An environmental group is challenging how Pennsylvania combines air emissions from interconnected Marcellus Shale infrastructure for regulatory purposes.

The Philadelphia-based Clean Air Council (CAC) recently asked the U.S. Environmental Protection Agency (EPA) to sanction the Pennsylvania Department of Environmental Protection (DEP) for not adequately enforcing air quality regulations, specifically when it comes to single source determinations.

The complex process helps regulators decide whether to aggregate several sources of air emissions and impose stricter permitting requirements if the emissions from those aggregated facilities hit thresholds that any single facility doesn’t reach on its own. Aggregation rules are purposefully vague to force regulators to make decisions on a case-by-case basis. Generally, sources are aggregated if they are from the same industry, interconnected and “contiguous or adjacent.”

The CAC said it reviewed 25 air permit reviews, but found that only five included a single source determination, all for MarkWest Liberty Midstream and Resources LLC’s processing plant in Houston, PA, in southwestern Pennsylvania.

In December 2010 then-Gov. Ed Rendell issued a policy document to help regulators define “contiguous or adjacent,” but Gov. Tom Corbett, who took office the following month, rescinded the guidance in February 2011 (see Shale Daily, March 3, 2011). When the Corbett administration issued its policy in October, it took a literal approach to defining “contiguous or adjacent” (see Shale Daily, Oct. 14, 2011).

“Over time, there was a tendency by some regulators to morph the meaning of ‘contiguous’ or ‘adjacent’ properties to mean only that operations on the properties be ‘interdependent,'” DEP Secretary Michael Krancer said, adding that this expanded definition isn’t supported by case law or existing state and federal regulations.

The EPA challenged the state’s policy guidance. “The draft guidance appears to alter the conventional way in which aggregation determinations have been made federally and by [DEP],” said Diana Esher, director of the air protection division for EPA Region 3, in comments to state officials in November (see Shale Daily, Dec. 7, 2011). Although Krancer said each determination would continue to be “applied on a case-by-case basis,” Esher said the new definition constituted a “bright line,” or a set measurement standard that could overshadow the specific factors in any given case.

In its recent petition, the CAC said the October policy “blatantly disregards longstanding EPA practice as well as the plain meaning of adjacency.” In making its change, the DEP pointed to the “quarter-mile rule of thumb” that states like Texas, Oklahoma and Louisiana use to measure “contiguous or adjacent.”

The CAC is increasingly targeting the DEP on shale issues. It appealed a DEP single source determination in early 2011, and that case is currently before the Pennsylvania Environmental Hearing Board. The group also recently challenged how the DEP is collecting information from shale operators for an upcoming air emissions inventory, forcing the state agency to request additional information from companies (see Shale Daily, Jan. 9).