In all Residence Districts, uses listed under Use Group VI shall be permitted within a distance of 30 feet from the outermost edge of the easement volume:

1. at the ground floor level of a building on a zoning lots with an easement volume serving an at- or below-grade mass transit station, or
2. at the two lowest stories of a building on a zoning lot with an easement volume serving an above-grade mass transit station.

Such uses may be permitted so long as that in buildings that include residential uses, such uses are located in a portion of the building that has separate access to the outside with no opening of any kind to the residential portion of the building, and that such uses are not located directly over any story containing dwelling units.