If improvements are required, pursuant to the provisions of this subchapter or any other provision of this code, plan and profile of proposed street improvements, prepared by a licensed civil engineer, shall be submitted to the City Engineer for review and approval prior to the issuance of a building permit. All improvements shall be completed prior to final approval of the building or structure by the Building Inspector, unless he shall find that by reason of special circumstances completion thereof may be postponed, but in such event, cash in an amount set by the Director of Public Works equal to the estimated cost of the improvements shall first be deposited with the city.
(`67 Code, § 5-6-3)