Buffers. A two-family duplex or townhouse development shall provide a permanently landscaped planting area of at least fifteen (15) feet in depth immediately adjacent to the boundary line, designed and planted to serve as a screening barrier from any adjoining and contiguous industrial, commercial, office, apartment or other residential district and including locations where a boundary is formed by a public street. In those instances where the boundary line abuts permanent natural features which function as buffers including, but not limited to, stream valleys, ponds, severe grade changes, or natural woodlands, the buffer may, at the discretion of the Township Council, be waived pursuant to the provisions of the Subdivision and Land Development Ordinance of 1980, Ordinance No. 837, as amended,[1] for that portion of the boundary. The planting area screening barrier shall be a row of evergreen trees, of a height of not less than six (6) feet when planted, spaced not more than ten (10) feet apart on centers, of such a species which attains a height at maturity of not less than twenty (20) feet.