Director of Technical Practices
Woodard & Curran
This presentation is the result of the work by a large number of people. Dan is the presenter. Dan is the Director of Technical Practices for Environmental Remediation Services at Woodard & Curran. He brings nearly 30 years of experience in site characterization, geochemistry, hydrology, and in-situ chemical and biological remediation. Dan holds a Ph.D. in geochemistry from Columbia University, and Master's and Bachelor's degrees in geology from the University of Florida.
PFAS Experts Symposium – Statements on Regulatory Policy, Toxicology, Transport/Fate, and Remediation for Per- and Polyfluoroalkyl Substance Contamination Issues
Sixty leaders in the scientific, engineering, regulatory, and legal communities assembled for the PFAS Experts Symposium on May 20-21, 2019 in Arlington, Virginia. The primary goal of the Symposium was to create a venue for experts representing the broad range of stakeholders affected by PFAS in the environment to provide opinions and trade viewpoints on assessment, toxicity, remediation, and management. The Symposium was structured as an interactive mix of panel discussions, platform presentations, and breakout groups for in-depth discussions. The following summarizes several consensus points developed as an outcome of the Symposium: (1) Regulatory and Policy Issues. If PFAS are designated “hazardous substances” at the Federal level, wide-reaching effects include listing of new Superfund sites solely for PFAS, application of stringent state standards as ARARs, additional characterization and remediation at existing sites, reopening of closed sites, and cost renegotiation among PRPs. TI waivers could play an increasingly important role in site management decisions due to strict cleanup objectives and limited remedial options that make remediation exceptionally costly or impracticable. (2) Chemistry and Analytics. Sample collection and analysis requires planning and specialized knowledge due to the presence of PFAS in common consumer products and sampling equipment, limitations of current analytical methods, nature and diversity of environmental samples, and data quality issues. Total Oxidizable Precursor (TOP) assay and Total Organic Fluorine (TOF) methods may be useful to scope the total PFAS impact and appropriate remedial designs. (3) Toxicology and Risk. Data for “replacement compounds” indicate they are less toxic and biologically persistent than legacy PFAS, but uncertainties remain regarding health effects, half-life, interspecies differences, and appropriate uncertainty factors. Given the thousands of PFAS that may be present in the environment, a more appropriate paradigm may be to develop toxicity criteria for groups of PFAS rather than individual PFAS. (4) Transport and Fate. Understanding transport and fate will require improved soil/rock/sediment extraction and analytical methods to quantify contaminant mass and flux. Physicochemical properties and corresponding transport and fate of most PFAS other than PFOA and PFOS, of branched and linear isomers of the same compound, of the interactions of PFAS with co-contaminants such as NAPLs, and the extension of experimental results at concentrations in the tens of micrograms to milligram per liter range rather than at the nanogram per liter range pertinent for PFAS, are not well known. (5) Existing Remediation Technologies and Research. Current technologies largely focus on separation (sorption, ion exchange, or sequestration) rather than destruction. Effective treatment will likely require complex treatment trains due to the diversity of PFAS properties. Precursor transformation pathways for the available destructive technologies are not well understood, and incomplete mineralization can result in generation of more mobile and/or toxic products. A paradigm shift to receptor protection rather than aquifer restoration may be appropriate due to the lack of destructive technologies, large and low concentration plumes, conservative cleanup levels, and associated financial limitations. The presentation will present a summary of the findings of the Symposium and address questions or comments regarding this information.