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                                                                    EXHIBIT 10.2

                                                                [EXECUTION COPY]

                      AMENDMENT TO ASSET PURCHASE AGREEMENT


                  AMENDMENT TO ASSET PURCHASE AGREEMENT, dated as of March 7,
2003 (this "Amendment"), by and among Tetra Tech, Inc., a Delaware corporation
("Tetra Tech"), Tetra Tech FW, Inc., a Delaware corporation and a direct
wholly-owned Subsidiary of Tetra Tech ("Purchaser"), Foster Wheeler, Ltd., a
Bermuda corporation ("FW Ltd."), Foster Wheeler, LLC, a Delaware limited
liability company and an indirect wholly-owned Subsidiary of FW Ltd. ("FW LLC"),
Foster Wheeler USA Corporation, a Delaware corporation and an indirect
wholly-owned Subsidiary of FW Ltd. ("FW USA", and together with FW Ltd. and FW
LLC, the "FW Guarantors"), Foster Wheeler Environmental Corporation, a Texas
corporation and a direct wholly-owned Subsidiary of FW USA ("FWENC"), and
Hartman Consulting Corporation, a Delaware corporation and a direct wholly-owned
Subsidiary of FWENC ("Hartman", and together with FWENC, the "Sellers"). Tetra
Tech, Purchaser, each of the FW Guarantors and each of the Sellers are
individually referred to herein as a "Party" and collectively referred to herein
as the "Parties". Capitalized terms used herein and not otherwise defined herein
shall have the respective meanings assigned to them in the Asset Purchase
Agreement (as defined below).

                              W I T N E S S E T H :
                               - - - - - - - - - -

                  WHEREAS, Tetra Tech, Purchaser, the FW Guarantors and the
Sellers are parties to an Asset Purchase Agreement, dated as of February 17,
2003 (as in effect on the date hereof, but prior to giving effect to this
Amendment, the "Asset Purchase Agreement"); and

                  WHEREAS, the Parties wish to amend the Asset Purchase
Agreement as herein provided;

                  NOW, THEREFORE, the Parties agree as follows:

I. Amendments to the Asset Purchase Agreement.

                  1. The definition of Savannah River Subcontract set forth in
Section 1.1 of the Asset Purchase Agreement is hereby deleted in its entirety
and the following new definition is hereby inserted in lieu thereof:

                           "Savannah River Subcontract" shall mean the
                  subcontract to be entered into by FWENC and FW USA at the
                  Closing, in the form of Exhibit C attached hereto.

                  2. Section 2.9(e) of the Asset Purchase Agreement is hereby
amended by inserting the following new language at the end thereof:

                  "(it being understood and agreed that FW USA shall also
                  deliver to Purchaser a duly executed counterpart of the
                  Savannah River Subcontract)".


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                  3. Section 2.10(e) of the Asset Purchase Agreement is hereby
deleted in its entirety and the following new language is hereby inserted in
lieu thereof:

                  "(e) Intentionally Omitted."

                  4. Section 5.6 of the Asset Purchase Agreement is hereby
amended by inserting the following new language at the end thereof:

                  "Purchaser agrees, for a period of seven (7) years following
                  the Closing, not to destroy or otherwise dispose of any such
                  books and records unless Purchaser first offers in writing to
                  surrender such books and records to FWENC (at the sole expense
                  of FWENC) and FWENC does not agree in writing to take
                  possession thereof during the 120 calendar day period after
                  such offer is made by Purchaser to FWENC. Furthermore, each
                  party will reasonably cooperate with the other parties, solely
                  at the expense of the party requesting such cooperation, in
                  the prosecution, defense or settlement of any actual or
                  threatened Action or other investigation by any Governmental
                  or Regulatory Authority or any other Person (including by
                  affording the requesting party, its counsel and accountants,
                  during normal business hours and without unreasonable
                  interference with the operations of the party providing such
                  cooperation, reasonable access to its employees, properties,
                  books and records relating to the Business and the right to
                  make copies and extracts therefrom, all at the sole expense of
                  the requesting party and upon reasonable request)."

                  5. Section 5.10 of the Asset Purchase Agreement is hereby
amended by inserting the following new subsection (d) at the end thereof:

                  "(d) The parties acknowledge that the Melton Valley
                  Subcontract to be entered into by the parties thereto shall
                  contemplate a subcontracting arrangement between Purchaser, on
                  the one hand, and FWENC, on the other hand, as provided
                  therein. If the consent of the DOE shall at any time be
                  required with respect to the Melton Valley Subcontract (or the
                  transactions contemplated thereby) on account of such
                  subcontracting arrangement, and the DOE refuses to consent to
                  such subcontracting arrangement (or imposes one or more
                  conditions to its consent which would adversely impact in a
                  material respect FWENC's economic interests in the Melton
                  Valley Contract) or unreasonably delays its consent (which
                  delay would adversely impact in a material respect FWENC's
                  economic interests in the Melton Valley Contract), in each
                  case as determined in good faith by FWENC, then the parties
                  shall enter into one or more amendments to the Melton Valley
                  Subcontract so as to provide for seconding or other
                  arrangements (on terms which are consistent in all material
                  respects with the then-existing terms of the Melton Valley
                  Subcontract and otherwise reasonably satisfactory to Purchaser
                  and FWENC) in lieu of the subcontracting arrangement and to
                  otherwise modify the Melton Valley Subcontract so that the
                  consent of the DOE shall no longer be required (or, if still
                  required, may be promptly obtained without any undue or
                  unreasonable burden on FWENC or any of its Affiliates (as
                  determined in good faith by FWENC)). Furthermore, Purchaser
                  agrees to, upon reasonable request from FWENC, cooperate in
                  good faith and to take such reasonable actions as may be
                  necessary or desirable (not materially inconsistent with the
                  commercial terms set forth in the Melton Valley Subcontract
                  and only so long as FWENC is not in material default under the
                  Melton Valley Subcontract) to enhance FWENC's ability to
                  receive from the DOE any and all amounts owing to it from time
                  to time under the Melton Valley Contract and to realize its
                  claims and rights thereunder and, in any event, Purchaser
                  agrees to refrain from taking any action that may adversely
                  affect in any material respect FWENC's ability to receive any
                  such amounts from the DOE or realize its claims and rights
                  thereunder; provided that, other than as described above, in
                  no event shall Purchaser be required to take, or refrain from
                  taking, any action that is adverse in any material respect to
                  its interests in respect of the Melton Valley Subcontract or
                  which would result in a breach or violation by Purchaser of
                  any of its then-existing contractual obligations or any
                  applicable Law."


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                  6. Section 5.11(c)(ii) of the Asset Purchase Agreement is
hereby amended by (x) deleting "on or before the Closing Date" appearing in the
first sentence thereof and inserting "as soon as practicable after the Closing
Date" in lieu thereof, and (y) deleting the third, fourth and fifth sentences
thereof in their entirety and inserting the following new sentences in lieu
thereof:

                  "No assets shall be transferred from the Foster Wheeler Inc.
                  401(k) Plan to the Purchaser Savings Plan; provided that the
                  Purchaser Savings Plan shall accept all or any portion of any
                  eligible rollover distribution (within the meaning of Section
                  402(c) of the Code), to the extent such eligible rollover
                  distribution consists of cash or an outstanding plan loan not
                  then in default, elected by a Transferred Employee to be
                  transferred from his or her individual account balance under
                  Foster Wheeler Inc. 401(k) Plan to the Purchaser Savings Plan
                  in a direct roll over (within the meaning of Section 402(c) of
                  the Code), to the extent permitted by Law, and subject to the
                  Sellers' and Purchaser's receipt from the other of evidence
                  satisfactory to the Sellers and Purchaser, respectively, that
                  the Purchaser Savings Plan and the Foster Wheeler Inc. 401(k)
                  Plan, respectively, are qualified under Sections 401(a) and
                  401(k) of the Code. As soon as practical after the Closing
                  Date, the Sellers shall cause the Foster Wheeler, Inc. 401(k)
                  Plan to make available for immediate lump-sum distribution the
                  account balance of each Transferred Employee."

                  7. Article XII of the Asset Purchase Agreement is hereby
amended by inserting the following new section at the end thereof:

                  "ss.12.14 Inconsistency Between Agreement and Any Subcontract.
                  To the extent that there is any inconsistency between this
                  Agreement, on the one hand, and the INEEL Subcontract, the
                  Melton Valley Subcontract or the Savannah River Subcontract,
                  on the other hand, then the applicable provisions of the INEEL
                  Subcontract, the Melton Valley Subcontract or the Savannah
                  River Subcontract, as the case may be, shall govern; provided
                  that in any event Section 5.10(d) shall at all times govern in
                  respect of the Melton Valley Subcontract."


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II. Miscellaneous.

                  1. This Amendment is limited as specified and shall not
constitute a modification, acceptance or waiver of any other provision of the
Asset Purchase Agreement or any other related document or agreement.

                  2. This Amendment may be executed in two (2) or more
counterparts, all of which shall be considered one and the same agreement and
shall become effective on the date (the "Amendment Effective Date") when two (2)
or more counterparts have been signed by each of the Parties and delivered
(including, without limitation, by way of facsimile transmission) to the other
Parties.

                  3. THIS AMENDMENT AND THE LEGAL RELATIONS BETWEEN THE PARTIES
SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF
NEW YORK, WITHOUT REGARD TO THE CONFLICT OF LAWS RULES THEREOF.

                  4. This Amendment shall be binding upon and shall inure to the
benefit of the parties hereto and their respective heirs, executors,
administrators, successors and permitted assigns.

                  5. From and after the Amendment Effective Date, all references
in the Asset Purchase Agreement and in any other related document or agreement
to the Asset Purchase Agreement shall be deemed to be references to the Asset
Purchase Agreement as modified hereby.

                [Remainder of this page intentionally left blank]



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                  IN WITNESS WHEREOF, each Party has caused its name to be
hereunto subscribed by its officer thereunto duly authorized all as of the day
and year first above written.


                                      TETRA TECH, INC.


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


                                      TETRA TECH FW, INC.


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


                                      FOSTER WHEELER, LTD.


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


                                      FOSTER WHEELER, LLC


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


                                      FOSTER WHEELER USA CORPORATION


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


                                      FOSTER WHEELER ENVIRONMENTAL
                                        CORPORATION


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

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                                      HARTMAN CONSULTING CORPORATION


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