EXHIBIT 10.1

INCREMENTAL TRANCHE A FACILITY COMMITMENT
ASSUMPTION AGREEMENT

dated as of July 5, 2006,

relating to the

SECOND AMENDED AND RESTATED CREDIT AGREEMENT

dated as of June 14, 2005,

among

WASHINGTON GROUP INTERNATIONAL, INC.,

THE LENDERS AND ISSUERS PARTY THERETO

and

CREDIT SUISSE,

as Administrative Agent

CREDIT SUISSE SECURITIES (USA) LLC,

as Sole Lead Arranger and Sole Bookrunner

INCREMENTAL TRANCHE A FACILITY COMMITMENT ASSUMPTION AGREEMENT dated as of July 5, 2006 (this “Agreement”), among WASHINGTON GROUP INTERNATIONAL, INC., a Delaware corporation (the “Borrower”), the Incremental Tranche A Facility Lenders party hereto (the “Incremental Tranche A Facility Lenders”) and CREDIT SUISSE, as administrative agent (in such capacity, the “Administrative Agent”).

A. Reference is made to the Second Amended and Restated Credit Agreement dated as of June 14, 2005, as amended (the “Credit Agreement”), among the Borrower, the Lenders and Issuers party thereto and Credit Suisse, as Administrative Agent.

B. Pursuant to Section 2.5(a) of the Credit Agreement, the Borrower has notified the Lenders under the Tranche B Facility that the Commitments thereunder (which aggregate $102,500,000 on the date hereof) will terminate on July 5, 2006 (the “Increase Effective Date”), subject to the concurrent effectiveness of this Agreement (the “Tranche B Facility Termination”).

C. Pursuant to Section 2.5(d) of the Credit Agreement, the Borrower has requested that the Incremental Tranche A Facility Lenders severally agree to provide the Borrower with additional Commitments under the Tranche A Facility (the “Incremental Tranche A Facility Commitments”) in the aggregate amount of $102,500,000 concurrent with the effectiveness of the Tranche B Facility Termination.

D. The Incremental Tranche A Facility Lenders are willing so to provide the Borrower with the Incremental Tranche A Facility Commitments, and the Administrative Agent is willing to consent thereto, in each case on the terms and subject to the conditions set forth herein and in the Credit Agreement.

E. Accordingly, in consideration of the mutual agreements herein contained and other good and valuable consideration, the sufficiency and receipt of which are hereby acknowledged, the parties hereto hereby agree as follows:

SECTION 1. Defined Terms; Terms Generally. Capitalized terms used and not defined herein shall have the meanings assigned to such terms in the Credit Agreement. The rules of construction set forth in Section 1.4 of the Credit Agreement shall apply equally to this Agreement. This Agreement shall be a “Loan Document” for all purposes of the Credit Agreement and the other Loan Documents.

SECTION 2. Incremental Tranche A Facility Lenders and Commitments. Schedule I attached hereto sets forth the name of each Incremental Tranche A Facility Lender and its Incremental Tranche A Facility Commitment as of the Increase Effective Date. The Incremental Tranche A Facility Commitment of each Incremental Tranche A Facility Lender shall be several and not joint. As of the Increase Effective Date, the aggregate amount of the Tranche A Facility shall be $350,000,000 and the aggregate

amount of the Tranche B Facility shall be zero. As of the Increase Effective Date, the Incremental Tranche A Facility Commitments shall be deemed to be Commitments under the Tranche A Facility for all purposes of the Credit Agreement and the other Loan Documents.

SECTION 3. Conditions Precedent. This Agreement shall become effective as of the Increase Effective Date upon the satisfaction on or prior to such date of the following conditions precedent:

(a)  The Administrative Agent shall have received counterparts of this Agreement that, when taken together, bear the signatures of the Borrower, the Incremental Tranche A Facility Lenders and the Administrative Agent.

(b)  On the Increase Effective Date, each of the statements set forth in clauses (b)(i) and (ii) of Section 3.2 of the Credit Agreement shall be true and correct, and the Administrative Agent shall have received a certificate to that effect dated such date and executed by a Responsible Officer of the Borrower.

(c)  The Administrative Agent shall have received (on behalf of itself and the Lenders) all fees and other amounts due and payable on or prior to the Increase Effective Date, including, to the extent invoiced, reimbursement or payment of all out-of-pocket expenses required to be reimbursed or paid by the Borrower hereunder or under any other Loan Document.

SECTION 4. Certain Agreements. For the avoidance of doubt and without limiting the application thereof, the parties hereto hereby agree that the provisions of Sections 11.3 and 11.4 of the Credit Agreement shall apply to the execution and delivery of, and the performance of the parties’ respective obligations under, this Agreement.

SECTION 5. Applicable Law. THIS AGREEMENT SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW YORK.

SECTION 6. Notices. All notices hereunder shall be given in accordance with the provisions of Section 11.8 of the Credit Agreement.

SECTION 7. Counterparts. This Agreement may be executed in counterparts (and by different parties hereto on different counterparts), each of which shall constitute an original but all of which when taken together shall constitute a single contract, and shall become effective as provided in Section 3 hereof. Delivery of an executed signature page to this Agreement by facsimile transmission shall be as effective as delivery of a manually signed counterpart of this Agreement.

SECTION 8. Headings. The headings and cover page of this Agreement are for convenience of reference only, are not part of this Agreement and are not to affect the construction of, or to be taken into consideration in interpreting, this Agreement.

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SECTION 9. Amendments, etc. This Agreement may not be amended, supplemented or otherwise modified other than in a writing signed by each of the parties hereto.

SECTION 10. Acknowledgement of Subsidiary Guarantors. Each of the Subsidiary Guarantors hereby acknowledges its receipt of a copy of this Agreement and its review of the terms and conditions hereof, and each of the Subsidiary Guarantors hereby consents to the terms and conditions of this Agreement and the transactions contemplated hereby, and hereby confirms its guarantee and, as applicable, its grant of Collateral under the Guaranty and the Collateral Documents, respectively, and agrees that such guarantee and any such grant of Collateral shall continue to be in full force and effect and shall inure to the benefit of the Secured Parties, including the Incremental Tranche A Facility Lenders as such in respect of their Incremental Tranche A Facility Commitments and the other Obligations owed to them from time to time.

[Remainder of page intentionally left blank]

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IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed by their respective authorized officers as of the day and year first above written.

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SIGNATURE PAGE TO THE
INCREMENTAL TRANCHE A FACILITY
COMMITMENT ASSUMPTION AGREEMENT
DATED AS OF JULY 5, 2006, TO THE
WASHINGTON GROUP INTERNATIONAL, INC.
SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF JUNE 14, 2005, AS AMENDED

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SIGNATURE PAGE TO THE
INCREMENTAL TRANCHE A FACILITY
COMMITMENT ASSUMPTION AGREEMENT
DATED AS OF JULY 5, 2006, TO THE
WASHINGTON GROUP INTERNATIONAL, INC.
SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF JUNE 14, 2005, AS AMENDED

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SIGNATURE PAGE TO THE
INCREMENTAL TRANCHE A FACILITY
COMMITMENT ASSUMPTION AGREEMENT
DATED AS OF JULY 5, 2006, TO THE
WASHINGTON GROUP INTERNATIONAL, INC.
SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF JUNE 14, 2005, AS AMENDED

7

SIGNATURE PAGE TO THE
INCREMENTAL TRANCHE A FACILITY
COMMITMENT ASSUMPTION AGREEMENT
DATED AS OF JULY 5, 2006, TO THE
WASHINGTON GROUP INTERNATIONAL, INC.
SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF JUNE 14, 2005, AS AMENDED

8

SIGNATURE PAGE TO THE
INCREMENTAL TRANCHE A FACILITY
COMMITMENT ASSUMPTION AGREEMENT
DATED AS OF JULY 5, 2006, TO THE
WASHINGTON GROUP INTERNATIONAL, INC.
SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF JUNE 14, 2005, AS AMENDED

9

SIGNATURE PAGE TO THE
INCREMENTAL TRANCHE A FACILITY
COMMITMENT ASSUMPTION AGREEMENT
DATED AS OF JULY 5, 2006, TO THE
WASHINGTON GROUP INTERNATIONAL, INC.
SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF JUNE 14, 2005, AS AMENDED

10

SIGNATURE PAGE TO THE
INCREMENTAL TRANCHE A FACILITY
COMMITMENT ASSUMPTION AGREEMENT
DATED AS OF JULY 5, 2006, TO THE
WASHINGTON GROUP INTERNATIONAL, INC.
SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF JUNE 14, 2005, AS AMENDED

11

SIGNATURE PAGE TO THE
INCREMENTAL TRANCHE A FACILITY
COMMITMENT ASSUMPTION AGREEMENT
DATED AS OF JULY 5, 2006, TO THE
WASHINGTON GROUP INTERNATIONAL, INC.
SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF JUNE 14, 2005, AS AMENDED

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SCHEDULE I

SCHEDULE II

Subsidiary Guarantors