What’s the Marcellus Shale?

Lately, it seems like the terms “Marcellus Shale” and “fracking” are popping up everywhere. There’s a lot of information — and misinformation — and it remains a hot-button topic among environmentalists, lawmakers, and the general public alike.

So what, exactly, is this chunk of rock everyone’s talking about? The Marcellus is a layer of black shale that stretches along much of the length of the northern Appalachian basin. In the United States, it reaches from southern New York, through Pennsylvania and into northern West Virginia. It’s named for a shale outcrop near the village of Marcellus, N.Y., and studies have shown it contains trillions of cubic feet of natural gas. Experts say natural gas — formed over millions of years from decayed animal and plant matter — is the cleanest burning of all the fossil fuels, and it’s being hailed by many as a “bridge fuel”: an energy source that can reduce our dependence on oil and coal while cleaner alternatives are developed.

The challenge is getting that gas, which is deep underground, out of the rock and into use, and that’s where “fracking” comes in. Fracking — a shortened form of the term “hydraulic fracturing” — is the process of injecting a fluid into the shale to create fissures that allow the gas to escape. The gas is then collected at a well, and then pumped into a truck or pipeline for shipping.

The process of fracking is what’s creating the most controversy. There are concerns not only about the potential for contaminated groundwater, but also about the amount of water the process consumes. To create the fluid, drillers add a variety of chemicals and substances — many of them toxic — to an incredible amount of water (according to Chesapeake Energy, fracking a typical well uses 4.5 million gallons). The fracking solution becomes even more polluted because of naturally occurring substances in the earth.

A 2004 study by the Environmental Protection Agency states that the fracking of coalbed methane reservoirs — which are closer to the surface than shale gas deposits —poses no risk to drinking water, but that study has come under fire by critics who say it wasn’t thorough enough. A 2008 Scientific American article claims “a series of contamination incidents have raised questions about that EPA study and ignited a debate over whether the chemicals used in hydraulic fracturing may threaten the nation’s increasingly precious drinking water supply.”

To help us make sense of the issue, Water Works enlisted the aid of award-winning author Seamus McGraw. McGraw has written extensively on the subject, including the book “The End of Country” and pieces for Popular Mechanics, Vice magazine and Pittsburgh Quarterly.

“Cornell professor Anthony R. Ingraffea has identified three key areas of concern about the process,” McGraw says. “The first is that frack water  … will somehow work its way up from the Marcellus through several thousand feet of stone to contaminate drinking water supplies. Ingraffea calls that scenario unlikely. Translated from science speak into English, that means ‘no way,'” McGraw says. “Though there was much made of a recent New York Times report that there was contamination in a West Virginia aquifer 30 years ago, that report has been called into question. Reports from the state at the time suggest that the rock-bearing aquifer may have been drilled for oil and gas itself before the state realized that it also contained potable water.”

McGraw says the second issue Ingraffea raises is the possibility of methane contamination: Deposits of gas — which are usually higher up in the ground than the shale — can migrate up through the drill bore and leech into aquifers. “That is a real problem,” he says. “It’s what happened in Dimock [Susquehanna County] and in Bradford County. It led to the establishment of tougher regulations … and that’s a major step in the right direction, but more needs to be done.”

The third problem Ingraffea identifies is contamination from surface spills — something that’s also already happened.  “We’ve had blowouts and surface spills on several occasions, and while so far most of the impact of those have been contained, it remains a real danger,” McGraw says.

McGraw thinks the bigger challenge is water that contains the “witches’ brew of heavy metals, salt, and mildly radioactive materials that mother nature whips up in the shale itself. Unlike the flowback water from fracking, this stuff oozes back over the 30 to 50 year lifetime of the well,” he says. McGraw worries it has the potential “to create a challenge long after we’ve stopped paying attention. There needs to be much greater attention focused on making sure that we’re aggressively monitoring the wells we’re drilling now in the out years.”

Any problems caused by fracking wouldn’t affect The Authority’s water supply. “I can see no scenario in which a fracking accident in those counties would impact [Authority] wells because there is no gas there, and will be no drilling there.”

Clearly, there are pros and cons to the gas extraction. Energy experts say that with proper safeguards and regulation, the Marcellus Shale can provide an invaluable fuel source at a crucial time for the United States. Many environmentalists say that groundwater contamination is inevitable, and that’s too high a price to pay for the potential benefits. Only time will tell who’s right. In the meantime, we’ll be keeping a close eye on the situation.

To read more about shale gas and fracking, take a look at the DEP’s overview on fracking; this article from The Wall Street Journal; and a shale gas primer from the U.S. Department of Energy.