FIRST AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.3

FIRST AMENDMENT

TO CREDIT AGREEMENT

THIS FIRST AMENDMENT TO CREDIT AGREEMENT (this “ Amendment ”), dated as of September 28, 2007, is by and among INFRASTRUX GROUP, INC., a Washington corporation (herein, together with its successors and assigns, the “ Borrower ”), INFRASTRUX HOLDINGS, LLC, a Delaware limited liability company (herein, together with its successor and assigns, (the “ Parent ”), each Subsidiary Guarantor signatory hereto, the Lenders signatories hereto, and CREDIT SUISSE, CAYMAN ISLANDS BRANCH, as the administrative agent for the Lenders (the “ Administrative Agent ”), the Swing Line Lender and an Issuing Bank.

W I T N E S S E T H:

WHEREAS, pursuant to that certain Credit Agreement dated as of November 3, 2006 (the “ Existing Credit Agreement ”) by and among the Borrower, the Parent, the Subsidiary Guarantors, the Lenders and the Administrative Agent, the Lenders provided a term loan facility and a revolving credit facility to the Borrower;

WHEREAS, the Borrower has requested that the Lenders agree to amend certain provisions of the Existing Credit Agreement; and

WHEREAS, the Administrative Agent and the Required Lenders are willing to make such amendments upon the terms and conditions contained in this Amendment;

NOW, THEREFORE, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, and in consideration of the agreements herein contained, the parties hereby agree as follows:

PART I

DEFINITIONS

SUBPART 1.1. Certain Definitions . Unless otherwise defined herein or the context otherwise requires, the following terms used in this Amendment, including its preamble and recitals, have the following meanings:

“ Additional Equity ” means $50,000,000 in good and immediately available Dollars received from the Parent as additional cash equity.

“ Amended Credit Agreement ” means the Existing Credit Agreement as amended hereby.

“ First Amendment Effective Date ” is defined in Subpart 3.1.

SUBPART 1.2. Other Definitions . Unless otherwise defined herein or the context otherwise requires, terms used in this Amendment, including its preamble and recitals, have the meanings provided in the Amended Credit Agreement.

PART II

AMENDMENTS TO EXISTING CREDIT AGREEMENT

Effective on the First Amendment Effective Date (and subject to the occurrence of the conditions set forth in Part III ), the Existing Credit Agreement is hereby amended in accordance with this Part II . Except as so amended, the Existing Credit Agreement shall continue in full force and effect.

SUBPART 2.1. Amendment to Article I . Article I of the Existing Credit Agreement is hereby amended by

(a) adding the following definitions in the appropriate alphabetical order:

“ Additional Prepayment Date ” has the meaning provided in Section 2.13(b)(xiv) .

“ First Amendment ” means that certain First Amendment to the Credit Agreement dated as of September 28, 2007 by and among the parties to this Agreement.

“ First Amendment Effective Date ” means September 28, 2007.

“ First Amendment Fees and Expenses ” means the sum of the amount required to be paid by the Borrower pursuant to (i) Subpart 3.3 of the First Amendment and (ii) Subpart 3.4 of the First Amendment.

“ Supplemental Cash Interest Amounts ” means all Supplemental Revolver Cash Amounts and all Supplemental Term Loan Cash Amounts.

“ Supplemental Revolver Cash Amount ” has the meaning provided in Section 2.09(h)(i) .

“ Supplemental Term Loan Cash Amount ” has the meaning provided in Section 2.09(h)(ii) .

“ Supplemental Term Loan Deferred Fee Amount ” has the meaning provided in Section 2.09(h)(ii) .

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“ Supplemental Interest Termination Date ” means the third Business Day after the date when the Borrower has both (a) paid in full in good and immediately available Dollars (i) all Supplemental Term Loan Deferred Fee Amounts (including without limitation all Supplemental Term Loan Deferred Fee Amounts that have accrued but are not yet due and all interest on the Supplemental Term Loan Deferred Fee Amounts, in each case, regardless of whether the Supplemental Term Loan Deferred Fee Amounts have been capitalized as Term Loans) and (ii) all Supplemental Cash Interest Amounts that have accrued and are unpaid, regardless of whether such Supplemental Cash Interest Amounts are due and (b) delivered written notice to the Administrative Agent (in form an substance reasonably satisfactory to the Administrative Agent) that it elects to cease payment of supplemental interest on the Loans as provided in Section 2.09(h) ; provided that it shall be a further condition of the occurrence of the Supplemental Interest Termination Date that (x) no Default or Event of Default shall have occurred and be continuing as of such date, (y) the Borrower shall have been in compliance with the financial covenants set forth in Section 7.07 (after giving effect to the occurrence of the Supplemental Interest Termination Date) as established by the Required Financial Information as of the end of the fiscal quarter ending immediately preceding such date and (z) the Borrower shall have provided the Administrative Agent any other supporting information regarding its compliance with such financial covenants as of the end of such fiscal quarter as the Administrative Agent shall reasonably request.

(b) adding the following new text after the close parenthesis and before the period at the end of the definition of “Consolidated Interest Expense”:

; provided, however, that in no event shall any Supplemental Term Loan Deferred Fee Amount be included in any determination of Consolidated Interest Expense

SUBPART 2.2. Supplemental Interest . Section 2.09(d) of the Existing Credit Agreement is amended by replacing “Notwithstanding the above provisions,” with “Notwithstanding the above provisions and Section 2.09(h) ,” and the following is hereby added to the Existing Credit Agreement as Section 2.09(h) :

(h) Supplemental Interest .

(i) Revolving Loans and Swing Loans . In addition to the interest required pursuant to Section 2.09(a) , Section 2.09(c) , Section 2.09(d) and/or any other provision of this Agreement or the other Loan Documents, the Borrower shall from and including the First Amendment Effective Date until and through the Supplemental Interest Termination Date make an additional cash payment on the outstanding principal amount of each Revolving Loan and each Swing Loan made by each Lender in an amount equal to either (A) 1.25% per annum or (B) so long

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as the Total Leverage Ratio of the Borrower and its Subsidiaries as of the end of the immediately preceding fiscal quarter, as established by the Required Financial Information (delivered in accordance with the terms and conditions herein), is less than 4.75 to 1.00, 1.00% per annum of the principal amount of each such outstanding Revolving Loan or Swing Loan, as applicable (the “ Supplemental Revolver Cash Amount ”). The rate for calculating the Supplemental Revolver Cash Amount shall be deemed to be 1.25% per annum as of and including the First Amendment Effective Date; after delivery of the Required Financial Information for the Borrower’s fiscal quarter ending September 30, 2007, such rate shall be determined pursuant to the provisions above. The Supplemental Revolver Cash Amount shall be paid on the date of the interest payments for the applicable Revolving Loan or Swing Loan as provided in Section 2.09(e) . In addition to the payment dates specified in Section 2.09(e) , on the Supplemental Interest Termination Date, the Borrower shall pay all outstanding Supplemental Revolver Cash Amounts on all Revolving Loans and Swing Loans as specified in the definition of Supplemental Interest Termination Date.

(ii) Term Loan . In addition to the interest required pursuant to Section 2.09(b) , Section 2.09(d) and/or or any other provision of this Agreement or the other Loan Documents, the Borrower shall from and including the First Amendment Effective Date until and through the Supplemental Interest Termination Date (A) make an additional cash payment on the outstanding principal amount of each Term Loan made by each Lender in an amount equal to either (I) 0.75% per annum or (II) so long as the Total Leverage Ratio of the Borrower and its Subsidiaries as of the end of the immediately preceding fiscal quarter, as established by the Required Financial Information (delivered in accordance with the terms and conditions herein), is less than 4.75 to 1.00, 0.50% per annum of the principal amount of each such outstanding Loan (the “ Supplemental Term Loan Cash Amount ”) and (B) increase the then outstanding principal of each Term Loan by an amount equal to 0.50% per annum of the principal amount of each such outstanding Loan (the “ Supplemental Term Loan Deferred Fee Amount ”). The rate for calculating the Supplemental Term Loan Cash Amount shall be deemed to be 0.75% per annum as of and including the First Amendment Effective Date; after delivery of the Required Financial Information for the Borrower’s fiscal quarter ending September 30, 2007, such rate shall be determined pursuant to the provisions above. The Supplemental Term Loan Cash Amount shall be paid, and the Supplemental Term Loan Deferred Fee Amount shall be capitalized as additional principal of the Term Loan upon which such Supplemental Term Loan Deferred Fee Amount is owed, in each case on the date of the interest payments for the applicable Term Loan as provided in Section 2.09(e) . In addition to the payment dates specified in Section 2.09(e) ,

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on the Supplemental Interest Termination Date, the Borrower shall pay all outstanding Supplemental Term Loan Cash Amounts and all Supplemental Term Loan Deferred Fee Amounts on all Term Loans as specified in the definition of Supplemental Interest Termination Date.

SUBPART 2.3. Excess Cash Flow . Section 2.13(b)(iv) of the Existing Credit Agreement is hereby amended by deleting Section 2.13(b)(iv) and replacing such section in its entirety with the following:

(iv) Excess Cash Flow . Within 120 days after the end of each fiscal year, the Borrower shall prepay the Loans and/or cash collateralize the reimbursement obligations of the Borrower hereunder in respect of Letters of Credit in an amount equal to 100% (if the Total Leverage Ratio as of the end of such fiscal year is equal to or greater than 4.00 to 1.00), 75% (if the Total Leverage Ratio as of the end of such fiscal year is less than 4.00 to 1.00 but equal to or greater than 2.50 to 1.00) or 50% (if the Total Leverage Ratio as of the end of such fiscal year is less than 2.50 to 1.00) of the Excess Cash Flow earned during such prior fiscal year (such prepayment to be applied as set forth in clause (xii) below).

SUBPART 2.4. Additional Prepayment . The following is hereby added to the Existing Credit Agreement as Section 2.13(b)(xiv):

(xiv) Additional Prepayment . Notwithstanding the provisions of Section 2.13(b)(vii) (which provisions shall not be applicable to the Additional Equity), not later than the Business Day immediately following the date when the Additional Equity is received by the Borrower, but in no event later than October 16, 2007 (such date, the “ Additional Prepayment Date ”), the Borrower shall make a prepayment in respect of the Term Loan (which prepayment shall be accompanied by interest on the applicable principal amount to be prepaid through the date of prepayment) in an amount such that the principal amount of the Term Loan prepaid on the Additional Prepayment Date is equal to the Additional Equity less the First Amendment Fees and Expenses. Such prepayment of the Term Loan pursuant to this clause (xiv) shall be applied pro rata to the remaining amortization payments thereof set forth in Section 2.13(d) .

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SUBPART 2.5. Financial Covenants . Section 7.07 of the Existing Credit Agreement is hereby amended by deleting Section 7.07 and replacing such section in its entirety with the following:

Section 7.07 Financial Covenants .

(a) Total Leverage Ratio . The Borrower will not permit the Total Leverage Ratio as of the end of any fiscal quarter of the Borrower and its Subsidiaries to be greater than (i) if the Supplemental Interest Termination Date has not occurred, the ratio set forth below opposite such period in Column A and (ii) if the Supplemental Interest Termination Date has occurred, the ratio set forth below opposite such period in Column B:

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(b) Interest Coverage Ratio . The Borrower will not permit the Interest Coverage Ratio as of the end of any fiscal quarter of the Borrower and its Subsidiaries to be less than (i) if the Supplemental Interest Termination Date has not occurred, the ratio set forth below opposite such period in Column A and (ii) if the Supplemental Interest Termination Date has occurred, the ratio set forth below opposite such period in Column B:

SUBPART 2.6. Management Fees . Section 7.09(e) of the Existing Credit Agreement is hereby amended by deleting Section 7.09(e) and replacing such section in its entirety with the following:

(e) subject to the conditions below, payments by the Borrower to Tenaska Capital Management, LLC under the Management Agreement in an aggregate amount not to exceed in any fiscal year (in each case