In the Midst of a Fracking Firestorm

Whatever your stance, one thing is certain: few energy issues today are as divisive as shale gas drilling and hydrofracturing, a process in which large volumes of water, sand and chemicals are pumped deep underground into gas wells at high pressure to crack open hydrocarbon-rich shale and extract its embedded natural gas.

Shale gas comprises about 15 percent of natural gas produced in the United States today. The federal Energy Information Administration estimates it will make up almost half of the nation’s gas production by 2035 as “fracking,” as one step in the process is commonly called, makes more and more deposits of shale gas accessible.

Supporters tout the process as a way to tap a plentiful domestic resource and bring jobs, prosperity and energy security to America at a time when we desperately need them.

Opponents paint it as an environmental travesty. They say it makes a lucky few rich but at the cost of polluted groundwater supplies and fractured communities, and possible risks to human health.

“You hear all kinds of claims, few of which are based on science,” says Avner Vengosh, professor of geochemistry and water quality at the Nicholas School of the Environment. “It’s become such a charged issue that it literally is tearing communities and families apart.”

In May, Vengosh and three colleagues at the Nicholas School landed squarely in the middle of the firestorm when they published the first peer-reviewed study documenting contamination of drinking water supplies near shale-gas drilling and fracking sites in the Marcellus Shale region of northeastern Pennsylvania and New York.

Their study, published in the Proceedings of the National Academy of Sciences, found high levels of leaked methane in well water near the drilling and fracking sites. The team analyzed water samples from 68 private shallow groundwater wells across five counties in the two states.

Fears about well-water contamination from methane, wastewater and fracking fluids have risen sharply in many communities overlying the Marcellus Shale formation as the pace of drilling and fracking accelerates there in recent years. Fracking fluids contain a proprietary mix of toxic and non-toxic chemicals that most companies did not disclose in the past but more are voluntarily disclosing now.

Some homeowners claim they can’t drink their well water any longer and say it wasn’t that way before the fracking began.

Proving anecdotal claims about tainted water—and assessing blame—can be tricky, says Robert B. Jackson, Nicholas Professor of Global Environmental Change and director of the Center on Global Change, “but at least some of the homeowners who claim that their wells were contaminated by shale-gas extraction appear to be right.”

The team’s study detected measurable amounts of methane in 85 percent of the collected samples, and levels were 17 times higher on average in wells located within a kilometer of active hydrofracking sites, says geologist Stephen Osborn, a former postdoctoral research associate with Jackson and Vengosh at the Nicholas School and Duke’s Center on Global Change, who was lead author of the study. (Osborn joined the faculty at California Polytechnic State University this summer.)

Tests showed that the methane collected from water wells within a kilometer of active sites had a chemical fingerprint similar to thermogenic methane, which is formed at high temperatures deep underground and is captured in gas wells.

No evidence, however, was found to support two of the most widespread public fears about fracking. Water samples showed no sign of contamination from chemical-laden fracking fluids, which are injected into gas wells to help break up shale deposits, nor did the samples contain “produced water,” the high-saline wastewater that is extracted back out of the wells with the gas after the shale has been fractured.

Because the study was the first peer-reviewed research on the contentious topic, Jackson, Vengosh, Osborn and fourth author Nathaniel Warner, a PhD student of Vengosh’s, braced themselves for a healthy dose of second-guessing when the paper was published. They’d already begun work to increase the size and geographic distribution of their sampling, fill in additional baseline data and lay the groundwork for a second, broader study.

“We were confident in our conclusions, but we also recognized the need to gather more data,” Jackson says.

What they didn’t anticipate was how heated and dogmatic the reaction to their study would become.

Natural gas industry lobbyists didn’t just disagree with the team’s interpretation, they denied the data outright and attacked the scientists’ motivation and credibility. Pro-fracking and anti-fracking activists alike extracted bits and pieces of the study and spun them to support their own agendas. Legislators, environmentalists, agency heads and community leaders cited the findings—sometimes with considerable poetic license—at public meetings, marches and rallies. Media coverage was all over the map, literally and ideologically. There seemed to be no middle ground. One local newspaper compared the study to a Rohrschach test because people from all sides saw what they wanted in it.

The atmosphere of entrenched denial and distrust shook the scientists but strengthened their resolve to dig deeper.

“We had no preconceived notions of what we’d find going into this research, so we felt we had an opportunity and responsibility to work with people on all sides to find answers,” says Vengosh.

“No one likes having a bulls-eye on your back,” Osborn adds, “but when your work generates a reaction this divided—and when you see how anxious homeowners are for straight answers—it underscores the urgency of bringing science to bear on the issue.”

Fracking 101

To understand how much is at stake in the fracking debate, you first have to understand a bit about the process itself.

The Energy Information Administration estimates the United States has 2,119 trillion cubic feet of recoverable natural gas, about 60 percent of which is “unconventional gas.” This means it’s trapped in low-permeable formations such as shale, coal beds or other geologic strata that hold the gas too tightly for conventional extraction processes to bring it to the surface cost-effectively without special stimulation.

Scientists and energy companies have long known these reserves exist. But it wasn’t until the last decade that advances in hydraulic fracturing and horizontal drilling technologies finally made large-scale production economically viable.

To frack a well, millions of gallons of fluid are pumped down its shaft at high pressure to create cracks in hydrocarbon-rich formations deep underground, allowing trapped gas to flow out and be extracted. The fluid contains “propping agents” such as sand to keep the fractures open, as well as friction reducers, surfactants, gelling agents, scale inhibitors, acids, corrosion inhibitors, antibacterial agents, clay stabilizers and other chemicals. The composition and proportions of these chemicals is not always public knowledge.

Fracking can substantially boost a well’s productivity, especially horizontally drilled wells that extend for up to two miles underground from the well pad. In some cases, the output of a fracked horizontal well can more than triple that of a conventional vertical well.

Because it delivers so much bang for the buck, fracking is now used to stimulate production in 90 percent of domestic oil and gas wells, according to the Interstate Oil and Gas Compact Commission. Its use in unconventional shale extraction is one of the fastest growing trends in American on-shore oil and gas production.

Supporters point to many environmental benefits. Natural gas, they note, contains more energy per pound than coal, and when burned it produces almost no mercury, sulfur dioxide and particulates. A horizontal well has a much smaller footprint on the surface of the Earth than multiple vertical wells would, and doesn’t require mountain-top removal or other destructive mining methods. Nor does it require disposal of coal ash residue, an emerging environmental concern.

“As a cleaner source of energy than coal, shale gas has a lot to recommend it,” Jackson agrees. “Our goal is to make it as clean and safe as possible.”

Despite precautions by industry, contamination of nearby shallow groundwater can occur through corroded well casings, spilled fracking fluids, leaked or improperly disposed wastewater, or, more controversially, the direct movement of methane gas or water from deep underground.

Shale gas is typically comprised of more than 90 percent methane, a tasteless, odorless gas that is flammable, poses a risk of explosion and, in very high concentrations, can cause asphyxiation.

At some locations near active fracking sites, methane levels in groundwater are so high that homeowners can light their tap water on fire. It’s a scene replayed over and over again in recent years in televised news reports, many of which have focused on a cluster of homes along Carter Road in Dimock, Penn., one of the communities included in the Nicholas School study.

Less attention has been paid to the possible health effects of drinking methane-contaminated water. Methane isn’t known to affect water’s potability, so it isn’t regulated under the U.S. Environmental Protection Agency’s National Primary Drinking Water Regulations. (The Duke team has called for an independent medical review to evaluate the effects of exposure to chronic low levels of methane in drinking water. Their recommendation is included in a white paper they’ve issued with a colleague from Duke’s Nicholas Institute for Environmental Policy Solutions.)

Some safety standards do exist, however. The U.S. Department of the Interior recommends removing nearby ignition sources, warning nearby occupants and taking steps to reduce the buildup when dissolved methane concentrations in water exceed 10 milligrams per liter. Immediate ventilation of the well head is recommended when levels exceed 28 milligrams per liter.

Average methane concentrations in the water samples collected within a kilometer of active gas wells in the Nicholas School study were about 22 milligrams per liter.

Point, Counterpoint

Industry advocates have said the study’s average 22-millgram-per-liter figure is distorted because it includes methane levels in the well water of homes along Carter Road, which, they contend, are a localized anomaly.

Not true, counters Osborn. “Our analysis shows that methane concentrations were 17 times higher on average in well water collected within a kilometer of active drilling sites across the study area, not just in known trouble spots like Dimock, although contamination was primarily observed in two counties,” he says.

The average methane concentrations for the study’s dataset were actually about five milligrams per liter higher when samples from Dimock were excluded, Warner notes. The highest levels found in the initial study—64.4 milligrams per liter—weren’t even from samples collected in Dimock; they came from sites in a different county altogether. Samples collected more recently from another site had methane concentrations above 100 milligrams per liter.

Evidence from the team’s other tests also points to a more generalized cause of the contamination.

Using carbon and hydrogen tracers, the scientists found that methane from samples within a kilometer of active sites had an isotopic fingerprint similar to deep-gas thermogenic methane. Samples collected outside a kilometer contained a mixed fingerprint of both thermogenic and biogenic methane, which forms at shallower depths and lower temperatures and is not associated with shale gas.

To confirm these findings, the scientists compared the dissolved gas chemistry of the water samples to the gas chemistry profiles of shale-gas wells in the region, using data from the Pennsylvania Department of Environmental Protection. Deep gas has a distinctive chemical signature.

“When we compared the dissolved gas chemistry in well water to methane from local gas wells,” Jackson says, “the signatures matched.

“The fact that we found similar patterns across the five counties, not just in Dimock, raises the question of how general the contamination is from shale gas wells in the region, and highlights the need for more research,” he says.

As the scope of the research expands, one issue that looms large is the question of wastewater.

Warner is now using state-of-the-art isotope technology to identify the geochemical fingerprints of produced water and fracking fluids so the team can track them in the environment and test for possible contamination of drinking water.

An active well can produce a million or more gallons of wastewater a month, Vengosh notes. The water is 10 to 20 times more saline than seawater. It’s naturally radioactive. And it can contain metals such as surfactants in concentrations far above those considered safe for drinking water or for release into the environment.

“Fracking fluid is injected into the well in one shot, but the extraction of produced wastewater continues over the well’s lifetime,” he says. “How do you treat and dispose of this large volume of radioactive brine that is continually generated?”

Companies used to dispose the wastewater in local waterways or send it to treatment plants, he says. In some cases, this led to problems in downstream communities, including Pittsburgh, where elevated levels of bromide in the treated wastewater generated toxic compounds known as trihalomethanes in chlorinated drinking water supplies. Earlier this year, the state of Pennsylvania requested a “voluntary” stop to the practice. Many companies have since sent their produced water to Ohio for recharge into deep aquifers there. Now, Ohio is saying it can no longer handle the volume.

“This is a huge issue, especially when you multiple it by the number of wells that are, or soon will be, producing wastewater,” Vengosh says.

Jackson’s group is following up on a different angle.

Graduate student Adrian Down and research scientist Jon Karr are trying to answer the question of how much methane reaches the atmosphere from shale gas drilling and from natural gas pipelines. Methane can interact with other gases in the atmosphere to form ozone, a pollutant, and is a much more potent greenhouse gas than carbon dioxide, Jackson explains. His group has recently deployed a new instrument that allows them to measure airborne methane concentrations and isotopic values in real time.

Seeking Solutions

Industry is expected to drill as many as 10,000 new wells in the next few years.

That timeline, the scientists say, adds urgency to their efforts to build consensus and find solutions.

In addition to their peer-reviewed study—which was funded by the Nicholas School and Center on Global Change, and started with help from Dean William L. Chameides—the researchers have worked with Brooks Rainey Pearson, policy counsel at Duke’s Nicholas Institute, to issue a white paper on hydrofracking (online at nicholas.duke.edu/cgc). It includes practical recommendations for monitoring and addressing potential environmental and human health risks.

They’re organizing an international symposium at Duke in coming months on the environmental impacts of shale gas drilling. The symposium has been funded by a $46,000 grant from the National Science Foundation.

They’ve returned to northeast Pennsylvania and New York several times in 2011 for weeklong trips to collect more samples, especially of baseline water quality from natural methane seeps and from water wells near sites slated for future drilling and fracking.

Offers to collaborate with industry on the research have been ignored.

“Given the chance of litigation, I can understand why industry is so defensive,” says Jackson. “We’re not saying don’t frack. We’re saying let’s be smart: Acknowledge the problem, do the due diligence, and put additional safeguards in place.”

Some people seem to be listening. A commission created by Pennsylvania’s governor is now urging beefed-up environmental protections, including the expansion of the presumptive liability zone around gas wells from 1,000 feet to 2,500 feet—a recommendation consistent with one made by the Duke team. Lawmakers crafting legislation in North Carolina have sought out the team’s expertise. The EPA has announced plans for its own study of fracking’s impact on water. The U.S. Department of Energy is soliciting a new round of expert advice on the issue. Increasing numbers of homeowners nationwide and from Canada are coming forward and asking to have their water tested by the Nicholas School scientists. Other universities, including Penn State, Texas and Temple, have unveiled plans to start testing wells, too.

It’s too early to claim a growing consensus on the divisive issue, says Vengosh with guarded optimism, “but we’re a lot further along than we were six months ago.”

Tim Lucas is the Nicholas School’s national media relations and marketing specialist.