Section 70A.540.090 - Gas collection and control system-Capping or removal(1) The department or local authority must allow the capping or removal of the gas collection and control system at a closed municipal solid waste landfill, provided the following three requirements are met: (a) The gas collection and control system was in operation for at least 15 years, unless the owner or operator demonstrates to the satisfaction of the department or local authority that due to declining methane rates, the municipal solid waste landfill will be unable to operate the gas collection and control system for a 15-year period;(b) Surface methane concentration measurements do not exceed the limits specified in RCW 70A.540.050; and(c) The owner or operator submits an equipment removal report to the department or local authority pursuant to RCW 70A.540.070 and the department's implementing rules adopted pursuant to RCW 70A.540.020.(2) Nothing in this section may be interpreted to modify or supersede requirements related to the capping or removal of gas collection and control systems that may exist under the state clean air act, the federal clean air act, or rules adopted pursuant to either the state clean air act or the federal clean air act.