Per- and polyfluoroalkyl substances (PFAS) are a class of emerging contaminants that have captured significant media and political attention in recent years in the United States and Canada. The United States Environmental Protection Agency has not promulgated national standards for these compounds as of yet and in lieu of national standards, states are enacting their own requirements. Parsons is conducting numerous PFAS investigations for Department of Defense (DoD) clients and industrial partners in the United States to meet individual state requirements. Investigations have focused on sites where eight carbon chain based aqueous film forming foam (AFFF) may have been used or spilled during historical firefighting operations, on industrial facilities where PFAS was utilized to produce commercial products, and on landfills where PFAS containing materials were previously disposed of. The primary objectives these PFAS investigations focus on the definition of PFAS impacts to natural media (soil, groundwater, surface water, etc.); the assessment of potential PFAS migration pathways between source areas and downgradient receptors; and, the identification of potentially unacceptable impacts and potentially imminent risk pathways. These objectives are complicated by often unclear or unspecified investigation and remedial goals and current shortfalls in approved and commercially available analytical methods to detect and quantify a significant portion of the 4,700+ compound PFAS universe.

The nature and extent of PFAS compounds are directly related to their release mechanisms (e.g., spraying of firefighting foam, aerial dispersion from an industrial facility, sewer discharges, or seepage from a landfill) that interact with the physical elements of the conceptual site model (CSM) (e.g., land use, topography, hydrology, stratigraphy, migration mechanisms, and transport pathways). Unique properties of PFAS further influence their fate and distribution. Consequently, insight and clarity are achieved by combining a robust 3D CSM with knowledge of PFAS release and transport characteristics. The CSM is supplemented and refined using the triad process of systematic planning, dynamic work strategies, and rapid measurement technologies, allowing for real-time collaboration with stakeholders regarding further investigation or prompt risk mitigation, such as point of entry treatment systems or soil removal actions. Perceived complexity of PFAS can be transformed into deeper insight by exploiting the variety of PFAS compounds and their unique properties, such as solubility, differential sorption, lack of volatility and recalcitrance through novel analysis.

These insights and efficiencies are demonstrated through experience with a variety of DoD and industrial sites where PFAS release is associated with use of fluorine-containing firefighting foams, industrial manufacturing of PFAS or PFAS-containing products, and leaching from landfills where PFAS-containing materials were disposed. Accelerated characterization and results communication on these sites has resulted the rapid definition of unacceptable impacts and the implementation of mitigation systems like point-of-use treatment on impacted water supply wells. This accelerated risk identification and mitigation paradigm has eliminated unacceptable impacts at many sites and enhanced public health much more rapidly than in the past. Rapid site characterization strategies, optimized data collection and management methodologies, innovative PFAS data analysis tools and advanced communication concepts will be presented using real world site data sets to provide the audience with reality-based means to advance their own projects.

Daniel Griffiths, Infrastructure Subject Matter Director and Government Services Technical Director, Parsons
Daniel Griffiths brings a strong geological science education and extensive experience to a wide variety of projects, focusing on streamlined site delineation and innovative remedy design and implementation. He has been designing and implementing investigation plans and stream-lined remedial solutions at industrial and US Department of Defense (DoD) sites for more than 20 years. He specializes in managing complex high priority sites impacted with chlorinated solvents, metals, explosive constituents, and emerging contaminants (PFAS and 1,4-dioxane). His past projects involve remedy selection and the design and installation of in-situ remediation applications to treat a variety of contaminants in unconsolidated and bedrock aquifers at industrial and DoD sites across the United States.

Dan is a contributing author on guidance documents related to in-situ remediation prepared by Parsons for the Air Force, Environmental Security Technology Certification Program, and Interstate Technology and Regulatory Council (ITRC). He is also the Parsons Infrastructure Subject Matter Director for groundwater restoration and a Parsons Government Services Technical Director for investigation, remedy selection, design, and implementation. Finally, Dan participates in and provides technical support and authorship to industry leading groups like the ITRC.

Per- and polyfluoroalkyl substances (PFAS) have been gaining wide regulatory attention globally. Lawsuits filed in numerous countries, public pressure, and uncertainties regarding the potential risk of this class of chemicals have led regulatory authorities to consider strict (or stricter) regulations for certain PFAS, including perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). For contaminated sediment sites, sudden detection of these chemicals may lead to concern and a push for sediment remediation, but there can be fundamental differences from the remedial approaches used for typical legacy pollutants in sediments, like PCBs. The fate characteristics of PFAS will impact site characterization approaches and viable remedial technologies.

This presentation will focus on the impact of detecting PFAS or PFOA at an existing contaminated sediment site, with an emphasis on impacts to ongoing site characterization and the remedial alternative evaluation process. The relevance of PFAS will depend on the levels detected, the media of concern, and the other site risks. Important questions to consider and factors to incorporate into the remedial investigation will be discussed, including, possible sources of PFAS, how and/or when to possibly assess risk of PFAS relative to other chemicals on the site, what to consider if fish tissue concentrations are a potential concern, and whether precursors should be a focus. Finally, we will discuss whether and how one can assess the impact of proposed remedial alternatives on PFAS concentrations. In particular, this talk will investigate if changes to existing remediation might provide a dual benefit of treating the original contaminant of potential concern along with the PFAS, if it determined that the PFAS is a contaminant of potential concern.

Daniel Opdyke, Senior Managing Engineer, Anchor QEA, LLC
Daniel Opdyke is a technical expert in multiple surface water and groundwater subjects, including design of monitoring programs; verification, analysis, and visualization of data; development of conceptual models; design and calibration of statistical and mechanistic models; and documentation and presentation of results to stakeholders. He has applied these skills to a variety of projects and disciplines, including groundwater availability, groundwater contaminant fate and transport, surface water availability, negotiation of water rights, surface water eutrophication, surface water contaminant fate and transport, groundwater and surface water interactions, chemical bioaccumulation, environmental flows, and freshwater inflows to estuaries. More recently, Daniel has worked in the area of PFAS, understanding their fate, transport, and potential bioaccumulation in surface and groundwater systems.

As the international focus on per- and polyfluoroalkyl substances (PFAS) continues to expand, there has been an increased effort directed towards investigating the presence of these compounds in multiple types of media. While over the past decade or so, investigative efforts largely targeted impacts associated with the use of aqueous film forming foam (AFFF) at release sites (such as airports and military bases), concerns regarding the presence of PFAS within the waste stream are increasingly driving investigative efforts into assessment of PFAS concentrations in biosolids and landfill leachate. The presence of PFAS in biosolids is often viewed as particularly problematic as studies have indicated the potential for PFAS uptake by crops. Yet, while the rapidly evolving regulatory landscape and advances in analytical techniques lead to both increasingly lower target concentrations and detection levels for PFAS parameters, an objective evaluation of the significance of the concentrations observed to date within biosolids is often overlooked. Given PFAS have been present within the industrial world for many decades – and thus can reasonably have been expected to be within the waste stream through that time period – should the presence of PFAS within waste-related media be inherently viewed as an important source of PFAS contamination in need of additional treatment or management?

This presentation will provide a survey of recent findings on PFAS concentrations in biosolids, the potential for PFAS to move into the food stream through the application of biosolids, and evaluations of human and ecological risks associated PFAS in land-applied biosolids. The review will cover recent toxicological studies, regulatory standards and guidelines, and available information on background PFAS exposure.

Krista Barfoot, Principal, Environmental Services, Stantec Consulting Limited
Krista Barfoot has over 23 years of industry experience, with extensive expertise in strategic site planning, risk assessment, vapour intrusion assessment, and risk management. Her technical expertise additionally extends to emerging contaminants (including per- and polyfluoroalkyl substances [PFAS]), excess soil management, non-aqueous phase liquid, risk mitigation measures, and stakeholder communication. She has led the development of the strategic approach for revitalizing several large, high-profile brownfield sites in Ontario; these efforts have included the consideration of PFAS as emerging contaminants, the management of non-aqueous phase liquids (NAPL) in place, and soil reuse.

Krista is a qualified person for risk assessment (per Ontario Regulation 153/04), chair of the Ontario Environmental Industry Association (ONEIA) Brownfields Committee, an ONEIA Excess Soils Sub-Committee member, and a member of the board of the Canadian Brownfields Network. Her studies and work have spanned the fields of chemistry, toxicology, pedology, geology, agrology, and ecology.