Forty feet abutting any other tract boundary and the closest point of any building wall, or support column in the case of roofed areas without walls, but excluding roof overhangs beyond walls and support columns; provided however, that a minimum yard depth of 35 feet shall be permitted for up to one half of the dwellings in the development. The location of the reduced thirty-five-foot yard depths shall be where such reduced depth will have a lessened impact on adjacent properties, as determined by the Planning Board during the site plan review process and made a condition of any approval that may be granted, In those locations where a yard depth of less than 40 feet is proposed, the Board may, at its discretion, require an increase in buffer depth, planting density or other enhanced buffer/screening techniques.