EXECUTIVE RETENTION AGREEMENT


         This  Agreement  between  Gregory A. Thornton  (you) and Harding Lawson
Associates Group Inc.  (Company) have been entered into as of February 17, 1999.
This  Agreement  promises  you  severance  benefits  if,  following  a Change of
Control,  a Potential Change in Control or a Change of Management,  (referred to
collectively  hereafter as the  "Change")  you are  terminated  without Cause or
resign for Good Reason during the Term of this Agreement.  Capitalized terms are
defined in the last section of this Agreement.

1. Purpose

         The  Company  considers  a  sound  and  vital  management  team  to  be
essential.  Management personnel who become concerned about the possibility that
the  Company  may  undergo a Change in  Control  or a Change in  Management  may
terminate employment or become distracted. Accordingly, the Board has determined
that  appropriate  steps should be taken to minimize the distraction  executives
may suffer from the  possibility of a Change in Control or Management.  One step
is to enter into this Agreement with you.

2. Your Promise

         If one or more of the events set forth in section 3 below occur  during
the Term of this  Agreement,  you  promise  not to  resign  for at least 12 full
calendar  months  except as  follows:  (a) you may  resign if you are given Good
Reason to do so; and (b) you may  terminate  employment on account of retirement
on or after attaining age 65 or because you become unable to work due to serious
illness or injury.

3. Events That Trigger Severance Benefits

(a) Termination After a Change in Management

         You will receive Severance Benefits under this Agreement if, during the
Term of this Agreement and within twelve months after a Change in Management has
occurred, your employment is terminated by the Company without Cause (other than
on account of your Disability) or you resign for Good Reason.

(b) Termination After a Change in Control

         You will receive Severance Benefits under this Agreement if, during the
Term of this  Agreement  and within  twelve months after a Change in Control has
occurred, your employment is terminated by the Company without Cause (other than
on account of your Disability) or you resign for Good Reason.

(c) Termination After a Potential Change in Control

         You also will  receive  Severance  Benefits  under this  Agreement  if,
during the Term of this  Agreement  and within  twelve  months after a Potential
Change in Control has occurred but before a Change in Control  actually  occurs,
your  employment is  terminated  by the Company  without Cause or you resign for
Good Reason,  but only if either:  (i) you are  terminated at the direction of a
Person who has entered into an agreement  with the Company that will result in a
Change in Control;  or (ii) the event  constituting  Good  Reason  occurs at the
direction of such Person.

(d) Successor Fails To Assume This Agreement

         You also will  receive  Severance  Benefits  under this  Agreement  if,
during the Term of this  Agreement,  a successor to the Company  fails to assume
this Agreement, as provided in Section 13(a).

4. Events That Do Not Trigger Severance Benefits

         You will not be entitled to Severance  Benefits if your employment ends
because you are  terminated for Cause or on account of Disability or because you
resign without Good Reason,  retire, or die. Except as provided in Section 3(c),
you will not be entitled to  Severance  Benefits  while you remain  protected by
this  Agreement and remain  employed by the Company,  its  affiliates,  or their
successors.

5. Termination Procedures

         If you are  terminated  by the Company  after the Change and during the
Term of this Agreement,  you will receive written notice of your  termination If
you are being  terminated for Cause,  your notice of termination  will include a
copy of a  resolution  duly adopted by the  affirmative  vote of not less than a
majority of the entire membership of the Board (at a meeting of the Board called
and held for the  purpose of  considering  your  termination  (after  reasonable
notice to you and an opportunity for you and your counsel to be heard before the
Board))  finding that,  in the good faith  opinion of the Board,  Cause for your
termination exists and specifying the basis for that opinion in detail.

6. Severance Benefits

(a) In General

         If you become entitled to Severance Benefits under this Agreement,  you
may receive all of the Severance Benefits  described in this Section.  Severance
benefits will be payable to you following your termination of employment only if
you deliver to the Company (on the form and by the deadline it prescribes)  your
executed  general release of all claims you may have against the Company and its
affiliates  relating to your termination of employment,  other than claims under
this Agreement,  indemnification rights for your acts in the course and scope of
your employment, or under ERISA-regulated employee benefit plans of the Company.

(b) Lump-Sum Payment in Lieu of Future Compensation

         In lieu  of any  further  cash  compensation  for  periods  after  your
employment ends, you will be paid a cash lump sum equal to 1.0 times your annual
base  salary  in effect  when your  employment  ends or,  if  higher,  in effect
immediately  before the  Change,  or Good Reason  event for which you  terminate
employment

(c) Group Insurance Benefit Continuation

         During the period  that begins  when you become  entitled to  Severance
Benefits  under  this  Agreement  and ends on the last day of the 12th  calendar
month beginning thereafter, the Company shall provide, at no cost to you or your
spouse or  dependents,  the life,  disability,  accident,  and health  insurance
benefits (or  substantially  similar  benefits) it was providing to you and your
spouse  and  dependents  immediately  before you became  entitled  to  Severance
Benefits under this Agreement (or  immediately  before a benefit  reduction that
constitutes  Good Reason,  if you  terminate  employment  for that Good Reason).
These benefits shall be treated as satisfying the Company's  COBRA  obligations.
After benefit  continuation  under this subsection ends, you and your spouse and
dependents will be entitled to any remaining COBRA rights.

(d) Acceleration of Vesting under Stock Option Plans

         To the extent  permitted by the terms of the plans or under  applicable
law,  your rights to options  granted  under any of the  Company's  stock option
plans shall be immediately vested.

(e) Allowance for Professional Services

         You will receive an allowance of $10,000 for your use for outplacement,
legal services,  tax advice, or other  professional  services in connection with
the  termination  of your  employment  with the Company.  Upon  presentation  of
invoices,  the  Company  will  pay the  service  providers  directly  until  the
allowance has been  exhausted.  If any balance  remains in the allowance fund at
the end of six months following termination, that balance will be paid to you in
a lump sum;  the unused  balance  shall be  determined  on the basis of invoices
received  by the  Company  on or before  the end of the  allowance  period.  The
Company shall have no other  responsibility  for expenses incurred by you except
as otherwise set forth in this Agreement.

(f) Payment of Accrued Personal Time Off ("PTO")

         The Company will pay you all PTO that has accrued through the date your
employment terminates. No additional PTO shall accrue thereafter.

(g)  Deferred Compensation Plans

         Your vested rights under the Company's  401(k) Salary Deferral Plan and
the Company's Rabbi Trust  Non-Qualified  Salary Deferral Plan shall continue to
be governed by the terms and  conditions of the Plan  documents  and  applicable
law.

7. Time for Payment

         You will be paid your cash Severance  Benefits within 15 days after you
become entitled to Severance Benefits under this Agreement (e.g., within 15 days
following your termination of employment

8. Relation to Other Severance Programs

         Your  Severance  Benefits  under  this  Agreement  are in  lieu  of any
severance  or  similar  benefits  that may be  payable  to you  under  any other
employment  agreement or other arrangement;  to the extent any such benefits are
paid to you,  they  shall be  applied  to  reduce  the  amount  due  under  this
Agreement.  This Agreement  constitutes the entire agreement between you and the
Company and its affiliates  with respect to such benefits.  Notwithstanding  any
other  provision of this  Agreement,  if you are  terminated  for any reason not
addressed by this Agreement,  other than termination for Cause, you will receive
separation benefits consistent with the Companys written severance policy or six
months salary, whichever is greater.

9. Disability

         Following  a Change in  Control,  while you are  absent  from work as a
result of physical or mental illness,  the Company will continue to pay you your
full salary and provide you all other  compensation  and benefits payable to you
under the Company's  compensation or benefit plans,  programs,  or arrangements.
These  payments  will  stop if and when your  employment  is  terminated  by the
Company for Disability or at the end of the Term of this Agreement, whichever is
earlier.  Severance  Benefits  under this  Agreement  are not payable if you are
terminated on account of your Disability.

10. Effect of Reemployment

         Your Severance  Benefits will not be reduced by any other  compensation
you earn or could have earned.

11. Successors

(a) Assumption Required

         In  addition  to  obligations  imposed  by  law on a  successor  to the
Company,  during  the  Term of this  Agreement  the  Company  will  require  any
successor to all or  substantially  all of the business or assets of the Company
expressly  to assume and to agree to perform  this  Agreement in the same manner
and to the same extent that the Company was required to perform.  If the Company
fails to obtain such an assumption and agreement  before the effective date of a
succession, you will be entitled to Severance Benefits as if you were terminated
by the  Company  without  Cause  on  the  effective  date  of  that  succession.
Notwithstanding  the  foregoing,  you and the  Company or its  successor  may in
writing agree to replace or modify the terms of this Agreement.

(b) Heirs and Assigns

         This  Agreement  will inure to the benefit of, and be  enforceable  by,
your personal or legal representatives,  executors, administrators,  successors,
heirs,  distributees,  devisees,  and  legatees.  If you die while any amount is
still  payable  to you under this  Agreement,  that  amount  will be paid to the
executor, personal representative, or administrator of your estate.

12. Amendments

         This Agreement may be modified only by a written agreement  executed by
you and the Chairman of the Board of Directors of the Company.

13. Governing Law

         This Agreement creates a "top hat" employee benefit plan subject to the
Employee  Retirement  Income  Security Act of 1974, and it shall be interpreted,
administered, and enforced in accordance with that law; the Company is the "plan
administrator."  To the extent that state law is  applicable,  the  statutes and
common law of the State of California  (excluding  its choice of law statutes or
common law) shall apply.

14.  Dispute Resolution

(a) Sole Remedy

                  Both you and the  Company  agree  that the sole and  exclusive
remedy for any alleged breach of this  Agreement by the other,  or for any other
dispute  arising out of any act or  omission  of you or the  Company  affecting,
involving or relating to this Agreement,  shall be final and binding arbitration
conducted  by and pursuant to the  Employment  Dispute  Resolution  Rules of the
American Arbitration Association in the County of San Francisco, California. The
Parties expressly waive venue in any other county or state in which they live or
might live.

(b) Time

         Before demanding  arbitration,  the Party making the demand shall serve
written notice upon the other Party of the alleged breach or claim. Such written
notice  must be served by hand  delivery  or by being  placed in the U.S.  Mail,
postage pre-paid,  return receipt requested,  or with an overnight mail delivery
service,  not more than  ninety  (90) days  after the  breach or after the claim
arises.  Failure  timely to serve such notice  shall  constitute a waiver of the
claim. The party upon whom the notice is served shall have thirty (30) days from
the date of receipt of the notice to respond.  If the party upon whom the notice
is served  fails to respond  within that time,  of if the claim is not  resolved
within  that  time,  the  party  seeking  arbitration  must  serve a demand  for
arbitration upon the American Arbitration Association within fourteen (14) days.
Failure timely to serve the demand shall constitute a waiver of the claim.

(c) Expenses and Attorneys' Fees

         The  prevailing  party in any such  proceeding,  as  determined  by the
arbitrator,  shall be entitled to an award of its reasonable attorneys' fees and
costs, including the full cost of the arbitration.

15. Limitation on Employee Rights

         This  Agreement  does  not give you the  right  to be  retained  in the
service of the Company.

16. Validity

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

17. Counterparts

         This Agreement may be executed in several  counterparts,  each of which
will be deemed an original,  but all of which will  constitute  one and the same
instrument.

18. Giving Notice

(a) To the Company

         All  communications  from you to the Company relating to this Agreement
must be sent to the  Company in writing,  addressed  as follows (or in any other
manner the Company notifies you to use):

         If Mailed           Harding Lawson Associates
                             Attention: Greg Klein
                             7655 Redwood Boulevard
                             P. O. Box 578
                             Novato, California 94948


         If Faxed            Harding Lawson Associates
                             Attention: Greg Klein
                             Fax:  (415) 892 - 0685
                             Tel.: (415) 892 - 0821

(b) To You

         All  communications  from the Company to you relating to this Agreement
must  be sent  to you in  writing,  addressed  as  indicated  at the end of this
Agreement.

19. Definitions

(a) Agreement

         "Agreement" means this contract, as amended.

(b) Beneficial Owner

         "Beneficial Owner" has the meaning set forth in Rule 13d-3 under the
Exchange Act.

(c) Board

         "Board" means the Board of Directors of the Company.

(d) Cause

         "Cause" means any of the following:

         (1)      Willful Failure to Perform Duties.  You continue  willfully to
                  fail to perform  your duties for the  Company  after a written
                  demand for  performance has been delivered to you by the Board
                  that  specifically  identifies how you have failed to perform.
                  Your  conduct  will  not  be   considered   "willful"  if  you
                  reasonably believed that you were acting in the best interests
                  of the  Company or if your  failure  to perform  was caused by
                  your physical or mental illness. You may not be terminated for
                  Cause under this  paragraph  after you have properly  notified
                  the Company that you are resigning for Good Reason.

         (2)      Willful Adverse Conduct.  You willfully engage in conduct that
                  is demonstrably and materially injurious to the Company or its
                  affiliates,  monetarily or otherwise. Your conduct will not be
                  considered  "willful" if you reasonably believed that you were
                  acting in the best interests of the Company.

(e) Change in Control

         "Change in  Control,"  means the first of the  following to occur after
the date of this Agreement:

         (1)      Acquisition  of Controlling  Interest.  Any Person becomes the
                  Beneficial Owner, directly or indirectly, of securities of the
                  Company representing 51 percent or more of the combined voting
                  power  of  the  Company's  then  outstanding  securities.   In
                  applying the preceding sentence,  securities acquired directly
                  from the Company or its  affiliates by or for the Person shall
                  not be taken into account.


         (2)      Merger  Approved.  The  shareholders  of the Company approve a
                  merger  or   consolidation  of  the  Company  with  any  other
                  corporation  unless:  (a) the voting securities of the Company
                  outstanding  immediately  before the  merger or  consolidation
                  would continue to represent  (either by remaining  outstanding
                  or by being converted into voting  securities of the surviving
                  entity) at least 60 percent of the  combined  voting  power of
                  the voting  securities of the Company or such surviving entity
                  outstanding  immediately  after such merger or  consolidation;
                  and (b) no Person  becomes the Beneficial  Owner,  directly or
                  indirectly,  of  securities  of the  Company  representing  51
                  percent or more of the combined  voting power of the Company's
                  then outstanding securities.

         (3)      Sale of Assets.  The  shareholders  of the Company  approve an
                  agreement for the sale or disposition by the Company of all or
                  substantially  all  of  the  Company's  assets  or a  plan  of
                  complete liquidation of the Company.

(f) Change in Management

         "Change  in  Management,"  means  the  Company  has  hired a new  Chief
Executive Officer ("CEO").

(g) Code

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

(h) Company

         "Company" means Harding Lawson  Associates Group Inc. and any successor
to its business or assets that (by operation of law, or  otherwise)  assumes and
agrees to perform this Agreement. However, for purposes of determining whether a
Change in  Control  has  occurred  in  connection  with such a  succession,  the
successor shall not be considered to be the Company.

(i) Disability

         "Disability"  means that,  due to physical or mental  illness:  (i) you
have been absent from the full-time  performance of your duties with the Company
for substantially all of a period of 6 consecutive  months; (ii) the Company has
notified  you that it intends to  terminate  you on account of  Disability;  and
(iii) you do not resume the full-time  performance of your duties within 30 days
after receiving notice of your intended termination on account of Disability.

(j) Exchange Act

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

(k) Good Reason

         "Good Reason" means the occurrence of any of the following without your
express written consent after the Change:

         (1)      Demotion.  Your duties and  responsibilities are substantially
                  and adversely altered from those in effect  immediately before
                  the  Change,  other  than  merely as a result  of the  Company
                  ceasing to be a public  company,  a change in your  title,  or
                  your transfer to an affiliate.

         (2)      Pay Cut. Your annual base salary is reduced other than as part
                  of across-the-board  salary reductions affecting all employees
                  of similar  status  employed  by the Company and any Person in
                  control of the Company.

         (3)      Relocation.  Your  principal  office is transferred to another
                  location, which increases your one-way commute to work by more
                  than 50 miles,  based on your  residence when the transfer was
                  announced  or, if you  consent to the  transfer,  the  Company
                  fails  to pay (or  reimburse  you) for all  reasonable  moving
                  expenses  you incur in changing  your  principal  residence in
                  connection  with the  relocation  and to indemnify you against
                  any  loss  you  may  realize  when  you  sell  your  principal
                  residence in connection with the relocation in an arm's-length
                  sale for adequate consideration. For purposes of the preceding
                  sentence,  your  "loss"  will be the  difference  between  the
                  actual  sales price of your  residence  and the higher of: (a)
                  your aggregate  investment in the  residence;  or (b) the fair
                  market value of the residence,  as determined by a real estate
                  appraiser designated by you and satisfactory to the Company.

         (4)      Discontinuance of Compensation Plan Participation.  Other than
                  as  part  of  an  across-the-board   reduction  affecting  all
                  employees  of similar  status  employed by the Company and any
                  Person  in  control  of the  Company,  the  Company  fails  to
                  continue,  or continue your participation in, any compensation
                  plan in which you participated  immediately  before the Change
                  that  is  material  to  your  total  compensation,  unless  an
                  equitable  substitute  arrangement  has been  adopted  or made
                  available on a basis not materially less favorable to you than
                  the plan in effect immediately  before the Change,  both as to
                  the  benefits  you  receive  and your  level of  participation
                  relative to other  participants.  The plans referred to in the
                  preceding   sentence   include  such   programs  as  Incentive
                  Compensation Plan and Incentive Stock Option Plan (if still in
                  effect immediately before the Change),  similar programs,  and
                  any substitute plans adopted before the Change.

         (5)      Discontinuance   of  Benefits.   Other  than  as  part  of  an
                  across-the-board  change  affecting  all  employees of similar
                  status  employed by the Company,  the Company stops  providing
                  you with benefits that, in the aggregate, are substantially as
                  valuable  to you as those you enjoyed  immediately  before the
                  Change  under  the  Company's   pension,   savings,   deferred
                  compensation,  life insurance,  medical,  health,  disability,
                  accident,  vacation,  and  any  other  fringe  benefit  plans,
                  programs, and arrangements.

         (6)      Notice  of  Prospective  Action.   During  the  Term  of  this
                  Agreement,  you are  officially  notified or it is  officially
                  announced that the Company will take any of the actions listed
                  above.

However, an event that is or would constitute Good Reason shall cease to be Good
Reason if: (a) you do not  terminate  employment  within 90 days after the event
occurs;  (b)  the  Company  reverses  the  action  or  cures  the  default  that
constitutes  Good  Reason  before you  terminate  employment;  or (c) you were a
primary  instigator  of the Good  Reason  event  and the  circumstances  make it
inappropriate  for you to receive benefits under this Agreement (e.g., you agree
temporarily  to  relinquish   your  position  on  the  occurrence  of  a  merger
transaction you negotiate). If you have Good Reason to terminate employment, you
may do so even if you  are on a leave  of  absence  due to  physical  or  mental
illness or any other reason.

(l) Person

         "Person" has the meaning given in Section  3(a)(9) of the Exchange Act,
as modified and used in Section  13(d) of that Act, and shall include a "group,"
as defined in Rule 13d-5  promulgated  thereunder.  However,  a Person shall not
include:  (i) the  Company or any of its  subsidiaries;  (ii) a trustee or other
fiduciary  holding  securities  under an employee benefit plan of the Company or
any of its subsidiaries;  (iii) an underwriter  temporarily  holding  securities
pursuant  to an  offering  of  such  securities;  or (iv) a  corporation  owned,
directly or indirectly,  by the stockholders of the Company in substantially the
same proportions as their ownership of stock of the Company.

(m) Potential Change in Control

         "Potential  Change in  Control"  means  that any of the  following  has
occurred during the term of this Agreement:

         (1)      Agreement Signed. The Company enters into an agreement that
                  will result in a Change in Control.

         (2)      Notice of Intent to Seek Change in Control. The Company or any
                  Person publicly  announces an intention to take or to consider
                  taking actions that will result in a Change in Control.

         (3)      Board Declaration.  With respect to this Agreement,  the Board
                  adopts a  resolution  declaring  that a  Potential  Change  in
                  Control has occurred.

(n) Severance Benefits

         "Severance  Benefits"  means  your  benefits  under  Section  6 of this
Agreement.

(o) Term of this Agreement

         "Term of this Agreement" means the period that commences on the date of
this Agreement and ends on the later of:

(1)      The last day of the 24th month from the date of this Agreement.
          or
(2)      The last day of the 12th month from the Change.





Date 02/22/99              /s/Greg P. Klein                        
                           Gregory P. Klein
                           Vice President - Human Resources


Date 02/17/99              /s/D. K. Stager                    
                           Donald K. Stager
                           Chairman - Compensation Committee



Date 02/17/99               /s/Gregory A. Thornton    
                            Gregory A. Thornton


Company notices to you shall be addressed as follows (or in any other manner you
notify the Company to use):


         If Mailed           Gregory A. Thornton
                             45 Molino Ave.
                             Mill Valley, Ca. 94941


         If Faxed            Gregory A. Thornton
                             Fax:    N/A
                             Tel.:   (415) 381 - 9059