EXHIBIT 10.6


 


FIFTH AMENDMENT


THIS FIFTH AMENDMENT (this “Amendment”) dated
as of September 24, 2003 is to the Credit Agreement (as previously amended, the
“Credit Agreement”) dated as of March 17, 2000 among TETRA TECH, INC.
(the “Company”), various financial institutions and BANK OF AMERICA,
N.A., as administrative agent (the ”Agent”).  Unless otherwise defined herein, terms
defined in the Credit Agreement are used herein as defined therein.


WHEREAS, the parties hereto desire to amend the Credit
Agreement as set forth below;


NOW THEREFORE, in consideration of the premises and
for other good and valuable consideration (the receipt and sufficiency of
which are hereby acknowledged), the parties hereto agree as follows:


SECTION 1  AMENDMENT.  Effective on (and subject to the occurrence of) the Amendment
Effective Date (as defined below), Section 2.1.2 of the Credit Agreement is
amended by replacing the reference to “$25,000,000” with “$50,000,000”.


SECTION 2  REPRESENTATIONS AND WARRANTIES.  The Company represents and warrants to the
Agent and the Banks that (a) each warranty set forth in Section 9 of the Credit
Agreement is true and correct as if made on the date hereof, (b) the execution
and delivery by the Company of this Amendment and the performance by the Company
of its obligations under the Credit Agreement as amended hereby (as so amended,
the “Amended Credit Agreement”) (i) are within the corporate powers of
the Company, (ii) have been duly authorized by all necessary corporate action,
(iii) have received all necessary governmental approval and (iv) do not and
will not contravene or conflict with any provision of law or of the charter or
by-laws of the Company or any Subsidiary or of any indenture, loan agreement or
other material contract, or any judgment, order or decree, which is binding
upon the Company or any Subsidiary, and (c) this Amendment and the Amended
Credit Agreement are the legal, valid and binding obligations of the Company,
enforceable against the Company in accordance with their terms, except as
enforceability may be limited by bankruptcy, insolvency or other similar laws
of general application affecting the enforcement of creditor’s rights or by
general principles of equity.


SECTION 3  EFFECTIVENESS.  The amendment set forth in Section 1 shall
become effective, as of the day and year first above written, on such date (the
“Amendment Effective Date”) that the Agent shall have received each of
the following: (a) counterparts of this Amendment executed by the Company and
the Required Banks; and (b) a Confirmation in the form of Exhibit A
hereto signed by the Company and each Subsidiary.


SECTION 4  MISCELLANEOUS.


4.1  Continuing
Effectiveness, etc.  As herein
amended, the Credit Agreement shall remain in full force and effect and is
hereby ratified and confirmed in all respects.


4.2  Counterparts.  This Amendment may be executed in any number
of counterparts and by the different parties on separate counterparts, and each
such counterpart shall be deemed to be an original but all such counterparts
shall together constitute one and the same Fifth Amendment.


4.3  Governing
Law.  This Amendment shall be a
contract made under and governed by the laws of the State of Illinois
applicable to contracts made and to be performed entirely within such State.


4.4  Successors
and Assigns.  This Amendment shall
be binding upon the Company and the Agent and their respective successors and
assigns, and shall inure to the benefit of the Company and the Agent and the
successors and assigns of the Agent.


4.5  Expenses.  The Company agrees to pay the reasonable
costs and expenses of the Agent (including attorneys’ fees) in connection with
the preparation, execution and delivery of this Amendment.

















Delivered at Chicago, Illinois, as of the day and year
first above written.




	
  TETRA
  TECH, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David W. King

  
	
  Title:

  	
  Chief Financial Officer

  
	
   

  
	
   

  
	
  BANK OF AMERICA, N.A.,
  as Administrative Agent

  
	
   

  	
   

  
	
  By:

  	
  /s/  Paul
  Folino

  
	
  Title:

  	
  Assistant Vice President

  
	
   

  
	
   

  
	
  BANK
  OF AMERICA, N.A., as Swing Line Bank, Issuing Bank and as a Bank

  
	
   

  	
   

  
	
  By:

  	
  /s/ 
  Jennifer L. Gerdes

  
	
  Title:

  	
  Vice President

  
	
   

  
	
   

  
	
  WELLS
  FARGO BANK, N.A., as Documentation Agent and as a Bank

  
	
   

  	
   

  
	
  By:

  	
  /s/ 
  Randall Repp

  
	
  Title:

  	
  Vice President

  
	
   

  
	
   

  
	
  HARRIS
  TRUST AND SAVINGS BANK, as Syndication Agent and as a Bank

  
	
   

  	
   

  
	
  By:

  	
  /s/ 
  Isabella Battista

  
	
  Title:

  	
  Vice President

  
	
   

  
	
   

  
	
  THE
  NORTHERN TRUST COMPANY

  
	
   

  	
   

  
	
  By:

  	
  /s/  Steven
  W. Ryan

  
	
  Title:

  	
  Vice President

  
	
   

  
	
   

  
	
  U.S.
  BANK, NATIONAL ASSOCIATION (formerly known as Pacific Century Bank,
  N.A.)

  
	
   

  	
   

  
	
  By:

  	
   

  
	
  Title:

  	
   

  






 


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EXHIBIT A


CONFIRMATION


Dated as of September 24, 2003


                Each of the undersigned hereby acknowledges and
agrees to the foregoing Fifth Amendment and the Amended Credit Agreement and
hereby confirms the continuing validity and enforceability of the Guaranty and
the Security Agreement after giving effect thereto.




	
  SCM
  CONSULTANTS, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Assistant Treasurer

  
	
   

  
	
   

  
	
  TETRA
  TECH EM INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  WHALEN
  & COMPANY, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Chief Financial Officer

  
	
   

  
	
   

  
	
  TETRA
  TECH NUS, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  MFG,
  INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  TETRA
  TECH CONSTRUCTION SERVICES, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  UTILITIES
  & C.C., INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  






 


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  COSENTINI
  ASSOCIATES, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  EVERGREEN
  UTILITY CONTRACTORS, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  KCM,
  INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  GEOTRANS,
  INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Assistant Treasurer

  
	
   

  
	
   

  
	
  FHC,
  INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  RIZZO
  ASSOCIATES, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  TETRA
  TECH RMC, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  WILLIAMS,
  HATFIELD & STONER, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  EXPERT
  WIRELESS SOLUTIONS, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David
  W. King

  
	
  Title:

  	
  Treasurer

  






 


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  DRAKE
  CONTRACTORS, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  VERTEX
  ENGINEERING SERVICES, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/ 
  David W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  MAXIM
  TECHNOLOGIES, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/ 
  David W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  SCIENCES
  INTERNATIONAL, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  WESTERN
  UTILITY CONTRACTORS, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  HARTMAN
  & ASSOCIATES, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/ 
  David W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  THE
  THOMAS GROUP OF COMPANIES, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David W. King

  
	
  Title:

  	
  Treasurer

  
	
   

  
	
   

  
	
  TETRA
  TECH FW, INC.

  
	
   

  	
   

  
	
  By:

  	
  /s/  David W. King

  
	
  Title:

  	
  Assistant Treasurer

  






 


 


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