CLEARFIELD, PA. - The contractor whose Pennsylvania operations were suspended by state environmental officials after a natural gas well blowout said Thursday that it had already idled its two Marcellus Shale rigs and is cooperating with the investigation.

Forbes Energy Services Ltd., of Alice, Texas, said it had "voluntarily and proactively" shut down its Marcellus rigs following the June 3 accident in Clearfield County, in which a well erupted and spewed natural gas and toxic fluids for 16 hours before it was brought under control. A Forbes oil field services subsidiary, C.C. Forbes Co., was working on the well at the time.

"Idling of the two rigs will have no material impact on our future results of operations," John Crisp, Forbes Energy's chief executive, said in a statement.

The Department of Environmental Protection suspended Forbes from any more well-completion activity on Wednesday. DEP Secretary John Hanger said Forbes had not been cooperating "to our satisfaction."

In an interview on Pennsylvania Cable Network on Wednesday night, Hanger said that investigators had attempted to question Forbes workers who were on the site about the incident, but the company "had directed its employees not to talk to us without representatives present."

There were no injuries and no fire in the incident, which occurred on a well operated by EOG Resources Inc. in a remote forested area owned by a hunting club. DEP on Monday suspended EOG from drilling activities until its investigation was completed.

EOG hired Forbes to complete the well - to clean it out and connect it to a pipeline.

DEP has characterized the environmental damage from the incident as "modest," but Hanger indicated Wednesday that some fluid may have escaped to a nearby stream.

The agency said 35,000 gallons of fluids were collected after the blowout. Most was contained on the gravel site where the well is located. DEP initially said a spring nearby showed a spike in "conductivity," an indication that it had been contaminated with salt water associated with gas-well production fluids.

DEP spokesman Neil Weaver now says a water sample taken on Monday in an unnamed tributary of Little Laurel Run 2,000 feet from the spring "displays elevated conductivity and other parameters often associated with flow back water from drilling activities.

"This indicates that some fluid was not effectively captured or there may be an additional pollution source," Weaver said in an e-mail late Wednesday. "EOG's environmental staff and their environmental consultants will continue to sample in this area."

Houston-based EOG is developing dozens of wells in the area in partnership with Seneca Resources Corp., which owns the leases. Some are on lands in Moshannon State Forest, which surrounds three sides of the Punxsutawney Hunting Club, where the accident occurred.

DEP has not yet released detailed tests of the spill or the well's wastewater that would indicate if the fluid contained any heavy metals or toxic elements that reside in deep geologic formations, such as barium, radium, arsenic or strontium. The tests might also indicate whether any of the three chemicals that EOG reported it used during the hydraulic fracturing process in May had escaped from the well.

"Fracking" is the process in which large amounts of high-pressure water, sand and chemicals are injected into a well to shatter the shale to release entrapped natural gas. The sand particles remain in the hairline fractures to allow pathways for the gas to escape. Much of the wastewater is recovered and recycled or treated and disposed.

EOG said the three chemicals it used in its frack fluid amounted to 0.135 percent of the total volume that was injected into the well. The additives reduce the fluid's friction and inhibit the formation of scale or bacterial slime that can clog the tiny fractures, reducing the flow of gas.

The trace amounts of frack fluids or exotic toxic elements found in the rock are of less concern to environmental officials than the potential damage caused by chlorides – salt – which can pollute drinking water and damage aquatic life.

Hanger, in his television appearance, assured callers that the state had not experienced an instance where fluids from the hydraulic fracturing process have contaminated underground drinking water supplies.

In an e-mail after the appearance, Hanger said it is not yet known if the Clearfield blowout will affect groundwater. "Too early in the investigation to say one way or another," he said.

Forbes said that no significant equipment was damaged during the blowout.

Elizabeth M. Ivers, an EOG spokeswoman, also says that the well appeared to be undamaged by the blowout. If it needed to be plugged, it would represent a significant loss because such wells typically cost about $4 million to develop.