Unless the context clearly requires otherwise, the definitions in this section apply throughout this chapter.

(1) "Biosolids" means municipal sewage sludge that is a primarily organic, semisolid product resulting from the wastewater treatment process, that can be beneficially recycled and meets all requirements under this chapter. For the purposes of this chapter, "biosolids" includes septic tank sludge, also known as septage, that can be beneficially recycled and meets all requirements under this chapter.

(2) "Department" means the department of ecology.

(3) "Local health department" has the same meaning as "jurisdictional health department" in RCW 70A.205.015.

(4) "Municipal sewage sludge" means a semisolid substance consisting of settled sewage solids combined with varying amounts of water and dissolved materials generated from a publicly owned wastewater treatment plant.