Ohio Environmental Protection Agency (Ohio EPA) has recently issued a package of draft general air permits that have been designed around a typical natural gas compressor station. Ohio EPA requested preliminary, informal comments on these draft general permits in September 2015 and plans to initiate a formal comment period after considering the initial feedback.
Ohio EPA expects that the draft general permits will cover the typical equipment found at a natural gas compressor station, including:
- Natural gas fired spark ignition compressor engines (four lean burn size choices [100-1350 hp], five rich burn size choices [100-3600 hp]) – The general permits incorporate emission limitations for NOx, CO, and VOC in accordance with NSPS JJJJ; however, rich burn engines are subject to Best Available Technology (BAT) limitations even more stringent than the NSPS standards.
- Diesel engines (two size choices [175-350 hp or 350-750 hp]) –The general permits incorporate emission limitations in accordance with NSPS IIII.
- Dehydrators – The general permit covers glycol dehydration units with a maximum throughput of 90 MMscf/day or less and incorporates requirements from 40 CFR 63, Subpart HH, if applicable.
- Flares (one open flare [<1 MMBtu/hr] or two enclosed flare choices [<10 MMBtu/hr or 10-20 MMBtu/hr]) –The general permits require flares to comply with applicable NSPS (40 CFR 60, Subpart OOOO) and NESHAP (40 CFR 63, Subpart HH) rules if used to control emissions from storage vessels or triethylene glycol dehydration units subject to these rules. The flares are also subject to emission limitations established as BAT.
- Compressors – This general permit covers reciprocating or centrifugal compressors located between the wellhead and the point of custody transfer to the natural gas transmission and storage segment which are designed to be driven by an engine or motor of less than 3600 horsepower. Regulated activities include compressor maintenance and blowdown releases. The general permit incorporates the requirements of 40 CFR 60, Subpart OOOO, and requires 100% capture and 98% control of emissions from the rod packing seals or wet or dry shaft seals, compressor isolation valves, and compressor blowdown vents.
- Equipment Leaks (pipes, valves, flanges, pumps, etc.) – This general permit establishes a VOC emission limit of 10 tons per year from fugitive equipment leaks, and requires the development and implementation of a leak detection and repair program (LDAR program) based on FLIR or Method 21 detection techniques.
- Liquid Storage Tanks sized to 470 barrels each or less – This general permit establishes a VOC emissions limitation of 0.34 ton per month averaged over a rolling 12-month period, and requires the use of add-on control devices to comply with the limitation. The permit also incorporates the standards of NSPS OOOO, if applicable.
- Truck Loading Operations – This general permit establishes a throughput limit of 1,200,000 gallons per year for any truck loading operations, and requires the use of add-on control devices to comply with the emission limitation.
- Pigging Operations – This general permit requires the use of add-on control devices for any pigging operations and the development of a written operating manual for pig launching and recovery.
Ohio EPA has also drafted qualifying criteria documents for each of the aforementioned permits, as well as an "Additional General Permit Guidance" document describing procedures for evaluating New Source Review (NSR) applicability and conducting air modeling analyses if necessary.
The draft general permits, qualifying criteria, and guidance document are available for on Ohio EPA's website.
If you have any questions regarding these draft general permits, please feel free to contact DJ Wheeler in Trinity's Columbus Office at (614) 433-0733.