The department shall evaluate compost, co-compost, and chemically fixed sewage sludge for use as solid waste landfill cover materials or for use as extenders for currently used cover material. Compost, co-compost, and chemically fixed sewage sludge products, when used as a substitute for or mixed with currently approved cover material, shall possess all the physical characteristics required in the definition of a cover material.
Ca. Pub. Res. Code § 42244