Identification and Characterization of the Air Deposition Pathway to PFAS Groundwater Contamination
Wednesday, June 19, 2019: 9:30 a.m.
Adam Janzen, PE
,
Barr Engineering Company
Evan Christianson, PG
,
Barr Engineering Company, Bloomington, MN
David Dahlstrom, PG
,
Barr Engineering Company, Bloomington, MN
Eric Edwalds
,
Barr Engineering Company, Bloomington, MN
Ray Wuolo, PE, PG
,
Barr Engineering Company, Bloomington, MN
Groundwater contamination is often the result of concentrated releases of hazardous substances to the land surface or the shallow subsurface. However, even highly dispersed releases of PFAS at the land surface, such as deposition of air emissions from industrial facilities, can result in groundwater contamination above the current part-per-trillion-level screening values and health advisory limits. Only very small quantities of PFAS are necessary to contaminate water to such low levels.
Barr has modeled transport of PFOA through air, soil, and water in settings in which the primary sources of PFOA were determined to be air emissions of PFOA from industrial facilities. PFOA was deposited on the surrounding land surface over hundreds of square kilometers and then leached through the unsaturated zone to the water table. A complex modeling sequence involving AERMOD (air deposition), SWB (infiltration rate), MODFLOW-UZF (unsaturated zone flow), MODFLOW-NWT (saturated zone flow), and MT3D-USGS (unsaturated and saturated transport) was used to simulate the complete pathway from the facility stacks to groundwater receptors. This integrated multi-media modeling approach for PFAS fate and transport can provide significant value in assessing potential for contamination, predicting future concentration trends, designing remedies, and estimating cleanup times.
Adam Janzen, PE, Barr Engineering Company
Adam Janzen is an environmental engineer at Barr Engineering Company. He has over seven years of experience in groundwater flow and transport modeling with application to contaminated site assessment and remediation, water supply development, and open-pit mine dewatering. He is also one of the instructors for the ITRC’s Geospatial Analysis for Optimization at Environmental Sites web-based training and a co-author of the accompanying guidance document. Adam has a BS from the University of Illinois at Urbana-Champaign and a MS from Princeton University, both in Civil & Environmental Engineering. He is a licensed professional engineer in Minnesota and Ohio.
Evan Christianson, PG, Barr Engineering Company, Bloomington, MN
Evan has more than 10 years of experience with groundwater flow modeling, GIS analysis and modeling, geophysical surveying, aquifer characterization, geologic mapping, data processing and visualization, and monitoring well installation and sampling. His work for municipalities and water management organizations includes conducting groundwater–surface water interaction assessments; developing integrated groundwater–surface water models; designing and calibrating three-dimensional groundwater flow models; delineating wellhead protection areas and drinking-water-supply management areas; and conducting aquifer vulnerability assessments.He has a BS in Geology from Gustavus Adolphus College and an MS in Geology from Iowa State University.
David Dahlstrom, PG, Barr Engineering Company, Bloomington, MN
Dave Dahlstrom is a hydrogeologist at Barr Engineering Company. He has over 32 years of experience in environmental consulting and specializes in site characterization, process identification, conceptualization, and computer-based simulation of groundwater flow systems and contaminant transport. Dave’s work is focused on the design and evaluation of predictive uncertainty of computer models of hydrologic systems and the use of these models in addressing water supply and environmental issues. He has a BS in Geology from Notre Dame and an MS in Geology from the South Dakota School of Mines and is registered as a professional geologist in five states.
Eric Edwalds, Barr Engineering Company, Bloomington, MN
Eric Edwalds has 30 years of experience with air dispersion modeling, ambient air monitoring, meteorology, emission calculations, and statistical analysis of environmental data. He first began modeling APFO/PFOA air emissions in 2006, helping a manufacturing client meet New Hampshire’s standards for regulated toxic air pollutants. His recent work includes conducting deposition modeling of PFAS compounds, which has involved calculating historical emissions from facility operational records to evaluate multimedia fate and transport of these substances.
Ray Wuolo, PE, PG, Barr Engineering Company, Bloomington, MN
Ray Wuolo is a vice president of Barr Engineering Co. in Minneapolis with over 30 years of experience as a computational hydrogeologist, specializing in numerical modeling of groundwater flow and solute transport. He is a licensed professional engineer and professional geologist in numerous states and Canadian provinces. Ray has served as associate editor of Ground Water, adjunct professor of hydrogeology at the University of St. Thomas, and on many academic and technical advisory boards. He received a BS in Geological Engineering from Michigan Tech and an MS from South Dakota School of Mines & Technology.
