Within Subdistrict F, the Chairperson of the City Planning Commission may modify the ground floor level requirements of paragraphs (b), (c) and (d) of Section 93-14 (Ground Floor Level Requirements), provided that the Chairperson certifies to the Commissioner of Buildings that such a change is the minimum necessary to accommodate the ventilation requirements of the below-grade rail operations. Any application for such change shall include a mechanical plan that conveys the extent of the needs and required modifications, as well as a letter from the Metropolitan Transportation Authority describing the needs for such modifications.