Areas not within designated open space
On any portion of a zoning lot not within designated open space, alteration of topography shall be permitted only in accordance with the provisions of this Section.
The ground elevation of land existing on September 11, 1975, may be modified by up to two feet of cut or fill, provided that such modification shall not result in the destruction of trees of six-inch caliper or more, unless authorized pursuant to other provisions of this Chapter. Modification of topography to a greater extent is permitted:
(a) in an area designated for building foundations, driveways or utilities for a proposed building or other structure whose location is approved by the Department of Buildings in accordance with the provisions of this Chapter; and
(b) in order to meet the legal mapped grades of a street, the existing topography of that portion of the zoning lot abutting such street may be modified to create a slope on the zoning lot of not less than one foot vertical to each two feet horizontal provided the slope is landscaped to prevent erosion.
Topographic modifications not permitted by the provisions of this Section may be permitted only by authorization of the City Planning Commission, pursuant to the provisions of Section 107-65.