(1) Sewage sludge is the solid, semisolid, or liquid residue generated during the treatment of domestic sewage in a treatment works. Biosolids are produced by treating sewage sludge to meet certain quality standards that allow it to be applied to the land for beneficial use. Septage is a class of biosolids that comes from septic tanks and similar systems receiving domestic wastes.

(a) Sewage sludge. Unless the context requires otherwise, "sewage sludge" is the term used in this chapter to refer to the residual material produced by a treatment works treating domestic sewage that does not meet the standards to be classified as biosolids or that is being disposed in a municipal solid waste landfill.

(b) Biosolids. Unless the context requires otherwise, "biosolids" is the term used in this chapter to refer to sewage sludge or septage that has been or is being treated to meet standards so that it can be applied to the land.

(c) Septage. Unless the context requires otherwise, "septage" is the term used in this chapter to refer to septage that is or will be managed as septage.

(2) The following sections apply only to biosolids or septage managed as biosolids originating from sewage sludge: WAC 173-308-150, 173-308-160, 173-308-170, 173-308-180, 173-308-200, 173-308-210, 173-308-250, and 173-308-260.

(3) WAC 173-308-270 addresses the management requirements for septage.

(4) Unless the context requires otherwise, all other sections apply to all biosolids, including septage.