RCW 70A.540.050 — Methane concentration limits.

1. (1) Except as provided in RCW 70A.540.040, beginning January 1st of the year following the year in which the department adopts rules to implement this chapter, or upon commencing operation of a newly installed gas collection and control system or modification of an existing gas collection and control system pursuant to RCW 70A.540.040, whichever is later, and except as provided by the department to accommodate significant technological improvements, which may include the installation of an energy recovery device or devices, not to exceed 24 months after the department adopts rules to implement this chapter, no location on a municipal solid waste landfill surface may exceed the following methane concentration limits, dependent upon whether the owner or operator of the municipal solid waste landfills conducts, pursuant to RCW 70A.540.060, instantaneous surface emissions monitoring or integrated surface emissions monitoring:

   1. (a) Five hundred parts per million by volume, other than nonrepeatable, momentary readings, as determined by instantaneous surface emissions monitoring; or
   2. (b) An average methane concentration limit of 25 parts per million by volume as determined by integrated surface emissions monitoring.

2. (2) Any reading exceeding the limits set forth in subsection (1) of this section must be recorded as an exceedance and the following actions must be taken:

   1. (a) The owner or operator must record the date, location, and value of each exceedance, along with retest dates and results. The location of each exceedance must be clearly marked and identified on a topographic map of the municipal solid waste landfill, drawn to scale, with the location of both the monitoring grids and the gas collection system clearly identified; and
   2. (b) The owner or operator must take corrective action, which may include, but not be limited to, maintenance or repair of the cover, or well vacuum adjustments. The location or locations of any exceedance must be remonitored within 10 calendar days of a measured exceedance.

3. (3) The requirements of this section do not apply to:

   1. (a) The working face of the landfill;
   2. (b) Areas of the landfill surface where the landfill cover material has been removed for the purpose of installing, expanding, replacing, or repairing components of the landfill cover system, the landfill gas collection and control system, the leachate collection and removal system, or a landfill gas condensate collection and removal system;
   3. (c) Areas of the landfill surface where the landfill cover material has been removed for law enforcement activities requiring excavation; or
   4. (d) Areas of the landfill in which the landfill owner or operator, or a designee of the owner or operator, is engaged in active mining for minerals or metals.

[ 2022 c 179 s 5.]