General Operating Permit 5 (or GP-5) controls air pollution from sources at natural gas compressor stations, processing plants, and transmission stations, through 5-year permits. (NOTE: General permits are issued to each source but they apply the same standards to all sources in a category.) In 2018, GP-5 was updated, in part to directly target methane; the previous version, issued in August 2013, only regulated methane indirectly.
GP-5 sets facility-wide emission limits for VOCs and other pollutants (but not methane directly) (Sec. 10). It requires permittees to notify local authorities when installing new components (Sec. 11); record emissions; and submit an annual report that is certified to be “true, accurate, and complete” (Sec. 13). Permits may be revoked for violations (Sec. 6(f)). The permits also include component-specific requirements:
* Glycol Dehydration Units with a potential to emit of at least 10 tons per year VOCs (or at least 200 tpy methane, after 8 Aug 2018) must control emissions by 85% if constructed before 2 Feb 2013, or 95% if after, using a flare, vapour recovery unit (VRU) or other air cleaning device.
* Natural Gas-Fired Engines must meet specified NOx, carbon monoxide, and non-methane/non-ethane hydrocarbon emission limits, depending on the age of the engine.
* Storage Vessels that emit at least 200 tpy methane, 2.7 tpy VOCs, or 1 tpy total hazardous air pollutants (HAPs) must use a VRU to capture 95% of emissions if installed on/after 8 Aug 2018. Tanker trucks unloading these vessels must use a vapour balancing system and pass a leak test.
* Pneumatic Pumps that emit at least 200 tpy methane, 2.7 VOCs, or 1 tpy total HAPs must reduce emissions 95% through a closed vent system if installed on/after 8 Aug 2018.
* Pigging Operations require best management practices to minimize emissions. If operations will exceed the emissions threshold (200 tpy methane, 2.7 tpy VOCs, 1 tpy total HAPs), must reduce emissions 95% with a flare, VRU, other air cleaning device or approved alternative method.
In addition, reciprocating compressors, centrifugal compressors, and pneumatic controllers must meet federal performance standards, and calculate emissions for inclusion in the annual state report. Finally, the permit requires monthly audible/visual/olfactory inspections for LDAR, as well as a quarterly survey with an infra-red camera. Detected leaks (> 500 ppm) must be repaired within 15 days. LDAR records shall be held for 5 years.