The appeal and character of the site shall be preserved or enhanced by retaining and protecting existing trees and other site features to the extent that they enhance the project and additional new plant material shall be added for privacy, shade, and to screen out objectionable features. Where needed for protection or screening purposes, appropriately designed fences, walls or planting shall be installed along property boundary lines, laundry yards, refuse collection points, playgrounds and other locations. (Prior gen. code § 8-97.5)