Where the tract contains all or any part of the site of a school, park or other public site, as shown on the general plan or as recommended by the commission, such site shall either be dedicated to the public or reserved for acquisition by the public within a specified period of time. An agreement shall be reached between the subdivider and the appropriate public agency regarding time, method and cost of such acquisition. In the event of failure to reach such agreement within a reasonable period of time for reasons satisfactory to the commission, the commission may determine that requirements of this section and sections 11-3-1 and 11-3-2 of this chapter have been met. (1988 Code § 14-3-1)