The Latest Update on the World’s First Injected Fluoro-Sorb® Barrier for PFAS

Over the past couple of years, VEI Contracting has been at the forefront of redefining in-situ PFAS treatment. Back in the spring 2023, we were awarded a preferred installer arrangement for Fluoro-Sorb® Adsorbent, making us the go-to contractor for in-situ injection applications of the technology across Canada. Then, in the fall of 2023, we leveraged our extensive experience with in-situ remediation injection-based techniques to create a reactive treatment zone for PFAS directly within the subsurface environment at a contaminated site.

This update brings you the latest performance data from the field, demonstrating how the “world’s first” injected Fluoro-Sorb® Adsorbent barrier to be installed is not only meeting, but exceeding, expectations at a challenging PFAS-impacted site in Alberta, Canada. This breakthrough offers environmental professionals and site managers a robust, minimally invasive solution for PFAS plume control.

Fire Fighters using Aqueous Film Forming Foam (AFFF)

Background and Challenge

PFAS, or per- and polyfluoroalkyl substances, are notorious for their persistence and toxicity in the environment and have long challenged remediation efforts. Fluoro-Sorb® Adsorbent has long been considered the leader in PFAS stabilization for soil mixing applications because it has many documented advantages over other common, general adsorbents like activated carbon (AC):

• It has been specifically engineered to capture and stabilize persistent PFAS compounds,
• It has a much higher adsorption capacity for PFAS than other adsorbents (such as AC),
• It is not significantly affected by other organic co-contaminants (unlike AC), and
• Much higher in-situ loading rates can be achieved via injection techniques – especially when compared to colloidal AC.

While the technology is well-established for the effective treatment of PFAS, the question remained as to whether Fluoro-Sorb® Adsorbent could be mixed with water to form a slurry (i.e., without swelling or agglomerating) to allow injection-based applications. After bench-scale testing in our treatability testing laboratory in the fall of 2022, and pilot-scale injection testing completed at a non-impacted site in the spring of 2023, everything looked promising. All that was needed was a PFAS impacted site at which to complete a real-world test. Alberta to the rescue!

The Study Site – A Storm Sewer Downgradient of a Fire Fighting Training Area (FFTA)

At a former firefighting training area in Alberta, where aqueous film forming foam (AFFF) was routinely used in the past, contaminated groundwater migration was a serious concern. In particular, high PFAS concentrations, up to 135,000 ng/L in the storm sewer bedding, posed a risk to a downstream, sensitive low-lying area. The challenge was to design an in-situ remediation strategy that could effectively attenuate these contaminants while accommodating variable PFAS concentrations and groundwater flow rates through the bedding material over the long term.

Concentrations of PFAS in Waters at the Storm Sewer Outfall Area

Field Application: Technical Overview

The pilot project in Alberta serves as a compelling case study for this technology. The conditions present at the site required a solution capable of handling high contaminant loads while preserving the natural hydraulic properties of the aquifer.

Conceptual Plan View of the Pilot-Scale Injection Area

Injection design and implementation details:

• Target Zone: A 9-meter section along the storm sewer bedding near the outfall was identified for treatment.
• Injection Strategy: A total of 14 injection points were installed at one-meter intervals along the treatment zone. This design was optimized to ensure an even distribution of the remedial amendment throughout the bedding material on both sides of the storm sewer pipe.
• Slurry Composition: A 43% slurry was prepared by mixing 728 kg of Fluoro-Sorb® P (powdered) with 1,680 liters of water, achieving an effective, in-situ loading rate of approximately 1.3% by weight relative to the surrounding storm sewer bedding material.
• Operational Efficiency: The entire injection process was completed within one day, demonstrating not only technical feasibility but also operational practicality.

Conceptual Cross-Section of the Pilot-Scale Injection Program

Maintaining Aquifer Integrity

One of the critical aspects of any in-situ remediation approach that relies on a treatment barrier is the impact on groundwater flow patterns. In this pilot project, rigorous hydraulic conductivity testing (using slug tests before and after the injection) indicated only a very small reduction – approximately 0.2 orders of magnitude. This slight change falls within the expected range of testing error and confirmed that the treatment would not hinder natural groundwater movement or disrupt the aquifer’s inherent properties.

Pre- and Post-Injection Hydraulic Conductivity Measurements

Performance Data: Impressive PFAS Attenuation

Post-Injection Performance Monitoring Zones

Groundwater monitoring over a nine-month period post-injection has yielded highly encouraging results. Samples collected from various zones within the reactive barrier showed:

• Total PFAS Reduction: In the middle treatment zone, total PFAS concentrations dropped by an average of 93% after nine months, with significant reductions (89%) already observed at the four-month point.
• Key Compound Attenuation: Detailed analyses revealed reductions of 91% for fluorotelomer sulfonic acids, 66% for perfluoroalkyl carboxylic acids, and an exceptional 97% for perfluoroalkyl sulfonates.

The results are particularly significant for key compounds such as PFOA and PFOS, which experienced reductions between 85% and 93%!

• Robust Performance Under Extreme Conditions: Even in upgradient areas where PFAS levels exceeded 140,000 ng/L, and during a high flux event resulting from a rapid snowmelt, the treatment barrier maintained its efficacy, demonstrating its capability to manage extreme contamination scenarios.

Detail of Pre- and Post-Treatment Groundwater Monitoring Results

These results not only validate the technical feasibility of the injection-based approach but also confirms that it can support long-term site management strategies.

Implications for the Future of In-Situ PFAS Remediation

The success of the Alberta pilot project marks a significant moment in PFAS remediation. By transforming innovative concepts into a scalable, field-ready solution, injected Fluoro-Sorb® Adsorbent barriers offer several compelling advantages:

• More Effective Adsorption of PFAS: Compared to the limited longevity and incomplete attenuation seen with AC-based approaches.
• Rapid Deployment: The injection process minimizes downtime and operational disruption at sites.
• Minimal Impact on Subsurface Flow: Maintaining natural groundwater movement ensures that remediation efforts do not compromise the aquifer or redirect contaminant migration pathways.
• High Efficacy: Dramatic reductions in both total PFAS and individual compounds demonstrate the technique’s robust performance even under extreme conditions.

The Injection Program for In-Situ Applications of Fluoro-Sorb®

For site managers and environmental professionals facing PFAS challenges, this breakthrough provides a clear, compelling alternative to traditional methods. Injected Fluoro-Sorb® Adsorbent’s ability to handle high contaminant loads and maintain groundwater flow integrity positions this approach as a promising risk management measure for PFAS-impacted sites. The technology provides a versatile, rapid, and effective solution that can be tailored to diverse site conditions and contamination profiles.

Conclusion: A Milestone in Environmental Innovation

The transition from the early conceptual discussions in the spring of 2023 to the visionary outlook of the fall of 2023, and finally to the tangible success demonstrated at the pilot site in Alberta, illustrates the rapid evolution of PFAS treatment technology. This pioneering injection project not only validates the potential of in-situ reactive barriers using modified clay in treating PFAS but also offers a promising pathway for sustainable, long-term management of one of today’s most challenging environmental pollutants. This technology provides a proven, scalable solution that can be customized to meet your specific needs.

VEI greatly appreciates the opportunity to partner with the Environmental Services Group (EGS) of the Royal Military College of Canada (RMC) on this important demonstration project!