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What We Think We Know
Drilling industry officials say they use a slew of engineering techniques--from sonar to magnetic resonance imaging--to study the underground explosions and strictly control the reach of hydraulic fracturing.
They say that the actual fracturing happens thousands of feet from water supplies and below layers of impenetrable rock that seals the world above from what happens down below.
Yet there are reasons for concern. Even if layers of rock can seal water supplies from the layer where fluid is injected, the gas well itself creates an opening in that layer. The well bore is supposed to be surrounded by cement, but often there are large empty pockets or the cement itself cracks under pressure. In many instances, the high pressure of the fluids being injected into the ground has created leaks of gas--and sometimes fluids--into surrounding water supplies.
A recent regional government study in Colorado concluded that the same methane gas tapped by drilling had migrated into dozens of water wells, possibly through natural faults and fissures exacerbated by hydraulic fracturing.
Dennis Coleman, a geologist in Illinois, has seen an example where methane gas has seeped underground for more than seven miles--several times what industry spokespeople say should be possible. He is a leading international expert on molecular testing whose company, Isotech Laboratories, does scientific research for government agencies, pharmaceutical companies and the oil and gas industry.
"There is no such thing as impossible in terms of migration," Coleman said. "Like everything else in life, it comes down to the probability. It is never a hard and fast thing."
In another case, benzene, a chemical sometimes found in drilling additives, was discovered throughout a 28-mile-long aquifer in Wyoming.
"It is common knowledge that the lower layers are full of irregularities and inconsistencies," said Patrick Jacobson, a rig worker who manages drilling fluid pumps and has worked on Wyoming drilling projects for more than 20 years. "I think anybody who works in the oil fields, if they tell you the truth, would tell you the same thing."
Scientists have found it difficult to determine whether hydraulic fracturing is responsible for these problems. In large part that's because the identities of the chemicals used in the fluids have been tightly held as trade secrets, so scientists don't know precisely what to look for when they sample polluted streams and taps.
Drilling companies disclose enough information to comply with labor regulations meant to keep workers safe, but that information normally consists of a product trade name and rarely includes a complete list of the chemicals it contains.
Recently, this has begun to change.
In September, New York State--as part of a lengthy environmental review meant to assess the risks of fracturing--made public a comprehensive list of 260 chemicals used in drilling fluids, which it had compiled from disclosures it required drilling companies to make. And several companies themselves have begun to advocate for more disclosure, in the hope that transparency may quell the public outcry that has kept them from drilling in valuable parts of New York State.
Chesapeake Energy, which last year told ProPublica that the chemicals are kept secret because "it is like Coke protecting its syrup formula," now says that disclosure would bring honest discussion.
"We as an industry need to demystify," Chesapeake CEO Aubrey McClendon said at an industry conference in September, "and be very up-front about what we are doing, disclose the chemicals that we are using, search for alternatives to some of the chemicals."
What is now needed most, according to scientists at the Environmental Protection Agency and elsewhere, is a rigorous scientific study that tracks the fracturing process and attempts to measure its reach into underground water supplies.
In Wyoming, EPA scientists with the Superfund program are conducting the first federal investigation of this kind, sampling available water sources and looking for any traces of the chemicals used in drilling. But Colorado's Thyne says a proper study would go a step further.
"The critical thing that has to be done is a systematic sampling of the background prior to drilling activity, during and after drilling activity," Thyne said. "Ideally, we would go out, we would put monitoring wells in and surround an area that was going to be fractured as part of normal operations. The budget for that kind of project would run ballpark $10 million. It's a relatively small project for the U.S. Geological Survey or the EPA to undertake."
Where Should The Waste Go?
On the East Coast, one of the most important unanswered questions about drilling is how to dispose of the chemically tainted wastewater that hydraulic fracturing produces.
Most drilling wastewater in other parts of the country is stored in underground injection wells that are regulated by the EPA under the Safe Drinking Water Act. However, the geology in the East makes injection less viable and less common. In New York and Pennsylvania, millions of gallons of drilling wastewater could eventually be produced each day.
That wastewater will likely be trucked to treatment plants that don't routinely test for most of the chemicals the wastewater contains and that may not be equipped to remove them. Currently, the plants also can't remove the high levels of total dissolved solids found in drilling wastewater--a mixture of salts, metals and minerals--that can increase the salinity of fresh water streams and interfere with the biological treatment process at sewage treatment plants, allowing untreated waste to flow into waterways. High TDS levels also can harm industrial and household equipment and affect the color and taste of water.
After the wastewater passes through the treatment plants, it is dumped back into public waterways that supply drinking water to at least 27 million Americans, including residents of Philadelphia and New York City. But without identification and routine testing for the problematic chemicals, it will be impossible to know how much of them are making their way to drinking water sources, or how they are accumulating over time. Evolving medical science says low-dose exposure to some of those chemicals could have much greater health effects than the EPA or doctors have previously thought.
"Managing produced water has always seemed like one of the large challenges, because this area geologically doesn't have the extensive network of underground injection wells," said Lee Fuller, vice president of government relations for the Independent Petroleum Association of America. "One challenge that industry has got is looking at developing [treatment] technology, which could be very costly."