Buildings containing residential units shall provide a minimum residential Amenity Space at a rate of 75 square feet per unit, with a maximum of 50% indoor. Open/outdoor Amenity Space may consist of rear lawns, preserved wooded and natural land, decks, patios, terraces, balconies, atria, swimming pools, or similar amenity. Areas used for stormwater detention and retention basins, as well as areas with slopes exceeding 15%, shall not count towards open/outdoor Amenity Space.