No portion of storm drainage facilities, such as detention basins, retention basin or septic fields, shall be permitted within the buffer area. Specifically, although such basins and septic fields may be grass covered or landscaped, no portion of said basins or septic fields may be included within the calculation of the required landscaped buffer, nor shall any required plantings of trees or other plant material be included within the calculation of the tree planting requirements of the landscaped buffer.