When using fill for grading a site or any disturbed portion thereof, fresh topsoil, or at a minimum clean fill shall be used. "Clean fill" shall mean material that is not contaminated by solid wastes, infectious wastes, brick, block, concrete, glass, ceramics, wallboard, plastic, wood, metal, or demolition debris. Clean fill may contain small amounts of gravel, roots and other elements naturally occurring in soil. In no event shall the use of clean fill for grading relieve the developer from the obligations of meeting the above obligations.