Associated Press

PITTSBURGH (AP) - At least two gas wells near a community that's complained of sudden drinking water pollution developed casing problems during the drilling process, but neither Rex Energy Corp. nor state environmental regulators disclosed those problems during recent discussions about the contamination.

A cement well casing is meant to prevent natural gas or fluids from leaking into nearby aquifers during the drilling and hydrofracturing, or fracking, of wells.

There's no proof that the casing problems _ or reported environmental violations _ at Rex drilling sites caused the water contamination for at least 10 households in the rural Woodlands community, about 30 miles north of Pittsburgh. But residents and environmental groups said on Monday that they were distressed to learn of the casing problems. The state Department of Environmental Protection, they said, doesn't seem to understand that the lack of full transparency fuels public mistrust.

Since early last year, people have complained of suddenly discolored and smelly water, unexplained illnesses, and tests that suggest the presence of industrial chemicals in their water.

"Stonewalling only enhances a public perception that DEP is not doing its job," said Jan Jarrett, president of the environmental group PennFuture. "It just makes everybody look bad, and makes the public nervous and more unsure of the industry as a whole."

DEP said Monday that Rex had corrected the casing issues. State records indicate no fines were levied.

Rex Energy spokesman Derek Smith said the company experienced two "well integrity issues" and took immediate corrective action.

"The string of steel casing that protects the groundwater was never jeopardized. We remain confident that our operations have not impacted ground water chemistry in this region," Smith said.

Rex also has said in a statement that extensive tests of area well water found "no notable differences in water chemistry between pre- and post-drill water quality tests of the water wells in question," but some residents disagree.

The company also notes that many other homeowners in the area haven't raised complaints or concerns about their well water, and DEP says the agency has conducted enough tests to make an informed, rational decision that the compounds did not come from drilling activity.

One resident with drinking water problems said she specifically asked DEP and company representatives if there had been any problems during nearby gas drilling.

"Both of them are like, `no, no, no,'" said Janet McIntyre.

But the agency's own records show that in September 2010, State College-based Rex was cited for either failing to report casing job problems within 24 hours or failure to submit a plan to correct the problem within 30 days. In November of that year the company was cited for a stream discharge of drilling waste, and failure to properly store, transport, or dispose of waste.

Rex acknowledged the well casing problems in a report on finances in late 2010, and suggested that up to five wells had such problems. A few months later, residents began complaining that their water was tainted. Rex said last week that one nearby well didn't use any of the chemicals that showed up in McIntyre's water tests in late August, 2011. But the AP found that another nearby well used as much as 66,446 gallons of petroleum distillates during the hydraulic fracturing process, which blasts water, sand and some chemicals deep underground to stimulate gas production.

McIntyre said DEP officials have refused to do follow-up tests on her water. Rex has said it plans to stop delivering water to people in the community on Feb. 29.

Jarrett said DEP should consider doing more.

"They ought to do everything they can to investigate that. Maybe there needs to be further study," she said, adding that for the public to have confidence that DEP is truly on top of the industry, people need to feel there's a proper response to their complaints.

(Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)