A contract let under this chapter requires the work to be done pursuant to the plans and specifications on file in the office of the district, subject to the approval of the engineer acting for the district, and must provide:

1.    That the board has the right to suspend the work at any time for improper construction and to relet the contract or to order a reconstruction of the work as to any part improperly done.

2.    The time within which the work must be completed.

3.    The period of time for which the work must be guaranteed as to workmanship and materials.

4.    The fund from which the contract price is to be paid by the district.

5.    That the consideration expressed in the contract is payable only in bonds drawn on the fund described in the contract.

6.    That the district assumes and incurs no general liability under the contract.

7.    That failure of the engineer to reject work and materials that are not up to specifications and acceptance of the job by the engineer does not release the contractor from liability for any failure on the contractor’s part to perform work or furnish materials in accordance with the plans and specifications.

The engineer acting for the district shall provide construction administration and observation of the work during its progress. In addition to any rights a district may have under its contract for construction of part or all of an improvement after a contract has been awarded and before work under the contract has been completed, a district, with the consent of the contractor and without advertising for bids, may order additional work done by that contractor of the same character as the work that was contracted for, whether within or without the improvement district for which the original contract was made, and upon the same terms and conditions specified in the original contract except as to time of performance, and at the same prices for the additional work; provided, that the total price payable to the contractor for the additional work may not exceed     twenty percent of the amount estimated by the engineer for the district to be payable for that character of work under the original contract.