All contracts for work to be done by such sanitary district, the expense of which will exceed  $25,000, shall be let to the lowest responsible bidder therefor. The board of trustees shall cause to be published a notice informing the public and contractors of the general nature of the work and of the fact that detailed plans, drawings and specifications are on file in the office of such board of trustees and calling for sealed proposals for the construction of the work to be done at a date not earlier than ten days after the last of such publications, such notice to be published as a Class II legal advertisement in compliance with the provisions of article three, chapter fifty- nine of this code, and the publication area for such publication shall be the sanitary district. Said board of trustees shall require each bidder to deposit with his or her respective bid a certified check for an amount not less than two and one-half percent of the engineer’s estimate of such work to insure the execution of the contract for which such bid is made. The board of trustees may impose such conditions as it may deem necessary upon the bidders with regard to bond and surety, guaranteeing the good faith and responsibility of such bidders, and the faithful performance of such work according to contract, or for any other purpose. The board of trustees shall have the right to reject any and all bids, but if it does reject all bids, before other bids may be received notices shall be published as originally required. The board of trustees shall have power to let portions of said proposed work under different contracts.

Any additions or extensions to any sewage disposal plant, or sewers or drains or any other work constructed under the provisions of this article, shall be built under contract entered into under the provisions of this section in the same manner as the contract for the original plant or work. The cost of such additions or extensions, and of any additional lands or rights-of-ways acquired by said board, may be met by the sale of additional bonds to be issued and sold by the trustees, and the levy of taxes and/or the collection of service charges to retire such bonds, all as provided in this article.

Emergency repairs shall be exempt from the bidding requirements of this section. For the purpose of this section, the term emergency repairs means repairs that if not made immediately will seriously impair the use of building components, systems, and public infrastructure or cause danger to persons using the building components, systems, and public infrastructure.