On the creation of a parking facility as provided under section 16-802 for the use of the general public, the city may lease such facility to one or more operators to provide for the efficient operation of the facility. Such lease shall be let on a competitive basis and no lease shall run for a period in excess of ten years. In granting any lease, the city shall retain such control of the facility as may be necessary to insure that the facility will be properly operated in the public interest and that the prices charged are reasonable. The provisions of sections 16-801 to 16-811 shall not be construed to authorize the city or the lessee of the facility to engage in the sale of any commodity, product, or service, or to engage in any business other than the purposes set forth in section 16-802.