General Operating Permit 5A (or, GP-5A) controls air pollution from sources at new or modified unconventional natural gas well sites and remote pigging stations. (NOTE: General permits are issued to each source but they apply the same standards to all sources in a category.) In 2018, GP-5A was created to replace a 2013 permit exemption, which was issued to new well sites that established certain fugitive emissions mitigation techniques including LDAR. In 2019, Pennsylvania considered extending methane regulation of existing well sites but opted not to take this action.
GP-5A sets 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.
• Reciprocating Compressors must replace rod packing after 26,000 hours of operation or 36 months since initial startup. Also, methane, VOC and HAP emissions must be captured from the rod packing with a VRU.
• Storage vessels constructed between 10 Aug 2013 and 8 Aug 2018, with a VOC emission rate of 2.7 tpy or HAP emission rate of 1.0 tpy, must install a VRU/closed vent system that reduces VOCs 95%. New vessels (on/after 8 Aug 2018) can also trigger this requirement by emitting at least 200 tpy of methane. Tanker trucks servicing 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.
• Liquids Unloading Operations require best management practices (i.e. plunger lift systems, soaping, swabbing) to mitigate emissions. Captured gas should be directed to a control device, production line, or controlled separator or storage vessel. The application to conduct liquids unloading must specify the practice that will be used to mitigate emissions.
In addition, controllers constructed after 23 Aug 2011 must meet federal requirements, 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. If two consecutive quarterly surveys detect fewer than 2% of the components are leaking, the permittee may shift to semi-annual inspections with an infra-red camera. (If more than 2% of the components are leaking during a semi-annual inspection, the permittee must revert to quarterly inspections.) Detected leaks (> 500 ppm) must be repaired within 15 days. LDAR records shall be held for 5 years.