340-239-0400 Permanent Shutdown and Removal of the Gas Collection and Control System When a landfill owner or operator has installed a gas collection and control system pursuant to OAR 340-239-0110, the owner or operator may permanently shutdown and remove the system only as provided in this rule. (1) The gas collection and control system at a closed landfill, or at a closed area of a landfill, may be capped or removed provided all of the following requirements are met: (a) The gas collection and control system was in operation for at least 15-years, unless the owner or operator can demonstrate to the satisfaction of DEQ that due to declining methane rates the owner or operator of the landfill will be unable to operate the gas collection and control system for a 15-year period. (b) The calculated or measured methane generation rate at the landfill is less than 664 metric tons (732 tons) per year on three successive test dates. For measured methane generation rates, the test dates must be no less than 90 days apart and no more than 180 days apart. The calculated methane generation rate must be calculated pursuant to OAR 340-239-0800(2). (c) Surface methane concentration measurements of methane do not exceed 200 ppmv. (d) The owner or operator submits an Equipment Removal Report to DEQ pursuant to OAR 340-239-0700(3)(b). (e) The concentration of methane gas at the landfill does not exceed 25 percent of the lower explosive limit for methane concentration in facility structures (excluding gas collection and control system components) or the lower explosive limit for methane concentration at the property boundary. (2) The owner or operator of the landfill that has capped or removed a gas collection and control system under section (1) of this rule must conduct surface methane concentration measurements over the portion of the landfill with the capped or removed gas collection and control system pursuant to OAR 340-239-0800(3) for at least eight consecutive calendar quarters after the gas collection and control system is capped or removed. The measurements must comply with the following requirements: (a) The walking grid in OAR 340-239-0800(3)(a)(B) may be reduced 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; (b) If there is no measured concentration of methane of 200 ppmv or greater from the surface of the closed landfill in any of these measurement events, the owner or operator must submit a final gas collection and control system Closure Notification to DEQ pursuant to OAR 340-239-0700(3)(a); and (c) If there is any measured concentration of methane of 200 ppmv or greater in any of these measurement events, other than nonrepeatable, momentary readings, as determined by instantaneous surface emissions monitoring, from the surface of the closed landfill, the owner or operator must comply with OAR 340-239-0110 through 340-239-0800. Statutory/Other Authority: ORS 468.020, ORS 468A.025, ORS 468A.040 & ORS 468A.050 Statutes/Other Implemented: ORS 468A.025, ORS 468A.040 & ORS 468A.050 History: DEQ 16-2021, adopt filed 10/04/2021, effective 10/04/2021