Comparing Rock Matrix Contaminant Profiles Downgradient of a DNAPL Source after 10 Years of Groundwater Dissolution
Tuesday, October 3, 2017: 10:10 a.m.
Andrew Buckley
,
University of Guelph, G360 Institute for Groundwater Research, Guelph, ON, Canada
Jessica Meyer, Ph.D.
,
G360 Institute for Groundwater Research, Guelph, ON, Canada
Diane Austin-Blaine
,
Golder Associates, Guelph, ON, Canada
Beth Parker, Ph.D.
,
University of Guelph, College of Physical and Engineering Science, G360 Institute for Groundwater Research, Guelph, Ontario, ON, Canada
Prior to 1970, over 70,000 L of dense non-aqueous phase liquids (DNAPLs) were released into the subsurface at a site in south central Wisconsin. The mixed organic DNAPL migrated through unconsolidated glacial sediments and shallow sedimentary bedrock, eventually accumulating about 56 meters below ground in a fractured sandstone. The objective of this study was to characterize the temporal evolution of contaminant mass in the source zone by comparing two co-located rock core volatile organic compound (VOC) concentration profiles, one collected in 2003 and the other in 2014. The rock core VOC profiles provided depth discrete and detailed (at least 1 sample/foot of core) quantification of the contaminant mass in the rock matrix. The 2003 core shows relatively uniform rates of mass accumulation with depth for most contaminants; whereas, the 2014 core shows highly variable rates of mass accumulation with depth, particularly in the shallow rock units. These results indicate variable attenuation rates for specific depth horizons. Comparison of total mass estimates for each core indicate an apparent mass loss of ~ 80%, most of which occurs in the shallow bedrock units. Assessment of specific contaminants shows declines in concentration for parent ethanes and ethanes, dichlormethane, and MIBK and increases in concentrations for daughter products (e.g., chloroethane, vinyl chloride). Core and borehole geophysical logs and hydraulic testing provide site-specific parameters for evaluating the role of various attenuation processes (e.g., dispersion, diffusion, sorption, abiotic and biotic degradation) influencing source zone fluxes and longevity. The insights from this temporal comparison will inform a process-based site conceptual model and improve remedial technology assessments.
Andrew Buckley, University of Guelph, G360 Institute for Groundwater Research, Guelph, ON, Canada
Mr. Buckley earned a civil engineering degree from Queens University in 2011 and is currently completing an MASc in engineering at the University of Guelph. He is interested in working to find solutions for a variety of groundwater contaminant and remediation issues.
Jessica Meyer, Ph.D., G360 Institute for Groundwater Research, Guelph, ON, Canada
Dr. Meyer is currently an adjunct professor in the School of Environmental Sciences at the University of Guelph and a senior research scientist for the G360 Institute for Groundwater Research. She earned a B.Sc. in Environmental Geology from the University of Montana and a M.Sc. (University of Waterloo) and Ph.D. (University of Guelph) in hydrogeology. Dr. Meyer’s research focuses on field based characterization of fractured sedimentary rock flow systems with emphasis on understanding the relationship between the hydraulic and geologic structure of the subsurface. In addition to her research experience, she has 14 years of experience managing large multifaceted field based research projects at industrial sites.
Diane Austin-Blaine, Golder Associates, Guelph, ON, Canada
Beth Parker, Ph.D., University of Guelph, College of Physical and Engineering Science, G360 Institute for Groundwater Research, Guelph, Ontario, ON, Canada
Beth L. Parker has her bachelors degree in environmental science and economics, Masters in environmental engineering and PhD in hydrogeology She is Professor in the School of Engineering and Director of G360 - The Centre for Applied Groundwater Research at the University of Guelph. She has more than 25 years of experience as a groundwater professional investigating subsurface contamination issues at industrial sites around the world. Her current research activities emphasize field and laboratory studies of DNAPLs in sedimentary rocks, clayey deposits, and heterogeneous sandy aquifers, and focus on the effects of diffusion into and out of low permeability zones and on DNAPL fate, plume attenuation, and controls on remediation. She is currently involved in research and technology demonstration projects at Superfund and RCRA facilities in the United States and similar sites in Canada, Europe and Brazil. In July 2007, she was awarded an NSERC Canada Industrial Research Chair in Fractured Rock Contaminant Hydrology. In December 2009, she received the John Hem Award from the Association of Groundwater Scientists and Engineers of the United States National Groundwater Association.
