On Parcels 8a, 8b, and 8d, where a shore public walkway is required, such shore public walkway shall have a minimum width of 30 feet, except that for shore public walkways adjoining the First Street Basin, the minimum width shall be 20 feet. The required minimum depth of a waterfront yard shall be 30 feet, except that for waterfront yards adjoining the First Street Basin, the minimum depth shall be 20 feet. An area equal to at least 25 percent of the area of the shore public walkway shall be planted, and one linear foot of seating shall be provided for every 125 feet of frontage along the Gowanus Canal.