In a B-2D District, no buildings or premises shall be used, nor shall any building or other structure be built, altered or erected to be used, for any purpose other than uses permitted in a B-1 District as set forth in § 341-19, without limit as to number of employees; provided that such uses are located on a lot having a frontage on a public thoroughfare of no less than 150 feet and a total area of no less than 60,000 square feet; that such lot be entirely within an area shown on the Master Plan of the City of Garfield as a designated shopping center; that the application for a building permit and/or certificate of occupancy include a site plan for the entire shopping center, including location of required parking, landscaping and traffic access and exit; and that such plan make provision for at least four separate permitted business establishments, each separated by a fire wall, no one of which shall exceed 20,000 square feet of ground floor area and all of which shall be constructed to at least 75% of their value before a certificate of occupancy shall be issued for any one of them.