EXHIBIT 2.6









                      AGREEMENT AND PLAN OF REORGANIZATION


                                      AMONG


                                      EMCON
                           (a California corporation);

                  ADVANCED ANALYTICAL SOLUTIONS DELAWARE, INC.
                            (a Delaware corporation);

                   ADVANCED ANALYTICAL SOLUTIONS INCORPORATED
                            (a Colorado corporation);

                                       AND

         THE SHAREHOLDERS OF ADVANCED ANALYTICAL SOLUTIONS INCORPORATED
                           (the Colorado Corporation)




                                  April 3, 1998


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                      AGREEMENT AND PLAN OF REORGANIZATION


         This AGREEMENT AND PLAN OF REORGANIZATION (the "Agreement") is made and
entered  into as of April 3, 1998 by and among EMCON,  a California  corporation
("EMCON"),  Advanced Analytical Solutions Delaware, Inc., a Delaware corporation
and  wholly-owned  subsidiary of EMCON ("Sub"),  Advanced  Analytical  Solutions
Incorporated,  a  Colorado  corporation  ("A2S")  and  the  Shareholders  of A2S
(collectively, the "A2S Shareholders").


                                    RECITALS

         A.  Pursuant to a statutory  merger of A2S with and into Sub,  with Sub
being  the  surviving  corporation  (the  "Merger"),  among  other  things,  the
outstanding  shares of A2S Common Stock ("A2S Common  Stock") shall be converted
into the right to receive the Merger  Consideration  (as defined in Section 1.6)
upon the terms and subject to the conditions set forth herein.

         B.  A2S,  EMCON  and  the  A2S  Shareholders  desire  to  make  certain
representations  and  warranties  and other  agreements in  connection  with the
Merger.

         C. The parties intend, by executing this Agreement,  to adopt a plan of
reorganization within the meaning of Section 368 of the Internal Revenue Code of
1986, as amended (the  "Code"),  and to cause the Merger to qualify as a forward
triangular  reorganization  under the provisions of Section  368(a)(2)(d) of the
Code.

         NOW,  THEREFORE,  in consideration of the covenants and representations
set forth  herein,  and for other good and valuable  consideration,  the parties
agree as follows:

         1.       The Merger.

                  1.1. The Merger.  At the Effective Time (as defined in Section
1.2) and subject to and upon the terms and  conditions  of this  Agreement,  the
Certificate of Merger attached hereto as Exhibit A (the "Certificate of Merger")
and the applicable provisions of the Delaware General Corporation Law ("Delaware
Law" or "DGL") and the law of the State of Colorado  ("Colorado Law"), A2S shall
be merged with and into Sub, the separate corporate existence of A2S shall cease
and Sub  shall  continue  as the  surviving  corporation.  Sub as the  surviving
corporation  after  the  Merger  is  hereinafter  sometimes  referred  to as the
"Surviving Corporation."

                  1.2. Closing;  Effective Time. The closing of the transactions
contemplated  hereby  (the  "Closing")  shall  take  place on April 3, 1998 (the
"Closing  Date").  The Closing  shall take place at the  offices of  Schlueter &
Associates,  P.C., 1050 17th Street,  Suite 1700, Denver,  Colorado 80265, or at
such other location as the parties hereto agree. In connection with the Closing,
the  parties  hereto  shall  cause the  Merger to be  consummated  by filing the
Certificate of Merger, together with the required officers'  certificates,  with
the  Secretary  of State of each of the  states of  Delaware  and  Colorado,  in
accordance  with the relevant  provisions  of Delaware Law and Colorado Law (the
time of such filing being the "Effective Time").

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                  1.3.  Effect of the Merger.  At the Effective Time, the effect
of the Merger shall be as provided in this Agreement,  the Certificate of Merger
and the applicable provisions of Delaware Law and Colorado Law. Without limiting
the generality of the foregoing, and subject thereto, at the Effective Time, all
the property, rights, privileges, powers and franchises of A2S shall vest in the
Surviving Corporation, and all debts, liabilities and duties of A2S shall become
the debts, liabilities and duties of the Surviving Corporation.

                  1.4.     Certificate of Incorporation; Bylaws.

                           (a)      At the Effective  Time, the Certificate of  
Incorporation  of Sub, as in effect  immediately  prior to the  Effective  Time,
shall be the Certificate of  Incorporation  of the Surviving  Corporation  until
thereafter  amended  as  provided  by  Delaware  Law  and  such  Certificate  of
Incorporation.
                           (b)      At the Effective  Time,  the Bylaws of Sub, 
as in effect immediately prior to the Effective Time, shall be the Bylaws of the
Surviving Corporation until thereafter amended.

                  1.5.     Directors  and  Officers.  At the  Effective  Time,  
the directors and officers of Sub immediately  prior to the Effective Time shall
be  the  directors  and  officers  of the  Surviving  Corporation,  until  their
respective successors are duly elected or appointed and qualified.

                  1.6.     Merger Consideration.  By virtue of the Merger, EMCON
shall  deliver the  following consideration (the "Merger Consideration") to the 
A2S Shareholders:

                           (a)      Cash   Consideration.   At  the  Closing,   
EMCON shall deliver to the A2S Shareholders an aggregate of Six Hundred Thousand
Dollars  ($600,000)  (the "Cash  Consideration")  as set forth in  Schedule  1.7
hereto.
                           (b)      EMCON Common Stock. At the Closing,  EMCON  
shall  deliver to the holders of A2S Common Stock (the "A2S  Capital  Stock") an
aggregate  of 123,077  shares of EMCON  Common Stock as set forth in Section 1.7
hereof .
                           (c)      Earnout Payments. During the first two years
following the Closing,  the A2S  Shareholders  shall be eligible to earn Earnout
Payments (as defined in Section  6.1(b)  hereof) up to an aggregate of $300,000,
subject to the terms and conditions of Section 6.1 hereof.

                  1.7.  Effect on Capital Stock At the Effective Time, by virtue
of the Merger and without any action on the part of EMCON, A2S or the holders of
any of the following securities:

                           (a) Conversion  of  A2S  Common  Stock.  Each  share 
of A2S Common Stock issued and  outstanding  immediately  prior to the Effective
Time shall be  converted  and  exchanged,  without any action on the part of the
holders  thereof,  into the right to receive 1.8648 shares of EMCON Common Stock
and  $9.0909  in Cash  Consideration  (the  "Exchange  Ratio"),  as set forth in
Schedule 1.7 hereto.
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                           (b)    Adjustments  to Exchange Ratio. The Exchange  
Ratio shall be adjusted to reflect fully the effect of any stock split,  reverse
split,  stock  dividend  (including any dividend or  distribution  of securities
convertible  into  EMCON  Common  Stock or A2S  Common  Stock),  reorganization,
recapitalization  or other like change with respect to EMCON Common Stock or A2S
Common Stock occurring after the date hereof and prior to the Effective Time.

                           (c)      Fractional Shares.  No fraction  of a share
of EMCON Common Stock will be issued,  but in lieu thereof each holder of shares
of A2S Common Stock who would  otherwise be entitled to a fraction of a share of
EMCON Common  Stock (after  aggregating  all  fractional  shares of EMCON Common
Stock to be received by such holder)  shall receive from EMCON an amount of cash
(rounded to the nearest  whole cent) equal to the product of (i) such  fraction,
multiplied by (ii) the Fair Market Value of EMCON Common  Stock.  The term "Fair
Market  Value" shall mean the closing price of EMCON Common Stock on the Closing
Date, as reported on the Nasdaq National  Market (the "Fair Market Value").  The
fractional share interests of each A2S shareholder shall be aggregated,  so that
no A2S shareholder  shall receive cash in respect of fractional  share interests
in an amount greater than the value of one full share of EMCON Common Stock.

                           (d)      Certificate  Legends.  The shares of EMCON 
Common  Stock to be  issued  pursuant  to this  Section  1 shall  not have  been
registered  and shall be  characterized  as  "restricted  securities"  under the
federal  securities  laws, and under such laws such shares may be resold without
registration  under the  Securities  Act or 1933,  as amended  (the  "Securities
Act"), only in certain limited circumstances. Each certificate evidencing shares
of EMCON  Common  Stock to be issued  pursuant to this  Section 1 shall bear the
following legend:
                  "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED
                  FOR  INVESTMENT  AND  HAVE  NOT  BEEN  REGISTERED   UNDER  THE
                  SECURITIES  ACT OF  1933.  SUCH  SHARES  MAY  NOT BE  SOLD  OR
                  OTHERWISE  TRANSFERRED  IN THE  ABSENCE  OF SUCH  REGISTRATION
                  WITHOUT AN EXEMPTION UNDER THE SECURITIES ACT OR AN OPINION OF
                  LEGAL COUNSEL  REASONABLY  ACCEPTABLE TO THE COMPANY THAT SUCH
                  REGISTRATION IS NOT REQUIRED."

         and any legends required by state securities laws.

                  1.8.     Surrender of Certificates.

                           (a)      EMCON to Provide Common Stock and Cash.  At 
the Closing, EMCON shall deliver to the A2S Shareholders certificates evidencing
the shares of EMCON Common Stock issuable pursuant to Section 1.7(a) in exchange
for shares of A2S Common Stock  outstanding  immediately  prior to the Effective
Time, and (ii) cash in an amount sufficient to permit payment of cash in lieu of
fractional shares.
                           (b)      Transfers of Ownership.  At the Effective  
Time,  the stock transfer books of the A2S shall be closed and there shall be no
further  registration of transfers of A2S Common Stock thereafter on the records
of the A2S. If any  certificate for shares of EMCON Common Stock is to be issued
in a name  other  than that in which the  Certificate  surrendered  in  exchange
therefor is registered,  it will be a condition of the issuance thereof that the
Certificate

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<PAGE>


so  surrendered  will be  properly  endorsed  and  otherwise  in proper form for
transfer and that the person requesting such exchange will have paid to EMCON or
any agent designated by it any transfer or other taxes required by reason of the
issuance of a  certificate  for shares of EMCON  Common  Stock in any name other
than  that  of  the  registered  holder  of  the  Certificate  surrendered,   or
established to the satisfaction of EMCON or any agent designated by it that such
tax has been paid or is not payable.

                  1.9. No Further  Ownership  Rights in A2S Capital  Stock.  The
Merger Consideration  delivered upon the surrender for exchange of shares of A2S
Capital  Stock in accordance  with the terms hereof  (including  any  dividends,
distributions or cash paid in lieu of fractional shares) shall be deemed to have
been issued in full  satisfaction of all rights pertaining to such shares of A2S
Capital Stock,  and there shall be no further  registration  of transfers on the
records of the Surviving  Corporation  of shares of A2S Capital Stock which were
outstanding  immediately  prior to the Effective  Time.  If, after the Effective
Time,  Certificates  are presented to the Surviving  Corporation for any reason,
they shall be canceled and exchanged as provided in this Section 1.

                  1.10.  Taking of Necessary  Action;  Further  Action.  Each of
EMCON  and A2S  will  take all  such  reasonable  and  lawful  action  as may be
necessary or desirable in order to effectuate the Merger in accordance with this
Agreement as promptly as possible. If, at any time after the Effective Time, any
further  action is  necessary  or  desirable  to carry out the  purposes of this
Agreement  and to vest the  Surviving  Corporation  with full  right,  title and
possession to all assets, property, rights, privileges, powers and franchises of
A2S,  the officers and  directors of EMCON are fully  authorized  in the name of
their  corporation  or  otherwise  to take,  and will take,  all such lawful and
necessary  action,  so  long  as  such  action  is not  inconsistent  with  this
Agreement.

         2.       Conditions to the Merger.

                  2.1.  Conditions  to  Obligations  of Each Party to Effect the
Merger. The respective obligations of each party to this Agreement to consummate
and effect this  Agreement  and the  transactions  contemplated  hereby shall be
subject to the  satisfaction  at or prior to the  Effective  Time of each of the
following  conditions,  any of which may be waived, in writing,  by agreement of
all the parties hereto:

                           (a)      Shareholder Approval.  This  Agreement  and 
the Merger shall be approved and adopted by all of the shareholders of the A2S.

                           (b)      Board  Approval.  This  Agreement  and the
Merger shall be approved and adopted by the Board of Directors of EMCON and A2S.

                           (c)      No Injunctions or Restraints;  Illegality. 
No temporary  restraining  order,  preliminary or permanent  injunction or other
order issued by any court of competent jurisdiction or other legal or regulatory
restraint or prohibition  preventing the consummation of the Merger shall be and
remain in effect, nor shall any proceeding  brought by an administrative  agency
or commission or other governmental  authority or  instrumentality,  domestic or
foreign,  seeking any of the  foregoing be pending,  which would have a Material
Adverse  Effect  on  either  EMCON  or on  EMCON  combined  with  the  Surviving
Corporation  after the Effective  Time, nor shall there be any action taken,  or
any statute, rule, regulation or order enacted, entered, enforced

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<PAGE>


or deemed  applicable to the Merger,  which makes the consummation of the Merger
illegal.  In the event an injunction or other order shall have been issued, each
party agrees to use its reasonable  diligent  efforts to have such injunction or
other order lifted.
                           (d)      Governmental  Approval.  EMCON and A2S and 
their respective  subsidiaries shall have timely obtained from each Governmental
Entity (as defined below) all approvals, waivers and consents, if any, necessary
for   consummation  of  or  in  connection  with  the  Merger  and  the  several
transactions contemplated hereby, including such approvals, waivers and consents
as may be required  under the  Securities  Act,  under state Blue Sky laws,  and
under HSR other than filings and  approvals  relating to the Merger or affecting
EMCON's  ownership  of A2S or any of its  properties  if failure to obtain  such
approval, waiver or consent would not have a Material Adverse Effect on EMCON or
on EMCON combined with the Surviving Corporation after the Effective Time.

                  2.2.   Additional   Conditions  to  Obligations  of  A2S.  The
obligations of A2S to consummate and effect this Agreement and the  transactions
contemplated  hereby  shall be  subject to the  satisfaction  at or prior to the
Effective Time of each of the following conditions,  any of which may be waived,
in writing, by A2S:

                           (a)      Representations,  Warranties and Covenants.
The  representations and warranties of EMCON in this Agreement shall be true and
correct in all material respects (except for such representations and warranties
that  are  qualified  by  their  terms  by  a  reference  to  materiality  which
representations and warranties as so qualified shall be true in all respects) on
and as of the Effective Time as though such  representations and warranties were
made on and as of such time and EMCON shall have  performed  and complied in all
material  respects  with  all  covenants,  obligations  and  conditions  of this
Agreement  required to be performed  and complied with by it as of the Effective
Time.
                                    (b)     Certificate   of  EMCON.  A2S  shall
have  been  provided  with a  certificate  executed  on  behalf  of EMCON by its
President  and  its  Chief  Financial  Officer  to the  effect  that,  as of the
Effective Time:
                                     (i)    all  representations  and warranties
made by  EMCON  under  this  Agreement  are true and  complete  in all  material
respects (except for such  representations  and warranties that are qualified by
their terms by a reference to materiality which  representations  and warranties
as so qualified shall be true in all respects); and

                                    (ii)    all  covenants,  obligations  and  
conditions  of this  Agreement  to be  performed by EMCON on or before such date
have been so performed in all material respects.

                           (c)      No Material  Adverse  Changes.  Since the 
Balance Sheet Date, there shall not have occurred any material adverse change in
the financial  condition,  properties,  assets  (including  intangible  assets),
liabilities,  business,  operations  or results of  operations  of EMCON and its
subsidiaries, taken as a whole.
                           (d)      Third  Party   Consents.   A2S  shall  have 
been  furnished with evidence  satisfactory  to it of the consent or approval of
those  persons  whose  consent or approval is  required in  connection  with the
Merger.

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<PAGE>


                           (e)      Injunctions  or  Restraints  on Conduct of 
Business. No temporary restraining order, preliminary or permanent injunction or
other  order  issued by any court of  competent  jurisdiction  or other legal or
regulatory  restraint  provision  limiting  or  restricting  EMCON's  conduct or
operation of the business of EMCON and its  subsidiaries,  following  the Merger
shall be in effect, nor shall any proceeding brought by an administrative agency
or commission or other  Governmental  Entity,  domestic or foreign,  seeking the
foregoing be pending.
                           (f)      Legal  Opinion.  A2S shall have  received a 
legal opinion from EMCON's in house legal counsel in  substantially  the form of
Exhibit B-1.

                  2.3 Additional  Conditions to the  Obligations  of EMCON.  The
obligation of EMCON to consummate and effect this Agreement and the transactions
contemplated  hereby  shall be  subject to the  satisfaction  at or prior to the
Effective Time of each of the following conditions,  any of which may be waived,
in writing, by EMCON:

                           (a)      Representations,  Warranties and Covenants.
The  representations  and warranties of A2S in this Agreement  shall be true and
correct in all material respects (except for such representations and warranties
that  are  qualified  by  their  terms  by  a  reference  to  materiality  which
representations and warranties as so qualified shall be true in all respects) on
and as of the Effective Time as though such  representations and warranties were
made on and as of such time and A2S shall have  performed  and  complied  in all
material  respects  with  all  covenants,  obligations  and  conditions  of this
Agreement  required to be performed  and complied with by it as of the Effective
Time.

                           (b)      Certificate  of  A2S.  EMCON  shall  have  
been provided with a certificate  executed on behalf of A2S by its President and
Treasurer to the effect that, as of the Effective Time:

                                    (i)    all  representations  and  warranties
made by A2S under this Agreement are true and complete in all material  respects
(except for such  representations  and  warranties  that are  qualified by their
terms by a reference to materiality,  which representations and warranties as so
qualified shall be true in all respects); and

                                    (ii)    all  covenants,  obligations  and  
conditions of this  Agreement to be performed by A2S on or before such date have
been so performed in all material respects.

                           (c)      Third  Party Consents.   EMCON  shall  have 
been  furnished with evidence  satisfactory  to it of the consent or approval of
those  persons  whose  consent or approval is  required in  connection  with the
Merger.
                           (d)      Injunctions  or  Restraints  on Conduct of 
Business. No temporary restraining order, preliminary or permanent injunction or
other  order  issued by any court of  competent  jurisdiction  or other legal or
regulatory  restraint  provision  limiting  or  restricting  EMCON's  conduct or
operation  of the  business of A2S and its  subsidiaries,  following  the Merger
shall be in effect, nor shall any proceeding brought by an administrative agency
or commission or other  Governmental  Entity,  domestic or foreign,  seeking the
foregoing be pending.

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                           (e)      Legal  Opinion.  EMCON  shall have received 
a legal  opinion from A2S's legal counsel in  substantially  the form of Exhibit
B-2.
                           (f)      No Material  Adverse Changes in Business.  
Since the Balance Sheet Date, there shall not have occurred any material adverse
change in the financial  condition,  properties,  assets  (including  intangible
assets),  liabilities,  business,  operations  or results of  operations of A2S,
taken as a whole.
                           (g)      Employment and Non-Competition  Agreements.
Each  of  William  J.  Hengemihle  and  Christopher  M.  Wittenbrink  (the  "Key
Employees") shall have accepted  employment with Sub pursuant to the terms of an
Employment and Non-Competition  Agreement  substantially in the form attached as
Exhibit C.
                           (h)      Consulting  Agreement.  Timothy M.  Keaten  
shall  have  entered  a  short-term  consulting  agreement  with  the  Surviving
Corporation  in the form  attached  hereto as  Exhibit  D and a  non-competition
agreement  with terms  substantially  the same as those  entered into by the Key
Employees.
                           (i)      No Material  Adverse  Changes.  Except for 
the funds  borrowed from Wells Fargo Bank,  N.A. under the A2S line of credit to
purchase the  promissory  note issued by Marty  Cuerdon to Bonnie  Cuerdon dated
February 20, 1993 (the  "Cuerdon  Promissory  Note") (which was disclosed to and
consented  to by EMCON),  there shall not have  occurred  any  material  adverse
change  (including,  but not limited to, cash  distributions or decreases in net
assets) in the A2S Balance Sheet (as defined in Section 0 hereof) since February
28, 1998, other than in the ordinary course of business and consistent with past
practice.
                           (j)      Release of Security  Interests.  Except for 
the security interests that exist under the credit arrangements  between A2S and
Well Fargo  Bank,  N.A.,  and leases or purchase  money  security  interests  in
certain  equipment of A2S, the A2S  Shareholders  shall have  delivered to EMCON
written evidence legally sufficient to terminate any and all security interests,
liens or other encumbrances on the outstanding shares of A2S Common Stock or the
assets of A2S.

         3.  Representations  and Warranties of the A2S Shareholders.  Except as
disclosed  in a  document  of  even  date  herewith  and  delivered  by the  A2S
Shareholders  to EMCON prior to the execution and delivery of this Agreement and
referring to the  representations  and  warranties in this  Agreement  (the "A2S
Disclosure  Schedule"),  each A2S  Shareholder,  as to himself,  represents  and
warrants to EMCON as follows (any representation or warranty of A2S herein shall
be deemed to be a representation and warranty of each A2S Shareholder):

                  3.1.  Organization,  Standing and Power.  A2S is a corporation
duly  organized,  validly  existing and in good  standing  under the laws of its
jurisdiction of organization.  A2S has the corporate power to own its properties
and to carry on its business as now being  conducted and is duly qualified to do
business and is in good standing in each jurisdiction in which the failure to be
so qualified and in good standing  would have a Material  Adverse Effect on A2S.
A2S has delivered a true and correct copy of the Articles of  Incorporation  and
Bylaws or other  charter  documents,  as  applicable,  of A2S each as amended to
date, to EMCON. A2S is not in violation of any of the provisions of its Articles
of Incorporation or Bylaws or equivalent  organizational documents. A2S does not
directly or  indirectly  own any equity or similar  interest in, or any interest
convertible or exchangeable or exercisable  for, any equity or similar  interest
in, any corporation, partnership, joint venture or other business association or
entity.

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                  3.2.  Authority.  As of the  Closing  Date,  A2S will have all
requisite  corporate  power and  authority to enter into this  Agreement  and to
consummate the  transactions  contemplated  hereby.  As of the Closing Date, the
execution  and  delivery  of  this  Agreement  and  the   consummation   of  the
transactions contemplated hereby will have been duly authorized by all necessary
corporate  action on the part of A2S. The  affirmative  vote of the holders of a
majority of the shares of A2S Common  Stock  outstanding  on the record date for
the written consent of shareholders  relating to this Agreement is the only vote
of the holders of any of A2S's Capital  Stock  necessary  under  Colorado Law to
approve this  Agreement  and the  transactions  contemplated  hereby.  As of the
Closing Date, the Board of Directors of A2S shall have (i) unanimously  approved
this Agreement and the Merger, (ii) determined that in its opinion the Merger is
in the best interests of the  shareholders  of A2S and is on terms that are fair
to such  shareholders and (iii) recommended that the shareholders of A2S approve
this  Agreement  and the  Merger.  This  Agreement  has been duly  executed  and
delivered  by A2S and  constitutes  the  valid  and  binding  obligation  of A2S
enforceable  against  A2S  in  accordance  with  its  terms,  except  that  such
enforceability  may be limited by  bankruptcy,  insolvency,  moratorium or other
similar  laws  affecting  or relating to  creditors'  rights  generally,  and is
subject to general  principles  of equity.  The  execution  and delivery of this
Agreement by A2S does not, and the consummation of the transactions contemplated
hereby will not conflict  with,  or result in any violation of, or default under
(with or without  notice or lapse of time, or both),  or give rise to a right of
termination,  cancellation or acceleration of any material obligation or loss of
any material benefit under (i) any provision of the Articles of Incorporation or
Bylaws of A2S, as amended,  or (ii) any  material  mortgage,  indenture,  lease,
contract  or other  agreement  or  instrument,  permit,  concession,  franchise,
license,  judgment,  order, decree, statute, law, ordinance,  rule or regulation
applicable  to A2S or any of its  properties  or assets.  No consent,  approval,
order or  authorization  of, or  registration,  declaration  or filing with, any
court,  administrative  agency or commission or other governmental  authority or
instrumentality ("Governmental Entity") is required by or with respect to A2S in
connection with the execution and delivery of this Agreement or the consummation
of the  transactions  contemplated  hereby,  except  for (i) the  filing  of the
Certificate of Merger,  together with the required  officers'  certificates,  as
provided  in  Section  0,  (ii)  filings  required  under  Regulation  D of  the
Securities Act of 1933, (iii) such consents, approvals, orders,  authorizations,
registrations,  declarations  and  filings as may be required  under  applicable
state securities laws and the securities laws of any foreign country;  (iv) such
filings as may be required under the  Hart-Scott-Rodino  Antitrust  Improvements
Act of 1976, as amended  ("HSR");  and (v) such other consents,  authorizations,
filings,  approvals and registrations  which, if not obtained or made, would not
have a Material Adverse Effect on A2S and would not prevent, or materially alter
or delay any of the transactions contemplated by this Agreement.

                  3.3.  Governmental   Authorization.   A2S  has  obtained  each
federal, state, county, local or foreign governmental consent,  license, permit,
grant, or other authorization of a Governmental Entity (i) pursuant to which A2S
currently  operates or holds any interest in any of its  properties or (ii) that
is  required  for the  operation  of A2S's  business  or the holding of any such
interest  and all of such  authorizations  are in full force and  effect  except
where the failure to obtain or have any such authorizations could not reasonably
be expected to have a Material Adverse Effect on A2S.

                  3.4. Title to Property.  A2S has good and marketable  title to
all of its  properties,  interests in properties and assets,  real and personal,
reflected in the A2S Balance Sheet or acquired  after the A2S Balance Sheet Date
(except properties, interests in properties and assets

                                       27

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sold or otherwise  disposed of since the A2S Balance  Sheet Date in the ordinary
course of business),  and with respect to leased  properties  and assets,  valid
leasehold interests therein,  free and clear of all mortgages,  liens,  pledges,
charges or encumbrances of any kind or character, except (i) the lien of current
taxes not yet due and  payable,  (ii)  such  imperfections  of title,  liens and
easements as do not and will not  materially  detract from or interfere with the
use  of the  properties  subject  thereto  or  affected  thereby,  or  otherwise
materially impair business operations  involving such properties and (iii) liens
securing  debt which is  reflected  on the A2S Balance  Sheet.  The property and
equipment of A2S that are used in the  operations of its  businesses  are in all
material respects in good operating condition and repair, subject to normal wear
and tear. All material properties used in the operations of A2S are reflected in
the A2S Balance Sheet to the extent  generally  accepted  accounting  principles
require the same to be reflected. All leases to which A2S is a party are in full
force and effect and are valid, binding and enforceable in accordance with their
respective terms, except as such enforceability may be limited by (i) bankruptcy
laws and other  similar laws  affecting  creditors'  rights  generally  and (ii)
general principles of equity,  regardless of whether asserted in a proceeding in
equity or at law. True and correct  copies of all such leases have been provided
to EMCON.  A2S owns no real  property.  True and correct copies of all such real
property leases have been provided to EMCON.

                  3.5. Capital  Structure.  The authorized  capital stock of A2S
consists  of  200,000  shares  of A2S  Common  Stock and  100,000  shares of A2S
Preferred  Stock.  As of the Closing Date,  there will be issued and outstanding
66,000  shares of A2S Common  Stock and no shares of A2S  Preferred  Stock.  All
outstanding  shares of A2S Common  Stock are duly  authorized,  validly  issued,
fully paid and  non-assessable  and are free of any liens or encumbrances  other
than any liens or encumbrances  created by or imposed upon the holders  thereof,
and are not subject to preemptive  rights or rights of first refusal  created by
statute,  the  Articles of  Incorporation  or Bylaws of A2S or any  agreement to
which A2S is a party or by which it is bound.

                           Except for the rights created  pursuant to this  
Agreement,  there are no other options,  warrants, calls, rights, commitments or
agreements  of any  character  to  which  A2S is a party or by which it is bound
obligating  A2S to issue,  deliver,  sell,  repurchase  or redeem or cause to be
issued,  delivered,  sold,  repurchased  or redeemed,  any shares of A2S Capital
Stock or obligating A2S to grant, extend,  accelerate the vesting of, change the
price of, or  otherwise  amend or enter  into any such  option,  warrant,  call,
right,  commitment or agreement.  There are no other  contracts,  commitments or
agreements  relating  to voting,  purchase  or sale of A2S's  capital  stock (i)
between or among A2S and any of its  shareholders  and (ii) to A2S's  knowledge,
between or among any of A2S's shareholders. All shares of outstanding A2S Common
Stock were issued in compliance with all applicable federal and state securities
laws.
                  3.6.  Financial  Statements.  A2S has  delivered  to EMCON its
unaudited  financial  statements for each of the fiscal years ended December 31,
1997 and December 31, 1996,  respectively,  and interim financial statements for
the two month  period  ended  February 28, 1998  (collectively,  the  "Financial
Statements").  The Financial Statements are complete and correct in all material
respects and have been prepared in accordance with generally accepted accounting
principles  (except that the  Financial  Statements  do not have notes  thereto)
applied on a consistent  basis  throughout  the periods  indicated and with each
other.  The Financial  Statements  fairly  present the  financial  condition and
operating  results  of A2S as of the  dates,  and  for  the  periods,  indicated
therein,  subject to normal end of period  adjustments.  A2S  maintains and will
continue  to  maintain  a  standard   system  of  accounting   established   and
administered in accordance with generally accepted accounting principles.

                                       28
<PAGE>


                  3.7. Absence of Certain Changes.  Since February 28, 1998 (the
"A2S Balance Sheet Date"), A2S has conducted its business in the ordinary course
consistent with past practice and there has not occurred:  (i) any change, event
or  condition  (whether or not covered by  insurance)  that has  resulted in, or
might  reasonably  be expected to result in, a Material  Adverse  Effect to A2S;
(ii) any  acquisition,  sale or transfer of any material asset of A2S other than
in the ordinary course of business and consistent with past practice;  (iii) any
change in accounting methods or practices  (including any change in depreciation
or  amortization  policies or rates) by A2S or any  revaluation by A2S of any of
its assets;  (iv) any  declaration,  setting aside,  or payment of a dividend or
other  distribution  with respect to the shares of A2S or any direct or indirect
redemption, purchase or other acquisition by A2S of any of its shares of capital
stock; (v) any material contract entered into by A2S, other than in the ordinary
course of business  and as  provided  to EMCON,  or any  material  amendment  or
termination of, or default under, any material  contract to which A2S is a party
or by which it is  bound;  (vi) any  amendment  or  change  to the  Articles  of
Incorporation  or Bylaws of A2S;  (vii) any increase in or  modification  of the
compensation  or  benefits  payable  or to become  payable  by A2S to any of its
directors or employees;  or (viii) any negotiation or agreement by A2S to do any
of the things  described in the preceding  clauses (i) through (vii) (other than
negotiations  with  EMCON and its  representatives  regarding  the  transactions
contemplated by this Agreement). At the Effective Time, there will be no accrued
but unpaid dividends on shares of A2S's capital stock.

                  3.8. Absence of Undisclosed  Liabilities.  A2S has no material
obligations  or  liabilities  of any  nature  (matured  or  unmatured,  fixed or
contingent)  other than (i) those set forth or  adequately  provided  for in the
Balance Sheet for the period ended February 28, 1998 (the "A2S Balance  Sheet"),
(ii) those  incurred in the  ordinary  course of business and not required to be
set  forth  in  the  A2S  Balance  Sheet  under  generally  accepted  accounting
principles,  (iii) those  incurred in the ordinary  course of business since the
A2S  Balance  Sheet  Date and  consistent  with past  practice;  and (iv)  those
incurred in connection with the execution of this Agreement.

                  3.9.  Litigation.  There is no private or governmental action,
suit, proceeding, claim, arbitration or investigation pending before any agency,
court or tribunal,  foreign or domestic, or, to the knowledge of A2S, threatened
against A2S or any of their  respective  properties  or any of their  respective
officers or directors (in their capacities as such) that, individually or in the
aggregate,  could  reasonably be expected to have a Material  Adverse  Effect on
A2S. There is no judgment,  decree or order against A2S, or, to the knowledge of
A2S,  any of their  respective  directors or officers  (in their  capacities  as
such),  that could  prevent,  enjoin,  or  materially  alter or delay any of the
transactions  contemplated  by this  Agreement,  or  that  could  reasonably  be
expected to have a Material  Adverse  Effect on A2S. All litigation to which A2S
is a party  (or,  to the  knowledge  of A2S,  threatened  to  become a party) is
disclosed in the A2S Disclosure Schedule.

                  3.10.  Restrictions  on  Business  Activities.   There  is  no
agreement,  judgment,  injunction, order or decree binding upon A2S which has or
could  reasonably  be expected to have the effect of  prohibiting  or materially
impairing any current or future  business  practice of A2S, any  acquisition  of
property by A2S or the conduct of business by A2S as  currently  conducted or as
proposed to be conducted by A2S.

                  3.11.    Intellectual Property.

                           (a)      A2S owns and has good and marketable title 
to, or is licensed or otherwise possesses legally enforceable rights to use, all
patents, patent applications, trademarks,

                                       29

<PAGE>


                           trade names,  service marks,  copyrights (whether  
registered or unregistered),  and any applications therefor, maskworks, maskwork
applications,  net  lists,  schematics,  technology,  know-how,  trade  secrets,
inventory,  ideas,  algorithms,   processes,   computer  software  programs  and
applications  (in both  source  code and object  code  form),  client  lists and
tangible or  intangible  proprietary  information  and  material  ("Intellectual
Property") that are used or currently proposed to be used in the business of A2S
as currently  conducted  or as proposed to be  conducted  by A2S,  except to the
extent that the failure to have such rights has not had and would not reasonably
be expected to have a Material Adverse Effect on A2S. A2S is the exclusive owner
of all  Intellectual  Property.  A2S has not  licensed  any of the  Intellectual
Property on an exclusive basis.

                           (b)    All patents, registered  trademarks,  service 
marks  and  copyrights  held  by  A2S  are  valid  and  subsisting.  A2S  is not
infringing, misappropriating or making unlawful use of, and has not received any
notice or other communication (in writing or otherwise) of any actual,  alleged,
possible or  potential  infringement,  misappropriation  or unlawful  use of any
proprietary asset owned or used by any third party. A2S (i) has not been sued in
any suit,  action or proceeding  which involves a claim of  infringement  of any
patents, trademarks,  service marks, copyrights or violation of any trade secret
or other  proprietary  right of any third  party;  and (ii) has not  brought any
action,  suit or proceeding for infringement of Intellectual  Property or breach
of any license or agreement  involving  Intellectual  Property against any third
party.
                           (c)     All  current and  former officers,  employees
and  consultants  of A2S  have  executed  and  delivered  to  A2S  an  agreement
(containing  no  exceptions  or  exclusions  from  the  scope  of its  coverage)
regarding the protection of proprietary information and the assignment to A2S of
any  Intellectual  Property  arising  from  services  performed  for A2S by such
persons, the form of which has been supplied to EMCON.

                  3.12.  Interested Party  Transactions.  A2S is not indebted to
any  director,  officer,  employee  or agent of A2S  (except  for amounts due as
normal salaries and bonuses and in reimbursement of ordinary  expenses),  and no
such person is indebted to A2S.

                  3.13.  Minute Books. The minute books of A2S made available to
EMCON  contain a complete and accurate  summary of all meetings of directors and
shareholders  or actions by written consent since the time of  incorporation  of
A2S through the date of this Agreement, and reflect all transactions referred to
in such minutes accurately in all material respects.

                  3.14. Complete Copies of Materials.  A2S has delivered or made
available true and complete  copies of each document which has been requested by
EMCON or its counsel in  connection  with their legal and  accounting  review of
A2S.

                  3.15.  Material  Contracts.  All the  material  contracts  and
agreements  to which A2S is a party are listed in  Schedule  3.15  hereto.  With
respect to each agreement so listed: (i) the agreement is legal, valid,  binding
and  enforceable  and in full force and effect with respect to A2S, and to A2S's
knowledge is legal,  valid,  binding,  enforceable  and in full force and effect
with respect to each other party  thereto,  in either case subject to the effect
of  bankruptcy,  insolvency,  moratorium  or other  similar laws  affecting  the
enforcement of creditors'  rights  generally and except as the  availability  of
equitable  remedies  may be limited by general  principles  of equity;  (ii) the
agreement will continue to be legal, valid,  binding and enforceable and in full
force and effect immediately  following the Closing in accordance with the terms
thereof as in effect prior to the Closing,  subject to the effect of bankruptcy,
insolvency,  moratorium  or other  similar laws  affecting  the  enforcement  of
creditors' rights generally and except as the availability of equitable

                                       30
<PAGE>


remedies may be limited by general  principles of equity;  and (iii) neither the
A2S nor, to A2S's  knowledge,  any other party, is in breach or default,  and no
event has occurred which with notice or lapse of time would  constitute a breach
of default by A2S or, to A2S's  knowledge,  by any such other  party,  or permit
termination,  modification or  acceleration,  under the agreement.  A2S is not a
party to any material oral contract,  agreement or other  arrangement other than
as may be disclosed in Schedule 3.15 hereto.

                  3.16. Accounts  Receivable.  Subject to any reserves set forth
in the  Financial  Statements,  the accounts  receivable  shown on the Financial
Statements  represent and will represent  bona fide claims  against  debtors for
sales and other charges, are collectible in accordance with their terms at their
recorded  amounts  and are not  subject to  discount  except for normal cash and
immaterial  trade  discounts.  The amount  carried  for  doubtful  accounts  and
allowances  disclosed in the  Financial  Statements is sufficient to provide for
any losses which may be sustained on revaluation of the receivables.

                  3.17  Customers  and  Suppliers.  As of the  date  hereof,  no
customer which  individually  accounted for more than 5% of A2S's gross revenues
during the 12 month period preceding the date hereof and no supplier of A2S, has
canceled or otherwise terminated, or made any written threat to A2S to cancel or
otherwise  terminate  its  relationship  with A2S or has at any time on or after
February 28, 1998  decreased  materially  its services or supplies to A2S in the
case of any such  supplier,  or its usage of the  services or products of A2S in
the case of such customer, and to A2S's knowledge,  no such supplier or customer
has  indicated  either  orally or in writing  that it will  cancel or  otherwise
terminate its  relationship  with A2S or to decrease  materially its services or
supplies to A2S or its usage of the services or products of A2S, as the case may
be. A2S has not knowingly  breached,  so as to provide a benefit to A2S that was
not intended by the parties,  any agreement  with, or engaged in any  fraudulent
conduct with respect to, any customer or supplier of A2S.

                  3.18.  Employees and Consultants.  The A2S Disclosure Schedule
or a  letter  delivered  to  EMCON by A2S  contains  a list of the  names of all
employees and  consultants of A2S,  their  respective  salaries or wages,  other
compensation and dates of employment and positions.

                  3.19.    Environmental Matters

                           (a)  The following terms shall be defined as follows:

                                    (i)     "Environmental  Laws"  shall  mean
any  federal,  state or  local  laws,  ordinances,  codes,  regulations,  rules,
policies  and  orders  that  are  intended  to  assure  the  protection  of  the
environment,  or that classify,  regulate,  call for the remediation of, require
reporting  with  respect to, or list or define air,  water,  groundwater,  solid
waste,  hazardous  or  toxic  substances,   materials,   wastes,  pollutants  or
contaminants,  or which are intended to assure the safety of employees,  workers
or other persons, including the public.

                                     (ii)   "Hazardous  Materials"  shall  mean
any  toxic  or  hazardous  substance,  material  or waste  or any  pollutant  or
contaminant,  or  infectious  or  radioactive  substance or material,  including
without  limitation,  those  substances,  materials  and  wastes  defined  in or
regulated under any Environmental Laws.

                           (b)      A2S is not and has not been in violation of 
any  Environmental  Law relating to the properties or facilities of A2S at which
any part of A2S's business is or has been

                                       31

<PAGE>

conducted.  A2S has not used, generated,  manufactured or stored on or under any
part of its  properties or facilities at which any part of A2S's  business is or
has been  conducted,  or transported to or from any part thereof,  any Hazardous
Materials in violation of any applicable  Environmental Laws. There has not been
any presence,  disposal, or release of any Hazardous Materials on, from or under
any part of A2S's  properties or facilities at which any part of A2S's  business
is  or  has  been  conducted.  No  civil,  criminal  or  administrative  action,
proceeding  or  investigation  is pending  against  A2S, or to A2S's  knowledge,
threatened against A2S, and A2S is not aware of any facts or circumstances which
could  form  the  basis  for  assertion  of  a  claim  or  liability,  regarding
non-compliance with Environmental Laws relating to A2S's business.

                  3.20.  Taxes. As used in this Agreement,  the terms "Tax" and,
collectively,  "Taxes"  mean any and all  federal,  state and local taxes of any
country,  assessments and other governmental  charges,  duties,  impositions and
liabilities,  including taxes based upon or measured by gross receipts,  income,
profits,  sales,  use and  occupation,  and value added,  ad valorem,  transfer,
franchise,  withholding,  payroll,  recapture,  employment,  excise and property
taxes, together with all interest,  penalties and additions imposed with respect
to such amounts and any obligations  under any agreements or  arrangements  with
any other person with respect to such amounts and  including  any  liability for
taxes of a predecessor entity.

                           (a)      A2S  has  prepared  and  timely  filed  all
returns, estimates, information statements and reports required to be filed with
any taxing  authority  ("Returns")  relating to any and all Taxes  concerning or
attributable  to A2S or its  operations  with  respect  to Taxes for any  period
ending on or before the  Closing  Date and such  Returns are true and correct in
all  material  respects  and have been  completed  in all  material  respects in
accordance  with  applicable  law or an adequate  reserve has been made for such
Taxes on the A2S Balance Sheet.

                           (b)      A2S, as of the Closing Date:  (i) will have 
paid all Taxes shown to be payable on such  Returns  covered by Section 3.20 (a)
and (ii) will have withheld with respect to its employees all Taxes  required to
be withheld.

                           (c)      There is no Tax  deficiency  outstanding or 
assessed or, to the best of A2S's  knowledge,  proposed  against A2S that is not
reflected  as a liability  on the A2S  Balance  Sheet nor has A2S  executed  any
agreements or waivers  extending any statute of  limitations on or extending the
period for the assessment or collection of any Tax.

                           (d)      A2S has no material liabilities for unpaid 
Taxes  that  have  not  been  accrued for or reserved on the A2S Balance  Sheet,
whether asserted or unasserted, contingent or otherwise.

                           (e)  A2S is not a party to any tax-sharing  agreement
or  similar  arrangement with  any other  party, or any contractual  obligation
to  pay  any  Tax obligations of, or with  respect to  any transaction  relating
to, any other person or to  indemnify  any other person with respect to any Tax.

                           (f)      A2S's Returns have never been audited by a 
government  or  taxing  authority,  nor is any  such  audit in  process  or
pending,  and A2S  has not been notified of any request for such an audit or
other examination.
                           (g)     A2S has never been a member of an  affiliated
group of  corporations  filing a consolidated federal income tax return.

                                       32
<PAGE>



                           (h)      A2S  is not aware of any plan or  intention 
on  the  part of its  shareholders  to  engage  in  any  sale or sales of EMCON
Common Stock to be received pursuant to the Merger. For purposes of this Section
3.20  (h),  the  term  "sale"  shall  include  any  sale,  exchange,   transfer,
distribution,  redemption  or reduction in any way of the risk of ownership  (by
short sale or otherwise), or other disposition, whether direct or indirect.

                           (i)      A2S has made available to EMCON  copies of 
all Returns  filed for all periods since its inception.

                           (j)     A2S has not filed any consent agreement under
Section 341(f)  of the Code or agreed to have Section 341(f)(4) apply to any 
disposition of assets owned by A2S.

                           (k)      A2S has not been at any time a United States
Real Property Holding Corporation within the meaning of Section 897(c)(2) of the
Code.

                           (l)    A2S is not a party to any contract, agreement,

plan or  arrangement,  including  but  not  limited to the  provisions of this
Agreement, covering any employee or former employee of A2S that, individually or
collectively,  could give rise to the  payment  of any amount  that would not be
deductible by A2S as an expense under applicable law.

                           (m)     A2S does not currently and has never met the 
criteria of a Qualified  Personal Service Corporation as defined in the Internal
Revenue Code Section  448(d)(2)and Treasury Regulations Section 1.448-1T(e)(3).

                  3.21.    Employee Benefit Plans.

                           (a)     Schedule 3.21 lists, with respect to A2S and 
any  trade  or business (whether or not  incorporated)  which is treated  as  a
single  employer with A2S (an "ERISA  Affiliate")  within the meaning of Section
414(b),  (c),(m) or (o) of the Code, (i) all material employee benefit plans (as
defined in Section 3(3) of the Employee  Retirement Income Security Act of 1974,
as amended  ("ERISA")),  (ii) each loan to a  non-officer  employee in excess of
$10,000,  loans to officers and directors and any stock option,  stock purchase,
phantom stock, stock appreciation  right,  supplemental  retirement,  severance,
sabbatical,  medical,  dental,  vision care,  disability,  employee  relocation,
cafeteria  benefit (Code Section 125) or dependent care (Code Section 129), life
insurance  or accident  insurance  plans,  programs or  arrangements,  (iii) all
bonus,  pension,  profit sharing,  savings,  deferred  compensation or incentive
plans,  programs or  arrangements,  (iv) other fringe or employee benefit plans,
programs or arrangements  that apply to senior management of A2S and that do not
generally  apply to all employees,  and (v) any current or former  employment or
executive  compensation  or severance  agreements,  written or otherwise,  as to
which  unsatisfied  obligations  of A2S of greater than  $10,000  remain for the
benefit  of or  relating  to,  any  present or former  employee,  consultant  or
director of A2S (together, the "A2S Employee Plans").

                           (b)      A2S has  furnished to EMCON a copy of  each
of  the  A2S  Employee  Plans and related  plan  documents  (including  trust
documents,  insurance  policies or contracts,  employee  booklets,  summary plan
descriptions and other  authorizing  documents,  and, to the extent still in its
possession, any material employee communications relating thereto) and has, with
respect  to  each  A2S  Employee  Plan  which  is  subject  to  ERISA  reporting
requirements,  provided copies of the Form 5500 reports filed for the last three
plan years. Any A2S Employee Plan

                                       33
<PAGE>


intended  to  be  qualified  under  Section  401(a)  of  the  Code  has  either
obtained from the Internal Revenue Service a favorable  determination  letter as
to its qualified  status under the Code,  including  all  amendments to the Code
effected  by the Tax  Reform  Act of 1986  and  subsequent  legislation,  or has
applied to the Internal Revenue Service for such a determination letter prior to
the expiration of the requisite period under applicable Treasury  Regulations or
Internal Revenue Service pronouncements in which to apply for such determination
letter and to make any amendments necessary to obtain a favorable determination,
or has  been  established  under a  standardized  prototype  plan  for  which an
Internal  Revenue  Service  opinion letter has been obtained by the plan sponsor
and is valid as to the adopting employer.  A2S has also furnished EMCON with the
most recent Internal Revenue Service determination or opinion letter issued with
respect to each such A2S  Employee  Plan,  and  nothing has  occurred  since the
issuance of each such letter  which  could  reasonably  be expected to cause the
loss of the  tax-qualified  status  of any A2S  Employee  Plan  subject  to Code
Section 401(a).

                           (c)    (i) None of the A2S  Employee Plans  promises
or  provides  retiree  medical or  other  retiree  welfare  benefits  to  any
person; (ii) there has been no "prohibited transaction," as such term is defined
in Section 406 of ERISA and Section  4975 of the Code,  with  respect to any A2S
Employee Plan, which could  reasonably be expected to have, in the aggregate,  a
Material Adverse Effect;  (iii) each A2S Employee Plan has been  administered in
accordance with its terms and in compliance with the requirements  prescribed by
any and all  statutes,  rules and  regulations  (including  ERISA and the Code),
except as would not have, in the aggregate,  a Material Adverse Effect,  and A2S
and each subsidiary or ERISA  Affiliate have performed all material  obligations
required to be  performed  by them  under,  are not in any  material  respect in
default  under or violation of and have no knowledge of any material  default or
violation by any other party to, any of the A2S Employee Plans; (iv) neither A2S
or ERISA  Affiliate is subject to any liability or penalty  under  Sections 4976
through  4980 of the  Code or Title I of ERISA  with  respect  to any of the A2S
Employee  Plans;  (v) all material  contributions  required to be made by A2S or
ERISA  Affiliate to any A2S Employee  Plan have been made on or before their due
dates and a  reasonable  amount has been accrued for  contributions  to each A2S
Employee Plan for the current plan years; (vi) with respect to each A2S Employee
Plan,  no  "reportable  event"  within  the  meaning  of  Section  4043 of ERISA
(excluding any such event for which the thirty (30) day notice  requirement  has
been  waived  under the  regulations  to  Section  4043 of ERISA)  nor any event
described in Section 4062, 4063 or 4041 or ERISA has occurred;  and (vii) no A2S
Employee Plan is covered by, and neither A2S or ERISA  Affiliate has incurred or
expects to incur any  liability  under  Title IV of ERISA or Section  412 of the
Code.  With  respect  to each A2S  Employee  Plan  subject to ERISA as either an
employee pension plan within the meaning of Section 3(2) of ERISA or an employee
welfare  benefit  plan  within the  meaning of  Section  3(l) of ERISA,  A2S has
prepared  in good  faith and timely  filed all  requisite  governmental  reports
(which were true and correct as of the date filed) and has  properly  and timely
filed and distributed or posted all notices and reports to employees required to
be filed,  distributed or posted with respect to each such A2S Employee Plan. No
suit, administrative proceeding, action or other litigation has been brought, or
to the knowledge of A2S is  threatened,  against or with respect to any such A2S
Employee  Plan,  including  any audit or  inquiry  by the IRS or  United  States
Department of Labor.  Neither A2S or other ERISA Affiliate is a party to, or has
made any  contribution  to or  otherwise  incurred  any  obligation  under,  any
"multiemployer plan" as defined in Section 3(37) of ERISA.

                           (d)      With  respect to each A2S Employee  Plan,  
A2S  and  each  of its United States  subsidiaries  have  complied  with (i) the
applicable  health care  continuation and notice  provisions of the Consolidated
Omnibus Budget Reconciliation Act of 1985 ("COBRA").

                                       34
<PAGE>

and   the   proposed    regulations   thereunder   and  (ii)   the   applicable
requirements  of the Family  Leave Act of 1993 and the  regulations  thereunder,
except to the extent  that such  failure to comply  would not in the  aggregate,
have a Material Adverse Effect.

                           (e)      The  consummation of the  transactions  
contemplated  by  this  Agreement will  not (i) entitle  any  current  or former
employee  or other  service  provider  of A2S or any other  ERISA  Affiliate  to
severance  benefits  or  any  other  payment  (including,   without  limitation,
unemployment  compensation,  golden  parachute  or bonus),  except as  expressly
provided in this Agreement or (ii)  accelerate the time of payment or vesting of
any such benefits,  or increase the amount of compensation due any such employee
or service provider.

                           (f)      There  has been no amendment  to,  written 
interpretation  or  announcement  (whether or  not  written)  by  A2S  or  other
ERISA Affiliate  relating to, or change in  participation or coverage under, any
A2S Employee  Plan which would  materially  increase the expense of  maintaining
such Plan above the level of expense  incurred with respect to that Plan for the
most recent fiscal year included in A2S's financial statements.

                  3.22.  Employee  Matters.   A2S  is  in  compliance  with  all
currently   applicable  laws  and  regulations   respecting   discrimination  in
employment,  terms and conditions of employment,  wages,  hours and occupational
safety and health and employment practices, except for such noncompliance as has
not and would not  reasonably be expected to have had a Material  Adverse Effect
on A2S,  and is not engaged in any unfair labor  practice.  There are no pending
claims  against A2S under any workers'  compensation  plan or policy or for long
term disability. A2S has no material obligations under COBRA with respect to any
former employees or beneficiaries  thereunder.  There are no proceedings pending
or, to the knowledge of A2S,  threatened,  between A2S and its employees,  which
proceedings  have or could  reasonably  be expected  to have a Material  Adverse
Effect on A2S.  A2S is not a party to any  collective  bargaining  agreement  or
other labor union contract nor does A2S know of any activities or proceedings of
any labor union to organize its  employees.  There has been no claim against A2S
based on actual or alleged  race,  age, sex,  disability or other  harassment or
discrimination,  or similar tortious conduct, nor, to A2S's knowledge,  is there
any basis for such claim.  In addition,  A2S has provided all employees with all
relocation  benefits,  stock  options,  bonuses  and  incentives,  and all other
compensation earned up through the date of this Agreement.

                  3.23. Insurance.  Schedule 3.23 lists each policy of insurance
and bonds held by A2S. A2S has  policies of insurance  and bonds of the type and
in amounts customarily carried by persons conducting businesses or owning assets
similar to those of A2S.  There is no material  claim  pending under any of such
policies or bonds as to which coverage has been  questioned,  denied or disputed
by the  underwriters  of such  policies or bonds.  All  premiums due and payable
under all such  policies  and bonds  have  been  paid and A2S are  otherwise  in
compliance  with the terms of such  policies and bonds.  A2S has no knowledge of
any threatened termination of, or material premium increase with respect to, any
of such policies.

                  3.24.  Compliance  With Laws. A2S has complied with, is not in
violation of and has not received any notices of violation  with respect to, any
federal state,  local or foreign statute,  law or regulation with respect to the
conduct of its business,  or the ownership or operation of its business,  except
for such violations or failures to comply as could not be reasonably expected to
have a Material Adverse Effect on A2S.

                                       35
<PAGE>



                  3.25.  Brokers' and Finders' Fees.  A2S has not incurred,  nor
will it incur,  directly or indirectly,  any liability for brokerage or finders'
fees or agents'  commissions or investment  bankers' fees or any similar charges
in connection with this Agreement or any transaction contemplated hereby.

                  3.26. Ownership of Shares and Options.  Except as set forth in
the  A2S  Disclosure   Schedule,   each  A2S  Shareholder  owns  of  record  and
beneficially the number of shares of A2S Common Stock,  indicated  opposite such
A2S Shareholder's  name in Schedule 1.7 hereto,  as applicable,  with full right
and authority to sell or exchange, as applicable, such securities hereunder, and
upon delivery of such shares  hereunder,  EMCON 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 EMCON is a party.

                  3.27. Execution,  Delivery and Enforceability of Agreement; No
Violation.  This  Agreement has been duly executed and delivered by or on behalf
of each  A2S  Shareholder,  and at the  Closing  any  other  documents  required
hereunder to be executed and  delivered by or on behalf of each A2S  Shareholder
will have been duly  executed and  delivered.  This  Agreement  constitutes  the
legal, valid and binding obligation of each A2S Shareholder, enforceable against
such A2S Shareholder 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
each A2S  Shareholder at Closing will  constitute  the legal,  valid and binding
agreements of each A2S Shareholder executing the same,  enforceable against such
A2S Shareholder 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 transactions
contemplated  by each A2S  Shareholder  will  violate,  or  constitute a default
under,  or permit the  acceleration of maturity of, except to the extent waived,
and indentures,  mortgages,  promissory notes,  contracts or agreements to which
such A2S  Shareholder  is a party or by which such A2S  Shareholder  or such A2S
Shareholder's properties are bound.

                  3.28.  Information  Supplied.  To the  Knowledge  of each  A2S
Shareholder,  neither this  Agreement,  the A2S  Financial  Statements,  the A2S
Disclosure  Schedule,  the Exhibits  attached to this  Agreement,  nor any other
certificate  or  document  furnished  or to be  furnished  by  A2S  or  the  A2S
Shareholders  pursuant to the terms of this Agreement,  contains or will contain
any untrue  statement of a material fact known to the A2S  Shareholders  or A2S,
respectively,  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.

                  3.29.  Residence  and  Domicile.  Each  A2S  Shareholder  is a
resident of, and  domiciled in, the State  indicated on Schedule 1.7 hereto,  as
applicable, as being the residence of such A2S Shareholder.

                  3.30. Brokers or Finders. Neither the A2S Shareholders nor any
of such A2S  Shareholders'  agents have  incurred any  obligation  or liability,
contingent or otherwise,  for brokerage or finders' fees or agents'  commissions
or other similar payment in connection  with this Agreement or the  transactions
contemplated hereby.

                                       36
<PAGE>



                  3.31.  Representations  Complete. To A2S's knowledge,  none of
the  representations  or  warranties  made by A2S herein or in any  Schedule  or
Exhibit hereto,  including the A2S Disclosure Schedule, or certificate furnished
by A2S pursuant to this  Agreement or any written  statement  furnished to EMCON
pursuant hereto or in connection with the transactions contemplated hereby, when
all such documents are read together in their entirety, contain, or will contain
at the Effective Time any untrue  statement of a material fact, or omits or will
omit at the Effective Time to state any material fact necessary in order to make
the statements  contained herein or therein,  in the light of the  circumstances
under which made, not misleading;  provided,  however, that for purposes of this
representation,   any  document   attached  hereto  that  provides   information
inconsistent  with or in addition to any other  written  statement  furnished to
EMCON in connection with the transaction contemplated hereby, shall be deemed to
supersede  any other  document  or  written  statement  furnished  to EMCON with
respect to such inconsistent or additional information.

         4. Representations and Warrantees of EMCON and Sub. Except as disclosed
in a document of even date  herewith and  delivered by EMCON to A2S prior to the
execution and delivery of this  Agreement  and referring to the  representations
and  warranties in this  Agreement (the "EMCON  Disclosure  Schedule"),  each of
EMCON and Sub represents and warrants to A2S as follows:

                  4.1.Organization, Standing and Power. Each of EMCON and Sub is
a corporation  duly organized,  validly  existing and in good standing under the
laws of its jurisdiction of  organization.  EMCON has the corporate power to own
its  properties  and to carry on its  business  as now  being  conducted  and as
proposed to be  conducted  and is duly  qualified  to do business and is in good
standing in each  jurisdiction  in which the failure to be so  qualified  and in
good standing  would have a Material  Adverse  Effect on EMCON.  EMCON is not in
violation of any of the provisions of its Articles of Incorporation or Bylaws or
equivalent organizational documents.

                  4.2. Authority. EMCON and Sub each has all requisite corporate
power  and  authority  to  enter  into  this  Agreement  and to  consummate  the
transactions  contemplated  hereby. The execution and delivery of this Agreement
and the  consummation  of the  transactions  contemplated  hereby have been duly
authorized by all necessary  corporate action on the part of EMCON and Sub. This
Agreement has been duly executed and delivered by EMCON and Sub and  constitutes
the valid and binding obligation of EMCON and Sub. The execution and delivery of
this  Agreement do not and the  consummation  of the  transactions  contemplated
hereby will not conflict  with,  or result in any violation of, or default under
(with or without  notice or lapse of time, or both),  or give rise to a right of
termination,  cancellation or acceleration of any material obligation or loss of
a material  benefit under (i) any provision of the Articles of  Incorporation or
Bylaws of EMCON or any of its  subsidiaries,  as amended,  or (ii) any  material
mortgage,  indenture,  lease,  contract or other agreement or instrument permit,
concession,   franchise,   license,   judgment,  order,  decree,  statute,  law,
ordinance,  rule or regulation applicable to EMCON or any of its subsidiaries or
their properties or assets.  No consent  approval,  order or authorization of or
registration,  declaration or filing with, any Governmental  Entity, is required
by or with respect to EMCON or any of its  subsidiaries  in connection  with the
execution and delivery of this Agreement by EMCON or the  consummation  by EMCON
of the  transactions  contemplated  hereby,  except  for (i) the  filing  of the
Certificate of Merger,  together with the required  officers'  certificates,  as
provided  in  Section  0, (ii) the  filing of a Form D with the  Securities  and
Exchange  Commission  in  accordance  with  Regulation D following the Effective
Time, (iii) the filing of a Form 8-K with the Securities and Exchange Commission
("SEC") and National Association of

                                       37
<PAGE>


Securities  Dealers ("NASD")  within 15 days  after  the  Closing Date, (iv) any
filings  as may be  required  under  applicable  state  securities  laws and the
securities  laws of any  foreign  country,  (v) such  filings as may be required
under HSR,  (vi) the filing with the Nasdaq  National  Market of a  Notification
Form for Listing of Additional Shares with respect to the shares of EMCON Common
Stock issuable upon conversion of the A2S Common Stock in the Merger,  and (vii)
such other consents, authorizations, filings, approvals and registrations which,
if not obtained or made,  would not have a Material  Adverse Effect on EMCON and
would  not  prevent,   materially   alter  or  delay  any  of  the  transactions
contemplated by this Agreement.

                  4.3. SEC Documents:  Financial Statements. EMCON has furnished
to  A2S a true  and  complete  copy  of  each  statement,  report,  registration
statement  (with the prospectus in the form filed pursuant to Rule 424(b) of the
Securities Act), definitive proxy statement, and other filing filed with the SEC
by EMCON since December 31, 1997, and, prior to the Effective  Time,  EMCON will
have  furnished A2S with true and complete  copies of any  additional  documents
filed  with the SEC by EMCON  prior to the  Effective  Time  (collectively,  the
"EMCON  SEC  Documents").  In  addition,  EMCON  has made  available  to A2S all
exhibits  to the EMCON SEC  Documents  filed  prior to the date  hereof and will
promptly  make  available  to A2S  all  exhibits  to any  additional  EMCON  SEC
Documents filed prior to the Effective Time. All documents  required to be filed
as  exhibits to the EMCON SEC  Documents  have been so filed,  and all  material
contracts so filed as exhibits  are in full force and effect  except those which
have expired in  accordance  with their terms,  and neither EMCON nor any of its
subsidiaries is in default thereunder.  As of their respective filing dates, the
EMCON SEC Documents  complied in all material  respects with the requirements of
the  Securities  Exchange Act of 1934, as amended (the  "Exchange  Act") and the
Securities  Act  and  none of the  EMCON  SEC  Documents  contained  any  untrue
statement of a material  fact or omitted to state a material fact required to be
stated therein or necessary to make the statements made therein, in light of the
circumstances  in which they were  made,  not  misleading,  except to the extent
corrected by a  subsequently  filed EMCON SEC Document prior to the date hereof.
The financial statements of EMCON, including the notes thereto,  included in the
EMCON SEC Documents (the "EMCON Financial  Statements"),  complied as to form in
all material  respects  with  applicable  accounting  requirements  and with the
published  rules and  regulations  of the SEC with  respect  thereto as of their
respective  dates, and have been prepared in accordance with generally  accepted
accounting  principles  applied on a basis  consistent  throughout  the  periods
indicated  and  consistent  with each other  (except as may be  indicated in the
notes  thereto or, in the case of  unaudited  statements  included in  Quarterly
Reports  on Form  10-Qs,  as  permitted  by Form  10-Q of the  SEC).  The  EMCON
Financial  Statements  fairly present the consolidated  financial  condition and
operating  results  of EMCON and its  subsidiaries  at the dates and  during the
periods  indicated  therein (subject,  in the case of unaudited  statements,  to
normal,  recurring  yearend  adjustments).  There  has been no  change  in EMCON
accounting  policies  except as  described  in the notes to the EMCON  Financial
Statements.

                  4.4. Absence of Certain Changes.  Since December 31, 1997 (the
"EMCON  Balance Sheet  Date"),  EMCON has conducted its business in the ordinary
course consistent with past practice and there has not occurred: (i) any change,
event or condition  (whether or not covered by insurance)  that has resulted in,
or might  reasonably  be  expected  to result in, a Material  Adverse  Effect to
EMCON; (ii) any acquisition,  sale or transfer of any material asset of EMCON or
any of its  subsidiaries  other  than in the  ordinary  course of  business  and
consistent  with past  practice;  (iii)  any  change in  accounting  methods  or
practices  (including any change in  depreciation  or  amortization  policies or
rates)  by EMCON or any  revaluation  by  EMCON of any of its  assets;  (iv) any
declaration,  setting aside, or payment of a dividend or other distribution with
respect to

                                       38
<PAGE>


the  shares  of  EMCON,  or  any  direct or  indirect  redemption,  purchase  or
other  acquisition  by EMCON of any of its  shares  of  capital  stock;  (v) any
material  contract  entered into by EMCON,  other than in the ordinary course of
business and as provided to A2S or any material  amendment or termination of, or
default under, any material contract to which EMCON is a party or by which it is
bound;  (vi) any  amendment or change to EMCON's  Articles of  Incorporation  or
Bylaws;  or  (vii)  any  negotiation  or  agreement  by  EMCON  or  any  of  its
subsidiaries  to do any of the things  described  in the  preceding  clauses (i)
through (vi) (other than negotiations with A2S and its representatives regarding
the transactions contemplated by this Agreement).

                  4.5. Absence of Undisclosed Liabilities. EMCON has no material
obligations  or  liabilities  of any  nature  (matured  or  unmatured,  fixed or
contingent)  other than (i) those set forth or  adequately  provided  for in the
Balance  Sheet  included  in EMCON's  Annual  Report on Form 10-K for the period
ended December 31, 1997 (the "EMCON Balance Sheet"),  (ii) those incurred in the
ordinary  course  of  business  and not  required  to be set  forth in the EMCON
Balance Sheet under generally accepted  accounting  principles,  and (iii) those
incurred in the ordinary  course of business  since the EMCON Balance Sheet Date
and consistent with past practice.

                  4.6.  Litigation.  There is no private or governmental action,
suit, proceeding, claim, arbitration or investigation pending before any agency,
court or tribunal,  foreign or domestic, or, to the knowledge of EMCON or any of
its subsidiaries,  threatened against EMCON or any of its subsidiaries or any of
their respective properties or any of their respective officers or directors (in
their  capacities  as  such)  that,  individually  or in  the  aggregate,  could
reasonably be expected to have a Material  Adverse Effect on EMCON.  There is no
judgment,  decree or order against EMCON or any of its  subsidiaries  or, to the
knowledge of EMCON or any of its subsidiaries, any of their respective directors
or  officers  (in their  capacities  as such) that  could  prevent,  enjoin,  or
materially  alter  or  delay  any  of  the  transactions  contemplated  by  this
Agreement,  or that could  reasonably  be  expected  to have a Material  Adverse
Effect on EMCON.

                  4.7. Governmental  Authorization.  Except where the failure to
obtain or have any of such EMCON Authorizations could not reasonably be expected
to have a Material  Adverse Effect on EMCON,  EMCON and each of its subsidiaries
have  obtained  each  federal,  state,  county,  local or  foreign  governmental
consent, license, permit, grant, or other authorization of a Governmental Entity
(i)  pursuant to which EMCON or any of its  subsidiaries  currently  operates or
holds any  interest in any of its  properties  or (ii) that is required  for the
operation of EMCON's or any of its subsidiaries'  business or the holding of any
such interest ((i) and (ii) herein collectively called "EMCON  Authorizations"),
and all of such EMCON Authorizations are in full force and effect.

                  4.8.  Broker's and Finders' Fees. EMCON has not incurred,  nor
will it incur,  directly or indirectly,  any liability for brokerage or finders'
fees or agents'  commissions or investment  bankers' fees or any similar charges
in connection with this Agreement or any transaction contemplated hereby.

                  4.9. Compliance With Laws. Each of EMCON and Sub have complied
with,  are not in  violation  of and have not  received any notices of violation
with respect to, any federal state, local or foreign statute,  law or regulation
with respect to the conduct of its  business,  or the  ownership or operation of
its business,  except for such  violations or failures to comply as could not be
reasonably expected to have a Material Adverse Effect on EMCON or SUB.

                                       39
<PAGE>


                  4.10. Brokers' and Finders' Fees. EMCON has not incurred,  nor
will it incur,  directly or indirectly,  any liability for brokerage or finders'
fees or agents'  commissions or investment  bankers' fees or any similar charges
in connection with this Agreement or any transaction contemplated hereby.

                  4.11. Execution,  Delivery and Enforceability of Agreement; No
Violation.  This  Agreement has been duly executed and delivered by or on behalf
of each of EMCON  and Sub,  and at the  Closing  any  other  documents  required
hereunder to be executed and  delivered by or on behalf of each of EMCON and Sub
will have been duly  executed and  delivered.  This  Agreement  constitutes  the
legal,  valid  and  binding  obligation  of each of EMCON  and Sub,  enforceable
against  each  of  EMCON  and  Sub 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 each of EMCON and Sub at Closing will  constitute  the legal,
valid and binding  agreements of EMCON and Sub  executing the same,  enforceable
against each of EMCON and Sub 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  transactions  contemplated  by each of EMCON  and Sub will
violate,  or constitute a default under, or permit the  acceleration of maturity
of, except to the extent waived,  and indentures,  mortgages,  promissory notes,
contracts  or  agreements  to which each of EMCON and Sub is a party or by which
EMCON and Sub or EMCON's and Sub's properties are bound.

                  4.12.  `Information  Supplied.  To the  Knowledge of EMCON and
Sub, neither this Agreement,  the Exhibits  attached to this Agreement,  nor any
other certificate or document  furnished or to be furnished by each of EMCON and
Sub pursuant to the terms of this Agreement, contains or will contain any untrue
statement  of a material  fact  known to EMCON or Sub,  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.

                  4.13.  Representations Complete. To EMCON's knowledge, none of
the  representations  or  warranties  made by EMCON  herein  or in any  Schedule
hereto,  including the EMCON Disclosure  Schedule,  or certificate  furnished by
EMCON pursuant to this  Agreement,  or the EMCON SEC  Documents,  or any written
statement   furnished  to  A2S  pursuant   hereto  or  in  connection  with  the
transactions  contemplated  hereby, when all such documents are read together in
their  entirety,  contains  or will  contain  at the  Effective  Time any untrue
statement  of a  material  fact or omits or will omit at the  Effective  Time to
state any  material  fact  necessary in order to make the  statements  contained
herein or therein,  in the light of the  circumstances  under  which  made,  not
misleading;  provided,  however,  that for purposes of this representation,  any
document  attached  hereto that  provides  information  inconsistent  with or in
addition to any other written statement  furnished to A2S in connection with the
transactions  contemplated  hereby,  shall be  deemed  to  supersede  any  other
document or written statement furnished to A2S with respect to such inconsistent
or additional information.

         5.       Conduct Prior To The Effective Time.

                  5.1.  Conduct of Business of A2S and EMCON.  During the period
from  the  date of this  Agreement  and  continuing  until  the  earlier  of the
termination  of this  Agreement  or the  Effective  Time,  each of A2S and EMCON
agrees  (except to the extent  expressly  contemplated  by this  Agreement or as
consented to in writing by the other), to carry on its and its subsidiaries'

                                       40
<PAGE>


business  in  the  usual regular and ordinary course  in  substantially the same
manner as  heretofore  conducted;  to pay and to cause its  subsidiaries  to pay
debts and Taxes when due subject (i) to good faith  disputes  over such debts or
Taxes and (ii) in the case of Taxes of A2S, to EMCON's  consent to the filing of
material Tax Returns if  applicable;  to pay or perform other  obligations  when
due, and to use all reasonable  efforts to preserve intact its present  business
organizations,  keep available the services of its and its subsidiaries' present
officers and key employees and preserve its and its subsidiaries'  relationships
with customers, suppliers, distributors, licensors, licensees, and others having
business  dealings  with it or its  subsidiaries,  to the end  that  its and its
subsidiaries'  goodwill  and  ongoing  businesses  shall  be  unimpaired  at the
Effective Time. Each of A2S and EMCON agrees to promptly notify the other of (x)
any event or occurrence not in the ordinary  course of its or its  subsidiaries'
business,  and of any event which could have a Material  Adverse  Effect and (y)
any material change in its  capitalization as set forth in Sections 3.5. Without
limiting the foregoing,  except as expressly  contemplated  by this Agreement or
the A2S Disclosure  Schedule or the EMCON Disclosure  Schedule,  neither A2S nor
EMCON,  respectively,  shall do, cause or permit any of the following, or allow,
cause or  permit  any of its  subsidiaries  to do,  cause or  permit  any of the
following, without the prior written consent of the other:

                           (a)      Charter  Documents.   Cause or permit any  
amendments  to  its  Articles  of Incorporation or Bylaws;

                           (b)      Dividends;  Changes  in  Capital  Stock.  
Except  for (i) the  purchase of  the  Cuerdon  Promissory Note and the related
release of the 10,000  shares of A2S common stock  delivered as security for the
Cuerdon  Promissory  Note,  or (ii) as  otherwise  approved in writing by EMCON,
declare or pay any  dividends  on or make any other  distributions  (whether  in
cash,  stock or  property)  in respect of any of its  capital  stock,  or split,
combine  or  reclassify  any of its  capital  stock or issue  or  authorize  the
issuance of any other  securities  in respect of, in lieu of or in  substitution
for shares of its capital stock, or repurchase or otherwise acquire, directly or
indirectly,  any shares of its  capital  stock  except  from  former  employees,
directors  and  consultants  in  accordance  with  agreements  providing for the
repurchase of shares in connection  with any termination of service to it or its
subsidiaries;

                           (c)    Other. Take, or agree in writing or otherwise
to  take,  any  of  the  actions  described  in  Sections  5.1 (a) through (b)
above, or any action which would cause a material breach of its  representations
or  warranties  contained  in this  Agreement  or  prevent  it  from  materially
performing or cause it not to materially perform its covenants hereunder.

                  5.2.  Conduct of Business  of A2S.  During the period from the
date of this  Agreement and continuing  until the earlier of the  termination of
this Agreement or the Effective Time,  except as expressly  contemplated by this
Agreement or the A2S Disclosure Schedule,  A2S shall not do, cause or permit any
of the following, without the prior written consent of EMCON:

                           (a)      Material Contracts.  Enter into any material
contract  or commitment,  or violate, amend   or otherwise  modify or waive any
of the terms of any of its material contracts, other than in the ordinary course
of business consistent with past practice;

                           (b)      Issuance of  Securities.  Issue, deliver or 
sell or  authorize  or propose the  issuance, delivery  or  sale of, or purchase
or  propose  the  purchase  of, any shares of its  capital  stock or  securities
convertible into, or subscriptions, rights, warrants or options to acquire, or

                                       41
<PAGE>


other  agreements  or commitments of any character obligating it to issue any
such shares or other convertible securities;

                           (c)      Intellectual  Property.  Transfer  to any  
person or entity  any  rights to its Intellectual Property other than in the 
ordinary course of business consistent with past practice;

                           (d)      Exclusive  Rights.  Enter into or amend any
agreements  pursuant  to  which any  other party is granted exclusive marketing
or  other  exclusive  rights  of any type or scope  with  respect  to any of its
products or technology;

                           (e)      Dispositions.  Sell, lease,  license or 
otherwise  dispose of or  encumber any  of its  properties or assets  which  are
material  individually  or in the  aggregate,  to its  business,  except  in the
ordinary course of business consistent with past practice;

                           (f)      Indebtedness.  Incur any  indebtedness for 
borrowed  money  or  guarantee  any such indebtedness or issue or sell any debt 
securities or guarantee any debt securities of others;

                           (g)      Agreements.  Enter into, terminate or amend,
in  a  manner  which  will  adversely  affect  the  business  of A2S (i) any
agreement  involving  an  obligation  to pay or the right to receive  $10,000 or
more, (ii) any agreement relating to the license,  transfer or other disposition
or acquisition of  intellectual  property rights or rights to market or sell A2S
products,  or (iii) any other  agreement  which is material  to the  business or
prospects of A2S.

                            (h)     Payment of  Obligations.  Pay, discharge or 
satisfy  in  an  amount in  excess of  $10,000  in  the  aggregate,  any  claim,
liability or obligation (absolute,  accrued, asserted or unasserted,  contingent
or otherwise) arising other than in the ordinary course of business,  other than
the payment,  discharge or  satisfaction  of  liabilities  reflected or reserved
against in the A2S Financial Statements;

                           (i)      Capital  Expenditures.  Make any capital  
expenditures,  capital  additions  or  capital  improvements  except  in  the
ordinary course of business and consistent with past practice;

                           (j)      Insurance.  Materially  reduce the amount of
any  material  insurance  coverage provided by existing insurance policies;

                           (k)      Termination  or Waiver.  Terminate or waive 
any right of  substantial  value, other than in the ordinary course of business;

                           (l)      Employee Benefit Plans;  New  Hires; Pay 
Increases.  Adopt or  amend  any  employee  benefit or stock purchase or option
plan,  or hire any new employee,  pay any special bonus or special  remuneration
(except  payments made pursuant to written  agreements  outstanding  on the date
hereof),  or increase the salaries or wage rates of its employees  except in the
ordinary course of business in accordance with its standard past practice;

                           (m)      Severance Arrangements.  Grant any severance
or  termination  pay (i) to any  director  or  officer  or (ii) to any  other
employee except (A) payments made pursuant to written agreements  outstanding on
the date hereof or (B) grants which are made in the ordinary  course of business
in accordance with its standard past practice;

                                       42
<PAGE>



                           (n)      Lawsuits.  Commence a lawsuit  other than  
(i)  for  the  routine  collection  of bills,  (ii) in  such cases where it in
good faith determines that failure to commence suit would result in the material
impairment of a valuable aspect of its business,  provided that it consults with
EMCON  prior  to the  filing  of such a suit,  or  (iii)  for a  breach  of this
Agreement;
                           (o)      Acquisitions.  Acquire or agree to acquire 
by  merging  or consolidating  with, or by  purchasing a substantial portion of
the  assets  of,  or by any  other  manner,  any  business  or any  corporation,
partnership,  association or other business  organization or division thereof or
otherwise acquire or agree to acquire any assets which are material individually
or in the aggregate, to its business;

                           (p)      Taxes.  Other than in the  ordinary  course 
of  business,  make  or change  any  material  election  in  respect of Taxes,
adopt or change any accounting method in respect of Taxes, file any material Tax
Return or any  amendment  to a  material  Tax  Return,  enter  into any  closing
agreement,  settle any  material  claim or  assessment  in respect of Taxes,  or
consent to any extension or waiver of the  limitation  period  applicable to any
material claim or assessment in respect of Taxes;

                           (q)      Revaluation.  Revalue any of its assets,  
including without  limitation writing down the value of  inventory  or writing  
off notes or accounts  receivable  other than in the  ordinary  course of
business; or

                           (r)      Other.  Take or agree in  writing  or  
otherwise  to  take, any of the actions described in Sections 5.2 (a) through
(q)  above,   or  any  action  which  would  cause  a  material  breach  of  its
representations  or  warranties  contained in this  Agreement or prevent it from
materially  performing  or  cause it not to  materially  perform  its  covenants
hereunder.

         6.       Additional Agreements.

                  6.1      Payment of Additional Merger Consideration.

                           (a)      In addition to the Merger Consideration to 
be  delivered  the A2S  Shareholders at the Closing  pursuant to Sections 1.6
and 1.7 hereof,  the A2S  Shareholders  will be  eligible to earn as  additional
consideration  for the Merger,  an aggregate  earnout amount up to Three Hundred
Thousand  Dollars  ($300,000)  in the form of cash and EMCON  Common  Stock (the
"Additional Consideration"),  subject to the Surviving Corporation achieving the
milestones set forth below. The form of the aggregate  Additional  Consideration
to be paid to the A2S Shareholders (pro rata based on the total number of shares
of A2S  Capital  Stock  held by each A2S  Shareholder  immediately  prior to the
Effective  Time)  will be 50% in cash and 50% in  shares of  unregistered  EMCON
Common  Stock  valued at the closing  price of EMCON Common Stock as reported on
the Nasdaq  National  Market on the first  business day  following the end of an
Earnings Period (as defined below).

                           (b)      In the event that the Surviving Corporation 
achieves  the  pretax  income  milestones (the "Income Milestones"), subject to
the  conditions set forth below,  during the two twelve month periods  following
the Effective Time (the "Earnings  Period"),  EMCON agrees to deliver to the A2S
Shareholders the aggregate earn-out payments (the "Earnout  Payments") set forth
opposite each Earnings Period, all as set forth below.

                                       43
<PAGE>






           Earnings Period            Income Milestone         Earnout Payments


             Months 1-12                $500,000                  $150,000
             Months 13-24               $600,000                  $150,000

         The  calculation  of the  Surviving  Corporation's  pretax  income  for
purposes  of this  Section  7.1 will be based on the  application  of  Generally
Accepted  Accounting  Principles,  consistently  applied,  including  the use of
accrual  accounting.  For purposes of calculating the Income  Milestones,  EMCON
shall  not  allocate  any  portion  of its  general  corporate  overhead  to the
Surviving Corporation. Notwithstanding the foregoing, to the extent EMCON incurs
expenses (e.g.  insurance,  legal,  outside  accounting,  etc.) directly for the
benefit of the  Surviving  Corporation,  or  otherwise  provides  administrative
services for the benefit of the Surviving  Corporation,  the actual cost of such
items (i.e.,  without any markup) shall be charged to the Surviving  Corporation
for purposes of such calculation.

                  6.2     Operation and Management of the Surviving Corporation.

                           (a)      The parties to this Agreement agree that, 
unless  subsequently  changed  with  the approval of the Board of Directors of
the  Surviving  Corporation,  the  Surviving  Corporation  will  retain the name
"Advanced  Analytical  Solutions,  Inc." While name  retention is primarily  for
client relation purposes, it symbolically  signifies the reasonable  operational
autonomy of the Surviving Corporation desired by the parties.

                           (b)      Immediately following the Effective Time, 
William  J.  Hengemihle   ("Hengemihle")  and  Christopher  M.  Wittenbrink
("Wittenbrink") shall be elected to the offices of President and Vice President,
respectively,  of the Surviving Corporation.  Hengemihle will report directly to
Gene  Herson  in his role as the  President  of  EMCON's  Professional  Services
Division.

                           (c)      Immediately  following the Effective  Time,
the  Board  of  Directors  of  Surviving   Corporation   shall  consist  of
Hengemihle, Wittenbrink, Gary McEntee and Michael Momboisse.

                           (d)      The parties hereto agree that the Surviving
Corporation  will  have  reasonable  autonomy  concerning  its  business affairs
as a manner of principle.  However,  the Surviving  Corporation accepts and will
abide by EMCON's business and personnel policies.  In this regard, the Surviving
Corporation  agrees to at least meet the minimum  standards  established for all
EMCON  operations with respect to EMCON's  policies  regarding human  resources,
employee  benefits,  insurance  coverage,  accounting  policies and  procedures,
contract administration and risk management.

                           (e)      EMCON will assist the Surviving Corporation 
in  setting  up its accounting  systems to comply  with EMCON's standards.  This
shall include  accrual  accounting,  similar charts of accounts and  integration
with EMCON's Sacramento Accounting Center.

                           (f)     Following the Closing, EMCON may, at its sole
option,  pay off all outstanding long  term  debt of the  Surviving Corporation.

                                       44
<PAGE>


                  6.3. Future Grant of Options to Purchase Common Stock of EMCON
EMCON  agrees to reserve  options to purchase  an  aggregate  of Fifty  Thousand
(50,000) shares of EMCON Common Stock (the "Options") for issuance to Hengemihle
and Wittenbrink and other key managers of the Surviving  Corporation  Hengemihle
and  Wittenbrink  deem  appropriate,  if any. The parties hereto intend that the
Options will be incentive  stock  options  granted  pursuant to EMCON's new 1998
Stock  Option  Plan  (the  "Option  Plan").  Such  treatment  however,  will  be
conditioned upon the formal approval of the Option Plan by EMCON's  shareholders
at the annual meeting of shareholders to be held May 28, 1998 (the  "Shareholder
Meeting").  In the event the  shareholders  do not approve the Option Plan,  the
Options will be granted  pursuant to a  nonqualified  plan and will,  therefore,
qualify as nonqualified stock options. In any event, the Options granted will be
granted  subject to the standard  terms and  conditions of the EMCON's  existing
stock option plan and agreements which provides,  among other things, for a five
year term and vesting in equal  installments over a four year period. No Options
will be granted prior to the date of the Shareholder Meeting. The exercise price
of the  Options  will be set at the  closing  price  of  EMCON  Common  Stock as
reported on the Nasdaq National Market on the date of such grant.

                  6.4.   Participation  in   Pay-for-Performance   Program.  The
executive  officers and continuing  managers of Surviving  Corporation  shall be
eligible to participate in EMCON's Pay-for-Performance program (the "Performance
Program").  For the twelve month period immediately following the Effective Time
(the "First  Performance  Period"),  the amount  accrued  under the  Performance
Program shall equal 50% of all pretax  profits of the Surviving  Corporation  in
excess of $500,000.  For the twelve month period following the First Performance
Period, the amount accrued under the Performance  Program shall equal 50% of all
pretax profits of the Surviving Corporation in excess of $600,000. Allocation of
the respective bonus pools among the Surviving Corporation employees shall be at
the discretion of the executive officers of the Surviving  Corporation,  subject
only to general  oversight and written consent of the Compensation  Committee of
the Board of Directors of EMCON.

                    At the  Closing,  EMCON shall loan Timothy M. Keaten the sum
of Two Hundred Twenty-Five  Thousand Dollars ($225,000) pursuant to the terms of
a three year full  recourse  promissory  note (the "Note") and pledge  agreement
("Pledge  Agreement"),  in the form attached hereto as Exhibit E, secured by the
EMCON  Common  Stock  to be  issued  to  Mr.  Keaten  as an A2S  Shareholder  in
connection  with the Merger as set forth in Schedule 1.7 hereto.  The Note shall
be due and  payable in full after three  years and shall bear  interest  payable
quarterly  at the rate of 8% per  annum,  calculated  on the  basis of a 360 day
year.

                  6.6.     Access to Information.

                           (a)      A2S shall afford EMCON and its accountants,
counsel  and  other representatives,  reasonable  access during normal business
hours  during  the  period  prior  to the  Effective  Time to (i)  all of  A2S's
properties,  books,  contracts,  commitments  and  records,  and (ii) all  other
information  concerning  the business,  properties and personnel of A2S as EMCON
may  reasonably  request.  A2S agrees to  provide to EMCON and its  accountants,
counsel  and other  representatives  copies  of  internal  financial  statements
promptly upon request.  EMCON shall afford A2S and its accountants,  counsel and
other representatives, reasonable access during normal business hours during the
period prior to the Effective  Time to (i) all of EMCON's and its  subsidiaries'
properties,  books,  contracts,  commitments  and  records,  and (ii) all  other
information  concerning the business,  properties and personnel of EMCON and its
subsidiaries as A2S may

                                       45
<PAGE>

reasonably  request.  EMCON  agrees  to  provide to  A2S  and its  accountants,
counsel  and other  representatives  copies  of  internal  financial  statements
promptly upon request.

                           (b)      Subject to compliance with  applicable law,
from  the  date  hereof until  the Effective  Time, each of EMCON and A2S shall
confer on a regular and frequent basis with one or more  representatives  of the
other party to report operational  matters of materiality and the general status
of ongoing operations.

                           (c)      No information or knowledge obtained in any
investigation  pursuant to  this  Section  6.6 shall  affect or  be deemed to
modify any  representation or warranty contained herein or the conditions to the
obligations of the parties to consummate the Merger.

                  6.7.  Confidentiality.  The parties acknowledge that EMCON and
A2S have previously  executed a non-disclosure  agreement dated May 2, 1997 (the
"Non-Disclosure   Agreement"),   which   Non-Disclosure   Agreement   is  hereby
incorporated  herein by reference and shall continue in full force and effect in
accordance with its terms.

                  6.8. Public  Disclosure.  Unless  otherwise  permitted by this
Agreement,  EMCON and A2S shall consult with each other before issuing any press
release or otherwise  making any public statement or making any other public (or
non-confidential)  disclosure  (whether  or  not  in  response  to  an  inquiry)
regarding the terms of this Agreement and the transactions  contemplated hereby,
and neither  shall issue any such press  release or make any such  statement  or
disclosure  without the prior approval of the other (which approval shall not be
unreasonably  withheld),  except  as may be  required  by law or by  obligations
pursuant to any listing agreement with any national  securities exchange or with
the NASD.

                  6.9.  Consents;  Cooperation.  Each of  EMCON  and  A2S  shall
promptly apply for or otherwise seek, and use reasonable best efforts to obtain,
all consents and approvals required to be obtained by it for the consummation of
the Merger,  including  those required under HSR, and shall use reasonable  best
efforts to obtain all necessary consents, waivers and approvals under any of its
material  contracts in connection with the Merger for the assignment  thereof or
otherwise.

                  6.10. Legal Requirements.  Each of EMCON and A2S will take all
reasonable  actions  necessary to comply  promptly  with all legal  requirements
which  may  be  imposed  on  them  with  respect  to  the  consummation  of  the
transactions contemplated by this Agreement and will promptly cooperate with and
furnish  information to any party hereto  necessary in connection  with any such
requirements  imposed upon such other party in connection with the  consummation
of the transactions  contemplated by this Agreement and will take all reasonable
actions necessary to obtain (and will cooperate with the other parties hereto in
obtaining) any consent, approval, order or authorization of or any registration,
declaration or filing with, any Governmental Entity or other person, required to
be obtained or made in connection with the taking of any action  contemplated by
this Agreement.

                  6.11.  Blue Sky Laws.  EMCON  shall  take such steps as may be
necessary to comply with the securities  and blue sky laws of all  jurisdictions
which are  applicable  to the issuance of the EMCON  Common Stock in  connection
with the  Merger.  A2S shall  use its best  efforts  to  assist  EMCON as may be
necessary to comply with the securities  and blue sky laws of all  jurisdictions
which are  applicable in  connection  with the issuance of EMCON Common Stock in
connection with the Merger.

                                       46
<PAGE>



                  6.12.  Nonaccredited  Shareholders.  Prior to the Closing, A2S
shall not take any action,  including  the granting of employee  stock  options,
that  would  cause  the  number  of A2S  shareholders  who are  not  "accredited
investors"  pursuant to Regulation D  promulgated  under the  Securities  Act of
1933, as amended, to increase to more than 35 during the term of this Agreement.

                  6.13.  Listing of Additional  Shares.  Following the Effective
Time,  EMCON shall file with the Nasdaq National Market a Notification  Form for
Listing of  Additional  Shares with  respect to the shares of EMCON Common Stock
issuable upon conversion of the A2S Common Stock in the Merger.

                  6.14.  Expenses.  The  parties  will each pay their own legal,
accounting  and  professional  expenses  ("Expenses")  in  connection  with  the
transactions  contemplated  hereby. In the event the Merger is consummated,  the
Expenses  incurred by A2S and/or its  shareholders  up to an aggregate  total of
$20,000 shall be paid by EMCON.

                  6.15.  Registration  of Shares  Issued in the  Merger.  At the
Closing,  EMCON shall grant to the A2S Shareholders  certain registration rights
set forth in the EMCON Registration  Rights Agreement with respect to the shares
of EMCON Common Stock issued in the Merger.

                  6.16.  Personal  Guarantees.  From and after the Closing Date,
EMCON  agrees to work  diligently  to have each of  William  J.  Hengemihle  and
Timothy M. Keaten released from his obligations and liability under the Personal
Guarantees.  The term  "Personal  Guarantee"  shall mean the personal  financial
guarantees  given by each of  William J.  Hengemihle  and  Timothy M.  Keaten in
connection  with certain debt  obligations  of A2S as set forth on Schedule 6.16
hereto.


         7.       Termination, Amendment and Waiver

                  7.1. Termination. This Agreement may be terminated at any time
prior to the Effective  Time (with  respect to Section  7.1(b)  through  Section
7.1(d), by written notice by the terminating party to the other party):

                           (a)      by the mutual written consent of EMCON and 
A2S;

                           (b)      by either EMCON or A2S if the Merger shall 
not  have  been  consummated by April 11, 1998,  provided,  however,  that  the
right to  terminate  this  Agreement  under  this  Section  7.1 (b) shall not be
available  to any party  whose  failure to  fulfill  any  obligation  under this
Agreement  has been the cause of or  resulted  in the  failure  of the Merger to
occur on or before such date;

                           (c)      by  either  EMCON  or  A2S  if a  court  of
competent  jurisdiction  or  other  Governmental  Entity  shall  have issued  a
nonappealable  final order,  decree or ruling or taken any other action, in each
case  having the  effect of  permanently  restraining,  enjoining  or  otherwise
prohibiting the Merger,  except,  if the party relying on such order,  decree or
ruling  or other  action  has not  complied  with  its  obligations  under  this
Agreement;

                           (d)      by  either  EMCON or A2S, if there has been
a  breach  of  any representation, warranty,  covenant  or agreement on the part
of the other  party set forth in this  Agreement,  which  breach  (i) causes the
conditions set forth in Section 2.2 (a) or (b) (in the case

                                       47
<PAGE>


of  termination  by  EMCON)  or  Section  2.3 (a) or (b)  (in  the  case of
termination  by A2S) not to be  satisfied  and (ii)  shall not have  been  cured
within  ten (10)  business  days  following  receipt by the  breaching  party of
written notice of such breach from the other party

                  7.2.  Effect of  Termination.  In the event of  termination of
this  Agreement  as provided in Section  7.1,  there  shall be no  liability  or
obligation on the part of EMCON, A2S or their respective officers, directors, or
shareholders,  except to the  extent  that  such  termination  results  from the
willful breach by a party of any of its representations, warranties or covenants
set forth in this  Agreement;  provided  that the  provisions of Section 0 shall
remain in full force and effect and survive any termination of this Agreement.

                  7.3.  Amendment  This  Agreement may be amended by the parties
hereto,  by action taken or authorized by their respective  Boards of Directors.
This  Agreement may not be amended  except by an instrument in writing signed on
behalf of each of the parties hereto.

                  7.4.  Extension;  Waiver  At any time  prior to the  Effective
Time,  the parties  hereto,  by action taken or authorized  by their  respective
Boards of Directors, may, to the extent legally allowed, (i) extend the time for
the  performance  of any of the  obligations  or other acts of the other parties
hereto,  (ii)  waive any  inaccuracies  in the  representations  and  warranties
contained  herein or in any document  delivered  pursuant hereto and (iii) waive
compliance  with any of the  agreements  or  conditions  contained  herein.  Any
agreement on the part of a party hereto to any such extension or waiver shall be
valid only if set forth in a written instrument signed on behalf of such party.

         8.       General Provisions.

                  8.1. Notices. All notices and other  communications  hereunder
shall be in writing and shall be deemed duly  delivered if delivered  personally
(upon  receipt),  or three (3) business days after being mailed by registered or
certified mail, postage prepaid (return receipt requested),  or one (1) business
day after it is sent by reputable  nationwide overnight courier service, or upon
transmission,  if sent via  facsimile  (with  confirmation  of  receipt)  to the
parties at the following  address (or at such other address for a party as shall
be specified by like notice):


         (a)      if to EMCON, to:

                  EMCON
                  400 S. El Camino Real, Suite 1200
                  San Mateo, CA  94402
                  Attention:  R. Michael Momboisse, Chief Financial Officer
                  Fax:     (650) 375-0763

                  with a copy to:

                  Gray Cary Ware & Freidenrich LLP
                  400 Hamilton Avenue
                  Palo Alto, CA  94301
                  Attention:  Eric J. Lapp, Esq.
                  Fax:     (650) 328-6561

                                       48
<PAGE>


         (b)      if to A2S, to

                  Advanced Analytical Solutions, Inc.
                  1331 17th Street, Suite 600
                  Denver, CO  80202
                  Attention:  William J. Hengemihle, President
                  Fax:     (303) 295-2692

                  with a copy to:

                  Schlueter & Associates, P.C.
                  1050 Seventeenth Street, Suite 1700
                  Denver, Colorado 80265
                  Attention: Henry F. Schlueter
                  Fax:     (303) 292-3883

         (c)      if to the A2S Shareholders:

                  William J. Hengemihle
                  51 Casselberry Drive
                  Audubon, Pennsylvania 19403

                  Christopher M. Wittenbrink
                  2715 South Pierce Street
                  Denver, Colorado 80227

                  Timothy M. Keaten
                  3048 East Clairton Drive
                  Highlands Ranch, Colorado 80126
                  Fax: (303) 703-0527

                  with a copy to:

                  Schlueter & Associates, P.C.
                  1050 Seventeenth Street, Suite 1700
                  Denver, Colorado 80265
                  Attention: Henry F. Schlueter
                  Fax:     (303) 292-3883

                  8.2.  Definitions.  In this  Agreement  any  reference  to any
event,  change,  condition or effect being "material" with respect to any entity
or group of entities  means any  material  event,  change,  condition  or effect
related to the financial  condition,  properties,  assets (including  intangible
assets),  liabilities,  business,  operations  or results of  operations of such
entity or group of  entities.  In this  Agreement  any  reference to a "Material
Adverse Effect" with respect to any entity or group of entities means any event,
change  or  effect  that  is  materially  adverse  to the  financial  condition,
properties,  assets, liabilities,  business, operations or results of operations
of such entity and its  subsidiaries,  taken as a whole.  In this  Agreement any
reference to a party's  "knowledge"  means such party's actual  knowledge  after
reasonable  inquiry of  officers,  directors  and other  employees of such party
reasonably believed to have knowledge of such matters.

                                       49
<PAGE>


                  8.3.  Counterparts  This  Agreement  may be executed in one or
more  counterparts,  all of which shall be considered one and the same agreement
and shall become  effective  when one or more  counterparts  have been signed by
each of the parties and delivered to the other parties, it being understood that
all parties need not sign the same counterpart.

                  8.4. Entire Agreement; Nonassignability;  Parties in Interest.
This  Agreement  and  the  documents  and  instruments   and  other   agreements
specifically  referred to herein or delivered  pursuant  hereto,  including  the
Exhibits,  the Schedules,  including the A2S  Disclosure  Schedule and the EMCON
Disclosure  Schedule (a) constitute the entire  agreement among the parties with
respect to the subject  matter  hereof and supersede  all prior  agreements  and
understandings,  both  written and oral,  among the parties  with respect to the
subject  matter hereof  except for the  Confidentiality  Agreement,  which shall
continue in full force and effect,  and shall  survive any  termination  of this
Agreement or the Closing,  in accordance with its terms; (b) are not intended to
confer upon any other person any rights or remedies hereunder,  and shall not be
assigned by  operation of law or  otherwise  without the written  consent of the
other party.

                  8.5.  Severability.  In the event that any  provision  of this
Agreement,  or the  application  thereof  becomes or is  declared  by a court of
competent  jurisdiction to be illegal,  void or unenforceable,  the remainder of
this  Agreement  will continue in full force and effect and the  application  of
such  provision to other  persons or  circumstances  will be  interpreted  so as
reasonably to effect the intent of the parties hereto. The parties further agree
to replace such void or  unenforceable  provision of this Agreement with a valid
and  enforceable  provision  that will  achieve,  to the  extent  possible,  the
economic, business and other purposes of such void or unenforceable provision.

                  8.6. Remedies Cumulative. Except as otherwise provided herein,
any and all  remedies  herein  expressly  conferred  upon a party will be deemed
cumulative with and not exclusive of any other remedy  conferred  hereby,  or by
law or equity  upon such  party,  and the  exercise by a party of any one remedy
will not preclude the exercise of any other remedy.

                  8.7.  Governing Law. This  Agreement  shall be governed by and
construed in accordance with the laws of California that might otherwise  govern
under  applicable  principles  of conflicts of law.  Each of the parties  hereto
irrevocably  consents to the exclusive  jurisdiction of any court located within
San Mateo County, State of California,  in connection with any matter based upon
or arising  out of this  Agreement  or the  matters  contemplated  hereby and it
agrees that process may be served upon it in any manner  authorized  by the laws
of the State of  California  for such  persons and waives and  covenants  not to
assert or plead any objection which it might otherwise have to such jurisdiction
and such process.

                    The parties hereto agree that they have been  represented by
counsel during the negotiation, preparation and execution of this Agreement and,
therefore,  waive the  application  of any law,  regulation,  holding or rule of
construction  providing that  ambiguities in an agreement or other document will
be construed against the party drafting such agreement or document.


                                       50

<PAGE>


         IN WITNESS WHEREOF,  A2S, EMCON and the Shareholders' Agent have caused
this Agreement to be executed and delivered by each of them or their  respective
officers thereunto duly authorized, all as of the date first written above.

"EMCON"

EMCON

By:    \o\ R. Michael Momboisse
       ----------------------------

Name:  R. Michael Momboisse
       ----------------------------

Title: CFO and VP Legal
       ----------------------------


"SUB"

ADVANCED ANALYTICAL SOLUTIONS 
   DELAWARE , INC.,
   a Delaware corporation

By:    \o\ R. Michael Momboisse
       ----------------------------

Name:  R. Michael Momboisse
       ----------------------------

Title: President
       ----------------------------


"A2S"
ADVANCED ANALYTICAL SOLUTIONS, 
   INCORPORATED,
   a Colorado corporation

By:    \o\ William J. Hengemihle
      ----------------------------

Name:  William J. Hengemihle
      ----------------------------

Title: President
      ----------------------------


                                       51


<PAGE>







"A2S SHAREHOLDERS"

\o\  William J. Hengemihle
------------------------------
William J. Hengemihle


\o\ Christopher M. Wittenbrink
------------------------------
Christopher M. Wittenbrink


\o\ Timothy M. Keaten
------------------------------
Timothy M. Keaten



                                       52
<PAGE>


List of Exhibits

Exhibit A             -        Certificate of Merger

Exhibit B-1           -        Legal Opinion of EMCON

Exhibit B-2           -        Legal Opinion A2S

Exhibit C             -        Employment and Non-Competition Agreement

Exhibit D             -        Consulting Agreement

Exhibit E             -        Promissory Note and Pledge Agreement

Exhibit F             -        Registration Rights Agreement


                                       53
<PAGE>

<TABLE>
<CAPTION>

                                                   Schedule 1.7

                                               Merger Consideration

    A2S SHAREHOLDER           STATE OF              NO. SHARES A2S                    CASH                        EMCON
                              RESIDENCE              COMMON STOCK                  CONSIDERATION               COMMON STOCK
    ---------------           --------              --------------                 -------------               ------------  
<S>                         <C>                          <C>                        <C>                            <C>

 William J. Hengemihle      Pennsylvania                 30,000                     $272,727                       55,944

   Timothy M. Keaten          Colorado                   30,000                     $272,727                       55,944

     Christopher M.           Colorado                    6,000                      $54,545                       11,189
      Wittenbrink

         Total                                           66,000                     $599,999                      123,077

</TABLE>

                                       54