The board may, within ten days after the time fixed for opening bids, by resolution adopted by a vote of two-thirds of its members, order that the proposed contract not be entered into and that the sanitary district itself perform the work according to the plans and specifications as adopted for the work. If it is so ordered, the district shall be considered the contractor. The district shall not be permitted to assess an amount in excess of the amount proposed by the lowest responsible bidder or, if no bids have been received, in excess of the amount of the estimate.