National Geographic has a series of articles on the shale gas boom in the US - A Dream Dashed by the Rush on Gas.
Both Hanger’s office and the gas industry maintain that if the process is done properly, there is no threat to drinking water when chemically treated water and sand are blasted underground to fracture shale to produce gas.
(Related: “Forcing Gas Out of Rock With Water”)
The hydraulic fracturing (fracking) fluid, about 4 million gallons (15 million liters) per well, is released into the shale layer at a depth of 4,000 to 8,500 feet (1,220 to 2,590 meters). (Related:Breaking Fuel From the Rock). That means that there is about a mile or more of rock between the shale and underground water sources used for drinking water. About 1 million Pennsylvania households, nearly 20 percent of residences in the state, draw their water from private wells that are relatively shallow. Wells in the western half of the state, for instance, would likely be drilled to depths of less than 150 feet (46 meters), according to the Pennsylvania Geological Survey.
The potential for contamination of drinking water aquifers is a major concern in the Keystone State, which has more people served by well water than any state but Michigan, according to a 2009 analysis year prepared for the state legislature. The chief bulwark against water pollution is a separating wall—a casing made of tons of steel and cement—built in each gas well not only to protect the environment, but also to ensure the valuable gas doesn’t escape.
Hanger says there hasn’t been a single confirmed case of frack fluid migrating from the shale layer deep underground to the shallow drinking water supplies in Pennsylvania. However, about 20 to 50 percent of the drilling liquid flows back to the surface, most of it right after the well is completed. And that’s when proven trouble can occur.
‘It’s Not Water of Any Kind’
This “produced water,” which includes the frack chemicals, is a super-salty brine, prone to bacterial growth, and potentially contaminated with heavy metals. “It smells like turpentine,” says Conrad Dan Volz, director of the Center for Healthy Environments and Communities at the University of Pittsburgh’s Graduate School of Public Health, who has been researching the environmental impact. “It’s not water of any kind.”
State regulations say the frack fluid has to be collected and disposed of as an industrial waste, or it can be treated and reused to drill more wells, a practice pioneered in Pennsylvania within the past year. (Related: “Forcing Gas Out of Rock With Water”) Hanger says the water reuse is in no small measure a result of the DEP’s tough stance on wastewater handling.
But in at least 130 cases documented since 2008 by the DEP, drilling wastewater has spilled into creeks and tributaries due to holding pond overflows, pump failures, and other errors. There have been at least two small fish kills. One occurred in October 2009, soon after Range started its program to reuse frack fluid: about 10,500 gallons (40,000 liters/250 barrels) leaked from a broken pipeline joint and killed about 170 creek chubs, blacknose dace, and other small fish, along with some salamanders and frogs in Brush Run, 30 miles southwest of Pittsburgh. Range says the fish killed collectively weighed about a pound. The company suspects vandalism, because bolts had been removed from the pipe connection. But no perpetrators have been tracked down, and the company was fined $140,000 for polluting a high-quality waterway. (Range since has switched to using unbolted high-density polyethylene pipeline to transfer its drilling fluid, Pitzarella says.)
In another case, involving East Resources* in north-central Pennsylvania, the state quarantined cattle exposed to wastewater that leaked from a containment pond and killed grass over 1,200 square feet on a farm. State agriculture officials said they acted to prevent contaminated beef from entering the food chain, since the water contained the heavy metal strontium, a substance especially toxic to children and one that lingers long in an animal’s system.
In a case that echoed the BP oil spill, although the results certainly weren’t as severe, an EOG Resources well blew out on June 3, with natural gas and frack fluid spewing for 16 hours from the gas well on hunting club land inside the Moshannon State Forest in central Pennsylvania.(Related: “Parks, Forests Eyed for the Fuel Beneath”) There should have been at least two pressure barriers or blowout preventers in the underground piping to prevent contaminated fluid from flowing to the surface, but only one barrier was in place, and it was damaged, the DEP’s investigation showed. EOG was hit with the harshest punishment to date by Pennsylvania’s shale regulators—a fine of $353,000 and temporary suspension from drilling.
The Dimock Case
But perhaps the most notorious Pennsylvania contamination case was in the northeastern part of the state, in rural Dimock Township, where natural gas was found in early 2009 to have contaminated the drinking water wells of 14 homes. Investigators were able to do a kind of “fingerprinting” to determine the source, and concluded the gas did not come from the Marcellus shale. But the state DEP contends that faulty well casing set into the ground by Cabot Oil & Gas as it drilled into the deep Marcellus allowed gas to migrate from more shallow geological formations into the groundwater. Dimock’s woes were recounted in the award-winning documentary film Gasland, forever linking the image of flammable drinking water to the Marcellus shale (even though the man who memorably set fire to his tap water in the film was in Colorado).