Opening Remarks
 

1:05 - 1:25 p.m.

Advancements in Analytical Techniques for PFAS Detection in Environmental Samples

Sarah Choye, Eurofins Environment Testing

Per- and polyfluoroalkyl substances (PFAS), often referred to as “forever chemicals,” are synthetic compounds widely used in industrial applications, consumer products, and firefighting foams. Due to their environmental persistence and potential health impacts, PFAS have become a significant focus of scientific research and regulatory scrutiny.

This session presents recent advancements in PFAS analytical testing for environmental matrices including water, soil, and air. Over the past two decades, analytical capabilities have expanded to include a greater number of PFAS analytes at lower detection limits, supported by increasingly robust instrumentation. The integration of isotope dilution techniques, as employed in EPA Methods 533 and 1633, has enhanced quantitation accuracy and precision across diverse sample types, while minimizing false positives and analytical errors.

Beyond EPA-approved methods, a suite of advanced analytical techniques has emerged to complement traditional approaches and provide deeper insights into both individual and total PFAS concentrations. These include rapid screening methods (e.g., ASTM D8421, EPA 8327, ASTM D7968) and unknown screening techniques such as branched and linear isomer analysis, EPA Method 1621, the Total Oxidizable Precursor (TOP) Assay, and non-targeted analysis (NTA). These tools offer practical solutions for site characterization and risk assessment.

This presentation will detail the principles, applications, and limitations of each advanced method, highlighting scenarios where their use enhances site-specific understanding. Collectively, these techniques help answer critical questions: Which PFAS are present, and in what concentrations?

1:25 - 1:45 p.m.

Geology-Focused CSM: Best Practice for PFAS Remediation Optimization

Michael Shultz, Geosyntec Consultants

The Environmental Sequence Stratigraphy (ESS) geology-focused technology is an innovative approach to managing PFAS-impacted groundwater projects and will significantly improve the subsurface conceptual site models (CSMs) for PFAS-impacted sites. As exemplified with several US Air Force facilities, ESS has proven to advance the understanding and management of PFAS occurring in the subsurface.  It is considered a “best practice” by the Air Force Civil Engineering Center (AFCEC) for guiding PFAS remedial investigations and remediation design optimization.

ESS is a well-established technology that has been practiced in the petroleum industry for several decades and has been successfully applied to groundwater remediation projects at US Air Force facilities over the past 15 years. US EPA published a 2017 Technical Issue Paper that presents ESS as a best practice for subsurface remediation optimization. The occurrence of PFAS in the subsurface is very complex due to its ubiquity, very low regulatory limit, and high mobility. The ESS approach presented applies proven methodology to existing site data resulting in a practical solution to PFAS challenges.

The methodology is a three step process to re-evaluate existing subsurface data by: 1) researching and understanding the regional geology and depositional systems that formed the subsurface, 2) reformatting existing site lithology data to emphasize vertical grainsize patterns to assess the genetic relationships between borehole lithology data, and 3) through the expertise of a trained stratigrapher, correlate between the borehole data and map out the geologic framework in 3 dimensions.  The result is a detailed depiction of the subsurface heterogeneity and, when integrated with site hydrogeology and groundwater chemistry data, defines the hydrostratigraphic units (HSUs) that control groundwater flow and contaminant migration.

Real world case studies will be presented showing that, without applying the ESS technology that define the HSUs underlying a PFAS-impact site, you are underutilizing your site data and oversimplifying your CSM which leads to increased uncertainty and project spend.

Coauthors: Rick Cramer and Colin Plank (Geosyntec Consultants)

1:45 - 2:05 p.m.

Multi-Year Passive In Situ Treatment of Per- and Polyfluoroalkyl Substances (PFAS) With an HRX Well

Craig Divine, Arcadis, Inc.

The Horizontal Reactive Treatment Well (HRX Well) is a relatively new remediation technology that can passively treat groundwater and reduce contaminant mass discharge within a contaminant plume. The HRX Well is a large‐diameter horizontal well that captures impacted groundwater through an upgradient screen, treats the groundwater via treatment media placed in the center cased section of the well, and then discharges treated water back to the aquifer through a downgradient screen. Herein, the results of the first field demonstration of an HRX Well designed to treat per‐ and polyfluoroalkyl substances (PFAS) are presented. Based on the results of treatability tests and numerical design modeling, the 645‐ft long HRX Well was constructed with removable cartridges containing granular activated carbon (GAC) for passive PFAS treatment. It has operated continuously with minimal operation and maintenance activity for more than 3 years. Total PFAS treatment efficiencies ranged from 53% to 74%, resulting in a sustained and average PFAS mass discharge reduction of approximately 5 mg/day. The HRX Well compares favorably (effectiveness, implementability, and lifecycle costs) to conventional alternatives, such as pump‐and‐treat. The estimated treatment zone width is approximately 20 ft, which could be increased by pumping. Multiple HRX Wells could be installed to address a wide treatment zone, and HRX Wells could be paired with other technologies in an overall plume treatment strategy. This study highlights the importance of understanding groundwater dynamics and PFAS concentration trends when designing the HRX Well and interpreting results. Furthermore, this demonstration an active (pumping) configuration dds only modest cost, but allows more operational control (i.e., the ability to specify flow rates) and increases capture. There are only a few demonstrated technologies for the treatment of PFAS‐impacted groundwater, and these results affirm that HRX Wells may be a viable in situ remediation technology for PFAS at some sites.

Coauthors: Jesse Wright (Arcadis, Inc.)
 

2:05 - 2:25 p.m.

A Long Way to Go: Envisioning PFAS Groundwater Remediation Across Thousands of Sites

Charles Newell, GSI Environmental, Inc.

Per- and polyfluoroalkyl substances (PFAS) present a persistent and widespread challenge to groundwater remediation due to their extreme stability, mobility, and the unprecedentedly environmental regulatory criteria for key PFAS like PFOA and PFOS. This work explores a critical reframing of national PFAS remediation strategy based on performance data, cost modeling, and risk reduction potential across over 10,000 hypothetical sites in the United States.

Using a combination of empirical data and scenario modeling, we compare conventional pump-and-treat (P&T) systems with in situ sorptive barriers, including colloidal activated carbon and replaceable media technologies, as well as an emerging framework for PFAS Monitored Retention (PMR). Our analysis highlights a stark trade-off: while high-cost, high-intensity remediation approaches can achieve near-complete reductions at individual sites, a lower-cost, rapid-deployment “Efficient” containment strategy may offer superior cumulative risk reduction at the national scale by addressing more sites sooner.

Model results indicate that such an Efficient strategy, achieving ~90% reductions in PFAS mass discharge via containment, could address all priority sites within 15 years using only one-third of a fixed nationwide remediation budget. These findings challenge traditional restoration paradigms and suggest that PFAS remediation will require adaptive, tiered approaches that prioritize near-term exposure prevention and long-term technological evolution.

We propose that national policy and regulatory frameworks consider redefining success metrics around risk containment and plume stabilization, rather than full aquifer restoration, as a pragmatic path forward. Continued research into in situ destruction remains essential, but interim strategies centered on scalable containment are likely to deliver the greatest impact with existing tools.

Coauthors: John S. Cook and David T. Adamson (GSI Environmental, Inc.); Paul B. Hatzinger (APTIM)

Open Discussion
 

BREAK
 

3:15 - 3:35 p.m.

Plasma's Role in PFAS Remediation

Selman Mujovic, Purafide

Emerging contaminants, such as per- and polyfluoroalkyl substances (PFAS), are prevalent, persistent, and toxic even at trace concentrations. Remediation managers need reliable technologies that convert waste streams into value streams and satisfy evolving regulations.

The current state-of-practice for PFAS management is separation, but this produces hazardous waste where disposal is expensive and introduces long-term liabilities. Hence, sustainable destruction is needed to break the contamination cycle. Plasma is an effective and efficient destruction technology, capable of breaking down the most refractory organics and synergizing existing treatment trains. While plasma is a promising technology for PFAS remediation, it has struggled to gain traction due to limited radical transport. Without consumables, Purafide’s Plasma Water Reactor (PWR) uses an innovative scaling design to enhance plasma ignition and propagation while minimizing energy consumption.

At sites where other destruction technologies have lagged, the PWR has demonstrated emerging contaminant destruction in various practical matrices, ranging from drinking water to reverse osmosis concentrate of leachate. For instance, in industry-impacted groundwater with a recalcitrant background matrix, electrochemical oxidation was ineffective whereas the PWR achieved efficient removal of 1,4-dioxane, PFAS, and other contaminants. The PWR also proved to be cost effective compared to unsustainable practices including deep-well injection. This presentation will explore how plasma works, which applications prove to be potent, and where it fits in treatment trains.

Coauthor: Luis Arias (Purafide)

3:35 - 3:55 p.m.

PFAS Systems Engineering: Ion Exchange Uptake Mechanisms and Practical Design Considerations

Larry Gottlieb, ResinTech, Inc.

This presentation addresses the critical knowledge gap in PFAS remediation by combining theoretical understanding of ion exchange mechanisms with practical guidance for designing and building effective Treatment systems. While abundant information exists about PFAS as environmental contaminants, implementation strategies remain underrepresented in technical discourse. The presentation examines PFAS compounds as anionic contaminants, explaining their chemical behavior, EPA regulatory limits established in April 2024, and why conventional water treatment approaches fail to address these persistent pollutants.

The technical discussion centers on anion exchange resin performance, which offers outstanding removal capabilities with high flow rates, smaller equipment, and high capacity. Through analysis of AIX systems with years of operational data, the presentation demonstrates reliable PFAS removal at varying contamination levels. Leaching data resins will be presented along with Advanced Time-of-Flight Secondary Ion Mass Spectrometry analysis of the exhausted resins. 

3:55 - 4:15 p.m.

Natural Resource Damages for Resilency, Habitat, Replacement Resources Restoration Project Valuation for PFAS Air Emissions Impacted Watershed

Jeffrey Andrilenas, The TBLS Group, LLC

At one of the oldest PFAS Chemical Manufacturing facilities in the US, the nexus to injury company Township conceived of 18 resiliency, resource replacement, and passive, low-tech PFAS removal projects via public outreach to craft a landscape ecology solutions approach to a watershed impacted by more than 70 years of air emissions. To qualify as a NRD project, the various projects which were designed to address a air emissions source conceptual site model affecting 10 natural resources. The solution based approach was conceptualized to address increasing surface water/storm water climate affected resiliency to two major rivers, groundwater restoration, soil runoff, sediments, replacement drinking water, and habitat impacts in order to lessen long-term exposure on the community. The project plan was conceptualized within a State Brownfield Economic Redevelopment Zone, for the chemical plant redevelopment, one of the first of its kind in the US. State of the practice phytoremediation and treatment wetlands technologies were conceptualized for use to minimize long-term watershed damages. The projects were valued by innovative GIS-based NRD valuation methodologies coupled with project cost analyses to forecast a probable NRD litigation settlement for one of the largest PFAS NRD cases in the US.

Coauthors: Frank Breen (Breen Geosciences), Tad Deshler (Coho Environmental), David Alford (iGeo Consulting), Matt Holthaus (WSP USA)

4:15 - 4:35 p.m.

Embracing the Complexities of PFAS Site Management

Amar Wadhawan, Noblis, Inc.

Site managers, decision-makers, and practitioners encounter considerable challenges when addressing PFAS impacted sites because of varied release sources in the environment, PFAS physical and chemical properties, and evolving regulations. Uncertainties associated with regulatory use of PFAS definition, risk assessments, and anthropogenic background at sites further compound the issues with establishing remedial goals and strategies. Moreover, cost-effectively treating large quantities of PFAS-impacted media to low regulatory levels continues to remain a major hurdle with conventional technologies. With the advancement of science, technology, and state of practice, however, new tools and approaches are being developed to overcome these challenges.

This presentation will discuss best practices and lessons learned from addressing PFAS at federal sites. It will focus on unique PFAS exposure scenarios; advanced models for PFAS fate and transport assessment and source identification; anthropogenic background determination, and current state of PFAS treatment technologies.

PFAS investigations at federal sites are being performed in a phased manner as achieving complete delineation of PFAS impacts is challenging because of unique migration pathways and constant lowering of screening levels. High resolution site characterization approaches using multiple in-situ tools, however, are employed at many sites to develop robust conceptual site models and provide an improved understanding of key PFAS fate and transport processes. Artificial intelligence-machine learning (AI-ML) approaches and computational tools are also applied for PFAS forensics to evaluate anthropogenic background and differentiate PFAS release sources. In addition to PFAS sorption technologies with tailored materials, emerging PFAS removal and destructive technologies such as foam fractionation, super critical water oxidation, sonolysis, and others are being field tested for PFAS-impacted media. While some of these technologies suffer from treatment efficiency decline due to matrix interferences, optimization with other pre-treatment and post-treatment technologies in a treatment train shows promise to achieve treatment goals and enable widespread adoption across federal sites.

Coauthor: Sam Yoon (Noblis, Inc.)

Open Discussion and Closing Remarks.

The organizers anticipate the discussion may extend beyond 5:00 p.m. to develop a comprehensive list of issues, challenges, information gaps, research needs, and other aspects of PFAS remediation.