After bids for making sewer extensions have been received and contract is awarded, the petitioner shall again be notified as to the entire cost of the sewer with the exception of the part of the sewer located within the intersection of any street or alley in the City and shall be allowed a period of thirty days after notification within which period he may make payment. The contractor will be held to his bid during this period. The entire cost of the part of such sewer located within the intersections of streets and alleys shall be paid by the City.
(1964 Code §303.18)