Where commonly or separately owned areas containing natural features of exceptional recreational, cultural or educational value to the public are dedicated to the City, without any cost to the City, pursuant to Section 105-701 (Applicability of large-scale residential development regulations), the City Planning Commission may by special permit allow, where appropriate, such portion of the zoning lot to be included in the zoning computation for floor area, open space, lot coverage and density regulations and other bulk computations.