That the use by the public of all public parking facilities acquired, constructed, installed or substantially reconstructed under the provisions of this act shall be free or for such charge or charges as shall be determined by the governing body to be collected either by parking meters or by attendants or othewise. The cost of maintaining, operating, and policing such facilities shall be borne by the city of from revenues resulting from any charges made by the governing body. Any surplus revenues over and above a reasonable reserve resulting from charges for the use of such facilities will be applied to reduce special assessments so long as any bonds issued hereinunder are outstanding. Thereafter any such surplus may be used as the governing body shall direct. [As added by Priv. Acts 1970, ch. 276, § 18]