feet above the Marcellus Shale. Pennsylvania regulations require companies to drill with air until they are below the aquifer, and directional drilling, or side tracking, The exploitation of massive Marcelthen line the hole. As a result, the the drill for the next 1000 feet so lus Shale natural-gas deposits in chances of fluids from hydraulic that the drill bit begins to move the Appalachian region of the fracturing entering drinking water horizontally. The operators then northeastern U.S. sounds like a are slim. drill horizontally for another 3000 dream. With energy concerns at the But finding and disposing of the feet. More than a million gallons of top of the nation’s agenda, this millions of gallons of water that water and chemical additives as natural-gas reservoir, located just hydraulic fracturing demands are well as about half a ton of sand are several hundred miles from East two major problems. With Coast urban centers, has hydraulic fracturing, “you drilling companies pouring aren’t even going to have a into the region. In Pennsylstream left,” Burnett says. vania, where development Treating the fluids brought is the most advanced, landup from the well is also a owners are eagerly signing problem. “The [brine] can’t mineral-rights leases. But go to a sewage treatment environmental groups and plant,” Burnett adds. some industry insiders “Those plants can’t handle warn that local communia multi-million-gallon slug ties and state regulators of salty water.” could be blindsided by the This spring, the first signs environmental conseof difficulty appeared when quences of the gas boom. PADEP shut down two drill David Burnett, technical sites because operators were director of the Global Pewithdrawing millions of galtroleum Research Institute Each deep-drilling and hydraulic-fracturing operation, like the one shown here, has a multi-million-gallon thirst. lons from creeks located at Texas A&M University, near their operations. The says that residents in ceninjected into the well at high presdrillers were also cited for other viotral and northeastern Pennsylvania, sure, which then fractures the rock. lations that included poorly conand other prime areas for drilling Among the additives that have structed and dangerous water the shale, should be braced for been used are guar gum, biocides, impoundments, inadequate erosion high-speed changes. During the and diesel fuel, although the three and sediment controls, and impast 7 years, exploitation of the major drilling service companies proper waste and fluid disposal. Barnett Shale, a similar geological agreed to stop using diesel fuel in Michael Brownell of the Susqueformation in Texas, “has turned 2003. The water pumped out of the hanna River Basin Commission says Fort Worth into a boom town like well contains the additives and that the current problems will pass Silver City, Nev., in its heyday,” he brine that were trapped in the gas when long-term operations can be says. Burnett’s research aims to formation, along with metals, sulestablished. He notes that companies minimize the environmental consefides, and radioactive materials. are negotiating with municipalities to quences of gas and oil drilling. The levels of metals and radioactivbuy the freshwater they need. But Buried more than a mile beneath ity are likely to be very low, EnBrownell admits that the commisthe surface, the Marcellus Shale’s gelder says. Still, radioactive sion’s regulatory staff of seven is vast amounts of natural gas have materials sometimes become constretched thin by the recent drilling long tantalized geologists. Now, centrated on the drilling interest. PADEP has 35 inspectors thanks to soaring natural-gas prices equipment. assigned to oversee operations and improved drilling throughout the state. A controversial 2004 U.S. EPA technologiessmainly hydraulic “The state maintains it’s on top of report rated the threat of hydraulic fracturing and horizontal the natural-gas rush and holds up fracturing to drinking water as drillingsan estimated 50 trillion the recent citations as proof, but to “minimal”. Thomas Rathbun of the cubic feet of gas could be recovus this looks like a slap on the wrist,” Pennsylvania Department of Enviered from the formation, according says Erin Mooney of Trout Unlimronmental Protection (PADEP) says to Pennsylvania State University ited, a conservation group. “What we that the state also estimates the geoscientist Terry Engelder. see is reaction to change, not forthreat to drinking water as minimal The technology involves vertiward planning,” she adds. because the drinking-water aquifer cally drilling a deep production is shallow. It lies more than 5000 well down to 5000 feet, and then —REBECCA RENNER TOM MURPHY
What lies beneath
10.1021/es802190h
2008 American Chemical Society
Published on Web 08/13/2008
October 15, 2008 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 7547
