UOG Wastewater Leaks and Spills: Fate and Transport of Chemical Constituents
Wednesday, April 26, 2017: 9:30 a.m.
Isabelle M. Cozzarelli
,
USGS WRD, Reston, VA
Unconventional oil and gas (UOG) wastewaters containing toxic and radioactive elements derived naturally, or from chemical additives, pose largely unknown risks to water resources and aquatic and human health. Exposure pathways include land application, leaky surface impoundments and pipelines, discharge of treated wastewaters, failures in well casings, or migration through fracture networks. During 2008-2015, recorded spills in North Dakota included over 20-million gallons of waste fluids. As part of a national assessment of the impacts of UOG activities, a team from USGS and collaborators are conducting interdisciplinary studies in regions of active development, including the Bakken formation and the Marcellus Shale. We are studying geochemical alterations of water, soil, and sediment samples from UOG wastewater-impacted sites, targeting potential contaminants of aquatic and human health concern or those compounds that could serve as useful tracers of waste materials in the event of a release to the environment.
In one North Dakota study area 3-million gallons of wastewater (containing 138,000 mg/L TDS, 16.2 mg/L Ba, and >1,000 mg/L Sr) from UOG production in the Williston Basin spilled into a small tributary of the Missouri River. Water quality, sediment, and bioassay samples were collected and analyzed for a broad range of organic and inorganic compounds to assess potential impacts from this spill. Results indicate the presence of inorganic markers of the wastewater and the persistence of geochemical alterations in the creek six months post-spill. Labile Ba and Sr concentrations extracted from sediments were higher downstream from the spill site than upstream. Radium concentrations in sediment were up to 5 times the background concentrations downstream from the spill site. Sequestration of elements from the wastewater spill onto the sediment limits movement in surface water downstream but could provide a long-term source to both groundwater and surface water if geochemical conditions change in the future.
Isabelle M. Cozzarelli, USGS WRD, Reston, VA
Dr. Isabelle Cozzarelli is a hydrologist in the National Research Program of the USGS in Reston, Virginia, where she conducts long-term research on the fate and geochemical effects of organic contaminants in subsurface and wetland environments. She uses an interdisciplinary approach that incorporates a combination of field and laboratory experiments in a variety of hydrogeologic environments. Dr. Cozzarelli received M.S. and Ph.D. degrees in Environmental Sciences from the University of Virginia and a B.S. in Geomechanical Engineering from the University of Rochester. More information about her research can be found at http://profile.usgs.gov/icozzare
