The Use of Groundwater Models in PFAS Investigations

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The Use of Groundwater Models in PFAS Investigations

By: Roger McCready, CPG

Published in January 2020 Focus on the Environment Newsletter

On Monday, December 2, 2019, the Ohio EPA and the Ohio Department of Health (ODH) released the Ohio Per- and Polyfluoroalkyl Substances (PFAS) Action Plan for Drinking Water. The stated focus of the action plan is to evaluate the potential risk of PFAS in both public and private drinking water systems in Ohio and assist communities in addressing these risks.

Under the plan, Ohio EPA will coordinate the collection of both raw and finished water samples from approximately 1,500 public water systems (PWS).  Ohio EPA and ODH expect to complete this work in 2020.  At that time, it will be determined which PWS have PFAS detected.  A likely next step will be for Ohio EPA and concerned citizen groups to begin searching for potential sources of PFAS that are reaching PWS. 

The generally accepted primary sources of PFAS are fire training\fire response sites, industrial sites, landfills, and wastewater treatment plant/discharge/biosolids1.  Two major concerns for owners and operators of potential PFAS source areas are: 1) has there been a PFAS release at my site? and 2) if so, where is it migrating?

Groundwater modeling is a tool that among other things can be used to predict the areal extent of groundwater contamination from source areas to potential receptors or in reverse from receptors such as Public Water Supplies to potential sources.  As with hydrocarbons and chlorinated solvents, groundwater models can be used to simulate the migration of PFAS compounds, such as PFOA and PFOS, for various relevant scenarios2.

PFAS specific modeling data is being collected and will probably continue to be collected at a rapid pace due to the importance of this issue.  As this data is made available, groundwater models can be improved\refined to better simulate the migration of PFAS plumes.

2 Simon JA, Abrams S, Bradburne T, et al. PFAS Experts Symposium: Statements on regulatory policy, chemistry and analytics, toxicology, transport/fate, and remediation for per- and polyfluoroalkyl substances (PFAS) contamination issues. Remediation. 2019;2931-48.

Roger McCready is a Senior Scientist with Cox-Colvin & Associates, Inc. He holds BS and MS degrees in Geology/Hydrogeology from Wright State University. Mr. McCready has 30+ years of experience working with commercial and industrial clients to manage and address environmentally impacted sites from small industrial sites to complex, contaminated river sites. The environmental liabilities of these sites range from a few thousand dollars to hundreds of millions of dollars. His work experience provides him the ability to view these sites from both the consulting and corporate perspectives. Mr. McCready specializes in soil, groundwater, and sediment impacted sites within various regulatory programs and is the CERCLA Practice Leader for Cox-Colvin.