Because a new subdivision creates a need for recreation areas, as well as for streets, the Council may require the dedication of a part of the subdivision for recreation or school area. The dedication need not exceed 8% of the total area of the subdivision plat. In addition, wherever the city plan shows a proposed public site larger than the area to be dedicated, the preliminary plan and final plat shall show the projected site and the city shall have one year in which to purchase the additional area. If the purchase has not been made within the year, the subdivider may proceed to subdivide the additional area.