Integrating Mitigation Strategies into Routine Operations and Maintenance
Challenge
A state regulatory agency issued a request for information to a commercial airport following the detection of PFAS impacts in a downstream recreational lake that serves as a drinking water source. Stormwater compliance sampling confirmed PFAS discharge from an airport outfall, requiring immediate investigation and mitigation.
TRC’s review identified a historical emergency response involving legacy aqueous film-forming foam (AFFF) more than 25 years ago as the primary source. Due to the persistence of PFAS, impacted grassy areas continued to act as long-term sources, transporting contaminants into the stormwater system through runoff and infiltration.
Conventional remediation approaches, such as excavation and disposal of impacted soil or installation of treatment systems, posed significant cost and operational challenges in an active airfield environment.
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Solution
To identify key PFAS transport pathways, TRC conducted a comprehensive investigation that included CCTV inspections and environmental sampling across the stormwater network under varying weather and flow conditions.
Advanced analytical methods, including forensic fingerprinting and stormwater modeling, were applied to evaluate flow dynamics and contaminant behavior. These insights informed a targeted mitigation strategy focused on controlling contaminant migration at the source.
Strategic infrastructure improvements were implemented, including installation of cured-in-place pipe (CIPP) liners to prevent PFAS migration from surficial soils into the stormwater system. Approximately 30% of the network was upgraded as part of this targeted approach.
Results
The solution delivered measurable outcomes, with post-mitigation sampling showing more than a 95% reduction in PFAS concentrations at the stormwater outfall.
Independent sampling by the state regulatory agency confirmed significant improvements in downstream water quality, including in the previously impacted recreational lake. Observed concentrations aligned with upstream baseline levels, indicating minimal contribution from the airport.
By avoiding large-scale excavation and treatment infrastructure, the airport mitigated potential costs reaching tens of millions of dollars while maintaining operational continuity. The approach also reduced regulatory risk and protected the airport’s reputation.
This mitigation strategy has since been successfully implemented at other commercial airports, demonstrating its scalability and effectiveness.