Notwithstanding anything to the contrary elsewhere in this chapter contained, in a Ga Industrial District, there shall be at least 1,800 square feet for the first 100 feet of street frontage and 18 square feet for each additional foot of street frontage, suitably shrubbed and landscaped, and any amount of additional land in the front yard landscaped in excess of said minimum but not exceeding nine square feet for each foot of street shall be credited against any required parking area. All drainage, paving, landscaping and seeding shall be as required by the Planning Board.