Except as otherwise specified in Section 17.52.430A, the height of a fence, wall or hedge shall be measured upward from the ground level beneath it; provided that where any fence, hedge, or wall in a required yard or along a lot line rises directly above or is parallel to and within six feet of the supporting portion of a retaining wall, one-half the supporting height of the retaining wall shall be deducted from the permitted height and the remainder measured upward from the level of the ground fill on the

higher side; and provided, further, that no fence or hedge shall extend upward from a retaining wall within thirty (30) feet of a street corner. (Prior gen. code § 8-60.57)