The owner or operator of a closed MSW landfill may propose to the department or local authority that a gas collection and control system be decommissioned and removed provided the following requirements are met: 

(1)(a) The gas collection and control system has been in operation for at least 15 years after an owner or operator has submitted a closure notification that has been approved, pursuant to WAC 173-408-170(8), or the owner or operator demonstrates to the satisfaction of the department or local authority that, due to declining gas flow, the MSW landfill will be unable to operate the gas collection and control system for a 15-year period after closure; and 

(b) The landfill has had no exceedance of the methane concentration limits, as determined by surface emissions monitoring conducted in accordance with WAC 173-408-100(2), on three successive test dates. The test dates must be no less than 90 days apart, and no more than 180 days apart.

(2) The owner or operator conducts a provisional shutdown of the gas collection and control system meeting the following conditions:

(a) The owner or operator of the landfill shuts down the collection and control system and conducts surface emissions monitoring over the portion of the landfill served by the shut-down gas collection and control system, in accordance with WAC 173-408-120(3) and (b) of this subsection, for at least eight consecutive calendar quarters;

(b) During the provisional shutdown period, the surface emissions monitoring walking grid described in WAC 173-408-120 (3)(a)(ii) may be increased to 100-foot spacing so long as the walking grid is offset by 25 feet each quarter so that by the end of one year of monitoring, the entire surface area has been monitored every 25 feet; and

(c) During the provisional shutdown period, if any measured concentration of methane from the surface of the closed landfill exceeds the applicable limit specified in WAC 173-408-100(2), the owner or operator must restart the shut-down portion of the gas collection and control system.

(3) If no surface emissions monitoring result exceeds the applicable limit specified in WAC 173-408-100(2) during the provisional shutdown period, and with the approval of the department or local authority, the owner or operator may proceed with permanent shutdown and removal of the gas collection and control system.

(4) Following approval by the department or local authority for a permanent shutdown of the gas collection and control system, the owner or operator may decommission and remove the gas collection and control system and must submit an equipment removal report to the department or local authority in accordance with WAC 173-408-170(9). 

(5) Subsequent to permanent shutdown of the gas collection and control system, any exceedance of the surface methane concentration limits may be cause for the department or local authority to require an owner or operator to control surface methane emissions. The required actions may include reestablishing a gas collection and control system.

(6) Nothing in this subsection 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.