TWELFTH AMENDMENT TO, AND WAIVER UNDER, CREDIT AGREEMENT

Exhibit 10.11.12

TWELFTH AMENDMENT TO, AND WAIVER UNDER, CREDIT AGREEMENT

THIS TWELFTH AMENDMENT TO, AND WAIVER UNDER, CREDIT AGREEMENT (this “ Twelfth Amendment ”) is made and entered into as of May 20, 2008, by and among the financial institutions identified on the signature pages hereof (such financial institutions, together with their respective successors and assigns, are referred to hereinafter each individually as a “ Lender ” and collectively as the “ Lenders ”), WELLS FARGO FOOTHILL, INC., a California corporation, as arranger and administrative agent for the Lenders (in such capacities, together with any successor arranger and administrative agent, “ Agent ”), and TRC COMPANIES, INC., a Delaware corporation (the “ Administrative Borrower ”), on behalf of all Borrowers.

WITNESSETH :

WHEREAS, the Administrative Borrower, the Administrative Borrower’s Subsidiaries party thereto, the Lenders and Agent are parties to that certain Credit Agreement, dated as of July 17, 2006 (as amended as of October 31, 2006, as of November 29, 2006, as of December 29, 2006, as of January 31, 2007, as of July 30, 2007, as of September 25, 2007, as of November 28, 2007, as of December 14, 2007, as of March 3, 2008, as of April 4, 2008, and as of April 22, 2008, and as the same may be further amended, modified, supplemented or amended and restated from time to time, the “ Credit Agreement ”);

WHEREAS, pursuant to Section 5.9 of the Credit Agreement, Borrowers are obligated to keep their and their Restricted Subsidiaries’ Inventory and Equipment (other than vehicles and Equipment out for repair or maintained with customers in the ordinary course of business) only at the locations specified on Schedule 4.5 ; provided , however , that Administrative Borrower may amend Schedule 4.5 so long as such amendment occurs by written notice to Agent not less than 30 days prior to the date on which such Inventory or Equipment is moved to such new location, so long as such new location is within the continental United States, and so long as, at the time of such written notification, the applicable Borrower provides Agent a Collateral Access Agreement with respect thereto (provided that a Collateral Access Agreement shall only be required to be delivered if books and records are maintained at such location);

 WHEREAS, TRC Environmental Corporation moved certain of its Inventory and Equipment, from 2313 W. Sam Houston Parkway North, Houston, Texas 77043 and 1500 City West Boulevard, Houston, Texas 77042 to 10011 Meadowglen, Houston, Texas 77042, without providing to Agent the notice and Collateral Access Agreement required by Section 5.9 of the Credit Agreement;

WHEREAS, pursuant to the Ninth Amendment to, and Waiver under Credit Agreement dated as of March 3, 2008 among the parties hereto, in consideration of the waiver provided therein by Agent and the Lenders, the Borrowers agreed to deliver to Agent a Collateral Access Agreement with respect to the Collateral located at 10011 Meadowglen, Houston, Texas 77042 (the “ Meadowglen Collateral Access Agreement ”) on or prior to April 30, 2008;

WHEREAS, the Borrowers have not yet delivered to Agent the Meadowglen Collateral Access Agreement (the “ Section 5.9 Default ”);

WHEREAS, pursuant to Section 6.16(a)  of the Credit Agreement, the Borrowers were required to achieve EBITDA of at least $9,018,000 for the 9-month period ended March 31, 2008 (the “ March 2008 EBITDA Requirement ”);

WHEREAS, the Borrowers have failed to comply with the March 2008 EBITDA Requirement (the “ March 2008 EBITDA Default ”, and together with the Section 5.9 Default, the “ Applicable Defaults ”);

WHEREAS, the Administrative Borrower has requested Agent and the Lenders to waive the Applicable Defaults, and Agent and the Lenders have agreed to do so subject to the terms and conditions set forth herein; and

WHEREAS, Agent, the Lenders and the Borrowers have agreed to amend the Credit Agreement, all as herein provided subject to the terms and conditions set forth herein;

NOW, THEREFORE, in consideration of the agreements and provisions herein contained, the parties hereto do hereby agree as follows:

Section 1.              Definitions .   Any capitalized terms used but not otherwise defined herein shall have the meanings ascribed to such terms in the Credit Agreement.

Section 2.              Waivers Under Credit Agreement .  Subject to the satisfaction of the terms and conditions set forth herein, Agent and the Required Lenders hereby (a) waive the Section 5.9 Default; provided that the waiver under this clause (a) shall be rescinded and no longer effective as of June 15, 2008 if the Borrowers fail to deliver to Agent the Meadowglen Collateral Access Agreement on or prior to June 15, 2008; and (b) waive the March 2008 EBITDA Default.

Section 3.              Amendments to Credit Agreement .  Subject to the terms and conditions set forth herein, the Credit Agreement is hereby amended, as of the Effective Date (defined below), as follows:

3.01.       Amendments to Schedule 5.3 of the Credit Agreement .  The left hand column in the third row of the table in Schedule 5.3 to the Credit Agreement relating to Parent’s Projections is hereby amended by adding the following at the end thereof: “; provided , further , that with respect to fiscal year 2009, Borrowers shall deliver the required information and documents to Agent on or prior to July 31, 2008.”

3.02.       Amendments to Section 6.16(a) of the Credit Agreement .  Section 6.16(a) of the Credit Agreement is hereby amended by deleting it in its entirety and inserting the following in lieu thereof:

(a)           Minimum EBITDA.  Fail to achieve EBITDA, measured on a quarterly basis, of at least the required amount set forth in the following table for the applicable period set forth opposite thereto:

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