Investigation of Hexavalent Chromium Matrix Diffusion at a Sedimentary Bedrock Superfund Site
Tuesday, September 24, 2013: 1:10 p.m.
Steven W. Chapman, M.Sc., P.Eng.
,
School of Engineering, University of Guelph, Guelph, ON, Canada
Beth L. Parker, Ph.D.
,
School of Engineering, G360, University of Guelph, Guelph, ON, Canada
Jiujiang Zhao
,
Department of Earth Sciences, University of New Brunswick, Fredericton, NB
Tom A. Al
,
Deptartment of Geology, University of New Brunswick, Fredericton, NB, Canada
Rick Wilkin
,
Office of Research and Development, EPA, Ada, OK
Katherine Ryan Mishkin
,
Superfund Division, USEPA Region 2, New York, NY
Diana M. Cutt, PG
,
Office of Research and Development, USEPA Region 2, New York, NY
Rich Puvogel
,
U.S. EPA Region 2, New York, NY
Rachel Barber
,
CH2M HILL, Parsippany, NJ
Amy Darpinian
,
U.S Army Corp of Engineers, Kansas City, MO
It is now well known that diffusion driven mass transfer between fractures and the rock matrix has major implications on plume fate and transport at contaminated sites overlying fractured bedrock aquifers. Restoration of these sites poses a major technical challenge since most available technologies only address the contaminated water in fractures and back diffusion from the matrix to the fractures causes rebound which acts to slow cleanup and reduce effectiveness of the remedial actions. A study of matrix diffusion and immobilization reactions of hexavalent chromium [Cr(VI)] is being conducted as part of the remedial investigation of contamination emanating from a Superfund site (a former electroplating facility) in New Jersey situated within the Newark Basin. Previous studies within this fractured sedimentary bedrock basin and elsewhere have primarily focused on dense non-aqueous phase liquid (DNAPL) sites with VOC contamination. This is the first study focused on chromium, which is a contaminant of concern at many Superfund sites nationwide. This study involved collecting a detailed profile of Cr(VI) concentrations in the bedrock matrix from continuous cores at one location within the plume. Besides diffusion into and out of the matrix, chemical reactions may also act to immobilize the Cr(VI) via conversion to immobile Cr(III) in the matrix, which is assessed in this study. Supporting investigations included borehole geophysics, transmissivity profiling, and installation of a multilevel well for depth discrete hydraulic head and groundwater sampling for comparison with rock core data. This presentation will provide an overview of the study approach, field and laboratory investigation and analytical techniques, interim results and implications. Ultimately this study is expected to provide a framework for understanding fracture network characteristics and transport pathways and matrix diffusion and reaction processes controlling Cr(VI) transport and fate, allowing a more accurate evaluation of risk to receptors, remediation technologies and cleanup timeframes.
Steven W. Chapman, M.Sc., P.Eng., School of Engineering, University of Guelph, Guelph, ON, Canada
Steven Chapman is a Senior Research Engineer/Hydrogeologist in the G360 Centre for Applied Groundwater Research in the School of Engineering at the University of Guelph. He is a Professional Engineer (Civil) with an M.Sc. from the University of Waterloo (Earth Sciences). Chapman has more than 15 years of hydrogeologic experience. His research focuses on contaminant behavior in unconsolidated porous media and sedimentary rock, involving high resolution site characterization at industrial and research sites and numerical modeling, with a focus on the role of diffusion including impacts on remediation performance.
Beth L. Parker, Ph.D., School of Engineering, G360, University of Guelph, Guelph, ON, Canada
Beth Parker, Ph.D., University of Guelph Professor in the School of Engineering and Director of the G360 Centre for Applied Groundwater Research, has more than 30 years of experience investigating subsurface contamination at numerous sites around the world, using high resolution data sets for site conceptual model development and testing. Her current research activities emphasize developing improved field and laboratory methods for characterizations and monitoring of industrial contaminants in sedimentary rocks, clayey deposits, and sandy aquifers, and focus on the effects of diffusion in low permeability zones, plume attenuation, and hydrogeologic controls on remediation.
Jiujiang Zhao, Department of Earth Sciences, University of New Brunswick, Fredericton, NB
Post doctoral fellow
Tom A. Al, Deptartment of Geology, University of New Brunswick, Fredericton, NB, Canada
Tom Al is an Associate Professor in the Department of Geology at the University of New Brunswick. His research interests include mineral-water reaction processes that affect transport of contaminants in groundwater and surface water, geochemical and hydrologic processes controlling the release and transport of metals from sulfide-bearing mine waste, and geochemical reaction processes associated with in-situ oxidation of organic contaminants in groundwater.
Rick Wilkin, Office of Research and Development, EPA, Ada, OK
Rick Wilkin is an environmental geochemist.
Katherine Ryan Mishkin, Superfund Division, USEPA Region 2, New York, NY
Katherine Ryan Mishkin serves as a Geologist in the Technical Support Section of Superfund in EPA Region 2.
Diana M. Cutt, PG, Office of Research and Development, USEPA Region 2, New York, NY
Diana Cutt, PG, is Superfund and Technology Liaison for the EPA Region 2 Office of Research and Development.
Rich Puvogel, U.S. EPA Region 2, New York, NY
Remedial project manager at EPA
Rachel Barber, CH2M HILL, Parsippany, NJ
Project manager at CH2M Hill
Amy Darpinian, U.S Army Corp of Engineers, Kansas City, MO
Project manager at Army Corp
