A city of the primary class may make and enter into any and all contracts and agreements with any individual, public or private corporation, or agency of this state or of the United States, as may be necessary or incidental to the performance of its duties and the execution of its powers under sections 15-269 to 15-276. In the exercise of this authority, such city may make such contracts and agreements as may be needed for the payment of the revenue bonds authorized by sections 15-269 to 15-276 and for the successful operation of the parking facilities. In the exercise of this authority, the city may lease or grant concessions for the use of the facilities or various portions thereof to one or more operators to provide for the efficient operation of the facilities, but no lease or concession shall run for a period in excess of thirty years. In granting any lease or concession, or in making any contract or agreement, the city shall retain such control of the facilities as may be necessary to insure that the facilities will be properly operated in the public interest and that the rates, charges, or prices are reasonable.