If the contractor shall perform the work designated in the contract properly, the governing body, from time to time as the work progresses and in its discretion, may pay such contractor between ninety and ninety-five percent of the amount earned under the contract to the time of payment as determined by estimates made by the engineer acting for the municipality. Any payments made under this section shall be by warrants drawn on the sewer and water connections assessment fund.
N.D.C.C. § 40-28-10