b) that may have the
effect of preventing,  delaying,  making illegal, or otherwise  interfering with
any of the Contemplated Transactions.

     8.7 Sellers'  Disclosure  Schedule.  The Sellers shall have provided  Buyer
full and complete and final copies of the  Sellers'  Disclosure  Schedule  which
shall reflect no material adverse changes in the Company's business or financial
condition from the date of this Agreement.

     8.8  Execution  by Sellers.  All of the Sellers  listed on Exhibit A hereto
shall have executed this Agreement.

     8.9 Employment  Agreement.  The Grimm Employment Agreement and the Gearhart
Employment Agreement shall be in full force and effect.

     8.10 Notes.  The EMCON Notes shall have been  executed and delivered by the
Buyer to the Sellers.

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<PAGE>

     8.11 Release of  Suretyship  Agreement.  The Company  shall have received a
release of all further obligations of the Company relative to NEP Sand & Gravel,
Inc., under that certain Suretyship Agreement dated as of April 8, 1996.

     9.  Conditions   Precedent  to  Sellers'  Obligation  to  Close.   Sellers'
obligations to sell their Common Shares,  and to take the other actions required
to be taken by Sellers at the  Closing  is  subject to the  satisfaction,  at or
prior to the Closing,  of each of the following  conditions (any of which may be
waived by Sellers).

     9.1  Accuracy  of  Representations.  All  of  Buyer's  representations  and
warranties in Section 5 must have been  accurate in all material  respects as of
the date of this  Agreement and must be accurate in all material  respects as of
the Closing Date as if made on the Closing Date.

     9.2 Approval of this  Agreement by Board of Directors.  This  Agreement and
the agreements  referenced herein must be approved by the Boards of Directors of
the Buyer and EMCON.

     9.3 Buyer's Performance.

     (c) All of the covenants and obligations  that Buyer is required to perform
or to comply with  pursuant to this  Agreement  at or prior to the Closing  must
have been performed and complied with in all material respects.

     (d) Buyer must have  delivered  each of the documents  (including the EMCON
Notes)  required to be  delivered by Buyer and EMCON and must have made the cash
payments required to be made by Buyer pursuant to Section 2.

     9.4  Consents.  Each of the Consents  required to be obtained to consummate
the Contemplated  Transactions must have been obtained and must be in full force
and effect.

     9.5 No Material  Adverse Change.  There shall have been no material adverse
change in Buyer's or EMCON's business,  financial condition or operating results
from the date of this Agreement.

     9.6 Buyer's Disclosure Schedule.  The Buyer shall have provided the Company
full and complete copies of Buyer's  Disclosure  Schedule which shall reflect no
material adverse changes in Buyer's or EMCON's business,  financial condition or
operating results from the date of this Agreement.

     9.7 Additional Documents.  Buyer and EMCON must have caused to be delivered
to Sellers:

     (a)  resolution  of  the  Boards  of  Directors  of  the  Buyer  and  EMCON
authorizing the Contemplated Transactions,  certified by the Secretary of Buyer;
and

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<PAGE>

     (b)  Certificates  of good standing for the Buyer and EMCON as of a date no
more than ten (10) days prior to the Closing Date.

     9.8 No Proceedings.  Since the date of this Agreement,  there must not have
been  commenced  or  threatened  in writing  against  Buyer,  the Company or any
Seller, or against any Person affiliated with Buyers, the Company or any Seller,
any  Proceeding  (a)  involving any material  challenge to, or seeking  material
damages  or  injunctive  relief  in  connection  with,  any of the  Contemplated
Transactions,  or (b) that may have the effect of preventing,  delaying,  making
illegal,  or otherwise  interfering with any of the  Contemplated  Transactions;
provided  however that this Section 9.9 may not be relied upon by the Company or
Sellers and this condition will be deemed to have been waived by the Sellers and
the Company if Buyer agrees to proceed to close  hereunder  and to indemnify the
Company and Sellers in full  against any damages  that may be incurred by reason
of any claim described in this Section.

     9.9  Execution.  The Sellers  listed on Exhibit A shall have  executed this
Agreement.

     9.10 Employment Agreements. The Grimm Employment Agreement and the Gearhart
Employment Agreement shall be in full force and effect.

     9.11.  Indebtedness of the Company. Buyer shall have arranged financing for
the  Company  such that as of the  Closing  Date,  all  corporate  and  personal
guarantees and suretyships of the Company's  indebtedness  shall be released and
discharged,  including  without  limitation,  the  suretyships  of the Company's
indebtedness  by Sellers and NEP Sand & Gravel,  Inc.  Buyer shall have arranged
for the  replacement of the two letters of credit issued by Dauphin Deposit Bank
and Trust  Company on behalf of the Company for the benefit of the  Pennsylvania
Department of Environmental  Protection,  in the amounts of $17,300 and $22,800.
Buyer shall have repaid indebtedness owed by the Company to William J. Holbrook,
in the amount at April 30, 1997 (after the scheduled  payment on April 15, 1997)
of approximately $72,249.99.

     10. Covenants After the Closing Date.

     10.1 Litigation Support. In the event and for so long as any party actively
is  contesting  or  defending  against any action,  suit,  proceeding,  hearing,
investigation, charge, complaint, claim, or demand in connection with:

     (a) any of the Contemplated Transactions; or

     (b)  any  fact,  situation,   circumstance,  status,  condition,  activity,
practice,  plan,  occurrence,   event,  incident,  action,  failure  to  act  or
transaction  on or prior to the Closing Date  involving  the  Company,  then the
other party shall  cooperate  with it and its counsel in the defense or contest,
make  available its personnel and provide such testimony and access to its books
and records as shall be necessary in connection with the defense or contest, all
at the sole cost and expense of the contesting or defending party.

 
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<PAGE>

     10.2 NEP Sand & Gravel  Receivable.  Contemporaneous  with the  anticipated
closing of the sale of NEP Sand & Gravel,  Inc. by the Sellers,  the outstanding
receivable  from NEP Sand & Gravel,  Inc.  to the Company  shall be  immediately
repaid in full.  In the event such  amount is not  repaid on or before  July 31,
1997, the amounts remaining  outstanding and unpaid from NEP Sand & Gravel, Inc.
shall be offset against and reduce,  on a pro rata basis, the principal  balance
of the EMCON Notes.

     10.3 Mining  License.  Explore,  Inc., a Pennsylvania  corporation of which
Sellers own  fifty-one  percent of the  outstanding  stock,  used the  Company's
mining license  number to apply for a mining permit to mine  dimension  stone at
the Clapsaddle Property.  Sellers expect that a mining permit for the Clapsaddle
Property will be issued in the Company's name. For a period of one year from the
Closing  Date (or  earlier  upon the sale or  discontinuance  of the  Clapsaddle
project),  Buyer shall cause the Company,  and the Company shall, allow Explore,
Inc.  to continue  using the  Company's  mining  license as  previously  used by
Explore,  Inc. and maintain the mining permit in the Company's name. The Company
shall,  and Buyer  agrees to cause the Company to,  cooperate  with  Sellers and
Explore,  Inc. (and take all steps reasonably  necessary or appropriate) to have
the permit issued in the Company's  name at no cost to the Company.  The Company
shall,  and Buyer agrees to cause the Company to,  transfer  (and take all steps
reasonably  necessary or  appropriate to transfer at no cost to the Company) the
mining permit to a person selected by Sellers.  Sellers  represent that Explore,
Inc.  will not  engage  in mining  activity  under the  mining  permit.  Sellers
represent that Explore, Inc.'s continued use of the Company's mining license and
the  issuance,  maintenance  and transfer of the mining  permit in the Company's
name shall not result in any cost or liability  to the Company.  In this regard,
Sellers  agree  to  indemnify   and  hold  harmless  the  Company   against  any
liabilities, damages, costs or expenses, arising from Explore, Inc.'s use of the
Company's  mining  license and the  issuance,  maintenance  and  transfer of the
mining permit in the Company's name.

     10.4 S Corporation Matters. Sellers, the Company and Buyer acknowledge that
upon the transfer of the Common  Shares by Sellers to Buyer,  the S  corporation
election  of the  Company  will  automatically  terminate  because  Buyer  is an
ineligible  shareholder for the valid continuation of S corporation  status. The
Sellers,  the Company and Buyer also  acknowledge  that  because more than fifty
percent  (50%) of the stock of the Company  stock will change  ownership  in the
current tax year,  under  I.R.C. ss  1362(e)(6)(D),  normal tax  accounting
methods,  and not a pro rata allocation,  will apply to the short S tax year and
short C tax year resulting from termination of the S corporation elections. Upon
execution of this  Agreement and  continuing  after the transfer,  Sellers,  the
Company and Buyer agree, without further  consideration,  to execute and deliver
promptly to the requesting party such further assignment, endorsement, and other
documents and instruments,  and to take all such further actions, as Seller, the
Company or Buyer may from time to time  reasonably  request  with respect to the
preparation  and  submittal  of tax  returns,  tax notices and other  documents,
including  without  limitation,  the  execution  and  delivery  of a consent  to
termination date of the S corporation election of the Company.

     10.5 Mountain View Job Bonus.  If the pre-tax  profit on [the Mountain View
Job]  exceeds  $60,000,  then  Buyer  shall  cause the  Company  to pay a $5,000
compensation bonus to Tim Hipps. In calculating  pre-tax profits on the Mountain
View Job, the Company  shall use the per job profit  calculation  method used by
the  Company  prior  to the  Closing  which  would  include,  for  example,  not
allocating administrative overhead to the Job.

                                       73
<PAGE>

                  11.      Termination.

     11.1 Termination  Event. This Agreement may also be terminated prior to the
Closing:

     (a) by written notice  delivered to the other parties hereto at or prior to
the Closing

     (i) by (A) Buyer if a Breach of any  provision of this  Agreement  has been
committed  by any Seller or by the Company or (B) the Company and the Sellers if
a Breach of any provision of this Agreement has been committed by the Buyer, and
such  Breach set forth in (A) or (B) has not been  waived,  or cured  within ten
(10) days after  receipt of written  notice of such Breach by the party  against
whom such Breach is alleged; or

     (ii) by the Buyer if the supplements to the Sellers'  Disclosure  Schedule,
disclose  a material  adverse  change in the  business,  financial  position  or
operating results of the Company, from that set forth on the Sellers' Disclosure
Schedule as delivered to the Buyer.

     (b) by written notice  delivered to the other parties hereto at or prior to
the Closing

     (i) by Buyer if any of the  conditions in Section 8 has not been  satisfied
as of the Closing  Date or if  satisfaction  of such a  condition  is or becomes
impossible  (other  than  through  the  failure  of  Buyer  to  comply  with its
obligations  under this Agreement) and Buyer has not waived such condition on or
before the Closing Date; or

     (ii) by Sellers  owning a majority of the Common Shares or the Company,  if
any of the conditions in Section 9 has not been satisfied as of the Closing Date
or if  satisfaction  of such a condition  is or becomes  impossible  (other than
through the  failure of Sellers or the Company to comply with their  obligations
under this Agreement) and Sellers and the Company have not waived such condition
on or before the Closing Date; or

     (c) by mutual consent of Buyer and the Sellers.

     11.2 Effect of Termination. Each party's right of termination under Section
11.1 in  addition  to any  other  rights it may have  under  this  Agreement  or
otherwise, and the exercise of a right of termination will not be an election of
remedies.  If this Agreement is terminated pursuant to Section 11.1, all further
obligations  and liabilities of the parties under this Agreement will terminate,
except as follows:

     (i) The obligations in Sections 13.1, 13.2 and 13.3 will survive;


                                       74
<PAGE>

     (ii) If this  Agreement is  terminated  by a party because of the Breach of
the  Agreement by another  party,  the  terminating  party's right to pursue all
legal remedies will survive such termination unimpaired.

                  12.      Survival; Remedies.

     12.1 Survival.  Notwithstanding any investigation conducted before or after
the  Closing  Date,  the  parties  hereto  will be  entitled  to rely  upon  the
representations  and  warranties of the other  parties  hereto set forth in this
Agreement  (as  modified  by each  party's  Disclosure  Schedule  attached as an
Exhibit to this Agreement). All representations and warranties in this Agreement
or in any  instrument  delivered  pursuant to this  Agreement  will  survive the
Closing.

     12.2 Limitation of Liability.  Sellers,  the Company,  EMCON or Buyer shall
have no liability with respect to a breach of this Agreement,  including without
limitation a breach of a representation,  warranty or covenant contained in this
Agreement,  until the total of all such  liabilities  against such party exceeds
$25,000  (provided  however,  that this  minimum  shall not apply to breaches of
Section 3.2 of this Agreement).  The parties agree that each Seller's  aggregate
liability with respect to his  breach(es) of this Agreement  shall be limited to
the purchase  price received by such Seller  pursuant to Section 2.2;  provided,
however,  that no such limitation of liability will apply to Damages incurred by
Buyer  or  EMCON  as  a  result  of  any   intentional   or  grossly   negligent
misrepresentation, action or failure to act by Seller(s).

     12.3 Survival.  Notwithstanding any investigation conducted before or after
the   Closing,   the   parties   hereto  will  be  entitled  to  rely  upon  the
representations  and  warranties of the other  parties  hereto set forth in this
Agreement.  All  representations  and  warranties  in this  Agreement  or in any
instrument  delivered pursuant to this Agreement will survive until the date one
(1) year after the Closing, at which time the representations and warranties set
forth in this  Agreement and all liability of the parties hereto with respect to
those  representations and warranties will terminate;  provided,  however,  that
thereafter a party hereto will remain liable with respect to any claim of breach
of a representation or warranty provided such claim has been asserted in writing
(specifying  in  reasonable  detail  the basis and  amount of such  claim) on or
before the date one (1) year after the Closing until such time as said claim has
been finally decided, settled, or adjudicated.

                  13.      General Provisions.

     13.1 Expenses.  Except as otherwise  expressly  provided in this Agreement,
each  party to the  Agreement  will bear  his,  her or its  respective  expenses
incurred in connection with the preparation,  execution, and performance of this
Agreement and the Contemplated Transactions,  including all fees and expenses of
agents, representatives, counsel, and accountants.

     13.2 Public  Announcements.  No party shall issue any press release or make
any public announcement related to the subject matter of this Agreement prior to
the  Closing  without the prior  written  approval of the Sellers and the Buyer;


                                       75
<PAGE>

provided,  however, that any party may make any public disclosure it believes in
good faith is required  by  applicable  law or any listing or trading  agreement
concerning  the  publicly-traded  securities  of such  party (in which  case the
disclosing  party will use its reasonable best efforts to advise the other party
prior to making the  disclosure  and consult with the other party  regarding the
content thereof).  The Sellers and Buyer will consult with each other concerning
the means by which the Company's  employees,  customers and suppliers and others
having  dealings  with  the  parties  will  be  informed  of  the   Contemplated
Transactions.

     13.3 Confidentiality. Between the date of this Agreement and five (5) years
after the date  hereof,  Buyer,  the  Company,  and  Sellers  will  maintain  in
confidence,  and will cause the  directors,  officers,  employees,  agents,  and
advisors of Buyer, the Company,  and the Sellers to maintain in confidence,  and
not  use to  the  detriment  of  another  party  any  written,  oral,  or  other
information  obtained in confidence  from another party in connection  with this
Agreement or the Contemplated  Transactions,  expressly including the reports of
all consultants  retained  pursuant to the terms of this  Agreement,  unless (a)
such information  becomes publicly available through no fault of such party, (b)
the use of such  information is necessary or appropriate in making any filing or
obtaining  any  consent  or  approval  required  for  the  consummation  of  the
Contemplated  Transactions,  or (c) the furnishing or use of such information is
required by legal proceedings.

     If the  Contemplated  Transactions  are not  consummated,  each  party will
return or destroy as much of such  written  information  as the party  providing
such information may reasonably request.

     13.4 Notices.  All notices,  consents,  waivers,  and other  communications
under this  Agreement  must be in  writing  and will be deemed to have been duly
given when (a) delivered by hand (with  written  confirmation  of receipt),  (b)
sent by telecopier (with written confirmation of receipt),  provided that a copy
is mailed  within three (3) business  days by registered  mail,  return  receipt
requested,  (c)  when  received  by  the  addressee,  if  sent  by a  nationally
recognized  overnight  delivery  service (receipt  requested),  or (d) three (3)
business days after being sent by registered or certified  mail,  return receipt
requested,  in each case to the appropriate addresses and telecopier numbers set
forth below (or to such other  addresses and  telecopier  numbers as a party may
designate by notice to the other parties):

          Sellers:        To each Seller at the address set forth on Exhibits A


          The Company:       National Earth Products, Inc.
                             245 Butler Avenue
                             Lancaster, PA  17601
                             Attn:  Charles Gearhart
                             Fax No.:  (717) 390-9896


                                       76
<PAGE>


          Buyer:             EMCON
                             400 S. El Camino Real, Suite 1200
                             San Mateo, California  94402
                             Attention:  R. Michael Momboisse, Esq.
                             Fax No.:  (415) 375-0763

                  13.5 Binding Arbitration;  Service of Process. In the event of
a dispute between the parties  related to or arising out of this Agreement,  the
Agents and representatives of the Buyer and the Company will meet promptly in an
effort to resolve the dispute  amicably.  If such  parties  cannot  agree upon a
resolution  within  thirty (30) days of any such party  requesting a meeting for
resolution  of a dispute,  then the matter will promptly be submitted to binding
arbitration in accordance with this Section 13.5.

     (a) Arbitration will be held in Philadelphia,  Pennsylvania,  in accordance
with the rules and  regulations  of the American  Arbitration  Association.  The
number of  arbitrators  will be one and will be selected in accordance  with the
rules and regulations of the American Arbitration Association. The determination
of the  arbitrator  will be  conclusive  and binding upon the  parties,  and any
determination  by the  arbitrator  of an award may be filed  with the clerk of a
court of competent  jurisdiction as a final  adjudication of the claim involved,
or  application  may be made to such court for judicial  acceptance of the award
and an order of enforcement,  as the case may be. Except to the extent otherwise
directed by the  arbitrator,  each party will bear its own  expenses,  including
legal and accounting fees, if any, with respect to the arbitration, and one-half
of  the  costs  of  the  arbitrator  and of the  fees  imposed  by the  American
Arbitration Association.

     (b)  In  any  arbitration  hereunder,  the  demand  for  arbitration  shall
specifically  delineate the claims asserted and the material issues with respect
thereto. Within thirty (30) days after filing a demand for arbitration, claimant
shall provide to respondent a list of all fact witnesses known to claimant,  the
names and curriculum  vitae of each expert  witness  anticipated to be called by
claimant,  and a copy of  relevant  documents.  Within  thirty  (30) days  after
receipt of the  foregoing  information,  respondent  shall provide to claimant a
list of all fact witnesses known to respondent,  the names and curriculum  vitae
of each expert witness  anticipated  to be called by  respondent,  and a copy of
relevant documents known to respondent. Within ten (10) days after discovery has
been closed by the arbitrator  (but in no event later than sixty (60) days prior
to the arbitration hearing),  claimant shall present to respondent a list of all
fact and expert witnesses anticipated to be called by claimant, a summary of the
substance  of  each  such  witness'  testimony,  and a  list  of  all  documents
anticipated  to be introduced  by claimant (and a copy of such  documents if not
previously provided to respondent). Within thirty (30) days after receipt of the
foregoing  information,  respondent shall present to claimant a list of all fact
and expert  witnesses  anticipated to be called by respondent,  a summary of the
substance  of  each  such  witness'  testimony,  and a  list  of  all  documents
anticipated to be introduced by respondent  (and a copy of such documents if not
previously  provided to claimant).  Any award by the arbitrator shall be subject
to all dollar and other limitations set forth in this Agreement.


                                       77
<PAGE>


     (c) A demand for arbitration may be served on Buyer or Sellers by certified
U.S. Mail,  postage prepaid,  or reliable  overnight  delivery  service,  to the
address set forth in Section 13.4 hereof.

                  13.6 Further Assurances. The parties agree (a) to furnish upon
request to each other such  further  information,  (b) to execute and deliver to
each other such other documents,  and (c) to do such other acts and things,  all
as the other party may  reasonably  request for the purpose of carrying  out the
intent of this Agreement and the documents referred to in this Agreement.

                  13.7  Waiver.  The rights and  remedies of the parties to this
Agreement are cumulative and not alternative.  Neither the failure nor any delay
by any party in exercising any right,  power,  or privilege under this Agreement
or the documents  referred to in this Agreement will operate as a waiver of such
right, power, or privilege, and no single or partial exercise of any such right,
power,  or privilege will preclude any other or further  exercise of such right,
power, or privilege or the exercise of any other right, power, or privilege.  To
the maximum  extent  permitted by applicable  law, (a) no claim or right arising
out of this  Agreement or the  documents  referred to in this  Agreement  can be
discharged by one party, in whole or in part, by a waiver or renunciation of the
claim or right unless in writing  signed by the other party;  (b) no waiver that
may be given by a party will be applicable  except in the specific  instance for
which it is given; and (c) no notice to or demand on one party will be deemed to
be a waiver of any  obligation of such party or of the right of the party giving
such  notice  or  demand  to take  further  action  without  notice or demand as
provided in this Agreement or the documents referred to in this Agreement.

                  13.8  Entire  Agreement  and   Modification.   This  Agreement
supersedes all prior agreements  between the parties with respect to its subject
matter and constitutes  (along with the documents referred to in this Agreement)
a complete and  exclusive  statement of the terms of the  agreement  between the
parties with respect to its subject  matter.  This  Agreement may not be amended
except by a written  agreement  executed  by the  party to be  charged  with the
amendment.

                  13.9     Sellers' Disclosure Schedule.

     (a) The disclosures in the Sellers' Disclosure  Schedule,  and those in any
Supplement  thereto,  must relate only to the  representations and warranties in
the Section of the Agreement to which they expressly relate and not to any other
representation  or warranty in this  Agreement,  unless it is obvious,  from the
disclosure,  in light of the circumstances  under which such disclosure is made,
that other representations and warranties are affected thereby.

     (b) In the event of any inconsistency between the statements in the body of
this  Agreement  and those in the Sellers'  Disclosure  Schedule  (other than an
exception  expressly set forth as such in the Company  Disclosure  Schedule with
respect to a specifically identified representation or warranty), the statements
in the body of this Agreement will control.

     13.10 Assignments, Successors, and No Third Party Rights. Neither party may
assign any of its rights under this  Agreement  without the prior consent of the
other parties,  which will not be unreasonably  withheld,  except that Buyer may
assign any of its rights  under this  Agreement to any  Subsidiary  of Buyer but
Buyer will not be  relieved  of its  obligations  hereunder  as a result of such
assignment.  Subject to the preceding sentence, this Agreement will apply to, be
binding in all respects  upon,  and inure to the benefit of the  successors  and


                                       78
<PAGE>

permitted  assigns of the  parties.  Nothing  expressed  or  referred to in this
Agreement  will be  construed  to give any Person other than the parties to this
Agreement any legal or equitable right,  remedy,  or claim under or with respect
to this Agreement or any provision of this Agreement.  This Agreement and all of
its  provisions  and  conditions  are for the sole and exclusive  benefit of the
parties to this Agreement and their successors and assigns.

                  13.11 Severability. If any provision of this Agreement is held
invalid  or  unenforceable  by any court of  competent  jurisdiction,  the other
provisions of this Agreement will remain in full force and effect. Any provision
of this  Agreement  held  invalid or  unenforceable  only in part or degree will
remain in full force and effect to the extent not held invalid or unenforceable.

                  13.12 Section Headings, Construction. The headings of Sections
in this  Agreement  are  provided for  convenience  only and will not affect its
construction  or  interpretation.  All  references  to  "Sections"  refer to the
corresponding Sections of this Agreement.  All words used in this Agreement will
be construed to be of such gender or number as the circumstances require. Unless
otherwise expressly provided,  the word "including" does not limit the preceding
words or terms.

                  13.13  Interpretation  of Agreement.  This  Agreement has been
submitted to the scrutiny of all parties hereto and their respective counsel and
shall be given a fair and reasonable  interpretation without consideration being
given to its having been drafted by either party or its counsel.

                  13.14  Time of  Essence.  With  regard  to all  dates and time
periods set forth or referred to in this Agreement, time is of the essence.

     13.15 Governing Law. This Agreement will be governed by and construed under
the laws of the  State of  Pennsylvania  without  regard  to  conflicts  of laws
principles.

                  13.16  Counterparts.  This Agreement may be executed in one or
more  counterparts,  each of which will be deemed to be an original copy of this
Agreement and all of which,  when taken  together,  will be deemed to constitute
one and the same agreement.


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


                                       79
<PAGE>





BUYER:                                          EMCON

ORGANIC WASTE TECHNOLOGIES, INC.,               EMCON, a California corporation
  a Delaware corporation


By: /s/R. Michael Momboisse                     By:   /s/R. Michael Momboisse
    ---------------------------------              --------------------------

Its:  Director                                 Its:  CFO & VP - Legal
     --------------------------------               -------------------------


SELLERS:                                     COMPANY

                                             NATIONAL EARTH PRODUCTS, INC, 
                                             a Pennsylvania corporation


    /s/Dennis M. Grimm                        By:   /s/Dennis M. Grimm 
- -------------------------------------           ------------------------------
Dennis M. Grimm                                   Dennis M. Grimm


 /s/Charles H. Gearhart                     Its:   President
- ------------------------------------            ------------------------------
Charles H. Gearhart

                                       80


                                  EXHIBIT 10.3

                                      EMCON
                      SALARY CONTINUATION PLAN PARTICIPANTS


                                 Monthly Payments
                         ------------------------------
                           Salary                             Date Payments
 Participant             Continuation    Non-compete           Commence
- ------------------------------------------------------------------------------

Thorley D. Briggs         $1,800          $1,200          January       1993
                          $1,200          $  800          July          1993
John G. Pacey                -0-          $1,080          January       1993
Donald R. Andres          $1,800          $1,200          January       1993
Richard J. Leach             -0-          $  819          January       1993
Fred W. Cope              $  600          $  400          January       1994
Robert E. Van Heuit          -0-          $  400          January       1994
H. Randolph Sweet         $1,350          $  900          April         1997
Eugene M. Herson          $1,800          $1,200          November      2000
                          $2,700          $1,800          November      2004
R. Michael Momboisse      $  600          $  400          January       2003
                          $1,200          $  800          November      2004
                          $  600          $  400          November      2006
Gary O. McEntee           $  600          $  400          November      2004









                                       81

                                  EXHIBIT 10.22

                                CONVERTIBLE NOTE


San Mateo, California
April 30, 1997                                                     $399,201.60

         FOR VALUE RECEIVED, EMCON, a California corporation (hereinafter called
the  "Borrower"),  hereby  promises  to  pay  to  Charles  H.  Gearhart,  or his
respective  registered assigns (the "Holder") or order, the sum of Three Hundred
Ninety-Nine  Thousand Two Hundred One Dollars and Sixty Cents ($399,201.60) (the
"Principal"),  on May 1,  2002,  and to pay  interest  on the  unpaid  principal
balance  hereof at the rate of eight percent (8%) per annum from the date hereof
until the same becomes due and payable.  Interest shall commence accruing on the
date hereof and shall be payable  quarterly on each July 31, October 31, January
31 and April 30 beginning on July 31, 1997, with all interest  remaining  unpaid
at maturity due at such time.  All payments of principal  and interest  shall be
made in lawful money of the United States of America. All payments shall be made
at the  address  of the  Holder,  as set forth in  Section  6.4 hereof or as the
Holder shall hereafter give to the Borrower by written notice made in accordance
with the provisions of this Note.

         The following terms shall apply to this Note:

                                    ARTICLE I

                         PROHIBITION AGAINST PREPAYMENT

         1.1      Borrower shall have no right to prepay this Note at any time.

                                   ARTICLE II

                        CONVERSION INTO BORROWER'S STOCK

     Holder shall have the right to convert the  Principal  into shares of EMCON
Common  Stock  pursuant  to the terms of this  Article  II. In such  event,  any
accrued but unpaid interest shall be immediately due and payable.

     2.1 Conversion Price. The number of shares of EMCON Common Stock into which
the Principal shall be converted  shall be the amount of the Principal,  divided
by the EMCON Conversion Price. The EMCON Conversion Price shall initially be Six
Dollars and Fifty Cents  ($6.50),  and shall be adjusted as set forth in Section
2.2. hereof.

     2.2 Adjustment to EMCON Conversion  Price. The EMCON Conversion Price shall
be adjusted as set forth in this Section 2.2.

                  (a) Subdivisions. In case Borrower shall at any time subdivide
the  outstanding  shares of EMCON Common Stock,  the EMCON  Conversion  Price in




                                       82
<PAGE>


effect immediately prior to such subdivision shall be proportionately decreased,
and in case the  Company  shall at any time  combine the  outstanding  shares of
EMCON Common Stock, the EMCON Conversion  Price in effect  immediately  prior to
such combination shall be proportionately  increased,  effective at the close of
business on the date of such subdivision or combination, as the case may be.

                  (b) Stock Dividends.  In case Borrower shall at any time pay a
dividend with respect to EMCON Common Stock payable in EMCON Common Stock,  then
the EMCON  Conversion Price in effect  immediately  prior to the record date for
distribution  of such  dividend  shall be adjusted to that price  determined  by
multiplying  the  EMCON  Conversion  Price in effect  immediately  prior to such
record date by a fraction  (i) the  numerator of which shall be the total number
of shares of EMCON Common Stock  outstanding  immediately prior to such dividend
and (ii) the  denominator  of which shall be the total number of shares of EMCON
Common Stock outstanding immediately after such dividend.

                  (c)    Reclassification    or   Merger.   In   case   of   any
reclassification,  change or conversion of the EMCON Common Stock (other than as
a result of a subdivision or combination described above and other than upon any
Acceleration Event, as defined below), Borrower shall have the right to receive,
upon  exchange of this Note  (which may occur at the option of the Holder  only)
the kind and amount of shares of stock,  other  securities,  money and  property
receivable upon such  reclassification,  change or conversion by a holder of the
number of shares of EMCON  Common  Stock  into  which  this Note  could  then be
exchanged.  The provisions of this  subparagraph  (c) shall  similarly  apply to
successive reclassifications, changes, and conversions.

         2.3  Authorized  Shares.  EMCON  convenants  that during the period the
conversion  right set forth in this Article exists,  EMCON will reserve from the
authorized  and unissued  EMCON  Common  Stock a sufficient  number of shares to
provide for the issuance of EMCON Common Stock upon the full  conversion  of the
Principal.  EMCON  represents  that upon issuance,  such shares will be duly and
validly issued, fully paid and non-assessable.

         2.4 Method of  Exchange.  Except as  otherwise  agreed by EMCON and the
Holder,  the Principal  balance of the Note may be converted in whole or in part
(provided at least $250,000 in Principal is converted) in up to two installments
by (i)  submitting  to EMCON a  conversion  notice  setting  forth the amount of
Principal to be converted and (ii)  surrendering  the Note held by the Holder at
the principle  office of EMCON. In the event of a partial  conversion EMCON will
thereafter  reissue a new Note for the  remaining  unpaid  Principal  balance or
terms otherwise identical to those set forth herein.

         2.5  Restrictions  Concerning  the Shares.  The shares of EMCON  Common
Stock to be held by the Holder pursuant to the exercise of the conversion rights
set forth herein may not be sold or  transferred  unless  either (i) such shares
first shall have been  registered  under the  Securities Act of 1933 (the "Act")
and  applicable  state  securities  laws or (ii) EMCON shall have been furnished
with an opinion of legal  counsel to the effect  that such sale or  transfer  is
exempt from the  registration  requirements of the Act and all applicable  state
securities laws. Each certificate for shares of EMCON Common Stock to be held by
the Holder that have not been so registered and that have not been sold pursuant
to an  exemption  that  permits  removal  of the  legend,  shall  bear a  legend
substantially in the following form, as appropriate:


                                       83
<PAGE>


         THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED.  THE SECURITIES HAVE BEEN
         ACQUIRED FOR INVESTMENT AND MAY NOT BE SOLD, TRANSFERRED OR ASSIGNED IN
         THE ABSENCE OF AN EFFECTIVE  REGISTRATION  STATEMENT FOR THE SECURITIES
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED,  OR AN OPINION OF COUNSEL
         THAT REGISTRATION IS NOT REQUIRED UNDER SAID ACT.

Upon the request of the Holder, EMCON shall remove the foregoing legend from the
certificate representing the EMCON Common Stock held by the Holder upon exercise
of the conversion  rights or issue to Holder a new certificate  therefor free of
any transfer legend, if, with such request, EMCON shall have received either (i)
an opinion of counsel  to the effect  that any such  legend may be removed  from
such  certificate,  or  (ii)  if the  present  paragraph  (k) of  Rule  144 or a
substantially  similar successor rule remains in force and effect,  satisfactory
representations from the Holder that Holder is not then, and has not been during
the proceeding three (3) months,  an affiliate of EMCON, and that a period of at
least two (2) years has elapsed since the later of the date the securities  were
acquired (as determined under Rule 144) from EMCON or an affiliate of EMCON.

         2.6      EMCON Registration.

                  (a)  If,  EMCON  shall   determine  to  register  any  of  its
securities  either for its own  account or the  account of a security  holder or
holders,  other than a registration  relating to employee  benefit  plans,  or a
registration relating solely to a Rule 145 transaction, or a registration on any
registration form that does not permit secondary sales, EMCON will:

                    (i) promptly give the Holder written notice thereof;

                    (ii) use its best  efforts to  include in such  registration
(and any related qualification under blue sky laws or other compliance),  except
as set forth in Section 2.6 (b) below, and in any underwriting involved therein,
all the shares of EMCON Common Stock  issued upon  conversion  of this Note (the
"Holder's Shares") specified in a written request or requests made by the Holder
and  received by EMCON  within  twenty  (20) days after the written  notice from
EMCON  described  in clause  (i) above is mailed  or  delivered  by EMCON.  Such
written request may specify all or a part of the Holder's Shares;

                    (iii)  furnish  such  number  of   prospectuses   and  other
documents  incident  thereto,  including  any  amendment of or supplement to the
prospectus, as the Holder from time to time may reasonably request;

                    (iv) cause all such EMCON Common Stock  registered  pursuant
hereunder to be listed on each securities  exchange on which similar  securities
issued by EMCON are then listed.

                                       84
<PAGE>

                  (b) If the  registration  of which EMCON gives notice is for a
registered public offering involving an underwriting,  EMCON shall so advise the
Holder as a part of the written notice given pursuant to Section  2.6(a)(i).  In
such event,  the right of Holder to  registration  pursuant to this  Section 2.6
shall be conditioned upon Holder's  participation  in such  underwriting and the
inclusion  of the Holder's  Shares in the  underwriting  to the extent  provided
herein.  The  Holder  shall  (together  with  EMCON  and the  other  holders  of
securities of EMCON with registration rights to participate therein distributing
their securities through such underwriting) enter into an underwriting agreement
in customary form with the  representative  of the  underwriter or  underwriters
selected by EMCON.

                  (c)  Notwithstanding  any other provision of this Section 2.6,
if  the  representative  of the  underwriters  advises  EMCON  in  writing  that
marketing   factors  require  a  limitation  on  the  number  of  shares  to  be
underwritten,  the  representative  may  (subject tot he  limitations  set forth
below)  exclude all Holder's  Shares  from,  or limit the number of the Holder's
Shares to be included  in, the  registration  and  underwriting.  EMCON shall so
advise the Holder and all other holders of EMCON securities (the "Other Shares")
requesting  registration and the number of Holder's Shares and Other Shares that
may be  included  shall  be  allocated  amount  the  Holder  and  other  selling
stockholders  requesting inclusion of shares pro rata on the basis of the number
of Holder's Shares and Other Shares that are requested to be registered.

                  (d) EMCON's  obligations  pursuant  to this  Section 2.6 shall
expire at such time as Holder may sell all Holder's Shares during any successive
two quarter period pursuant to Rule 144 under the Act.

                  (e)  All  Registration   Expenses  (as  hereinafter   defined)
incurred  in  connection  with any  registration,  qualification  or  compliance
pursuant  to this  Section  2.6  hereof  shall be borne by  EMCON.  All  Selling
Expenses (as hereinafter  defined) relating to securities so registered shall be
borne by the Holder. For purposes hereof,  Registration  Expenses shall mean all
expenses  incurred  in  effecting  any  registration   pursuant  to  this  Note,
including, without limitation, all registration, qualification, and filing fees,
printing  expenses,  escrow fees, fees and  disbursements  of counsel for EMCON,
blue sky fees and  expenses,  and  expenses  of any  regular or  special  audits
incident to or required by any such registration,  but shall not include Selling
Expenses  and fees and  disbursements  of counsel for Holder.  Selling  Expenses
shall mean all underwriting  discounts and selling commissions applicable to the
sale of the  Holder's  Shares and fees and  disbursements  of counsel for Holder
(other  than the fees and  disbursements  of counsel  included  in  Registration
Expenses).

                                   ARTICLE III

                                     OFFSET

         3.1 Offset. The Holder acknowledges that this Note is being made by the
Borrower  pursuant to that certain Stock Purchase  Agreement,  dated as of April
30,  1997,  by and among the  Borrower,  Organic  Waste  Technologies,  Inc.,  a
Delaware  corporation  and the  holders  of the  outstanding  capital  stock  of
National  Earth  Products,  Inc. (the "Stock  Purchase  Agreement").  The Holder
further acknowledges that he or she is bound by the Stock Purchase Agreement and
that the  Principal  due  hereunder  may be reduced by any  amounts due from the
Holder to Borrower pursuant thereto.

                                       85
<PAGE>

                                   ARTICLE IV

                                  ACCELERATION

         4.1 Notwithstanding  anything to the contrary herein, in the event that
any of the events set forth in Section 4.1 (each, an "Acceleration Event") shall
occur at any time after the date hereof,  then, subject to the qualification set
forth below,  the Principal and all interest thereon shall, at the option of the
Holder, be immediately due and payable.

                  (a) upon a  consolidation  or merger of EMCON with or into any
other corporation or corporations (other than a wholly-owned subsidiary of EMCON
and other than a merger in which  EMCON is the  surviving  corporation),  or the
sale, transfer or other disposition of all or substantially all of the assets of
EMCON;

                  (b) upon a change in ownership of Fifty  Percent (50%) or more
of the stock of Borrower  to a single  buyer or an  affiliated  group of buyers,
resulting in a change in the majority of the Board of Directors of Borrower from
the  Board of  Directors  as it  existed  immediately  prior to such  change  in
ownership;

                  (c) upon the  liquidation,  dissolution  or  winding up of the
Borrower or the  consolidation  or merger of the Borrower  with and into another
corporation  (other  than a  merger  in  which  the  Borrower  is the  surviving
corporation);

         provided, however, that upon any Acceleration Event, no amount shall be
due and payable  hereunder in the event that the Holder has exchanged  this Note
for Common Stock of EMCON, pursuant to the Note Agreement.

                                    ARTICLE V

                                EVENTS OF DEFAULT

         If any of the following events of default (each, an "Event of Default")
shall occur:

          5.1.  Failure to Pay Principal or Interest.  The Borrower fails to pay
the Principal or interest when due;

         5.2 Receiver or Trustee.  The Borrower shall make an assignment for the
benefit of creditors,  or apply for or consent to the  appointment of a receiver
or trustee for it or for a substantial part of its property or business, or such
a receiver or trustee shall otherwise be appointed;

                                       86
<PAGE>

          5.3 Bankruptcy. Bankruptcy, insolvency,  reorganization or liquidation
proceedings or other  proceedings for relief under any bankruptcy law or any law
for relief of debtors shall be instituted by or against the Borrower,

         then upon the  occurrence and during the  continuation  of any Event of
Default,  then, at the option of the Holder,  the Principal and all interest due
thereon shall be  immediately  due and payable,  and the Borrower shall have all
other remedies available at law or equity.

                                   ARTICLE VI

                                  MISCELLANEOUS

         6.1 Late  Charge.  The  Borrower  shall pay to the Holder a late charge
equal to 1.5% per month, but not to exceed the maximum rate allowable by law, on
any amount due hereunder that is not received by the Holder within 10 days after
the date on which such amount is due. Borrower agrees that it would be extremely
difficult or impractical  to determine the Holder's  actual damages in the event
of such late payment,  that the amount specified above is a reasonable  estimate
of such damages and that such amount  shall  constitute  liquidated  damages for
such late payment.  The foregoing provision shall not be construed to extend the
due date for any amount required to be paid hereunder.  The Holder shall have no
obligation to accept any late payment not accompanied by such late charge.

         6.2  Collection  Costs and Expenses.  The Borrower shall pay all costs,
fees and expenses (including court costs and reasonable attorneys fees) incurred
by the Holder in collecting or attempting to collect any amount that becomes due
hereunder or in seeking legal advice with respect to such collection or an Event
of Default.

         6.3 Failure or Indulgence Note Waiver.  No failure or delay on the part
of the Holder in the exercise of any power,  right or privilege  hereunder shall
operate as a waiver  thereof,  nor shall any single or partial  exercise  of any
such power,  right or privilege preclude other or further exercise thereof or of
any other right, power or privileges.

         6.4 Notices. All notices,  consents,  waivers, and other communications
under this  Agreement  must be in  writing  and will be deemed to have been duly
given when (a) delivered by hand (with  written  confirmation  of receipt),  (b)
sent by telecopier (with written confirmation of receipt),  provided that a copy
is mailed  within three (3) business  days by registered  mail,  return  receipt
requested,  (c)  when  received  by  the  addressee,  if  sent  by a  nationally
recognized  overnight  delivery  service (receipt  requested),  or (d) three (3)
business days after being sent by registered or certified  mail,  return receipt
requested,  in each case to the appropriate addresses and telecopier numbers set
forth below (or to such other  addresses and  telecopier  numbers as a party may
designate by notice to the other parties):

         Holder:  Charles H. Gearhart
                           1054 Hunters Path
                           Lancaster,  PA  17601

         Borrower:         EMCON
                           400 South El Camino Real, Suite 1200
                           San Mateo, California  94402
                           Attn:  Chief Financial Officer
                           Facsimile: 415/375-0763



                                       87
<PAGE>

         6.5 Amendment Provision.  The term "Note" and all reference thereto, as
used  throughout  this  instrument,  shall mean this  instrument  as  originally
executed,  or  if  later  amended  or  supplemented,   then  as  so  amended  or
supplemented.

          6.6 Governing Law. This Note shall be governed by the internal laws of
the State of California, without regard to the principles of conflict of laws.

         6.7  Confession  of  Judgment.  THE  FOLLOWING  PARAGRAPH  SETS FORTH A
WARRANT OF ATTORNEY TO CONFESS JUDGMENT  AGAINST THE BORROWER.  IN GRANTING THIS
WARRANT OF  ATTORNEY TO CONFESS  JUDGMENT  AGAINST THE  BORROWER,  THE  BORROWER
HEREBY KNOWINGLY,  INTENTIONALLY AND VOLUNTARILY, AND, ON THE ADVICE OF SEPARATE
COUNSEL OR THE BORROWER,  UNCONDITIONALLY WAIVES ANY AND ALL RIGHTS THE BORROWER
HAS OR MAY HAVE TO  PRIOR  NOTICE  AND AN  OPPORTUNITY  FOR  HEARING  UNDER  THE
RESPECTIVE  CONSTITUTIONS  AND LAWS OF THE UNITED STATES AND THE COMMONWEALTH OF
PENNSYLVANIA.

                  As further security for payment hereunder and upon an event of
default, Borrower authorizes and empowers any attorney of any court of record of
Pennsylvania  or  elsewhere  to appear for and CONFESS  JUDGMENT  against it and
immediately  execute  on  such  judgment,   without  notice  of  such  immediate
execution,  for the then  unpaid  principal  amount and  interest  of this Note,
together with late charges,  costs of suit and reasonable  attorneys' fees, with
or without  declaration  or stay of execution,  and with release of errors,  for
which this Note or a copy hereof shall serve as a sufficient warrant. This power
to CONFESS  JUDGMENT  against Borrower shall not be exhausted by any exercise of
the power  and shall  continue  from  time to time and at all times  until  full
payment of all amounts due under this Note.

         IN WITNESS  WHEREOF,  Borrower has caused this Note to be signed in its
name by its duly authorized officer as of the 30th day of April, 1997.

                     EMCON

                     By:  /S/
                          --------------------------------
                     Name: R. Michael Momboisse
                           --------------------------------
                     Title: CFO & VP Legal
                            ------------------------------




                                       88
<PAGE>



                                CONVERTIBLE NOTE


San Mateo, California
April 30, 1997                                                 $400,798.40

         FOR VALUE RECEIVED, EMCON, a California corporation (hereinafter called
the  "Borrower"),  hereby  promises to pay to Dennis M. Grimm, or his respective
registered  assigns (the  "Holder") or order,  the sum of Four Hundred  Thousand
Seven  Hundred  Ninety  Eight  Dollars  and  Forty  Cents   ($400,798.40)   (the
"Principal"),  on May 1,  2000,  and to pay  interest  on the  unpaid  principal
balance  hereof at the rate of eight percent (8%) per annum from the date hereof
until the same becomes due and payable.  Interest shall commence accruing on the
date hereof and shall be payable  quarterly on each July 31, October 31, January
31 and April 30 beginning on July 31, 1997, with all interest  remaining  unpaid
at maturity due at such time.  All payments of principal  and interest  shall be
made in lawful money of the United States of America. All payments shall be made
at the  address  of the  Holder,  as set forth in  Section  6.4 hereof or as the
Holder shall hereafter give to the Borrower by written notice made in accordance
with the provisions of this Note.

         The following terms shall apply to this Note:

                                    ARTICLE I

                         PROHIBITION AGAINST PREPAYMENT

         1.1      Borrower shall have no right to prepay this Note at any time.

                                   ARTICLE II

                        CONVERSION INTO BORROWER'S STOCK

         Holder  shall have the right to convert  the  Principal  into shares of
EMCON Common Stock pursuant to the terms of this Article II. In such event,  any
accrued but unpaid interest shall be immediately due and payable.

         2.1 Conversion  Price.  The number of shares of EMCON Common Stock into
which the  Principal  shall be converted  shall be the amount of the  Principal,
divided  by the  EMCON  Conversion  Price.  The  EMCON  Conversion  Price  shall
initially be Six Dollars and Fifty Cents  ($6.50),  and shall be adjusted as set
forth in Section 2.2.
hereof.

          2.2 Adjustment to EMCON  Conversion  Price. The EMCON Conversion Price
shall be adjusted as set forth in this Section 2.2.

                  (a) Subdivisions. In case Borrower shall at any time subdivide
the  outstanding  shares of EMCON Common Stock,  the EMCON  Conversion  Price in
effect immediately prior to such subdivision shall be proportionately decreased,
and in case the  Company  shall at any time  combine the  outstanding  shares of
EMCON Common Stock, the EMCON Conversion  Price in effect  immediately  prior to
such combination shall be proportionately  increased,  effective at the close of
business on the date of such subdivision or combination, as the case may be.

                                       89
<PAGE>

                  (b) Stock Dividends.  In case Borrower shall at any time pay a
dividend with respect to EMCON Common Stock payable in EMCON Common Stock,  then
the EMCON  Conversion Price in effect  immediately  prior to the record date for
distribution  of such  dividend  shall be adjusted to that price  determined  by
multiplying  the  EMCON  Conversion  Price in effect  immediately  prior to such
record date by a fraction  (i) the  numerator of which shall be the total number
of shares of EMCON Common Stock  outstanding  immediately prior to such dividend
and (ii) the  denominator  of which shall be the total number of shares of EMCON
Common Stock outstanding immediately after such dividend.

                  (c)    Reclassification    or   Merger.   In   case   of   any
reclassification,  change or conversion of the EMCON Common Stock (other than as
a result of a subdivision or combination described above and other than upon any
Acceleration Event, as defined below), Borrower shall have the right to receive,
upon  exchange of this Note  (which may occur at the option of the Holder  only)
the kind and amount of shares of stock,  other  securities,  money and  property
receivable upon such  reclassification,  change or conversion by a holder of the
number of shares of EMCON  Common  Stock  into  which  this Note  could  then be
exchanged.  The provisions of this  subparagraph  (c) shall  similarly  apply to
successive reclassifications, changes, and conversions.

         2.3  Authorized  Shares.  EMCON  convenants  that during the period the
conversion  right set forth in this Article exists,  EMCON will reserve from the
authorized  and unissued  EMCON  Common  Stock a sufficient  number of shares to
provide for the issuance of EMCON Common Stock upon the full  conversion  of the
Principal.  EMCON  represents  that upon issuance,  such shares will be duly and
validly issued, fully paid and non-assessable.

         2.4 Method of  Exchange.  Except as  otherwise  agreed by EMCON and the
Holder,  the Principal  balance of the Note may be converted in whole or in part
(provided at least $250,000 in Principal is converted) in up to two installments
by (i)  submitting  to EMCON a  conversion  notice  setting  forth the amount of
Principal to be converted and (ii)  surrendering  the Note held by the Holder at
the principle  office of EMCON. In the event of a partial  conversion EMCON will
thereafter  reissue a new Note for the  remaining  unpaid  Principal  balance or
terms otherwise identical to those set forth herein.

         2.5  Restrictions  Concerning  the Shares.  The shares of EMCON  Common
Stock to be held by the Holder pursuant to the exercise of the conversion rights
set forth herein may not be sold or  transferred  unless  either (i) such shares
first shall have been  registered  under the  Securities Act of 1933 (the "Act")
and  applicable  state  securities  laws or (ii) EMCON shall have been furnished
with an opinion of legal  counsel to the effect  that such sale or  transfer  is
exempt from the  registration  requirements of the Act and all applicable  state
securities laws. Each certificate for shares of EMCON Common Stock to be held by
the Holder that have not been so registered and that have not been sold pursuant
to an  exemption  that  permits  removal  of the  legend,  shall  bear a  legend
substantially in the following form, as appropriate:


                                       90
<PAGE>

         THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED.  THE SECURITIES HAVE BEEN
         ACQUIRED FOR INVESTMENT AND MAY NOT BE SOLD, TRANSFERRED OR ASSIGNED IN
         THE ABSENCE OF AN EFFECTIVE  REGISTRATION  STATEMENT FOR THE SECURITIES
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED,  OR AN OPINION OF COUNSEL
         THAT REGISTRATION IS NOT REQUIRED UNDER SAID ACT.

Upon the request of the Holder, EMCON shall remove the foregoing legend from the
certificate representing the EMCON Common Stock held by the Holder upon exercise
of the conversion  rights or issue to Holder a new certificate  therefor free of
any transfer legend, if, with such request, EMCON shall have received either (i)
an opinion of counsel  to the effect  that any such  legend may be removed  from
such  certificate,  or  (ii)  if the  present  paragraph  (k) of  Rule  144 or a
substantially  similar successor rule remains in force and effect,  satisfactory
representations from the Holder that Holder is not then, and has not been during
the proceeding three (3) months,  an affiliate of EMCON, and that a period of at
least two (2) years has elapsed since the later of the date the securities  were
acquired (as determined under Rule 144) from EMCON or an affiliate of EMCON.

         2.6      EMCON Registration.

                  (a)  If,  EMCON  shall   determine  to  register  any  of  its
securities  either for its own  account or the  account of a security  holder or
holders,  other than a registration  relating to employee  benefit  plans,  or a
registration relating solely to a Rule 145 transaction, or a registration on any
registration form that does not permit secondary sales, EMCON will:

                    (i) promptly give the Holder written notice thereof;

                    (ii) use its best  efforts to  include in such  registration
(and any related qualification under blue sky laws or other compliance),  except
as set forth in Section 2.6 (b) below, and in any underwriting involved therein,
all the shares of EMCON Common Stock  issued upon  conversion  of this Note (the
"Holder's Shares") specified in a written request or requests made by the Holder
and  received by EMCON  within  twenty  (20) days after the written  notice from
EMCON  described  in clause  (i) above is mailed  or  delivered  by EMCON.  Such
written request may specify all or a part of the Holder's Shares;

                    (iii)  furnish  such  number  of   prospectuses   and  other
documents  incident  thereto,  including  any  amendment of or supplement to the
prospectus, as the Holder from time to time may reasonably request;

                    (iv) cause all such EMCON Common Stock  registered  pursuant
hereunder to be listed on each securities  exchange on which similar  securities
issued by EMCON are then listed.


                                       91
<PAGE>

         (b) If the registration of which EMCON gives notice is for a registered
public offering involving an underwriting, EMCON shall so advise the Holder as a
part of the written notice given pursuant to Section  2.6(a)(i).  In such event,
the  right of Holder  to  registration  pursuant  to this  Section  2.6 shall be
conditioned upon Holder's  participation in such  underwriting and the inclusion
of the Holder's Shares in the  underwriting to the extent provided  herein.  The
Holder shall  (together  with EMCON and the other holders of securities of EMCON
with registration  rights to participate  therein  distributing their securities
through such  underwriting)  enter into an  underwriting  agreement in customary
form with the  representative  of the  underwriter or  underwriters  selected by
EMCON.

         (c)  Notwithstanding  any other  provision  of this Section 2.6, if the
representative  of the  underwriters  advises  EMCON in writing  that  marketing
factors  require a limitation  on the number of shares to be  underwritten,  the
representative  may (subject  tot he  limitations  set forth below)  exclude all
Holder's  Shares from, or limit the number of the Holder's Shares to be included
in, the registration and underwriting.  EMCON shall so advise the Holder and all
other holders of EMCON securities (the "Other Shares")  requesting  registration
and the number of Holder's Shares and Other Shares that may be included shall be
allocated amount the Holder and other selling stockholders  requesting inclusion
of shares  pro rata on the  basis of the  number of  Holder's  Shares  and Other
Shares that are requested to be registered.

         (d) EMCON's  obligations  pursuant to this  Section 2.6 shall expire at
such time as Holder  may sell all  Holder's  Shares  during any  successive  two
quarter period pursuant to Rule 144 under the Act.

         (e) All  Registration  Expenses (as  hereinafter  defined)  incurred in
connection with any registration,  qualification or compliance  pursuant to this
Section 2.6 hereof shall be borne by EMCON. All Selling Expenses (as hereinafter
defined) relating to securities so registered shall be borne by the Holder.  For
purposes  hereof,  Registration  Expenses  shall mean all  expenses  incurred in
effecting any registration pursuant to this Note, including, without limitation,
all registration,  qualification,  and filing fees,  printing  expenses,  escrow
fees, fees and  disbursements of counsel for EMCON,  blue sky fees and expenses,
and  expenses  of any regular or special  audits  incident to or required by any
such  registration,  but  shall  not  include  Selling  Expenses  and  fees  and
disbursements   of  counsel  for  Holder.   Selling   Expenses  shall  mean  all
underwriting  discounts  and selling  commissions  applicable to the sale of the
Holder's Shares and fees and disbursements of counsel for Holder (other than the
fees and disbursements of counsel included in Registration Expenses).
                                   
                                  ARTICLE III

                                     OFFSET

         3.1 Offset. The Holder acknowledges that this Note is being made by the
Borrower  pursuant to that certain Stock Purchase  Agreement,  dated as of April
30,  1997,  by and among the  Borrower,  Organic  Waste  Technologies,  Inc.,  a
Delaware  corporation  and the  holders  of the  outstanding  capital  stock  of
National  Earth  Products,  Inc. (the "Stock  Purchase  Agreement").  The Holder
further acknowledges that he or she is bound by the Stock Purchase Agreement and
that the  Principal  due  hereunder  may be reduced by any  amounts due from the
Holder to Borrower pursuant thereto.

                                       92
<PAGE>


                                   ARTICLE IV

                                  ACCELERATION

         4.1 Notwithstanding  anything to the contrary herein, in the event that
any of the events set forth in Section 4.1 (each, an "Acceleration Event") shall
occur at any time after the date hereof,  then, subject to the qualification set
forth below,  the Principal and all interest thereon shall, at the option of the
Holder, be immediately due and payable.

                  (a) upon a  consolidation  or merger of EMCON with or into any
other corporation or corporations (other than a wholly-owned subsidiary of EMCON
and other than a merger in which  EMCON is the  surviving  corporation),  or the
sale, transfer or other disposition of all or substantially all of the assets of
EMCON;

                  (b) upon a change in ownership of Fifty  Percent (50%) or more
of the stock of Borrower  to a single  buyer or an  affiliated  group of buyers,
resulting in a change in the majority of the Board of Directors of Borrower from
the  Board of  Directors  as it  existed  immediately  prior to such  change  in
ownership;

                  (c) upon the  liquidation,  dissolution  or  winding up of the
Borrower or the  consolidation  or merger of the Borrower  with and into another
corporation  (other  than a  merger  in  which  the  Borrower  is the  surviving
corporation);

         provided, however, that upon any Acceleration Event, no amount shall be
due and payable  hereunder in the event that the Holder has exchanged  this Note
for Common Stock of EMCON, pursuant to the Note Agreement.

                                    ARTICLE V

                                EVENTS OF DEFAULT

         If any of the following events of default (each, an "Event of Default")
shall occur:

          5.1.  Failure to Pay Principal or Interest.  The Borrower fails to pay
the Principal or interest when due;

         5.2 Receiver or Trustee.  The Borrower shall make an assignment for the
benefit of creditors,  or apply for or consent to the  appointment of a receiver
or trustee for it or for a substantial part of its property or business, or such
a receiver or trustee shall otherwise be appointed;



                                       93
<PAGE>

          5.3 Bankruptcy. Bankruptcy, insolvency,  reorganization or liquidation
proceedings or other  proceedings for relief under any bankruptcy law or any law
for relief of debtors shall be instituted by or against the Borrower,  then upon
the occurrence and during the continuation of any Event of Default, then, at the
option of the Holder,  the  Principal  and all  interest  due  thereon  shall be
immediately  due and  payable,  and the Borrower  shall have all other  remedies
available at law or equity.

                                   ARTICLE VI

                                  MISCELLANEOUS

         6.1 Late  Charge.  The  Borrower  shall pay to the Holder a late charge
equal to 1.5% per month, but not to exceed the maximum rate allowable by law, on
any amount due hereunder that is not received by the Holder within 10 days after
the date on which such amount is due. Borrower agrees that it would be extremely
difficult or impractical  to determine the Holder's  actual damages in the event
of such late payment,  that the amount specified above is a reasonable  estimate
of such damages and that such amount  shall  constitute  liquidated  damages for
such late payment.  The foregoing provision shall not be construed to extend the
due date for any amount required to be paid hereunder.  The Holder shall have no
obligation to accept any late payment not accompanied by such late charge.

         6.2  Collection  Costs and Expenses.  The Borrower shall pay all costs,
fees and expenses (including court costs and reasonable attorneys fees) incurred
by the Holder in collecting or attempting to collect any amount that becomes due
hereunder or in seeking legal advice with respect to such collection or an Event
of Default.

         6.3 Failure or Indulgence Note Waiver.  No failure or delay on the part
of the Holder in the exercise of any power,  right or privilege  hereunder shall
operate as a waiver  thereof,  nor shall any single or partial  exercise  of any
such power,  right or privilege preclude other or further exercise thereof or of
any other right, power or privileges.

         6.4 Notices. All notices,  consents,  waivers, and other communications
under this  Agreement  must be in  writing  and will be deemed to have been duly
given when (a) delivered by hand (with  written  confirmation  of receipt),  (b)
sent by telecopier (with written confirmation of receipt),  provided that a copy
is mailed  within three (3) business  days by registered  mail,  return  receipt
requested,  (c)  when  received  by  the  addressee,  if  sent  by a  nationally
recognized  overnight  delivery  service (receipt  requested),  or (d) three (3)
business days after being sent by registered or certified  mail,  return receipt
requested,  in each case to the appropriate addresses and telecopier numbers set
forth below (or to such other  addresses and  telecopier  numbers as a party may
designate by notice to the other parties):


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<PAGE>



         Holder:  Dennis M. Grimm
                           1035 Eshelman Mill Road
                           Lancaster,  PA  17602

         Borrower:         EMCON
                           400 South El Camino Real, Suite 1200
                           San Mateo, California  94402
                           Attn:  Chief Financial Officer
                           Facsimile: 415/375-0763

          6.5 Amendment Provision. The term "Note" and all reference thereto, as
used  throughout  this  instrument,  shall mean this  instrument  as  originally
executed,  or  if  later  amended  or  supplemented,   then  as  so  amended  or
supplemented.

          6.6 Governing Law. This Note shall be governed by the internal laws of
the State of California, without regard to the principles of conflict of laws.

          6.7  Confession  of Judgment.  THE  FOLLOWING  PARAGRAPH  SETS FORTH A
WARRANT OF ATTORNEY TO CONFESS JUDGMENT  AGAINST THE BORROWER.  IN GRANTING THIS
WARRANT OF  ATTORNEY TO CONFESS  JUDGMENT  AGAINST THE  BORROWER,  THE  BORROWER
HEREBY KNOWINGLY,  INTENTIONALLY AND VOLUNTARILY, AND, ON THE ADVICE OF SEPARATE
COUNSEL OR THE BORROWER,  UNCONDITIONALLY WAIVES ANY AND ALL RIGHTS THE BORROWER
HAS OR MAY HAVE TO  PRIOR  NOTICE  AND AN  OPPORTUNITY  FOR  HEARING  UNDER  THE
RESPECTIVE  CONSTITUTIONS  AND LAWS OF THE UNITED STATES AND THE COMMONWEALTH OF
PENNSYLVANIA.

                  As further security for payment hereunder and upon an event of
default, Borrower authorizes and empowers any attorney of any court of record of
Pennsylvania  or  elsewhere  to appear for and CONFESS  JUDGMENT  against it and
immediately  execute  on  such  judgment,   without  notice  of  such  immediate
execution,  for the then  unpaid  principal  amount and  interest  of this Note,
together with late charges,  costs of suit and reasonable  attorneys' fees, with
or without  declaration  or stay of execution,  and with release of errors,  for
which this Note or a copy hereof shall serve as a sufficient warrant. This power
to CONFESS  JUDGMENT  against Borrower shall not be exhausted by any exercise of
the power  and shall  continue  from  time to time and at all times  until  full
payment of all amounts due under this Note.

         IN WITNESS  WHEREOF,  Borrower has caused this Note to be signed in its
name by its duly authorized officer as of the 30th day of April, 1997.

                     EMCON

                     By:  /S/
                          --------------------------------
                     Name:   R. Michael Momboisse
                            ------------------------------
                     Title: CFO & VP Legal
                            ------------------------------

                                       95

                                 
                                 EXHIBIT 10.23

                                LEASE AGREEMENT


         THIS LEASE,  dated this 4th day of April,  1997 for reference  purposes
only, is made and entered into by and between  EMCON,  a California  corporation
("Landlord") and Columbia Analytical  Services,  Inc., a Washington  corporation
("Tenant").

         Landlord and Tenant agree to the terms,  covenants  and  conditions  of
this Lease, as follows:






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<PAGE>

1.  PREMISES.  Landlord  hereby  leases to Tenant and Tenant  hereby leases from
Landlord those certain premises (the "Premises") described on the Lease Summary.
The term  "Buildings"  as used  herein  shall mean the entire  laboratories  and
administrative  buildings  more  particularly  described  in  Exhibit A attached
hereto.  The term "Property" shall mean and include all of the area described in
Exhibit "A" attached hereto and all of the buildings, improvements, fixtures and
equipment now or hereafter situated thereon.

2. USE. 

        2.1 Permitted Uses. Tenant shall use the Premises solely for the purpose
stated on the Lease Summary and for no other purpose.

        2.2 Compliance with Law.  Tenant shall, at Tenant's sole cost,  promptly
comply  with  all  laws,  ordinances,   codes,  rules,  orders,  directives  and
regulations of governmental authority (collectively, "Governmental Regulations")
regulating  the condition,  use or occupancy of the Premises,  including but not
limited  to,  any  alterations,   additions  or   modifications   (collectively,
"Alterations") to the Premises required by Governmental Regulations.

        2.3  Restriction  on Use.  Tenant shall not use or permit the use of the
Premises  in any  manner  that  will  tend to create  waste on the  Premises  or
constitute  a nuisance  to any other  occupant or user of the  Buildings  or the
Property or any property adjacent thereto or do or keep anything that will cause
cancellation of or an increase in rates of any insurance covering the Buildings.
Tenant shall not use any apparatus, machinery or other equipment in or about the
Premises  that may cause  substantial  noise or vibration  or overload  existing
electrical  systems,  and shall not place any loads upon the floors,  walls,  or
ceilings of the Premises which may  jeopardize  the structural  integrity of the
Buildings or any part  thereof.  Tenant shall not make any  penetrations  of the
roof or exterior of the  Buildings or attach any  antennas or equipment  thereon
without the prior written  approval of Landlord  which will not be  unreasonably
withheld.  Any  penetrations  of the roof allowed by Landlord  shall be properly
flashed and caulked and shall be removed  and the roof  membrane  restored  upon
expiration  of the Lease term.  No  materials or articles of any nature shall be
stored  outside  the  Premises,   unless  in  compliance   with  any  applicable
Governmental Regulations.

        2.4 Hazardous Materials

                A. Definitions.  As used herein, the term "Hazardous Material" -
shall mean any substance:  (i) the presence of which requires  investigation  or
remediation under any federal,  state or local statute,  regulation,  ordinance,
order,  action,  policy or common  law;  (ii) which is or  becomes  defined as a
"hazardous  waste,"  "hazardous  substance,"  pollutant or contaminant under any
federal,  state or local  statute,  regulation,  rule or ordinance or amendments
thereto including, without limitation, the Comprehensive Environmental Response,
Compensation  and  Liability  Act (42 U.S.C.  Section  9601 et seq.)  and/or the
Resource  Conservation and Recovery Act (42 U.S.C.  Section 6901 et seq.); (iii)
which  is  toxic,  explosive,  corrosive,  flammable,  infectious,  radioactive,
carcinogenic,  mutagenic,  or otherwise hazardous and is or becomes regulated by
any  governmental   authority,   department,   commission,   board,   agency  or
instrumentality  of the United States,  the State of Washington or any political
subdivision  thereof;  (iv)  the  presence  of which  on the  Premises  poses or
threatens to pose a known material risk to the health or safety of persons on or


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about the Premises; (v) without limitation which contains gasoline,  diesel fuel
or  other  petroleum  hydrocarbons;   (vi)  without  limitation  which  contains
polychlorinated biphenyls (PCBs), asbestos or urea formaldehyde foam insulation;
or (vii) without limitation radon gas.

                B.  Tenant  shall  not use,  analyze,  store,  dispose,  handle,
transport,  release,  discharge or generate any Hazardous  Materials in, on, to,
under,  from or about the Premises or Buildings,  except in accordance  with all
governmental laws, rules and regulations.

                C. Tenant shall not cause or permit any Hazardous Materials used
by Tenant to be discharged into the plumbing or sewage system of the Building or
onto the land underlying the Building or anywhere on the Property. Tenant shall,
at its sole cost,  comply with any and all Governmental  Regulations  respecting
the handling,  use, storage and disposal of Hazardous  Materials used by Tenant.
Tenant shall,  at its sole cost,  make any and all  improvements to the Premises
necessary to assure legal and safe use of Tenant's Hazardous Materials. All such
improvements  shall  be  subject  to  Landlord's  approval  in  accordance  with
Paragraph 10 hereof.  Tenant shall remove all Hazardous Materials used by Tenant
or brought onto the  Premises or the Property by Tenant prior to the  expiration
of the Lease term or sooner termination thereof.

                D. Tenant shall  indemnify,  defend and hold  Landlord  harmless
from and against  any and all claims,  judgments,  liability,  damage,  decrees,
liens, demands,  taxes,  penalties,  fines,  expenses,  costs (including but not
limited to those costs  associated  with  investigation,  removal  and  remedial
activities as may be sought, initiated or required in connection with any local,
state or  federal  governmental  or  private  party  demands  or  claims),  fees
(including without limitation attorneys fees), obligations,  orders, liabilities
or  losses  (including  without  limitation,  diminution  in  the  value  of the
Property,  damages for the loss or restriction on the use,  marketability or any
other amenity of the Property)  (all of the foregoing  collectively  referred to
hereinafter as  "Environmental  Claims"),  which arise during or after the Lease
term as a result of Tenant's use, storage,  disposal,  transportation,  release,
discharge or  generation  of any  Hazardous  Materials at, in, onto or under the
Property,  or any contamination of the Property caused by Tenant.  The foregoing
indemnity ("Tenant's  Environmental  Indemnity") shall survive the expiration or
earlier  termination  of this Lease.  Tenant agrees to defend all  Environmental
Claims on behalf of Landlord with counsel reasonably acceptable to Landlord.

                E.  Without  limiting  the  foregoing,  if there is a release or
discharge  of any  Hazardous  Materials  at, in,  onto or under the  Property or
contamination  of  the  Property  that  is  covered  by  Tenant's  Environmental
Indemnity,  Tenant  shall  promptly  take all  action,  at its sole cost,  as is
necessary to return the  Property to the  condition  required by all  applicable
laws and regulations,  provided that Landlord's  written approval of such action
shall first be obtained and Landlord's  approval of any  remediation  plan shall
not be unreasonably withheld.

                F.  Landlord  shall  have the  right to enter the  Premises  and
Property  and  perform  such  environmental   investigations,   remediation  and
assessments of the Premises as Landlord shall in Landlord's sole discretion deem
advisable.  Landlord  shall provide  Tenant with at least two (2) business days'
notice  prior  to  entering  the  Premises  hereunder,  except  in the  case  of
emergency.  Landlord shall use reasonable efforts to minimize  interference with


                                       98
<PAGE>

Tenant's business,  but shall not be liable for any interference caused thereby.
The  cost  of  any  such  investigation,  remediation  or  assessment  shall  be
reimbursed  by Tenant to Landlord  within thirty (30) days of receipt of written
invoices therefor only if any contamination found has been caused by Tenant.

                  G.  If at  anytime  Tenant  shall  become  aware  of  or  have
reasonable cause to believe that any Hazardous Materials have come to be located
on  or  beneath  the  Premises  or  Property.  Tenant  shall,  immediately  upon
discovering  such presence or suspected  presence of Hazardous  Materials,  give
written  notice  of such  condition  to  Landlord.  In  addition,  Tenant  shall
immediately  notify  Landlord  in  writing  if Tenant  becomes  aware of (1) any
enforcement,   cleanup,   removal  or  other   governmental   regulatory  action
instituted,  completed,  or threatened relating to any Hazardous Materials on or
about the  Property,  (2) any claim made or  threatened  by any  person  against
Tenant,  Landlord  or  the  Property  relating  to  damage,  contribution,  cost
recovery,  compensation,  loss or injury relating from or claimed to result from
any Hazardous  Materials  that have come to be located on or about the Property,
and (3) any reports  made to any local,  state or federal  environmental  agency
arising out of or in  connection  with any  Hazardous  Materials on or about the
Property,   including  any  complaints,   notices,  warnings  or  violations  in
connection therewith.

                H. Any  default  under this  Paragraph  2.4 shall  constitute  a
material default enabling  Landlord to exercise any of the remedies set forth in
this Lease.

3.       TERM

         3.1 Commencement  Date. The Commencement Date of the term of this Lease
shall be as set forth in the Lease Summary.  If the  Commencement  Date is other
than the first day of a calendar month,  the Lease term shall be extended by the
number of days remaining in the month during which the Commencement Date occurs,
and Base Rent for such period shall be a prorated  portion of the same Base Rent
set forth in the Lease Summary for the first calendar month of the Lease term.

         3.2  Proration.  In the event that the Lease term  commences  on a date
other than the first day of a calendar  month,  Tenant  shall pay to Landlord on
the Commencement  Date as rent for the period from the Commencement  Date to the
first day of the next  succeeding  calendar  month that  proportion  of the rent
payable hereunder which the number of days between the Commencement Date and the
first day of the next  succeeding  calendar  month bears to thirty (30).  In the
event that the Lease term for any reason  ends on a date other than the last day
of a calendar  month,  on the first day of the last calendar  month of the Lease
term,  Tenant shall pay to Landlord as rent for the period from the first day of
said last  calendar  month to and including the last day of the term hereof that
proportion of the rent then due  hereunder  which the number of days between the
first day of said last calendar  month and the last day of the term hereof bears
to thirty (30).

4.       RENT

        4.1 Base Rent.  Tenant shall pay monthly base rent ("Base  Rent") in the
amounts set forth on the Lease Summary to Landlord  without  deduction,  offset,
prior notice,  or demand,  in advance on the first day of each calendar month of
the Lease  term and in lawful  money of the  United  States.  Base Rent shall be
abated for months 1 through 24  provided  Tenant is not in default of any of its
obligations under this Lease.


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<PAGE>

        4.2 Additional Rent.

           A.  Tenant  shall pay to Landlord in addition to Base Rent during the
Lease  term  additional  rent  ("Additional  Rent")  equal  to  the  sum  of the
following:

              1.  Tenant's  Share of all Real  Property  Taxes  relating  to the
Property as set forth in Paragraph 11, unless Tenant shall pay the Real Property
taxes directly to the charging authority;

              2.  Tenant's  Share  of all  Operating  Expenses  relating  to the
Buildings  and the  Property as set forth in  Paragraph  7, except to the extent
Tenant maintains and repairs the Buildings as provided herein;

              3. All other charges,  costs and expenses which Tenant is required
to pay hereunder and all damages, costs and expenses which Landlord may incur by
reason of default of Tenant or failure on Tenant's part to comply with the terms
of this Lease, including attorney's fees and court costs; and

           B. In the event of nonpayment by Tenant of Additional Rent,  Landlord
shall have all the rights and remedies with respect  thereto as Landlord has for
nonpayment  of Base Rent.  Tenant's  Share of all expenses to be paid by it with
respect to the  Buildings  and  Tenant's  Share of all expenses to be paid by it
with  respect to the  Property are  separately  set forth in the Lease  Summary.
Except  as  provided  below,  Additional  Rent  due  hereunder  shall be paid to
Landlord  within thirty (30) days of written  notice by Landlord.  At Landlord's
option,  Tenant shall pay to Landlord monthly,  in advance,  on the first day of
each  calendar  month  Tenant's  Share of an amount  estimated by Landlord to be
Landlord's   approximately  monthly  expenditure  for  such  items  included  in
Additional Rent (the "Estimated Monthly  Expense").  Actual expenses incurred by
Landlord shall be reconciled  against the Estimated Monthly Expense by Landlord,
at its  option,  or at the end of each  calendar  quarter  or year.  Within  one
hundred twenty (120) days  following each calendar  quarter or year, as the case
may be,  Landlord  shall  furnish  Tenant a  statement  of the  actual  expenses
incurred  by  Landlord  for such  period.  If  Tenant's  total  payments  of the
Estimated  Monthly  Expense  for such  period are less than the amount of actual
expenses  incurred by Landlord,  Tenant shall pay to Landlord the amount of such
deficiency within thirty (30) days after receipt of such statement.  If Tenant's
total payments of the Estimated  Monthly Expense exceed actual expenses incurred
by Landlord for such period,  Landlord shall apply the excess amount against the
next  payment of Base Rent or  Additional  Rent due  hereunder or any other sums
then due under this Lease, at Landlord's sole discretion.  The Estimated Monthly
Expense may be adjusted by  Landlord  upon thirty (30) days'  written  notice to
Tenant.  The respective  obligations of Landlord and Tenant under this paragraph
shall survive the  expiration or earlier  termination of the term of this Lease,
and if the term hereof shall expire or shall otherwise  terminate on a day other
than the last day of a calendar  year, the actual  Additional  Rent incurred for


                                      100
<PAGE>

the calendar year in which the Lease term expires or otherwise  terminates shall
be  determined  and settled on the basis of the  statement of actual  Additional
Rent for such  calendar year and shall be prorated in the  proportion  which the
number of days in such calendar year  preceding  such  expiration or termination
bears to 365.

           C.  Audit.  Tenant  shall have the  right,  at such time and place as
Landlord may reasonably  designate,  to inspect and audit  Landlord's  books and
records related to the operation and maintenance of the Building for the purpose
of verifying  Landlord's  adjusted  year-end  statement  of  Operating  Expenses
payable by Tenant.  Tenant may employ an independent  public  accounting firm to
conduct  the audit.  The costs of the audit  shall be paid by Tenant  unless the
audit shows that Landlord's adjusted statement  over-charged Tenant its share of
Operating costs by more than ten percent (10%), in which case Landlord shall pay
all Tenant's costs of the audit.

        4.3 Late  Charge and  Interest.  Tenant  hereby  acknowledges  that late
payment by Tenant to  Landlord of Base Rent,  Additional  Rent or other sums due
hereunder  (collectively,  "Rent")  will  cause  Landlord  to  incur  costs  not
contemplated  by this  Lease,  the  exact  amount  of  which  will be  extremely
difficult to ascertain.  Such costs include,  but are not limited to, processing
and accounting charges, and late charges which may be imposed on Landlord by the
terms of any  mortgage  or deed of trust  covering  the  Building  or  Property.
Accordingly, if any installment of Rent due from Tenant shall not be received by
Landlord  within (10) days after such amount shall be due, then Tenant shall pay
to Landlord a late charge equal to five percent (5%) of such overdue amount. The
parties  hereby  agree that such late charge  represents  a fair and  reasonable
estimate of the costs  Landlord  will incur by reason of late payment by Tenant.
Acceptance of such late charge by Landlord shall in no event constitute a waiver
of Tenant's  default with respect to such overdue amount,  nor prevent  Landlord
from exercising any of the other rights and remedies granted  hereunder.  In the
event any Rent due hereunder remains delinquent for a period in excess of thirty
(30) days,  Tenant  shall pay to  Landlord,  in  addition  to the late  payment,
interest from and after said date at the rate of twelve  percent (12%) per annum
(the  "Interest  Rate") until paid in full.  Payment of such interest  shall not
excuse or cure any default by Tenant.

        4.4 Place of Payment.  All payments of Rent shall be paid to Landlord at
its  office as shown on the Lease  Summary  or to such  other  person or to such
other place as Landlord may from time to time designate in writing.

        4.5  Security  Deposit.  Tenant shall not be required to post a security
deposit.

5. PARKING.  Tenant shall have the right to use all available parking spaces for
the Property in accordance with the local zoning rules.

6.  MAINTENANCE  AND  REPAIRS 

        6.1 General.  Except as otherwise  specifically  provided herein, Tenant
shall, at Tenant's sole cost, keep in good and safe condition, order and repair,
and  replace  when  necessary,  all  non-structural  portions  of the  Building,
including  all areas of the Building and exterior  portions  thereof and outside
areas,   including  without  limitation,   (1)  all  plumbing,   automatic  fire
extinguishing  and  sewage  systems,  including  water and drain  lines,  sinks,
toilets,  faucets,  drains,  showers and water  fountains,  (2) all parts of the
heating,  ventilation and air  conditioning  system ("HVAC System")  serving the
Buildings,  including all ducts, pipes, vents,  compressors,  Building fans, air
handlers,  thermostats,  time clocks,  boilers,  heaters,  and supply and return
grills serving the Building,  (3) all electrical  and lighting  facilities,  and
other  operating  systems,  appliances,  and  equipment  serving  the  Building,
including all wiring, panels, conduit, outlets, lighting fixtures, lamps, bulbs,
tubes  and  ballasts,  (4) the  elevator  and all  components  thereof,  (5) all
fixtures, interior walls, interior and exterior surfaces of exterior walls, wall


                                      101
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coverings,  window coverings,  carpets,  floors, floor coverings,  partitioning,
ceilings  and  ceiling  tiles,  (6)  all  windows  (including  glazing),  doors,
entrances,  truck  doors,  glass,  plate  glass  and  skylights  located  in the
Building, and (7) all landscaping and parking areas, including routine cleaning,
maintenance, patching, resealing, repairing and restripping.

        Tenant shall  maintain the HVAC system in accordance  with EPA and State
of Washington  DOE mandated  requirements.  Tenant shall have the benefit of all
warranties available to Landlord regarding the equipment in the HVAC System, the
roof  membrane and other  equipment or items in the Building  which are Tenant's
obligation  to  maintain.  All  repairs and  maintenance  required to be made by
Tenant  hereunder  shall be made  promptly  by a  licensed  contractor  with new
materials   of  like  kind  and   quality.   If  the  repair  work  affects  the
non-structural  parts  of the  Building  and the  estimated  cost of any item of
repair  exceeds  $25,000,  then Tenant  shall first  obtain  Landlord's  written
approval  of the scope of work,  plans  therefor,  materials  to be used and the
contractor.  Landlord's  approval  thereof shall not be  unreasonably  withheld.
Tenant  hereby  waives the benefit of any statute now or  hereinafter  in effect
which would  otherwise  afford  Tenant the right to make  repairs at  Landlord's
expense or to terminate  this Lease  because of  Landlord's  failure to keep the
Premises in good condition, order and repair. Upon expiration of the Lease Term,
Tenant  shall  deliver  the HVAC System in good  working  order,  condition  and
repair.

        6.2 Certain Capital  Expenditures  by Landord.  Landlord shall maintain,
repair and  replace  if, and when  necessary,  all  structural  portions  of the
Building,  including the roof  structure,  roof  membrane,  foundation and floor
slabs;  and shall be  responsible  for repaving the parking  areas,  if and when
necessary,  with the costs of any such  structural  repairs and  replacements or
repaving  to be divided  over 120 months and Tenant will  reimburse  Landlord by
making  supplemental  monthly payments equal to 1/120th of such costs each month
for the remaining duration of the Lease and; such monthly supplemental  payments
to be  considered  additional  Operating  Expenses  for  which  Tenant  shall be
responsible in accordance with Section 4.2.

7.       OPERATING EXPENSES

        7.1 Tenant's Obligation to Reimburse. Tenant shall pay Tenant's Share of
all Operating  Expenses (as  hereinafter  defined) as may be paid or incurred by
Landlord  during the term of this Lease as Additional  Rent in  accordance  with
Paragraph 4.2 hereof.  The term  "Operating  Expenses" shall mean the sum of the
following:

           A. All costs or expenses  paid or incurred  by  Landlord,  if any, in
maintaining,  operating and repairing the Buildings,  excluding only those items
required to be maintained by Tenant at its sole cost, pursuant to Paragraph 6.


                                      102
<PAGE>



           B. The cost of  insurance  carried by  Landlord  in  accordance  with
Paragraphs  12.4 and 12.5 hereof and fairly  allocable to the Building,  and any
insurance deductible payable under such policies.

           C. The cost of all utilities furnished to the Premises if not paid by
Tenant directly.

           D. The additional monthly amounts, if any, payable by Tenant pursuant
to Paragraph 6.2 above.

        7.2 Tenant's Negligence.  Notwithstanding  anything in Paragraphs 7.1 to
the  contrary,  and  subject  to the waiver of  subrogation  rights set forth in
Paragraph  12.7,  Tenant shall pay for the entire  uninsured cost of maintaining
and repairing  the  Buildings  and the exterior  areas thereof and any insurance
deductible if such cost or deductible is incurred as a result of the  negligence
or willful misconduct of Tenant, its agents, customers,  employees,  contractors
or invitees.

8. ACCEPTANCE AND SURRENDER OF PREMISES.  Except as otherwise expressly provided
herein,  by entry  hereunder,  Tenant  accepts the Premises as being in good and
sanitary order,  condition and repair and accepts the Buildings and improvements
included in the Premises in their present  condition and without  representation
or warranty by Landlord as to the condition of the Buildings or as to the use or
occupancy which may be made thereof.  Except as otherwise expressly provided for
herein,  Landlord shall not be responsible  for any tenant  improvements  to the
Premises of any kind or nature whatsoever.  Tenant agrees on the last day of the
Lease  term,  or on the sooner  termination  of this  Lease,  to  surrender  the
Premises  promptly to Landlord in good condition and repair  (damages by acts of
God, fire, normal wear and tear excepted),  with all interior walls painted,  or
cleaned  so that  they  appear  freshly  painted,  and all  holes  in the  walls
repaired,  patched and  repainted,  all floors  cleaned  and waxed,  all carpets
cleaned and  shampooed  and  replaced to the extent of  excessive  wear  through
failure to use carpet shields,  all broken,  damaged,  stained or  nonconforming
ceiling  tiles  replaced.  The HVAC  System and roof  membrane  shall be in good
condition and repair. Landlord shall have the right, at its expense, to retain a
qualified and licensed roof and HVAC contractor to perform an inspection thereof
and do an inventory of all components  thereof which need repair or replacement.
Tenant shall perform all such repair and  replacement  reasonably  designated by
such contractor.  All plumbing,  electrical and lighting systems,  both interior
and  exterior  shall be in good repair and  condition.  Tenant  shall remove all
monument and other signs and repair any damage caused thereby.  The term "normal
wear and  tear"  shall be deemed  to  exclude  items of  neglected  or  deferred
maintenance.  All alterations,  additions,  and improvements which may have been
made in,  to,  or on the  Premises  by Tenant  (except  movable  trade  fixtures
installed at the expense of Tenant) shall be  surrendered  in good condition and
repair, except that Tenant shall ascertain from Landlord within thirty (30) days
before the end of the Lease term whether  Landlord  desires to have the Premises
or any part or parts  thereof  restored  to their  condition  and  configuration
existing when the Premises were  delivered to Tenant,  and if Landlord  shall so
desire, then Tenant shall restore said Premises or such part or parts thereof to
their condition  existing before the Lease term, at Tenant's sole cost,  except,
however,  that  Tenant's  obligation  to restore if elected by Landlord does not
include the removal of the Tenant  Improvements  outlined in Paragraph 40. On or


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before the end of the Lease term or sooner  termination  of this  Lease,  Tenant
shall  remove all of Tenant's  personal  property  and trade  fixtures  from the
Premises,  and all property not so removed  shall be deemed  abandoned by Tenant
and title to same shall  thereupon  pass to  Landlord  without  compensation  to
Tenant.  Upon  termination  of this  Lease,  Landlord  may remove  all  moveable
furniture  and  equipment  so abandoned by Tenant,  at Tenant's  sole cost,  and
repair any damage caused by such removal.

9.       ALTERATIONS.

        9.1  Landlord's   Consent.   Tenant  shall  not  make  any  alterations,
improvements,   additions,   or   utility   installations   (collectively,   the
"Alterations")  in, on or about the Premises  without  Landlord's  prior written
consent, which shall not be unreasonably withheld, except for any non-structural
alterations  to the  interior of the  Premises  which do not exceed  twenty-five
thousand  dollars  ($25,000)  in cost  per  project.  As used  herein,  the term
"utility  installation" means power panels, wiring,  florescent fixtures,  space
heaters, conduits, air conditioning and plumbing.

        9.2 Plans and Permits.  Any alteration that Tenant desires to make in or
about the Premises and which requires the consent of Landlord shall be presented
to Landlord in written form for  Landlord's  approval,  with  proposed  detailed
plans and  specifications  therefor,  including  an  original  sepia at 1/8 inch
scale,  prepared at Tenant's sole cost. Any consent by Landlord thereto shall be
deemed  conditioned  upon Tenant's  acquisition of all permits  required to make
such Alterations from all appropriate  governmental  agencies, the furnishing of
copies thereof to Landlord prior to commencement of the work, and the compliance
by Tenant  with all  conditions  of said  permits  in a prompt  and  expeditious
manner, all at Tenant's sole cost. Landlord shall be deemed to have consented to
any alteration,  improvement  addition or utility installation if Landlord fails
to respond  within ten (10) business  days of receipt of the plans,  permits and
documents  referenced  herein and written request for Landlord's  consent.  Upon
completion  of any such  Alterations,  Tenant  shall,  at  Tenant's  sole  cost,
immediately deliver to Landlord "as-built" plans and specifications therefor. No
later than January 10th each year during the Lease term, Tenant shall deliver to
Landlord bluelines and mylar plan updates showing the configuration of the floor
plan in the Building.

        9.3 Construction  Work Done by Tenant.  Except as hereinafter  provided,
all  construction  work  required  or  permitted  to be done by Tenant  shall be
performed  by a  licensed  contractor  approved  by  Landlord  and in a  prompt,
diligent,  and good and  workmanlike  manner.  In lieu of the foregoing,  Tenant
shall have the right to use its own work crews. All such construction work shall
conform in quality and design with the Premises  existing as of the Commencement
Date and shall not diminish the value of the Buildings or the Property. All such
construction   work  shall  be  performed  in  compliance  with  all  applicable
Governmental Regulations.

        9.4 Roof Repairs.  Any  installation of air  conditioning  equipment and
duct  work  or  antennas  on  the  roof  permitted  by  Landlord  and  requiring
penetration  of the roof shall be properly  flashed and caulked.  Any  equipment
placed by Tenant on the roof shall be elevated and supported by Tenant so as not
to create vibration or inhibit drainage or repair and maintenance of the roof.

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        9.5 Title to Alterations.  Unless Landlord  requires the removal thereof
as set  forth in this  Paragraph  9, any  Alterations  which  may be made on the
Premises by Tenant shall,  upon expiration or termination of this Lease,  become
the  property of Landlord  and shall  remain  upon and be  surrendered  with the
Premises at the expiration or sooner termination of this Lease. Without limiting
the generality of the foregoing,  all heating,  lighting,  electrical (including
all  wiring,  conduits,  main  and  subpanels),   air  conditioning,   plumbing,
partitioning (except movable partitions), drapery, and carpet installations made
by Tenant,  regardless of how affixed to the  Premises,  together with all other
alterations  that have become an  integral  part of the  Premises,  shall be and
become the property of Landlord upon expiration or termination of this Lease and
shall not be deemed trade  fixtures,  and shall  remain upon and be  surrendered
with the  Premises  at the  expiration  or  sooner  termination  of this  Lease.
Tenant's furnishings,  machinery and equipment,  except that which is affixed to
the  Premises  so that it  cannot  be  removed  without  material  damage to the
Premises,  shall remain the property of Tenant and may be removed by Tenant, and
Tenant shall, at Tenant's sole cost, immediately after removal repair any damage
to the  Premises  caused  thereby.  Tenant shall be solely  responsible  for the
maintenance  and  repair  of any  and all  Alterations  made  by  Tenant  to the
Premises.

        9.6  Notice.   Tenant  shall  give  Landlord   notice  of  the  date  of
commencement  of any work in the  Premises  not less  than ten (10)  days  prior
thereto, and Landlord shall have the right to post notices of non-responsibility
or similar notices in or on the Premises in connection therewith.

10.  UTILITIES  AND  SERVICES.  Tenant  shall pay all  charges  for water,  gas,
electricity,  telephone,  refuse  pickup,  janitorial  services,  and all  other
utilities  and services  supplied or furnished to the Buildings and the Property
during the term of this Lease, together with any taxes thereon,  directly to the
charging  authority.  In no event  shall  Landlord  be liable to Tenant  for any
failure or  interruption  in utility or  service  unless  caused by the  willful
misconduct  of Landlord.  No failure or  interruption  of any such  utilities or
services  shall  entitle  Tenant to terminate  this Lease or to withhold rent or
other  sums due  hereunder.  Landlord  shall not be  responsible  for  providing
security guards or other security  protection for any portion of the Premises or
the  Property,  and  Tenant  shall at its own  expense  provide  or obtain  such
security  services as Tenant  shall  desire to ensure the safety of the Premises
and the Property.

11.      TAXES.

        11.1 Real  Property  Taxes.  Tenant  shall pay  directly to the charging
authority  Tenant's  Share of all Real Property Taxes (as  hereinafter  defined)
which  become due during the Lease  term.  If  Landlord is required to make such
payments  because  Tenant fails to do so, such  payments  shall be reimbursed by
Tenant to Landlord  promptly on demand,  as Additional  Rent in accordance  with
Paragraph 4.2 hereof.  The term "Real Property  Taxes" as used herein shall mean
(1) all  taxes,  assessments,  levies,  and other  charges of any kind or nature
whatsoever,   general  and  special,  foreseen  and  unforeseen  (including  all
installments  of principal  and interest  required to pay any general or special
assessments   for  public   improvements   and  any  increases   resulting  from
reassessments  caused  by  any  change  in  ownership  of the  Property)  now or
hereafter imposed by any governmental or quasi-governmental authority or special


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or community  facilities  district having the direct or indirect power to tax or
levy assessments,  which are levied or assessed against,  or with respect to (a)
the value,  occupancy,  ownership  or use of, all or any portion of the Property
(as now constructed or as may at any time hereafter be constructed,  altered, or
otherwise changed) or Landlord's interest therein;  (b) any improvements located
on the Property (regardless of ownership); (c) the fixtures, equipment and other
property  of  Landlord,  real or  personal,  that  are an  integral  part of the
Property;  (d) the gross receipts,  income and rentals from the Property, or (e)
the use of public utilities or energy in the Buildings;  (2) all charges, levies
or fees in the nature of a tax or assessment  imposed by reason of environmental
regulation  or  other  governmental   control  of  the  Property;   (3)  excise,
transaction,  sales,  privilege  or other taxes now or  hereafter  imposed  upon
Landlord  as a result  of this  Lease;  and (4) all  costs  and fees  (including
attorneys'  fees) incurred by Landlord in contesting any Real Property Taxes and
in negotiating  with public  authorities as to any Real Property Taxes, but only
to the extent of savings realized by Tenant as a result thereof.  If at any time
during the Lease term the taxation or assessment  of the Property  prevailing as
of the  Commencement  Date shall be altered so that in lieu of or in addition to
any Real  Property  Taxes  described  above there  shall be levied,  assessed or
imposed  (whether by reason of a change in the method of taxation or assessment,
creation of a new tax or charge, or any other cause) an alternate, substitute or
additional  tax or charge (a) on the value,  use or occupancy of the Property or
Landlord's interest therein; (b) on or measured by the gross receipts, income or
rentals from the Property;  (c) on Landlord's  business of leasing the Property;
or (d)  computed in any manner with respect to the  operation  of the  Property,
then any such tax or charge,  however  designated,  shall be included within the
meaning of the term "Real Property Taxes".  Notwithstanding  the foregoing,  the
term "Real  Property  Taxes"  shall not  include  estate,  inheritance,  gift or
franchise  taxes of  Landlord  or the federal or state net income tax imposed on
Landlord's income from all sources.

        11.2 Taxes on Tenant's Property.

           A. Tenant shall pay at least ten (10) days prior to  delinquency  all
taxes, license fees and public charges assessed or levied against all equipment,
personal  property or trade fixtures  placed by Tenant in or about the Premises.
If any such taxes,  fees or charges are levied against  Landlord or the Property
or if the assessed  value of the Premises is increased by the inclusion  therein
of the value placed upon such equipment,  personal property or trade fixtures of
Tenant and if Landlord pays the taxes,  fees or charges based on such  increased
assessment, which Landlord shall have the right to do regardless of the validity
thereof,  Tenant shall upon demand, repay to Landlord the taxes, fees or charges
so levied  against  Landlord,  or the portion of such taxes  resulting from such
increase in the assessment.

           B. If  Tenant's  improvements  in the  Premises,  whether  installed,
and/or  paid for by  Landlord  or Tenant and  whether or not affixed to the real
property so as to become a part  thereof,  are  assessed  for real  property tax
purposes  at a valuation  higher than the  valuation  at which  standard  office
improvements in other space in the Property are assessed, then the real property
taxes and assessments  levied against Landlord or the Property by reason of such
excess assessed  valuation  shall be deemed to be taxes levied against  personal
property of Tenant and shall be governed by the  provisions of Paragraph  11.2A.
If the records of the County Assessor are available and sufficiently detailed to
serve as a basis for determining whether said Tenant's improvements are assessed
at a higher  valuation than standard  office  improvements in other space on the
Property,  such records  shall be binding on both  Landlord  and Tenant.  If the
records of the County  Assessor are not  available or  sufficiently  detailed to
serve as a basis for making such determination,  the actual cost of construction
shall be used.


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12.      INSURANCE.

        12.1 Tenant's Liability Insurance.  Tenant shall, at Tenant's sole cost,
keep in force  during the Lease term a policy of  commercial  general  liability
insurance  covering  property damage and liability for personal injury occurring
in, on or about the Premises, the Buildings and the Property, with limits in the
amount of at least $2,000,000 per occurrence for injuries to or death of persons
and  $1,000,000  per  occurrence  for property  damage,  and with a  contractual
liability  endorsement  insuring Tenant's  performance of Tenant's obligation to
indemnify Landlord contained in Paragraph 13.

        12.2 Tenant's Casualty  Insurance.  Tenant shall, at Tenant's sole cost,
maintain  during the Lease term a policy or policies of fire and property damage
insurance in "all risk" form,  with a sprinkler  leakage and flood  endorsement,
insuring the personal property, inventory; and trade fixtures, within the leased
Premises for the full  replacement  cost thereof.  The proceeds form any of such
policies shall be used for the repair or replacement of such items so insured.

         12.3 Form and  Certificates.  Each policy of  insurance  required to be
carried by Tenant  pursuant to Paragraphs  12.1 and 12.2 shall be with a company
approved by Landlord and shall name  Landlord and such other parties in interest
as Landlord  reasonably  designates as additional  insured.  Tenant's  insurance
policy shall also be primary  insurance,  without right of contribution from any
policy carried by Landlord, and shall contain a cross-liability and severability
endorsement.  A certificate of insurance  shall be provided to Landlord prior to
the Commencement Date which indicates that the coverage required hereunder is in
effect and which  provides  that such  policy is not  subject  to  cancellation,
expiration  or change,  except upon thirty  (30) days' prior  written  notice to
Landlord.

        12.4 Landlord's Liability Insurance. Landlord shall maintain a policy or
policies of commercial  general liability  insurance insuring Landlord (and such
other entities as may be designated by Landlord)  against liability for personal
injury,  bodily  injury or death and damage to property  occurring  or resulting
from an occurrence  in, on, or about the Property with such coverage as Landlord
may from time to time determine is reasonably necessary for its protection.

        12.5 Property Insurance.  Landlord shall obtain and keep in force during
the term of this Lease a policy or  policies  of  insurance  for the  benefit of
Landlord covering loss or damage to the Buildings,  and the Property  (excluding
coverage of  merchandise,  fixtures,  equipment  and leasehold  improvements  of
Tenant)  in  the  amount  of  the  full  replacement  value  thereof,  providing
protection  against  all  perils  included  within the  classification  of fire,
extended coverage,  vandalism,  malicious mischief, special extended perils (all
risk),  including  earthquake,  flood,  sprinkler leakage,  boiler and machinery
coverage and an inflation  endorsement.  In addition,  Landlord shall obtain and
keep in force,  during the term of this Lease, a policy of rental loss insurance
covering a period of one year,  commencing  on the date of loss,  with  proceeds
payable to Landlord,  which  insurance shall also cover all Real Property Taxes,
Operating Expenses,  and other sums payable by Tenant hereunder for said period.


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All proceeds under such policies of insurance shall be payable to Landlord,  and
Tenant  shall have no interest  in or right to such  proceeds.  Tenant  shall be
responsible  for paying  any  deductible  under the  property  insurance  policy
carried by Landlord  hereunder,  not to exceed Fifty Thousand Dollars  ($50,000)
per occurrence.

        12.6  Payment.  Tenant  shall pay to  Landlord  during  the term  hereof
Tenant's  Share of the premiums and  deductibles  for any insurance  obtained by
Landlord pursuant to Paragraphs 12.4 and 12.5; provided,  however, that Tenant's
responsibility  to pay  Landord for the  premium  cost of rental loss  insurance
shall not  exceed  $500 per year and the  deductible  cost  shall not exceed Ten
Thousand  Dollars  ($10,000)  per  occurrence.  Landlord  may  obtain  liability
insurance  for the Building  separately,  or together  with other  buildings and
improvements  under blanket policies of insurance.  In such case Tenant shall be
liable for only such portion of the  premiums  for such blanket  policies as are
allocable to the Premises, as reasonably determined by the insurer or Landlord.

        12.7 Waiver of  Subrogation.  Tenant and Landlord each hereby waives any
and all  rights of  recovery  against  the  other,  and  against  the  officers,
employees, agents and representatives of the other, for loss of or damage to the
property of the waiving  party or the property of others  under its control,  to
the  extent  such loss or damage  is  covered  by  proceeds  received  under any
insurance  policy carried by Landlord or Tenant and in force at the time of such
loss or damage.  Tenant and  Landlord  shall,  upon  obtaining  the  policies of
insurance required  hereunder,  give notice to the insurance carrier or carriers
that the foregoing mutual waiver of subrogation is contained in this Lease.

        12.8 No Limitation of Liability.  Landlord makes no representation  that
the limits of liability  insurance specified to be carried by Tenant or Landlord
under the terms of this  Lease are  adequate  to protect  any  party.  If Tenant
believes that the insurance  coverage  required under this Lease is insufficient
to adequately  protect Tenant,  Tenant shall provide,  at its own expense,  such
additional insurance as Tenant deems adequate.

13.  WAIVER  AND  INDEMNIFICATION.  Landlord  shall not be liable to Tenant  and
Tenant hereby waives all claims  against  Landlord for any injury to or death of
any person or damage to or destruction of property in or about the Premises, the
Buildings or the  Property or to Tenant's  business  from any cause  whatsoever,
including without limitation,  from theft, gas, fire, steam, oil, electricity or
leakage of any character from the roof, walls,  basement or other portion of the
Premises, the Buildings or the Property, from rain, or defects in or breakage of
pipes,  sprinklers,  plumbing,  HVAC or other sources,  excluding,  however, the
active gross negligence or willful misconduct of Landlord, its agents, servants,
employees,  invitees,  or contractors.  Tenant shall indemnify,  defend and hold
harmless Landlord, its agents,  lenders,  partners and officers from and against
any and all claims,  judgments,  damage,  demands,  losses,  expenses,  costs or
liability  arising in connection with injury to person or property from Tenant's
use of the  Premises,  or from the  conduct  of  Tenant's  business  or from any
activity,  work or things done,  permitted or suffered by Tenant in or about the
Premises  or the  Property  by Tenant or by any of  Tenant's  agents,  servants,
employees,  invitees or contractors,  or from any breach or default by Tenant in
the  performance of any  obligation on the part of Tenant to be performed  under
the  terms  of  this  Lease  (all  of the  foregoing  collectively  referred  to


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hereinafter  as "General  Indemnity  Claims"),  excluding,  however,  the active
negligence and willful misconduct of Landlord, its agents, servants,  employees,
invitees,  or contractors.  Tenant agrees to defend all General Indemnity Claims
on behalf of Landlord,  with counsel acceptable to Landlord.  The obligations of
Tenant  contained in this  Paragraph  shall survive the  expiration of the Lease
term, or sooner termination thereof.

14.  LIENS.  Tenant shall keep the Premises and the Property free from any liens
arising out of any work performed, materials furnished or obligation incurred by
Tenant.  In the event  that  Tenant  shall not,  within ten (10) days  following
notice of the  imposition  of any such lien,  cause the same to be  released  of
record,  Landlord shall have, in addition to all other remedies  provided herein
and by law, the right,  but no  obligation,  to cause the same to be released by
such means as Landlord shall deem proper,  including payment of the claim giving
rise to such lien. All sums paid by Landlord for such purpose,  and all expenses
incurred by it in connection  therewith,  shall be payable to Landlord by Tenant
on demand with interest at the Interest Rate.

15.  ASSIGNMENT AND SUBLETTING.

         15.1 Consent Required. Except as hereinafter provided, Tenant shall not
assign,  transfer,  encumber, grant any concession or license or hypothecate the
leasehold estate under this Lease, or any interest therein, and shall not sublet
the  Premises,  or any  part  thereof,  or any  right or  privilege  appurtenant
thereto, or suffer any other person or entity to occupy or use the Premises,  or
any  portion  thereof  without,  in each  case,  the prior  written  consent  of
Landlord.   Collectively,   all  of  the  foregoing   prohibited  actions  shall
hereinafter  be  referred  to  as a  "Transfer"  of  the  Lease.  The  following
conditions or standards shall be satisfied as a condition to Landlord's  consent
to a proposed  Transfer:  (1) The proposed  transferee shall expressly assume in
writing  (or in the  case  of a  sublessee  agree  to be  bound  by)  all of the
provisions,  covenants  and  conditions of the Lease on the part of Tenant to be
kept and performed;  (2) the proposed  transferee shall satisfy  Landlord's then
current  credit  standards and in Landlord's  reasonable  opinion shall have the
financial  strength and  stability to perform all of the  obligations  of Tenant
under this Lease as and when due;  (3) the  proposed  use of the Premises by the
proposed  transferee shall be lawful and be consistent with the permitted use of
the Premises under this Lease and shall not violate any restriction in any other
lease with tenants  occupying  other portions of the Property;  (4) Tenant shall
pay  Landlord's   actual   attorneys'  fees  incurred  in  connection  with  the
negotiation,  review and processing of all proposed Transfer  documents;  (5) at
the time of the proposed  Transfer,  Tenant  shall not be in default  under this
Lease; (6) the proposed  transferee shall not be a governmental entity and shall
not hold any exemption from the payment of ad valorem or after taxes which would
prohibit  Landlord from  collecting  from the transferee  any amounts  otherwise
payable under this Lease;  and (7) except for  Transfers to affiliated  entities
permitted by  Paragraph  15.6 hereof,  the  proposed  Transfer  shall be at fair
market rent.

         15.2  Documentation.  In  connection  with any  Transfer  which  Tenant
desires to make,  Tenant  shall  provide to Landlord the name and address of the
proposed  transferee,  and true and complete copies of all documents relating to
Tenant's prospective agreement to Transfer,  and audited financial statements of
the  proposed  transfer  for the past two (2)  years,  or such  other  financial
information as is reasonably  acceptable to Landlord.  Tenant shall also specify
in writing on an itemized basis all  consideration  to be received by Tenant for
such  Transfer  in the  form of lump sum  payments,  installments  of  rent,  or
otherwise.  For purposes of this  Paragraph 15, the term  "consideration"  shall
include,  without  limitation,  all monies or other  consideration  of any kind,

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including but not limited to, bonus money, and payments (in excess of book value
thereof)  for  Tenant's  assets,  fixtures,  inventory,   accounts,  good  will,
equipment, furniture, general intangibles, and any capital stock or other equity
ownership  of  Tenant.  Within  thirty  (30)  days  after  the  receipt  of such
documentation  and other  information,  Landlord  shall notify Tenant in writing
that Landlord  elects to terminate  this Lease as to the portion of the Premises
to be  Transferred  or if  Landlord  does not elect any such  termination,  then
Landlord shall either (1) consent in writing to the proposed  Transfer,  subject
to the terms and  conditions  hereinafter  set forth,  or (2)  notify  Tenant in
writing that Landlord refuses such consent and stating the reasons therefor.

         15.3  Additional  Terms and  Conditions.  As a condition to  Landlord's
granting  its  consent to any  Transfer,  except as to any  Permitted  Transfer,
Landlord may require that Tenant pay to Landlord, as and when received by Tenant
seventy-five  percent  (75%) of any excess of  consideration  to be  received by
Tenant in  connection  with said Transfer over and above the rental amount fixed
by this Lease and payable by Tenant to  Landlord,  provided  that  Tenant  shall
first be entitled to deduct Leasing  commissions and advertising  costs incurred
in obtaining the subtenant or assignee and any unamortized  Tenant  Improvements
paid by Tenant in connection with such Transfer. Each Transfer to which Landlord
has  consented  shall  be an  instrument  in  writing  in form  satisfactory  to
Landlord,  and shall be executed by both Tenant and the transferee,  as the case
may be.  Each  such  Transfer  agreement  shall  recite  that it is and shall be
subject and  subordinate  to the  provisions of this Lease,  that the transferee
accepts  such  Transfer and agrees to perform all of the  obligations  of Tenant
thereunder,  and that the  termination of this Lease shall,  at Landlord's  sole
election, constitute a termination of such Transfer. In the event Landlord shall
consent to a Transfer,  Tenant shall nonetheless remain primarily liable for all
obligations  and  liabilities  of Tenant  under this  Lease,  including  but not
limited  to  the  payment  of  Rent.  Each  proposed  Transfer   agreement  that
constitutes a sublease,  license or concession  shall provide that Landlord,  at
its option,  may require the sublessee,  licensee or  concessionaire  to pay all
rent due under such sublease, license or concession directly to Landlord instead
of  Tenant  to the  extent  Tenant  is in  default  of  payment  of any Rent due
hereunder.

         15.4 Partnership. If Tenant is a partnership, a transfer,  voluntary or
involuntary,  of all or any  part  of an  interest  in the  partnership,  or the
dissolution of the partnership,  shall be deemed a Transfer requiring Landlord's
prior written consent.

        15.5  Corporation.  If Tenant is a corporation  any dissolution or other
reorganization of Tenant
shall constitute a Transfer.

         15.6  Permitted  Transfers.   Tenant  shall  be  entitled  to  Transfer
("Permitted  Transfer")  this Lease to any parent or subsidiary  corporation  or
upon merger, sale of stock or consolidation without the prior written consent of
Landlord.  No  permitted  Transfer  shall  relieve  Tenant  of  any  obligations
hereunder.

         15.7  Landlord's  Remedies.  Subject to  Paragraph  15.6,  any Transfer
without  Landlord's prior written consent shall at Landlord's  election be void,
and shall  constitute a default under this Lease. The consent by Landlord to any
Transfer  shall not  constitute a waiver of the provisions of this Paragraph 15,
including the requirement of Landlord's prior written  consent,  with respect to

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any  subsequent  Transfer.  If Tenant  shall  purport to assign this  Lease,  or
sublease  all or any  portion of the  Premises,  or permit any person or persons
other than  Tenant to occupy the  Premises,  without  Landlord's  prior  written
consent, Landlord may collect rent from the person or persons then or thereafter
occupying  the Premises and apply the net amount  collected to the Rent reserved
herein, but no such collection shall be deemed a waiver of Landlord's rights and
remedies  under  this  Paragraph  15, or the  acceptance  of any such  purported
assignee,  sublessee  or  occupant,  or a  release  of Tenant  from the  further
performance by Tenant of covenants on the part of Tenant herein contained.

16.      DEFAULT BY TENANT.

        16.1  Event  of  Default.  The  occurrence  of any  one or  more  of the
following  events (an "Event of Default") shall  constitute a default and breach
of this Lease by Tenant:

           A. The  failure  by Tenant to make any  payment  of Rent or any other
payment  required  to be made by Tenant  hereunder,  as and when  due,  and such
failure  shall not have been cured  within ten (10) days  after  written  notice
thereof from Landlord;

           B. Tenant's failure to perform any other term,  covenant or condition
contained in this Lease and such failure  shall have  continued  for thirty (30)
days after  written  notice of such failure is given to Tenant;  provided  that,
where such  failure  cannot  reasonably  be cured  within  said  thirty (30) day
period, Tenant shall not be in default if Tenant commences such cure within said
thirty (30) day period and thereafter diligently continues completion thereof;

           C. Tenant's failure to continuously and  uninterruptedly  conduct its
business in the Premises for a period of more than ninety (90) consecutive days,
or  Tenant's  removal of all or  substantially  all of its  equipment  and other
possessions from the Premises,  without  providing  security  protection for the
Premises reasonably satisfactory to Landlord;

           D.  Tenant's  assignment  of  its  assets  for  the  benefit  of  its
creditors;

           E.  The  sequestration  of,  attachment  of,  or  execution  on,  any
substantial  part of the property of Tenant or on any property  essential to the
conduct of Tenant's  business on the  Premises,  and Tenant shall have failed to
obtain a return or release on such property within thirty (30) days  thereafter,
or  prior to sale  pursuant  to such  sequestration,  attachment  or  execution,
whichever is earlier;

           F.  An  entry  of any of  the  following  orders  by a  court  having
jurisdiction,  and such order shall have  continued  for a period of thirty (30)
days:  (1) an order for relief in any  proceeding  under  Title 11 of the United
States Code, or an order adjudicating Tenant to be bankrupt or insolvent; (2) an
order  appointing  a  receiver,  trustee or  assignee  of  Tenant's  property in
bankruptcy or any other proceeding;  or (3) an order directing the winding up or
liquidation of Tenant; or



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           G. The filing of a petition to commence against Tenant an involuntary
proceeding  under Title 11 of the United  States Code,  and Tenant shall fail to
cause such petition to be dismissed within thirty (30) days thereafter.

        16.2  Remedies.  Upon any  Event of  Default,  Landlord  shall  have the
following remedies, in addition to all other rights and remedies provided by law
or equity:

           A.  Landlord  shall be  entitled to keep this Lease in full force and
effect for so long as Landlord does not terminate  Tenant's  right to possession
(whether or not Tenant  shall have  abandoned  the  Premises)  and  Landlord may
enforce all of its rights and remedies under this Lease,  including the right to
recover Rent and other sums as they become due under this Lease; or

           B. Landlord may terminate the Tenant's  right to possession by giving
Tenant written notice of termination. Any termination under this paragraph shall
not release Tenant from the payment of any sum or performance  then due Landlord
or from any  claim for  damages  or Rent  previously  accrued  or then  accruing
against Tenant.

           In the event  this Lease is  terminated  pursuant  to this  Paragraph
16.2B., Landlord may recover from Tenant:

              (i) the worth at the time of award of the  unpaid  rent  which had
been earned at the time of termination; plus

              (ii) the  worth at the time of award of the  amount  by which  the
unpaid  rent which would have been earned  after  termination  until the time of
award  exceeds  the amount of such  rental  loss for the same period that Tenant
proves could have been reasonably avoided; plus

              (iii)  the  worth at the time of award of the  amount by which the
unpaid  rent for the  balance  of the term after the time of award  exceeds  the
amount of such  rental loss for the same  period  that  Tenant  proves  could be
reasonably avoided; plus

              (iv) any other amount necessary to compensate Landlord for all the
detriment proximately caused by Tenant's failure to perform Tenant's obligations
under this Lease,  or which in the ordinary  course of things would be likely to
result therefrom,  including but not limited to attorneys' fees, court costs and
remodeling expenses.

              The  "worth at the time of award" of the  amounts  referred  to in
subparagraphs  (i) and  (ii) of this  Paragraph  16.2B.  shall  be  computed  by
allowing  interest at the lower of five percent (5%) per annum plus the discount
rate of the Federal  Reserve  Bank of San  Francisco,  or the maximum  rate then
permitted by law. The "worth at the time of award" of the amount  referred to in
subparagraph  (iii) of this  paragraph  shall be  computed by  discounting  such
amount at the discount rate of the Federal  Reserve Bank of San Francisco at the
time of award plus one percent (1%).  The term "Rent" as used in this  paragraph
shall include all sums required to be paid by Tenant to Landlord pursuant to the
terms of this Lease.

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        C. This Lease may be terminated by a judgment specifically providing for
termination,  or by Landlord's delivery to Tenant of written notice specifically
terminating  this  Lease.  In no event  shall  any one or more of the  following
actions  by  Landlord,  in the  absence of a written  election  by  Landlord  to
terminate  this  Lease,  constitute  a  termination  of the Lease or a waiver of
Landlord's right to recover damages under this Paragraph 16:

           (i) appointment of a receiver in order to protect Landlord's interest
hereunder;

           (ii) consent to any  subletting of the Premises or assignment of this
Lease by Tenant, whether pursuant to provisions hereof concerning subletting and
assignment or otherwise; or

           (iii) any other action by Landlord or Landlord's  agents  intended to
mitigate  the adverse  effects of any breach of this Lease by Tenant,  including
without  limitation  any action taken to maintain and preserve the Premises,  or
any action taken to relet the Premises or any portion thereof for the account of
Tenant and in the name of Tenant.

        16.3 No Relief From  Forfeiture  After  Default.  To the fullest  extent
allowed by Washington law, Tenant waives all rights of redemption or relief from
forfeiture  under RCW  59.12.010 et seq.,  and under any other present or future
law,  in the event  Tenant is  evicted  or  Landlord  otherwise  lawfully  takes
possession of the Premises by reason of any Event of Default.

        16.4 Landlord's Right to Perform Tenant's  Obligations.  If Tenant shall
at any time fail to make any  payment or perform  any other act  required  to be
made or performed by Tenant under this Lease,  then  Landlord may, but shall not
be obligated to after five (5) business  days notice,  except in the case of any
emergency,  make such payment or perform  such other act to the extent  Landlord
may deem desirable,  and may, in connection therewith,  pay any and all expenses
incidental  thereto and employ  counsel.  No such  action by  Landlord  shall be
deemed a waiver by  Landlord of any rights or  remedies  Landlord  may have as a
result of such  failure by Tenant,  or a release of Tenant from  performance  of
such obligation. All sums so paid by Landlord,  including without limitation all
penalties,  interest and costs in connection therewith, shall be due and payable
by Tenant to  Landlord  on the day  immediately  following  any such  payment by
Landlord. Landlord shall have the same rights and remedies for the nonpayment of
any such sums as Landlord may be entitled to in the case of default by Tenant in
the payment of Rent.

        16.5  Additional  Rent. For purposes of any unlawful  detainer action by
Landlord  against Tenant pursuant to RCW 59.12.010,  or any similar or successor
statutes,  Landlord  shall be  entitled  to  recover  as Rent not only such sums
specified  in  Paragraph  4 as Base  Rent  and  Additional  Rent as may  then be
overdue, but also all such additional sums of Rent as may then be overdue.

        16.6 Remedies Not Exclusive.  No remedy or election  hereunder  shall be
deemed  exclusive but shall,  wherever  possible,  be cumulative  with all other
remedies herein provided or permitted at law or in equity.

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17.      DEFAULT BY LANDLORD.

        17.1 Cure Period.  Landlord  shall not be deemed to be in default in the
performance  of any obligation  required to be performed by it hereunder  unless
and until it has failed to  perform  such  obligation  within the period of time
specifically  provided herein,  or if no period of time has been provided,  then
within  thirty (30) days after  receipt of written  notice by Tenant to Landlord
specifying therein the nature such obligation;  provided,  however,  that if the
nature of  Landlord's  obligation  is such that more than  thirty  (30) days are
reasonably required for its performance, then Landlord shall not be deemed to be
in default if it shall  commence  such  performance  within such thirty (30) day
period and thereafter diligently complete such obligation.

        17.2  Mortgage  Protection.  In the event of any  default on the part of
Landlord,  Tenant  will  give  notice by  registered  or  certified  mail to any
beneficiary  of a deed of trust  or  mortgagee  of a  mortgage  encumbering  the
Premises  whose address shall have been  furnished to Tenant,  and before Tenant
shall  have  any  right  to  terminate  this  Lease,  Tenant  shall  grant  such
beneficiary  or mortgagee a reasonable  period within which to cure the default,
if such action is necessary to effect a cure.

18.  SUBORDINATION  AND MORTGAGES.  In the event  Landlord's  title or leasehold
interest is now or hereafter  encumbered by a deed of trust upon the interest of
Landlord in the land and buildings in which the demised  Premises are located to
secure a loan from a lender  (hereinafter  referred to as "Lender") to Landlord,
Tenant  shall,  within ten (10)  business  days of the  request by  Landlord  or
Lender,  execute  and deliver to Landlord  an  agreement  subordinating  Tenants
rights under this Lease to the lien of such deed of trust,  in form requested by
the Lender.  Notwithstanding the foregoing, Tenant's possession under this Lease
shall not be  disturbed  if Tenant is not in default and so long as Tenant shall
pay all Rent and observe and  perform  all of the  provisions  set forth in this
Lease, and any subordination  agreement shall expressly recognize Tenant's right
to continued occupancy under this Lease in accordance with the foregoing.

19. ENTRY BY LANDLORD.  Landlord shall at all reasonable  times and upon two (2)
business days' prior notice (except in emergencies)  have the right to enter the
Premises to inspect  them,  to perform  any  services to be provided by Landlord
hereunder,  to show  the  Premises  to  prospective  purchasers,  mortgagors  or
tenants, to post notices of  nonresponsibility  and to alter,  improve or repair
the Premises  and any portion of the  Property,  all without  abatement of rent;
provided,  however,  that  Landlord  shall use  reasonable  efforts to  minimize
interference  with  Tenant's  business.  Landlord  shall have the right to erect
scaffolding  and other  structures  in or through the Premises  when  reasonably
required  for by any work to be performed  by  Landlord.  Landlord  shall at all
times  retain a key with which to unlock all of the doors to the  Premises in an
emergency,  and any entry to the Premises  obtained by Landlord  shall not under
any circumstances be construed or deemed to be a forcible or unlawful entry into
or a detainer of the Premises or an eviction, actual or constructive,  of Tenant
from the Premises or any portion thereof.

20. VACATION OR ABANDONMENT.  Tenant shall not vacate or abandon the Premises at
any time during the term of this Lease  (except that Tenant may vacate for up to
thirty  (30)  during  any  twelve  (12)  month  period so long as it pays  Rent,



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provides an on-site  security  guard during  normal  business  hours from Monday
through Friday, and otherwise performs its obligations hereunder), and if Tenant
shall  abandon,  vacate or surrender said Premises,  or be  dispossessed  by the
process of law, or otherwise, any personal property belonging to Tenant and left
on the Premises shall be deemed to be abandoned, at the option of Landlord.

21.      DAMAGE OR DESTRUCTION.

        21.1 Partial  Damage-Insured.  Subject to the  provisions  of Paragraphs
21.3 and 21.4,  if the  Buildings  are  damaged to the extent of less than fifty
percent (50%) of the then  replacement cost thereof  (excluding  excavations and
foundations)  or the  Laboratory  Building is damaged to the extent of less than
thirty-three  and one-third  percent (33 1/3%)  (collectively,  the "Replacement
Cost"),  and such  damage  was  caused by an act or  casualty  covered  under an
insurance  policy  obtained by Landlord or Tenant  pursuant to Paragraph 12.4 or
12.5, and the proceeds of such insurance  received by Landlord are sufficient to
repair the damage,  Landlord  shall at Landlord's  expense repair such damage as
soon as  reasonably  possible  and this Lease  shall  continue in full force and
effect;  provided  that if the repair will take more than one hundred and eighty
(180) days to complete from the date of damage,  as  reasonably  estimated by an
independent licensed contractor mutually agreeable to the parties (the "Approved
Contractor"),  either  party  shall  have the right to  terminate  this Lease by
delivering written notice of such election to the other party within thirty (30)
days after receiving written notice of the Approved Contractor's  estimated time
to complete such repair.  In such event,  this Lease shall  terminate  effective
ninety (90) days after delivery of such written notice.

        21.2 Partial  Damage-Uninsured.  Subject to the provisions of Paragraphs
22.3 and 22.4,  if at any time during the term hereof the  Buildings are damaged
and the proceeds  received by Landlord are not sufficient to repair such damage,
or such damage was caused by an act or casualty  not covered  under an insurance
policy  obtained  by  Landlord or Tenant  pursuant  to  Paragraph  12.4 or 12.5,
Landlord  may at  Landlord's  option  either (1) repair  such  damage as soon as
reasonably  possible  at  Landlord's  expense,  in which  event this Lease shall
continue in full force and effect,  or (2) give written notice of termination of
this Lease to Tenant within thirty (30) days after the date of the occurrence of
such damage,  with the effective date of such  termination to be the date of the
occurrence  of such  damage.  Notwithstanding  the  foregoing,  if  such  repair
hereunder will take more than one hundred and eighty (180) days to complete from
the date of damage, as reasonably  estimated by an Approved  Contractor,  either
party shall have the right to terminate this Lease by delivering  written notice
of such  election to the other  party  within  thirty (30) days after  receiving
written  notice of the Approved  Contractor's  estimated  time to complete  such
repair.  In such event,  this Lease shall terminate  effective  ninety (90) days
after delivery of such written notice.

        21.3 Total Destruction. If at any time during the term hereof either the
Premises  or  the  Buildings  are  destroyed  to the  extent  of  sixty-six  and
two-thirds  percent  (66 2/3%) or more of the then  Replacement  Cost,  from any
cause  whether or not covered by the  insurance  obtained  pursuant to Paragraph
12.4 or 12.5, this Lease shall at the option of Landlord or Tenant  terminate as
of the date of such destruction.  Landlord or Tenant shall exercise its right to
terminate  this Lease,  if at all, by delivery of notice of  termination  to the


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other party within thirty (30) days after the date that Tenant notifies Landlord
of the occurrence of such damage. In the event neither party elects to terminate
this Lease,  Landlord shall at Landlord's  expense repair such damage as soon as
reasonably  possible,  and this Lease  shall  continue in full force and effect,
subject to the provisions of Paragraph 21.5.

        21.4 Damage Near End of Term.  If the Premises are  destroyed or damaged
in whole or in  material  part  during the last year of the Lease term and if it
would take more than ninety (90) days to repair or restore the Premises,  either
Landlord or Tenant may terminate this Lease as of the date of occurrence of such
damage by giving written  notice thereof to other party of such election  within
thirty (30) days after the date of occurrence of such damage.

        21.5  Abatement  of  Rent.  Notwithstanding  anything  to  the  contrary
contained  in this Lease,  if the Premises  are  partially  damaged and Landlord
repairs or restores them pursuant to the  provisions of this  Paragraph 21, Base
Rent and  Additional  Rent payable  hereunder  for the period  commencing on the
occurrence  of  such  damage  and  ending  upon  completion  of such  repair  or
restoration shall be abated in proportion to the extent to which Tenant's use of
the Premises is impaired  during the period of repair;  provided  that,  nothing
herein shall be construed to preclude  Landlord  from being  entitled to collect
the  full  amount  of any  rental  loss  insurance  proceeds.  Except  for  such
abatement,  if any,  Tenant shall have no claim against  Landlord for any damage
suffered by reason of any such damage, destruction, repair or restoration.

        21.6 Waiver. Tenant waives the provisions of any applicable law, and any
similar or successor  statutes  relating to termination of leases when the thing
leased  is  substantially  or  entirely  destroyed,  and  agrees  that  any such
occurrence shall instead be governed by the terms of this Lease.

        21.7  Tenant's  Property.  Landlord's  obligation  to rebuild or restore
shall  not  include   restoration   of  Tenant's  trade   fixtures,   equipment,
merchandise, or any improvements, alterations or additions made by Tenant to the
Premises.

        21.8 Notice of Damage. Tenant shall notify Landlord within five (5) days
after  the  occurrence  thereof  of any  damage  to all  or any  portion  of the
Premises.  In no event shall  Landlord have any  obligation to repair or restore
the Premises  pursuant to this  Paragraph  21 until a reasonable  period of time
after  Landlord's  receipt of notice  from Tenant of the nature and scope of any
damage to the  Premises,  and a reasonable  period of time to collect  insurance
proceeds  arising from such damage (unless such damage is clearly not covered by
insurance then in effect covering the Premises).

        21.9 Replacement  Cost. The  determination in good faith by the Approved
Contractor of the estimated cost of repair of any damage,  or of the Replacement
Cost, shall be conclusive for purposes of this Paragraph 21.

22.  EMINENT  DOMAIN.  If all or any part of the Premises  shall be taken by any
public or quasi-public authority under the power of eminent domain or conveyance
in lieu thereof, this Lease shall terminate as to any portion of the Premises so
taken or conveyed on the date when title vests in the  condemnor,  and  Landlord


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shall be entitled to any and all payment,  income,  rent, award, or any interest
therein  whatsoever  which may be paid or made in connection with such taking or
conveyance, and Tenant shall have no claim against Landlord or otherwise for the
value  of any  unexpired  term  of this  Lease.  Notwithstanding  the  foregoing
paragraph,  any compensation  specifically  awarded Tenant for loss of business,
Tenant's personal property, moving cost or loss of goodwill, shall be and remain
the property of Tenant.  If (i) any action or  proceeding  is commenced for such
taking of the Premises or any part thereof, or if Landlord is advised in writing
by any entity or body having the right or power of condemnation of its intention
to condemn the  Premises or any portion  thereof,  or (ii) any of the  foregoing
events occur with respect to the taking of any other portion of the Buildings or
Property not leased hereby, and Landlord shall decide to discontinue the use and
operation of the Buildings or Property, or decide to demolish,  alter or rebuild
the Buildings or Property,  then, in any of such events  Landlord shall have the
right to  terminate  this Lease upon  thirty (30) days prior  written  notice to
Tenant.  In the event of a partial  taking or conveyance  of the Premises  under
power of eminent domain,  if the portion of the Premises taken or conveyed is so
substantial  that the  Tenant  can no longer  reasonably  conduct  its  business
therein,  Tenant shall have the right to terminate  this Lease within sixty (60)
days from the date of such taking or conveyance, upon written notice to Landlord
of its  intention to terminate  the Lease.  Upon  delivery of such notice,  this
Lease shall  terminate on the last day of the calendar  month next following the
month in which such notice is given, upon payment by Tenant of the Rent from the
date of such taking or  conveyance to the date of  termination.  If a portion of
the Premises be taken by  condemnation or conveyance in lieu thereof and neither
Landlord nor Tenant shall  terminate this Lease as provided  herein,  this Lease
shall  continue in full force and effect as to the part of the  Premises  not so
taken or  conveyed,  and the Rent herein shall be  thereafter  be reduced to the
extent by Tenant's use or occupancy of the Premises has been adversely affected.
The rights of Landlord and Tenant regarding any taking or conveyance under power
or threat of eminent  domain  shall be governed by the terms of this  paragraph,
and each party waives the provisions of Washington Law allowing  either party to
petition a court to terminate this Lease in the event of a partial taking of the
Premises.

23. SALE OR CONVEYANCE BY LANDLORD.  In the event of a sale or conveyance of the
Property  or  any  interest  therein,   by  any  owner  of  the  reversion  then
constituting Landlord, the transferor shall thereby be released from any further
liability  upon any of the terms,  covenants or conditions  (express or implied)
herein contained in favor of Tenant, and in such event, insofar as such transfer
is  concerned,  Tenant  agrees  to  look  solely  to the  responsibility  of the
successor in interest of such  transferor in and to the Property and this Lease.
This Lease  shall not be  affected  by any such sale or  conveyance,  and Tenant
agrees to attorn to the successor in interest of such transferor.

24.  ATTORNMENT TO LENDER OR THIRD PARTY.  In the event the interest of Landlord
in the land and buildings in which the leased Premises are located (whether such
interest  of  Landlord  is a fee title  interest  or a  leasehold  interest)  is
encumbered by deed of trust,  and such interest is acquired by the lender or any
third party through  judicial  foreclosure  or by exercise of a power of sale at
private  trustee's  foreclosure  sale,  Tenant  hereby  agrees  to attorn to the
purchaser at any such  foreclosure  sale and to recognize  such purchaser as the
Landlord  under this Lease.  In the event the lien of the deed of trust securing
the loan from a Lender to Landlord  is prior and  paramount  to the Lease,  this
Lease shall  nonetheless  continue in full force and effect for the remainder of
the unexpired term hereof,  at the same rental herein  reserved and upon all the
other terms, conditions and covenants herein contained.



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25.  HOLDING  OVER.  Any  holding  over by  Tenant  after  expiration  or  other
termination  of the term of this Lease  with the  written  consent  of  Landlord
delivered to Tenant shall not  constitute a renewal or extension of the Lease or
give Tenant any rights in or to the leased Premises except as expressly provided
in this Lease. Any holding over after the expiration or other termination of the
term of this Lease,  with the consent of  Landlord,  shall be  construed to be a
tenancy from month to month, on the same terms and conditions  herein  specified
insofar as applicable except that the monthly Base Rent shall be increased to an
amount equal to one hundred  twenty-five percent (125%) of the monthly Base Rent
required during the last month of the Lease term.

26. ESTOPPEL  CERTIFICATE.  Tenant shall at any time upon not less than ten (10)
business days' prior written notice to Landlord execute, acknowledge and deliver
to Landlord a statement in writing (i) certifying  that this Lease is unmodified
and in full  force and  effect  (or,  if  modified,  stating  the nature of such
modification  and certifying that this Lease,  as so modified,  is in full force
and  effect)  and the date to  which  the Rent  and  other  charges  are paid in
advance,  if any,  and  (ii)  acknowledging  that  there  are not,  to  Tenant's
knowledge, any uncured defaults on the part of Landlord hereunder, or specifying
such  defaults,  if any, are claimed.  Any such  statement  may be  conclusively
relied  upon by any  prospective  purchaser  or  encumbrancer  of the  Premises.
Tenant's  failure to deliver such statement within such time shall be conclusive
upon Tenant that this Lease is in full force and  effect,  without  modification
except as may be represented by Landlord,  that there are no uncured defaults in
Landlord's performance, and that not more than one month's rent has been paid in
advance.

27. CONSTRUCTION  CHANGES. It is understood that the description of the Premises
and the location of ductwork,  plumbing and other facilities therein are subject
to such minor  changes as  Landlord or  Landlord's  architect  determines  to be
desirable in the course of construction of the Premises, and no such changes, or
any changes in plans for any other  portions of the  Property  shall affect this
Lease or entitle  Tenant to any  reduction  of Rent  hereunder  or result in any
liability of Landlord to Tenant. Landlord does not guarantee the accuracy of any
drawings  supplied to Tenant and  verification  of the accuracy of such drawings
rests with Tenant.

28. RIGHT OF LANDLORD TO PERFORM.  All terms,  covenants and  conditions of this
Lease to be  performed  or observed by Tenant  shall be performed or observed by
Tenant at Tenant's  sole cost and expense and without any  reduction of Rent. If
Tenant shall fail to pay any sum of money, or other Rent, required to be paid by
it  hereunder  or shall fail to perform any other term or covenant  hereunder on
its part to be performed,  and such failure shall continue for five (5) business
days  after  written  notice  of  Landlord's  intent  to  perform  such  term of
condition,  Landlord, without waiving or releasing Tenant from any obligation of
Tenant  hereunder,  may, but shall not be obligated to, make any such payment or
perform any such other term or covenant on Tenant's  part to be  performed.  All


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sums so paid by Landlord and all necessary costs of such performance by Landlord
together  with  interest  thereon  at the  Interest  Rate  from the date of such
payment or  performance  by  Landlord,  shall be paid by Tenant to  Landlord  on
demand by Landlord,  and Landlord shall have the same rights and remedies in the
event of nonpayment by Tenant as in the case of failure by Tenant in the payment
of Rent hereunder.

29. ATTORNEYS' FEES. In the event that either Landlord or Tenant should bring an
action or proceeding for the possession of the Premises, including on appeal and
petition for review for the recovery of any sum due under this Lease, or because
of the breach of any  provision of this Lease,  or for any other relief  against
the other party  hereunder,  then all costs and expenses,  including  reasonable
attorneys'  fees,  incurred by the prevailing party therein shall be paid by the
other party.

30. WAIVER.  The waiver by either party of the other party's  failure to perform
or observe any term,  covenant or condition  herein contained to be performed or
observed by such waiving  party shall not be deemed to be a waiver of such term,
covenant  or  condition  with  respect  to any  subsequent  failure of the party
failing  to perform or  observe  the same or any other  such term,  covenant  or
condition therein contained, and no custom or practice which may develop between
the parties hereto during the term hereof shall be deemed a waiver of, or in any
way affect,  the right of either party to insist upon performance and observance
by the other party in strict accordance with the terms hereof.

31. NOTICES. All notices, demands,  requests,  advices or designations which may
be or are required to be given by either party to the other  hereunder  shall be
in writing. All notices, demands,  requests, advices or designations by Landlord
to Tenant shall be sufficiently  given,  made or delivered if sent by commercial
courier or by United  States  certified or  registered  mail,  postage  prepaid,
addressed to Tenant at the Premises. All notices, demands,  requests, advices or
designations  by Tenant to Landlord shall be sent by United States  certified or
registered mail, postage prepaid, addressed to Landlord at its address set forth
on the Lease  Summary.  Each  notice,  request,  demand,  advice or  designation
referred  to in this  paragraph  shall  be  deemed  received  on the date of the
personal service or delivery thereof in the manner herein provided,  as the case
may be.

32.  EXAMINATION  AND  CONDITION OF LEASE.  Submission  of this  instrument  for
examination  or signature by Tenant does not  constitute  a  reservation  of the
Premises or option for a lease,  and this instrument is not effective as a lease
or otherwise until its execution and delivery by both Landlord and Tenant.

33.  AUTHORITY.  If Tenant is a corporation  or a partnership,  each  individual
executing this Lease on behalf of said corporation or partnership represents and
warrants that he is duly  authorized to execute and deliver this Lease on behalf
of said  corporation  or  partnership  in  accordance  with the  by-laws of said
corporation the  partnership  agreement and that this Lease is binding upon said
corporation or partnership in accordance with its terms.

34. LIMITATION OF LIABILITY.  Tenant and all successors and assigns covenant and
agree  that,  in the event of any actual or alleged  failure,  breach or default
hereunder by Landlord:


                                      119
<PAGE>

              (i) the sole and  exclusive  remedy shall be against  Landlord and
Landlord's assets;

              (ii) no partner or owner of  Landlord  shall be sued or named as a
party in any suit or action  (except as may be necessary to secure  jurisdiction
of the partnership);

              (iii) no service of process  shall be made  against any partner of
Landlord (except as may be necessary to secure jurisdiction of the partnership);

              (iv) no partner or owner of  Landlord  shall be required to answer
or otherwise plead to any service of process;

              (v) no  judgment  will be taken  against  any  partner or owner of
Landlord;

              (vi) any judgment  taken  against any partner or owner of Landlord
may be vacated and set aside at any time without hearing;

              (vii) no writ of execution  will ever be levied against the assets
of any partner or owner of Landlord;

              (viii) these  covenants and  agreements  are  enforceable  both by
Landlord and also by any partner or owner of Landlord.

              Tenant agrees that each of the foregoing  covenants and agreements
shall be applicable to any covenant or agreement either  expressly  contained in
this Lease or imposed by statute or at common law.

35.      MISCELLANEOUS AND GENERAL PROVISIONS.

        A. Tenant shall not,  without the written  consent of Landlord,  use the
name of the  Buildings for any purpose other than as the address of the business
conducted by Tenant in the Premises.

        B. This Lease shall in all  respects be  governed  by and  construed  in
accordance  with the laws of the State of  Washington.  If any provision of this
Lease shall be invalid,  unenforceable or ineffective for any reason whatsoever,
all other provisions hereof shall be and remain in full force and effect.

        C.  The  term  "Premises"  includes  the  space  leased  hereby  and any
improvements now or hereafter  installed therein or attached  thereto.  The term
"Landlord" or any pronoun used in place  thereof  includes the plural as well as
the singular and the  successors  and assigns of Landlord.  The term "Tenant" or
any pronoun  used in place  thereof  includes the plural as well as the singular
and individuals,  firms, associations,  partnerships and corporations, and their
and each of their respective heirs,  executors,  administrators,  successors and
permitted  assigns,  according to the context hereof, and the provisions of this



                                      120
<PAGE>

Lease  shall   inure  to  the  benefit  of  and  bind  such  heirs,   executors,
administrators, successors and permitted assigns. The term "person" includes the
plural  as  well  as  the  singular  and   individuals,   firms,   associations,
partnerships and  corporations.  Words used in any gender include other genders.
If there be more than one Tenant the  obligations of Tenant  hereunder are joint
and  several.  The  paragraph  headings  of this  Lease are for  convenience  of
reference only and shall have no effect upon the construction or  interpretation
of any provision hereof.

        D.  Time is of the  essence  of this  Lease  and of each  and all of its
provisions.

        E. At the expiration or earlier  termination of this Lease, Tenant shall
execute, acknowledge and deliver to Landlord, within ten (10) days after written
demand from Landlord to Tenant, any quitclaim deed or other document required by
any reputable title company,  licensed to operate in the State of Washington, to
remove the cloud or encumbrance  created by this Lease from the real property of
which the Premises are a part.

        F. This  instrument  along  with any  exhibits  and  attachments  hereto
constitutes  the entire  Agreement  between  Landlord and Tenant relative to the
Premises and this  agreement  and the exhibits and  attachments  may be altered,
amended or revoked only by an instrument in writing  signed by both Landlord and
Tenant.  Landlord and Tenant agree hereby that all prior or contemporaneous oral
agreements  between and among  themselves  and their  agents or  representatives
relative  to the  leasing  of the  Premises  are  merged in or  revoked  by this
agreement.

        G.  Neither  Landlord nor Tenant shall record this Lease or a short form
memorandum hereof without the consent of the other.

        H. Tenant further agrees to execute any amendments  required Landlord in
order to obtain financing for the Property, so long as Tenant's rights hereunder
are not substantially affected.

        I. All Paragraphs  listed in the Lease Summary as additional  paragraphs
are added hereto and are included as a part of this Lease.

        J. Clauses,  plats and riders, if any, signed by Landlord and Tenant and
endorsed on or affixed to this Lease are a part hereof.

        K. Tenant  covenants  and agrees that no  diminution  or shutting off of
light,  air or view by any structure which may be hereafter  erected (whether or
not by  Landlord)  shall in any way  affect  his  Lease,  entitle  Tenant to any
reduction of Rent hereunder or result in any liability of Landlord to Tenant.

        L. The  voluntary  or other  surrender  of this Lease or the Premises by
Tenant or a mutual cancellation of this Lease shall not work as a merger and, at
the option of Landlord,  shall either terminate all or any existing subleases or
subtenancies  or  operate  as an  assignment  to  Landlord  of all  or any  such
subleases or subtenancies.


                                      121
<PAGE>

        M. Tenant  acknowledges  that  Landlord  may assign its interest in this
Lease to a partnership or a limited  liability  company upon  acquisition of the
Property and that Tenant shall  thereafter  look solely to such  partnership  or
limited  liability  company for  performance  of all of  Landlord's  obligations
hereunder.

36.  BROKERS.  Tenant  warrants  that it had dealings  with only the real estate
brokers or agents listed on the Lease Summary in connection with the negotiation
of this Lease and that it knows of no other real  estate  broker or agent who is
entitled to a commission in connection with this Lease.

37. SIGNS AND WINDOW COVERINGS. No sign, placard, picture,  advertisement,  name
or notice shall be inscribed,  displayed or printed or affixed on or to any part
of the outside of the Premises or any exterior windows of the Premises except in
compliance with all  Governmental  Regulations.  Upon expiration or other sooner
termination  of this Lease,  Tenant at Tenant's sole cost and expense shall both
remove  such sign and  repair  all  damage in such a manner  as to  restore  all
aspects  of  the  appearance  of the  Premises  to the  condition  prior  to the
placement of said sign.

38. ADDITIONAL PARAGRAPHS. Paragraphs 39 through 40 in the attached Addendum and
Exhibits A are added hereto and made part of this Lease.

     IN WITNESS  WHEREOF,  Landlord and Tenant have executed and delivered  this
Lease as of the day and year first above written.

LANDLORD:                                     TENANT:

EMCON,                                        COLUMBIA ANALYTICAL SERVICES, INC.
a California corporation                      a Washington corporation



By: /s/R. Michael Momboisse                  By: /s/Steven W. Vincent
    --------------------------------             -----------------------------

Its:   CFO & VP Legal                       Its:  President
     ------------------------------              -----------------------------



                                      122
<PAGE>



                                ADDENDUM TO LEASE

         The   Addendum  is  executed  by  and  between   EMCON,   a  California
corporation,  as  Landlord,  and  Columbia  Analytical  Services,  a  Washington
corporation,  as Tenant,  with respect to those certain Premises located at 1317
13th Street, Kelso, Washington 98626-2845.  This Addendum is an integral part of
the Lease to which it is attached. The provisions of this Addendum supersede the
provisions of the Lease to the extent inconsistent therewith.

39. FIRST RIGHT OF REFUSAL TO PURCHASE  PROPERTY.  If Landlord receives an offer
to purchase  the Property at any time during the term of this Lease and Landlord
desires to accept  such  offer,  then  Landlord  shall  first  offer to sell the
Property  to Tenant upon the same terms and  conditions  by  delivering  written
notice to Tenant of all of the terms and  conditions of the third party's offer;
provided,  however,  that  Tenant  shall  receive as a credit  against  any down
payment  requirement,  the then current net book value on Tenant's  books of the
costs expended by Tenant with  Landlord's  consent after the Lease  Commencement
Date for construction of additional  buildings or building  additions or for the
buildout of the second floor of the administration  building.  Such notice shall
constitute  an offer to sell the Property to Tenant on the terms and  conditions
contained in the notice.  Tenant  shall have fifteen (15) days after  receipt of
said notice in which to notify  Landlord in writing  that  Tenant  accepts  such
offer. Tenant shall accept such offer, if at all, only by executing the purchase
agreement  attached  with  Landlord's  notice and returning the same to Landlord
within  the  fifteen  (15) day  period.  If Tenant  so  executes  said  purchase
agreement and timely  returns the same to Landlord,  Landlord  shall execute the
purchase  agreement and return a fully executed copy to Tenant.  If Tenant fails
to execute the purchase  agreement or to return the same to Landlord within said
fifteen (15) day period, then Landlord shall be entitled to sell the Property to
any other party on such terms as Landlord  desires;  provided that, the purchase
price for any purchase agreement entered into with any such third party shall be
no less than that previously offered to Tenant,  unless Landlord has first again
offered the Property to Tenant for sale on the terms  provided in this Paragraph
39. The right of first  refusal  under this  paragraph  is granted for  Tenant's
personal  benefit and may not be assigned or  transferred  by Tenant,  except in
connection with a Permitted Transfer.  Likewise, if Tenant does not exercise its
right of first refusal hereunder, and the Property is sold to a third party, the
right of first  refusal set forth  herein shall  terminate  and be of no further
force or effect.  Notwithstanding the terms of any offer received by Landlord to
purchase the Property  from a third party,  the purchase  agreement  provided by
Landlord to Tenant  hereunder  shall  provide  that Tenant  shall  purchase  the
Property "As  Is,"without  any  representation  or warranty by Landlord.  Tenant
shall close the escrow on the  purchase of the  Property  within sixty (60) days
after it notifies Landlord in writing of Tenant's acceptance of Landlord's offer
to sell the Property to Tenant hereunder.

40.      OPTION TO PURCHASE PROPERTY.

         A. Subject to the terms and  conditions  hereof and  provided  that the
Property has not been previously conveyed to a third party pursuant to the terms
set forth in Paragraph 40 above,  Tenant shall have an option (the  "Option") to
purchase  the  Property.  The Option  shall be  exercised,  if at all, by Tenant
delivering written notice of its exercise of the Option to Landlord prior to the
earlier of (i) the date ninety (90) months after Landlord  acquires title to the


                                      123
<PAGE>

Property,  or (ii) the date of Tenant's  election  not to exercise  its right of
first refusal  under  Paragraph 39 hereof if the Property is in fact sold to the
third party pursuant to the terms and conditions set forth in the right of first
refusal  notice.  In the event  Tenant  shall  fail to  deliver  written  notice
exercising the Option when required,  the Option shall  automatically  terminate
and be of no further force or effect.  Tenant may not exercise the Option during
any period of an Event of Default  under this  Lease.  If Tenant  exercises  the
Option in a timely manner, Landlord shall be obligated to sell, and Tenant shall
be obligated to purchase,  the Property, as hereinafter  provided.  The purchase
price (the  "Purchase  Price") for the Property  shall be the greater of (i) the
Property's  appraised  fair market  value,  as determined in Paragraph 40B below
reduced by an amount  equal to the total of all  supplemental  payments  paid by
Tenant to Landlord under the provisions of Paragraph 6.2 of this Lease,  or (ii)
the then  current net book value of the  Property  as carried on the  Landlord's
books.

        B. If the Tenant  exercises the Option,  Tenant and Landlord each shall,
within ten (10) business days from the date Tenant notifies Landlord of Tenant's
exercise of the Option, appoint a real estate appraiser who shall be a member of
the American  Institute of Real Estate Appraisers  ("AIREA") and such appraisers
shall each  determine  the fair  market  value of the  Property,  including  all
improvements thereon. Each such appraiser shall have no less than five (5)years'
experience  appraising   commercial  property  in  Kelso,   Washington  and  the
surrounding  County. Such appraisers shall, with twenty (20) business days after
their appointment,  complete their appraisals and submit their appraisal reports
to Landlord  and Tenant.  If the fair market  value  established  in the two (2)
appraisals  varies by five  percent  (5%) or less of the higher  appraisal,  the
average of the two shall be  controlling.  If said fair market  value  varies by
more than five percent (5%) of the higher  value,  said  appraisers,  within ten
(10)  days  after  submission  of the  last  appraisal,  shall  appoint  a third
appraiser  who shall be a member of the AIREA and who shall also be  experienced
in the appraisal of commercial properties in the vicinity of the Property.  Such
third appraiser  shall,  within twenty (20) business days after his appointment,
determine by appraisal the fair market value of the Property taking into account
the same factors  referred to above, and submit his appraisal report to Landlord
and Tenant.  The fair market value  determined  by the third  appraiser  for the
Property  shall be  controlling,  unless  it is less  than that set forth in the
lower appraisal previously  obtained,  in which case the value set forth in said
lower  appraisal  shall be  controlling,  or unless it is greater  than that set
forth in the higher appraisal previously obtained,  in which case the rental set
forth in said higher  appraisal  shall be  controlling.  The appraisal shall not
take into account any costs expended by Tenant after the Lease Commencement Date
for  construction  of  additional  buildings or building  additions  and for the
build-out of the second floor of the administration building. If either Landlord
or Tenant fails to appoint an appraiser,  or if an appraiser appointed by either
of them  fails,  after his  appointment,  to submit  his  appraisal  within  the
required period in accordance with the foregoing, the appraisal submitted by the
appraiser  properly  appointed  and timely  submitting  his  appraisal  shall be
controlling.  If the two appraisers  appointed by Landlord and Tenant are unable
to agree upon a third  appraiser  within the required  period in accordance with
the foregoing,  application  shall be made within twenty (20) days thereafter by
either  Landlord or Tenant to the AIREA,  which  shall  appoint a member of said
institute  willing to serve as appraiser.  The cost of all appraisals under this
subparagraph shall be borne equally by Landlord and Tenant.


                                      124
<PAGE>

        C. Once the Purchase Price has been determined by the parties,  close of
escrow  shall take place  sixty  (60) days  thereafter.  At the close of escrow,
Landlord  shall  convey fee title to the  Property to Tenant "As Is" and without
warranty  or  representation.  The  Purchase  Price  shall be paid by  Tenant to
Landlord  in cash at the close of escrow.  Seller  shall pay its normal  closing
costs,  including title insurance premiums,  real estate excise taxes, and other
transfer  taxes.  Purchaser  shall  pay  its  normal  closing  costs,  including
recording of the Deed and recording of any loan  documents  and title  insurance
for any lender that may be involved in financing the cash Purchase Price. Seller
and Purchaser shall each pay one-half of the escrow fees.

        D. The Option  rights set forth in this  Paragraph  40 are  personal  to
Tenant and may not be  transferred  or  assigned,  except in  connection  with a
Permitted Transfer.

                                       LANDLORD:
                                       EMCON,
                                       a California corporation

Date: 4/4/97                           By: /s/R. Michael Momboisse
     ------------------------------       ------------------------------------

                                       Its:   CFO & VP Legal
                                           -----------------------------------
                                       TENANT:
                                       COLUMBIA ANALYTICAL SERVICES, INC.
                                       a Washington corporation

Date:    4/4/97                        By:  /s/Steven W. Vincent
     -----------------------------        -----------------------------------
                                      
                                       Its:  President
                                            ----------------------------------





                                      125
<PAGE>





State of Washington        On April 4th, 1997
County of Cowlitz
                           Before me,
                           personally  appeared  Stephen W.  Vincent, 
                           President  of Columbia Analytical Services, Inc.,

                           personally  known  to  me to be
                           the   person   whose   name  is
                           subscribed    to   the   within
                           instrument, and acknowledged to
                           me that he executed the same in
                           his  authorized  capacity,  and
                           that  by his  signature  on the
                           instrument  the person,  or the
                           entity upon behalf of which the
                           person   acted,   executed  the
                           instrument.

                           WITNESS  my hand  and  official
                           seal.

                           __________________________________
                           Notary's Signature


State of Washington        On April 4th, 1997
County of Cowlitz
                           Before me,
                           personally  appeared R,  Michael  Momboisse,  
                           the Chief  Financial Officer and Vice President
                           of EMCON,

                           personally  known  to  me to be
                           the   person   whose   name  is
                           subscribed    to   the   within
                           instrument, and acknowledged to
                           me that he executed the same in
                           his  authorized  capacity,  and
                           that  by his  signature  on the
                           instrument  the person,  or the
                           entity upon behalf of which the
                           person   acted,   executed  the
                           instrument.

                           WITNESS  my hand  and  official
                           seal.


                           _____________________________________
                           Notary's Signature


                                       126

                                  EXHIBIT 11.1

                                      EMCON
                         COMPUTATION OF INCOME PER SHARE
                      (In thousands except per share data)

<TABLE>
<CAPTION>

                                                                                                             Three months ended
                                                                                                                  March 31,

                                                                                                          1997                 1996
                                                                                                          ----                 ----
<S>                                                                                                        <C>                  <C>

Net income ...............................................................................               $  961               $   34
 Proforma interest income related to modified
  treasury stock method ..................................................................                  N/A                   48
                                                                                                         ------               ------

Adjusted net income ......................................................................               $  961               $   82
                                                                                                         ======               ======

Weighted average number of common shares
 outstanding during the period ...........................................................                8,535                8,457

Common and common equivalent shares outstanding
 for the purpose of calculating primary net income per share .............................                8,472                  N/A
Common equivalent shares from outstanding
 stock options using the modified treasury
 stock method ............................................................................                  N/A                  959
Incremental shares to reflect full dilution (1) ..........................................                    0                    0
                                                                                                         ------               ------

Total shares for purposes of calculating diluted
 income per share (1) ....................................................................                8,472                9,416
                                                                                                         ======               ======

Primary income per share .................................................................               $ 0.08               $ 0.01
                                                                                                         ======               ======

Fully diluted income per share ...........................................................               $ 0.08               $ 0.01
                                                                                                         ======               ======
</TABLE>

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

(1)    This  calculation  is submitted in accordance  with  Regulation  S-K Item
       601(b)(11)  although  not  required by footnote 2 to  paragraph 14 to APB
       opinion No. 15, because it results in dilution of less than 3%.




                                      127


<TABLE> <S> <C>

<ARTICLE>                5
<LEGEND>

                                   EXHIBIT 27

     This schedule  contains summary  financial  information  extracted from the
consolidated balance sheets,  consolidated statements of income and consolidated
statements of cash flows included in the Company's Form 10-Q for the three month
period  ended March 31,  1997,  and is qualified in its entirety by reference to
such financial statements and the notes thereto.
</LEGEND>
<CURRENCY>                                                     U.S. DOLLARS
       
<S>                                                                     <C>
<PERIOD-TYPE>                                          3-MOS
<FISCAL-YEAR-END>                                      DEC-31-1997
<PERIOD-START>                                         JAN-1-1997
<PERIOD-END>                                           MAR-31-1997
<EXCHANGE-RATE>                                        1
<CASH>                                                    7,901,000
<SECURITIES>                                                      0
<RECEIVABLES>                                            35,841,000
<ALLOWANCES>                                              1,226,000

<INVENTORY>                                                       0
<CURRENT-ASSETS>                                         48,731,000
<PP&E>                                                   29,558,000
<DEPRECIATION>                                           15,036,000
<TOTAL-ASSETS>                                           89,413,000
<CURRENT-LIABILITIES>                                    17,040,000
<BONDS>                                                           0
<COMMON>                                                 42,059,000
                                             0
                                                       0
<OTHER-SE>                                                        0
<TOTAL-LIABILITY-AND-EQUITY>                             89,413,000
<SALES>                                                  27,581,000
<TOTAL-REVENUES>                                         27,581,000
<CGS>                                                    12,606,000
<TOTAL-COSTS>                                            12,606,000
<OTHER-EXPENSES>                                         13,080,000
<LOSS-PROVISION>                                            501,000
<INTEREST-EXPENSE>                                          331,000
<INCOME-PRETAX>                                           1,063,000
<INCOME-TAX>                                                372,000
<INCOME-CONTINUING>                                         691,000
<DISCONTINUED>                                                    0
<EXTRAORDINARY>                                                   0
<CHANGES>                                                         0
<NET-INCOME>                                                691,000
<EPS-PRIMARY>                                          0.08
<EPS-DILUTED>                                          0.08
        



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