a1 US Geological Survey–Leetown Science Center, Northern Appalachian Research Laboratory, Wellsboro, Pennsylvania
a2 Penn State Marcellus Center for Outreach and Research, University Park, Pennsylvania
The increasing world demand for energy has led to an increase in the exploration and extraction of natural gas, condensate, and oil from unconventional organic-rich shale plays. However, little is known about the quantity, transport, and disposal method of wastes produced during the extraction process. We examined the quantity of waste produced by gas extraction activities from the Marcellus Shale play in Pennsylvania for 2011. The main types of wastes included drilling cuttings and fluids from vertical and horizontal drilling and fluids generated from hydraulic fracturing [i.e., flowback and brine (formation) water]. Most reported drill cuttings (98.4%) were disposed of in landfills, and there was a high amount of interstate (49.2%) and interbasin (36.7%) transport. Drilling fluids were largely reused (70.7%), with little interstate (8.5%) and interbasin (5.8%) transport. Reported flowback water was mostly reused (89.8%) or disposed of in brine or industrial waste treatment plants (8.0%) and largely remained within Pennsylvania (interstate transport was 3.1%) with little interbasin transport (2.9%). Brine water was most often reused (55.7%), followed by disposal in injection wells (26.6%), and then disposed of in brine or industrial waste treatment plants (13.8%). Of the major types of fluid waste, brine water was most often transported to other states (28.2%) and to other basins (9.8%). In 2011, 71.5% of the reported brine water, drilling fluids, and flowback was recycled: 73.1% in the first half and 69.7% in the second half of 2011. Disposal of waste to municipal sewage treatment plants decreased nearly 100% from the first half to second half of 2011. When standardized against the total amount of gas produced, all reported wastes, except flowback sands, were less in the second half than the first half of 2011. Disposal of wastes into injection disposal wells increased 129.2% from the first half to the second half of 2011; other disposal methods decreased. Some issues with data were uncovered during the analytical process (e.g., correct geospatial location of disposal sites and the proper reporting of end use of waste) that obfuscated the analyses; correcting these issues will help future analyses.
Environmental Practice 14:1–10 (2012)
(Received May 15 2012)
(Revised August 14 2012)
(Accepted September 10 2012)
c1 Kelly O. Maloney, USGS–Leetown Science Center, Northern Appalachian Research Laboratory, 176 Straight Run Road, Wellsboro, PA 16901; (phone) 570-724-3322 ext. 239; (fax) 570-724-2525; (e-mail) email@example.com
Kelly O. Maloney is a research ecologist with the US Geological Survey's Leetown Science Center Northern Appalachian Research Laboratory in Wellsboro, Pennsylvania. He earned his PhD in biology from Auburn University in 2004. His current areas of research include investigating the effects of anthropogenic stressors on stream water quality and biological condition, identifying the ecological flow requirements for aquatic biota, elucidating the factors driving patterns in biodiversity, and developing decision support tools for better management of river ecosystems.
David A. Yoxtheimer, PG, is a hydrogeologist/extension associate with Pennsylvania State University's Marcellus Center for Outreach and Research. He earned his BS in earth science from Pennsylvania State University, where he is currently completing his PhD in geosciences. Prior to joining Penn State, David worked as an environmental consultant for 18 years. His areas of expertise include water supply development, geophysical surveying, environmental permitting, karst hydrogeology, shale energy geology, and integrated water resource management.