No indication of unusual levels of pollutants that would suggest a potential health concern for local residents or emergency responders was found as a result of fires at a Chevron Appalachia well site in Greene County, PA, earlier this year, according to Pennsylvania’s Department of Environmental Protection (DEP).

“While none of the pollutant levels were found to be a threat to health, there were higher concentrations of propane, heptane and 1,2,4-trimethylbenzene than are typically found in other rural areas across the state,” DEP said in areport released Wednesday. “However, DEP cannot verify that these concentrations occurred because of the fire and uncontrolled gas leak.”

Heptane often comes from crude oil and is used in paints and solvents; 1,2,4-trimethylbenzene is usually found in coal tar or oil; and the higher concentrations of propane are believed to have come from nearby storage tanks, DEP said.

In addition, data collected by DEP’s Bureau of Radiation Protection “found no radiation levels that were above normal background levels,” DEP said in a separate report.

In a notice of violations sent to Chevron earlier this month, DEP said natural gas was emitted uncontrollably into the air and production fluids discharged into the air and onto the well pad between the time of the explosion and the capping of the wells two weeks later (see Shale Daily, April 11).

The explosion and fires Feb. 11 at Chevron’s Lanco 6H and Lanco 7H wells in Dunkard Township, about 70 miles south of Pittsburgh, was one of the worst the state has seen in modern history and the largest accident yet at an unconventional well in the state (see Shale Daily, Feb. 11). One worker was killed and another injured in the incident. The fires didn’t extinguish themselves until Feb. 15 (see Shale Daily, Feb. 18; Feb. 14; Feb. 13; Feb. 12).

DEP took air samples from several locations, both upwind and downwind of the well pad beginning the day after the explosion and fires through Feb. 20. The samples were analyzed for 57 toxic air pollutants. Samples tested for radiation levels were gathered from three locations on both Feb. 13 and Feb. 14, DEP said.

In a recent notice of nine violations stemming from the explosion and resulting fires, DEP alleged that Chevron refused unrestricted access to properly identified agency personnel at the well site the day of the incident. DEP’s also alleged a failure to effectively prevent an explosion; failure to prevent waste of gas due to inadequate blowout equipment; failure to contain fugitive air emissions and the modification or operation of an air contamination source without department approval.

Chevron has a significant footprint in the Marcellus Shale, where it has about 714,000 net acres under lease, according to company documents and calculations by NGI’s Shale Daily. It has 40 permits to drill in Dunkard Township, in a part of the state where operators have flocked to produce liquids-rich gas (see Shale Daily, Dec. 12, 2013).