1. The board of trustees is hereby authorized and empowered to construct the works and improvements provided for in the plan adopted, by letting a contract or contracts for such works and improvements either as a whole or in sections, and when such contract or contracts are to be let, they shall be advertised and let to the lowest and best bidder as determined by said board. Such bidder shall give a good and approved bond in such amount as may be determined by said board, but in no event be less than the amount of the contract price, payable to the district with sureties satisfactory to said board, conditioned that the bidder will properly carry out the contract for such work and improvements and pay all bills incurred by him in the carrying out of said contract.

2. Said contract shall be in writing and to which shall be attached and made a part thereof complete plans and specifications of the work to be done and the improvements to be made under such contract, which plans and specifications shall be prepared by the chief engineer and shall be incorporated in and attached to the contract, which contract shall be prepared by the attorney for the district and before the work is commenced shall be approved by the board of trustees and signed by the president of the board and the contractor, and shall be executed in duplicate.

3. The chief engineer shall be superintendent of all the works and improvements and shall, whenever required, make a full report to said board of all work done and improvements made.