Wash. Rev. Code § 80.82.010
Closure and postclosure plans for certain facilities
(1) A facility subject to closure under either RCW 80.80.040(3)(c) or a memorandum of agreement under RCW 80.80.100, or both, must provide the department of ecology with a plan for the closure and postclosure of the facility at least twenty-four months prior to facility closure or twenty-four months prior to start of d…