The state Department of Environmental Protection said newly updated requirements for natural gas-powered engines used at Marcellus Shale gas compressor stations tighten existing emissions standards by 75 to 90 percent.
But the changes only confirm existing industry emissions technology, according to environmentalists, and could allow air quality to worsen because emissions of pollutants from individual wells wouldn't be aggregated.
The new compressor station engine emissions standards for nitrogen oxides, volatile organic compounds, formaldehyde and carbon are part of an updated but narrower DEP General Permit-5, or GP-5, published in Friday's Pennsylvania Bulletin.
The DEP is proposing that those wellhead and impoundment operations be exempted from requirements to get a plan approval and operating permit if they meet emissions limits and monitoring criteria stricter than federal standards.
DEP Secretary Michael Krancer said in a department news release the new approach to controlling gas well drilling, storage tank and compressor station emissions will result in pollution reductions.
But the general permit only confirms existing industry practices, said David Presley, an attorney with the Clean Air Council, one of eight environmental and community groups to raise concerns about the permit revision.
"The new GP-5 definitely ratchets down emissions, but only from the limits contained in the general permit language form 2006," Mr. Presley said. "They actually match what the industry has been doing for the past two years."
Mr. Presley said DEP also did not address concerns expressed by the U.S. Environmental Protection Agency that the state's failure to control the aggregated emissions from the state's Marcellus Shale developments could cause a decline in air quality.
There are more than 400 compressor stations operating in the state. Residents living near some of those stations have complained about emissions and air quality, and the Clean Air Council this week reported that the levels of nitrogen oxides in the air near one of those, in Lycoming County, was nearly three times higher than the national ambient air quality standard. Nitrogen oxides contribute to the creation of unhealthy ground-level ozone, smog and acid rain.
Mr. Presley also questioned whether Marcellus Shale well pad operations are insignificant enough emitters of pollutants to qualify as an "exemption."
A recent "industry study out of New York state found wells can emit up to 20 tons of volatile organic compounds a year. That doesn't sound like an insignificant source," he said. "Exemptions can be granted to anything DEP deems an insignificant source, but we think the authority is shaky on this. It's something we're looking at."
The final general permit document and proposed exemptions document, plus more information, are available at www.dep.state.pa.us (click "Air" then "Bureau of Air Quality") or call 1-717-787-4325.
The DEP will accept comments on the proposed exemptions until March 19. Written comments, suggestions or objections to the wellhead and impoundment exemptions should be submitted to Krishnan Ramamurthy, environmental program manager, Division of Permits, Bureau of Air Quality, 12th Floor, Rachel Carson State Office Building, P.O. Box 8468, Harrisburg, PA 17105-8468; or at firstname.lastname@example.org - environment - health