What Is It?: A compressor station is an industrial facility that receives natural gas — typically from natural gas wells via pipelines called gathering lines (or less commonly from other compressor stations) — removes the water, and compresses the gas to the pressures needed in a long-distance natural gas transmission line.

Compressor stations are sometimes given an alternate designation such as Pumping Station or Dew Point Control Facility.

Why Does It Matter?: Compressor stations are a significant source of air pollution. Compressing the gas requires large engines, which are typically powered by natural gas. Emissions from gas-fired compression engines are somewhat similar to emissions from diesel engines. Picture a lot full of 18-wheelers idling at full throttle 24x7. The equipment that removes water from gas can also be a significant source of air pollution. Emissions from compressor stations can include nitrogen oxides, hazardous air pollutants, formaldehyde, and other hydrocarbons that are known to cause cancer or be dangerous to health.

Several families who live close to compressor stations have suffered serious health problems, including rashes (both outside the body and inside in places like the nose), nosebleeds, vertigo, neurological problems, and toxins that have shown up in the blood.

What Kind of Permits Does it Need?: Air pollution is is regulated by the DEP under its Air Quality Program. In DEP-speak, an Air Quality Permit is known as a “Plan Approval”. Most compressor stations in Pennsylvania qualify for a General Permit known as GP-5. General Permit means a permit which is drafted in advance of particular applications; when a midstream company applies for a General Permit, if their application is satisfactory they are given the “canned” permit (though conditions may be attached). A General Permit is an expedited permit for which there is no public comment period. (Though there is a public comment period for the General Permit itself.)

Air pollution permits tend to be quite complex.

Noise is not regulated by the EPA or the DEP; it may be regulated by the municipality through zoning.

Act 13 included a model zoning ordinance which includes provisions for zoning of compressor stations. Any municipality enacting stricter zoning provisions than the Act 13 model ordinance was denied its share of the Marcellus Shale Impact Fee. This provision was struck down by the Pennsylvania Supreme Court.

In Fayette County, for zoning purposes a compressor station has been considered a Public/Private Works under section §1000-203 Table 1 of the Fayette County Zoning ordinance, and noise is allowed up to 90 db under §1000-503. (The Act 13 model zoning ordinance specified a noise limit of 60 db but was much more permissive of where compressor stations could be located.)