Per- and Polyfluoroalkyl Substances (PFAS)

Aqueous Film Forming Foam used for fire suppression contains PFAS Aqueous Film Forming Foam used for fire suppression contains PFAS

PFAS are challenging contaminants becasue most PFAS constituents cannot be detected using conventional analytical techniques. Remediation options that may address one PFAS constituent may not work for others, and only partial treatment may be achievable. Byproducts of treatment may not be detected and thus their risk is unknown. Risk-based standards for PFAS in soil and water are extremely low. Investigation and management of PFAS sites require an innovative, adaptable and educated team, actively involved in (not just aware of) current research, and capable of developing and optimizing new approaches in response to policy updates and technological advances.

What are PFAS?

PFAS, formerly known as "perfluorinated compounds" (PFCs), are emerging compounds of increasing importance for a broad spectrum of industrial sites and waterways. PFAS are a family of organic substances whose molecular structures contain multiple fluorine (F) atoms in place of hydrogen (H) atoms. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are the two most widely-recognized, environmentally-relevant PFAS, although there are hundreds of PFAS of potential significance, and little is known about these compounds.

Why are PFAS so Challenging?

The sources of PFAS in the environment (e.g., Aqueous Film Forming Foam [AFFF] or misting for electroplating) are typically comprised of complex mixtures of hundreds of individual PFAS constituents. The majority of PFAS constituents cannot be detected using conventional analytical techniques. Progress is being made towards developing analytical techniques to improve the detection of these constituents, including recent research by Geosyntec and partners developing nuclear magnetic resonance (NMR)-based analytical techniques and total fluoride field screening, but it may be years before comprehensive site characterization is achievable. The behavior of PFAS constituents in the environment can also vary widely depending on the composition of the PFAS mixture, the presence of co-contaminants, the introduction of oxidants or reductants into the environment. Maintaining fluoride mass balance while monitoring byproducts of degradation reactions is critical to understanding remedial success, but is currently difficult to achieve. As such, it is essential that knowledgeable practitioners, who fundamentally understand the limitations and challenges associated with PFAS, direct investigation and remediation efforts to achieve successful mitigation of risk at PFAS sites.

Our experts look at the “bigger picture” using rigorous and fundamental scientific principles. We utilize various tools in appropriate and defensible ways for client advocacy in regulatory negotiations, property transactions, claim disputes, and smart site management.


Site-Specific Technical Reviews and Investigation Strategies

U.S. Air Force Civil Engineer Center, Multiple Confidential Clients
  • Critically reviewed site data, conceptual site models, and identified gaps
  • Prepared scientifically-rigorous PFAS data collection plans and work plans

In-Situ Treatment to Enhance PFAS Removal and Destruction

SERDP/ESTCP, Navy, University of California at Berkeley
  • Conducted site characterization and site-specific treatability studies
  • Demonstrated at field-scale a two-step thermally-enhanced low-pH persulfate oxidation and GAC sorption for PFAS mass removal and degradation

Development of Real-Time PFAS Analytical Methods

Geosyntec Internal R&D, Collaboration with Eurofins Eaton Analytical
  • Funded development of a mobile analytical instrument for real-time PFAS analysis in the field
  • Developed an Nuclear Magnetic Resonance technique for full spectrum PFAS characterization

Human Health Risk, Fate, and Chemical Liability Assessment

Minneapolis-St. Paul, Minnesota
  • Evaluated human health risks due to bioaccumulation of PFAS in fish
  • Assessed Total Maximum Daily Load (TMDL)
  • Liability analysis, litigation support and stakeholder communications

Community Outreach and Regulatory Policy Adherence

Issaquah Valley Aquifer, King County Washington
  • Managed the operational, public and regulatory issues associated with the revision of EPA's PFOS advisory limit downward to 0.07 ug/L
  • Initiated discussions with surrounding water purveyors and state regulatory agencies on future management of the aquifer system

Expert Panel Regarding PFAS Regulation

RAAF Base Williamtown, Australia
  • Technical support advising expert panel on PFAS regulation
  • Critical review and data gap analysis of conceptual site model
  • Peer review and advice for sampling and data interpretation

Catalyzing Knowledge Transfer Among Key Stakeholders

SERDP/ESTCP, Collaboration with Oregon State University
  • Authored peer-reviewed publications and keynote presentations at internationally-renowned conferences
  • Prepared up-to-date reference documents, frequently asked questions (FAQs), and online videos on PFAS chemistry, fate and transport, and site management options
Geosyntec Consultants
Geosyntec is a consulting and engineering firm that works with private and public sector clients to address new ventures and complex problems involving our environment, natural resources, and civil infrastructure.

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