On January 31, the Pennsylvania Department of Environmental Protection (PADEP) finalized revisions to its “GP-5” air quality general permit, which include significantly reduced allowable emission limits. According to PADEP, the revisions to GP-5 impose emissions limits that are 75 to 90 percent stricter than current limits for the most common engines used at compressor stations.

GP-5 authorizes the construction, modification and/or operation of certain natural gas compression and processing facilities (i.e., dehydration, compression, fractionation and storage) that are not subject to Title V or New Source Review permitting requirements. Specifically, covered facilities include natural gas-fired spark ignition combustion engines, simple cycle turbines, centrifugal compressors, storage vessels, glycol dehydration units, fractionation process units, equipment leaks, pneumatic controllers and sweetening units. While the permit covers facilities used on a gathering line, the permit does not apply to facilities used on a natural gas transmission line.