The Department may approve alternate methods for disposal of hard rock spoil, including fill placement by dumping in a single lift, provided the services of a registered professional engineer experienced in the design and construction of earth and rockfill embankments are utilized. For this section, hard rock spoil shall be defined as rockfill consisting of at least 80% by volume of sandstone, limestone, or other rocks that do not slake in water. Spoil shall be transported and placed in a specified and controlled manner which will ensure stability of the disposal area. The method of spoil placement shall be designed to ensure mass stability and prevent mass movement.
25 Pa. Code § 88.311