<PAGE>
 
                                                                   EXHIBIT 10.68

                                   AGREEMENT


     THIS AGREEMENT is made and entered into as of the _____________ day of JULY
21, 1997 by and between SALT LAKE CITY CORPORATION, a municipal corporation of 
the State of Utah, (hereinafter "City") and Meadow Valley Contractors, Inc., 
hereinafter "Contractor", whose address is 1598 North Hillfield Road Suite C 
Layton, Utah 84041;

                                  WITNESSETH:

     The Contractor and the City, for the consideration hereinafter named, agree
as follows:

1.   SCOPE OF WORK.

     A.   Contractor agrees to furnish all labor, materials and equipment 
          necessary to perform all of the Work required in the Contract 
          Documents for the Project titled Taxiway G Extension - North End, No.
          54 1077 0276.

2.   TIME OF COMPLETION.

     A.   The Work under this Agreement shall commence following issuance of the
          Notice to Proceed and shall be completed within the time allowed 
          indicated on Page B-3 of the Contractor's Bid.

3.   CONSIDERATION.

     A.   The City shall pay the Contractor for the performance of all
          obligations set forth herein the sum of Eight Million Nine Hundred
          Ninety-Nine Thousand Five Hundred Three Dollars. ($8,999,503.00); 
          subject to the provisions of paragraph 3C below and Article 9 of this 
          Agreement.

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     B.   The Schedules of Prices hereunder are pursuant to Contractor's Bid 
          dated June 11, 1997.

     C.   The City agrees to pay and the Contractor agrees to accept for full
          performance of this Agreement, the lump sum agreed upon, or a sum
          which is based upon the actual quantities used or constructed in
          accordance with the Contract Documents or a combination thereof. All
          measurements will be performed by the City's Engineer or his
          authorized representative. The sum also includes the cost of all
          bonds, insurance, permits and fees required herein and all charges,
          expenses or assessments of whatever kind or character. Claims for
          services allegedly furnished by Contractor but not specifically
          provided for herein shall not be honored by the City.

4.   LIQUIDATED DAMAGES.

     A.   Time is the essence of this Agreement. In view of the difficulty of
          determining the City's damages caused by late completion the parties
          hereby agree, fix and determine that the Contractor shall be
          responsible to pay the City liquidated compensatory damages in such
          amounts and upon such terms as are specified below.

     B.   Contractor agrees that the payment of liquidated damages shall
          commence on the calendar day after the date fixed for completion
          including any extensions of additional time which may have been
          allowed in writing. From and after said date, the City shall be
          entitled to deduct and retain said liquidated damages out of any
          monies which may be due or become due to the Contractor, and the City
          may require the Contractor to pay the City liquidated damages for each
          calendar day after said date until the City accepts the project as
          substantially complete.

     C.   Liquidated damages shall be in the amount specified on page B-3 of the
          Contractor's bid.

     D.   After the City has accepted substantial completion, liquidated damages
          shall not accrue while the City makes

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     damages from such a disturbance. The parties agree that Contractor will pay
     as liquidated damages for each such disturbance the sum of $1,000 to cover
     such damage and expense, which sum may be deducted from the Contractor's
     compensation.

28.  CONTROLLING LAW.

     A.   The interpretation of this Agreement shall be governed by the laws of
          the State of Utah. Any court action arising from this Agreement shall
          be brought in a federal or state court with appropriate jurisdiction
          in the City of Salt Lake, State of Utah.

29.  ASSIGNMENT.

     A.   This Agreement or any benefit, obligation or part thereof cannot
          be assigned by either party without the prior written consent of the
          other.

     IN WITNESS WHEREOF, the parties have executed this Agreement as of the day 
and year first above written.

                                        SALT LAKE CITY CORPORATION

                                        By /s/ Russell Widmar
                                          -------------------------------------
                                              EXECUTIVE DIRECTOR -
                                          SALT LAKE CITY AIRPORT AUTHORITY
ATTEST:

/s/ Christine Meeker
--------------------------
CHIEF DEPUTY CITY RECORDER


                                        /s/ Kenneth D. Nelson            (Seal)
              [ SEAL ]                  --------------------------------
                                              VICE PRESIDENT


                                        MEADOW VALLEY CONTRACTORS, INC.  (Seal)
                                        --------------------------------
                                               CONTRACTOR

                                        
                                        ________________________________ (Seal)

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                              CITY ACKNOWLEDGMENT
                              -------------------

STATE OF UTAH       ) 
                    :
COUNTY OF SALT LAKE )


     On the 21 day of July, 1997, personally appeared before me RUSSELL
C. WIDMAR and CHRISTINE MEEKER, who being by me duly sworn, did say that they
are the EXECUTIVE DIRECTOR - SALT LAKE CITY AIRPORT AUTHORITY and CHIEF DEPUTY
CITY RECORDER, respectively, of SALT LAKE CITY CORPORATION, and said persons
acknowledged to me that said corporation executed the same.


                                        /s/ Scott C. Crandall
                                        ---------------------------------------
                                        NOTARY PUBLIC, residing in 
                                                              SALT LAKE COUNTY
                                                              -----------------


My Commission Expires:         [SEAL]

_________________________

                        





                          CORPORATION ACKNOWLEDGMENT
                          --------------------------

STATE OF UTAH      )
                   :
COUNTY OF SALT LAKE)

     On the 30 day of June, 1997, personally appeared before me KENNETH D. 
NELSON, who being by me duly sworn did say that he is the VICE PRESIDENT of 
MEADOW VALLEY CONTRACTORS, INC., a corporation, and that the foregoing 
instrument was signed in behalf of said corporation by authority of a resolution
(or bylaws) of its Board of Directors; and said persons acknowledged to me that 
said corporation executed the same.

             /s/ Lisa Forsling                   Layton, Utah
             --------------------------      ---------------------------------
                 LISA FORSLING               NOTARY PUBLIC, residing in 

                                                           ___________________

My Commission Expires:

 July 24, 2000                                         [SEAL]
-------------------------

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