In either a planned unit development or a hillside subdivision or portions thereof which have an average lot size of 20,000 square feet or larger and having an average slope in excess of 10 percent prior to grading, the Commission, in the exercise of its discretion, may modify the foregoing requirements of this chapter in a manner that will result in the best possible utilization of the land to be subdivided, giving consideration to the topography and natural cover of the land, the general character of the proposed subdivision, the proposed zoning and the desirability of minimizing grading upon the site. (Ord. 3153 § 2 (Exh. C), 2010; Ord. 2100 § 1, 1985; Ord. 1369, 1971; prior code § 28.903).