Regulators have been hard-pressed to keep tabs on the vast wastewater volumes ever since, as development of the Marcellus Shale has expanded across the state.
"It was a warning signal, and we treated it that way," said John Hanger, then-secretary of the state Department of Environmental Protection. DEP ordered Monongahela River sewage-treatment plants to reduce the volumes of drilling wastewater they accepted by more than 90 percent, a reduction that remains in place today.
State regulators also began to rewrite wastewater rules, resulting in strict new discharge standards that went into effect this year, over the industry's objections.
Those actions began to close the door on the relatively cheap option of discharging inadequately treated wastewater, forcing the gas industry to develop the practice it now touts as the solution to Pennsylvania's problem: recycling.
"There just wasn't enough treatment capacity," said Tony Gaudlip, director of strategic planning and development for Range Resources Corp., the Texas company that pioneered Marcellus development.
Drillers say they can recycle contaminated wastewater by mixing it with the fresh water used in new drilling operations. The blended water is pumped into wells during hydraulic fracturing or "fracking," a process that involves pumping millions of gallons of water, sand and chemicals under high pressure deep into the earth to shatter the shale to release gas molecules.
Initially, drilling companies believed they would have to practically purify the water in an energy-intensive distillation process to make it reusable in new drilling operations. They were concerned the wastewater would clog up the new wells. But they discovered that even minimally treated wastewater did not impair a new well's performance. Recycled water typically comprises between 10 percent and 20 percent of the water used in a fracking job.
"We had a lot to learn about water in the last three years," said Gaudlip.
Now, less than three years after recycling operations began, the industry and regulators claim that up to 90 percent of the wastewater recovered from shale drilling is recycled. About 2,700 Marcellus wells have been drilled to date, with 50,000 more projected in coming decades.
Anti-drilling activists say the industry's recycling claims are exaggerated. Earlier this month, The Inquirer reported that is it impossible to verify those claims because of flawed DEP record-keeping.
"We need better monitoring and better oversight," said Myron Arnowitt, state director of Clean Water Action, an environmental advocacy group.
Despite recycling efforts, the gas industry still disposes of millions of gallons of salty wastewater at municipal or industrial treatment plants that critics say do not adequately treat it. (Almost all that has been discharged outside the Delaware watershed, where the Philadelphia region draws its public water supplies).
Environmental activists and federal regulators are stepping up pressure on Gov. Corbett's administration to clamp down on questionable wastewater discharges.
After a New York Times report that drillers may have sent wastewater containing high levels of radiation to treatment plants unable to process such waste, the U.S. Environmental Protection Agency on March 7 instructed Pennsylvania officials to speed up testing for radioactive contaminants. (Preliminary tests indicated no elevated levels of radiation in seven rivers into which the wastewater had been discharged.)
The EPA's regional administrator, Shawn M. Garvin, also encouraged the state to reevaluate the discharge permits for wastewater plants not equipped to treat drilling wastes.
At the same time, environmental groups led by Clean Water Action filed notice with two municipal sewer authorities in the Monongahela basin that they would sue to force them to stop accepting gas-drilling wastewater.
The two facilities, in McKeesport and Franklin Township, Greene County, reduced acceptance of Marcellus wastewater after 2008. But the legal notice says recent water samples still show elevated levels of several contaminants found in such wastewater: TDS, chlorides, bromides, barium, and strontium.
"We cannot wait any longer to rely on the state and EPA to act," Arnowitt said.
Even some industry supporters say the science of recycling wastewater has advanced so far in three years that there is no need to allow continued discharges of drilling wastes through municipal treatment plants, which merely dilute the most serious contaminants.
"The municipal plants have no reason to take this water, that's just my personal opinion," said Kelvin Gregory, assistant professor of civil and environmental engineering at Carnegie Mellon University, who has studied recycling operations. "There's no need to put further stress on streams when there are other cost-effective methods of dealing with the wastewater."
Wastewater disposal is part of a larger debate on hydraulic fracturing, which contributed to the development of large shale-gas deposits that have dramatically increased the nation's reserves.
The EPA, which called hydraulic fracturing safe in a 2004 study that has come under fire as biased, last year launched a new examination of the process. That is scheduled to be completed next year.
In Texas and other states where shale drilling has taken off, gas operators dispose of their wastewater in federally regulated injection wells, which pump the fluids into deep formations that can absorb liquid. The target reservoirs are confined by impermeable rock, to prevent the fluid from migrating upward.
But Pennsylvania's geology does not lend itself to injection wells - only seven are licensed in the state.
While engineers learned quickly that wastewater did not require a high level of treatment to work in a recycling operation, it still required some treatment.
For example, Range Resources discovered that wastewater at least needed an antibacterial additive after a retention pond went sour and neighboring farmers got a whiff. "It smells, it stinks, it's not good for business," said Gaudlip.
Range solved that problem by sending its wastewater to an industrial treatment plant, which removes sediment and reduces metals such as barium and strontium. Chlorine is added to kill the bacteria.
Other operators are developing similar recycling programs. "There's nothing in flowback water that's particularly difficult for an environmental engineer to manage," said Carnegie Mellon's Gregory.
Anadarko Petroleum Corp., which operates large holdings in the state's forests, treats wastewater at mobile plants in the field, reducing distances it has to be trucked.
"We're trying to get the iron out, the solids out, and treating it for bacteria," said Scott Chesebro, Anadarko's engineering manager for Appalachian operations. "There are several ways to treat water. This process works for us."
The state's new treatment standards have inspired some entrepreneurs to respond to the demands of the market.
In Williamsport, a regional hub for drilling operations in northern Pennsylvania, Martin J. Muggleton and his partners recognized that "water resources were going to be the big limitation on Marcellus Shale development."
"We saw this as an enterprise early on," he said.
So Muggleton, a principal in the Larson Design Group, said his large Williamsport architectural and engineering firm decided to build on its experience with wastewater treatment to construct a plant to assist drillers recycling wastewater.
"In 2008, we told people, 'We're not going to put salt in the river,' " he said. "That's not a sustainable approach."
Last year, Muggleton's firm opened TerrAqua Resource Management, a 77,000-square-foot facility in Williamsport. TerrAqua removes contaminants such as sediments and metals, which are pressed into a cake and trucked as residual solid waste to landfills. (The material is tested for radiation, but so far, he said, none has exceeded limits).
Water treated by TerrAqua retains its high salt content, so it can't be discharged into a river. Drillers that bring their wastewater to TerrAqua are required to fill their trucks with treated water for recycling before they leave the plant.
During the last six months of 2010, TerrAqua treated 17 million gallons or about 7.5 percent, DEP records say, of the 225 million gallons drillers reported they disposed of statewide during that period.
In nearly a year of operation, TerrAqua has now treated 35 million gallons.
In another part of Williamsport, entrepreneur Daniel J. Ertel also saw opportunity in treating drilling wastewater.
Ertel's company, Eureka Resources L.L.C., incorporates a thermal process that essentially distills the wastewater after it goes through conventional treatment to remove sediments.
Wastewater treated in the more expensive Eureka process practically meets drinking-water standards, Ertel said, and can be discharged into the Williamsport sewer system. He said it is the only treatment plant in the state that meets DEP's new discharge requirements.
"There's a market for this," said Ertel. His plant processed about 10.3 million gallons of wastewater during the last six months of 2010, according to state reports.
What's left after the process is a heavily concentrated salty brine that is trucked to an injection well in Ohio.
More intensive, expensive treatment processes may have a bigger market as development of the Marcellus Shale matures.
For now, drilling operators say, so many new wells are being drilled that most wastewater can potentially be recycled.
Contact staff writer Andrew Maykuth at 215-854-2947 or firstname.lastname@example.org.