Firefighting Training Areas as Concentrated PFAS Sources
Dedicated firefighting training areas — where recruits and active firefighters practice suppression techniques using AFFF — represent some of the highest-density PFAS contamination sites globally. Unlike accidental AFFF releases during actual fires, training area discharges were repeated, planned, and often uncontrolled with respect to environmental fate. Foam was applied to burn pits, flowed across unpaved surfaces, and infiltrated directly to soil and groundwater without engineered containment. Decades of this practice at facilities operated by municipal fire departments, industrial fire brigades, military installations, and civil aviation training centers have produced a global inventory of contaminated sites.
The characteristics that make training area contamination distinctive are high PFAS concentration in source zone soils, large plume extent relative to source zone volume due to rapid groundwater transport of mobile PFAS compounds, and compound profiles reflecting the AFFF formulations in use at each facility across its operational history. Sites that used AFFF formulations from multiple eras and manufacturers show layered compound profiles that include both ECF-derived and fluorotelomer-derived compounds.
North American Case Studies
In the United States, EPA-funded site assessments at former military and civilian training areas have documented groundwater PFAS plumes extending kilometers from source zones, with PFAS concentrations in source zone groundwater ranging from tens of micrograms per liter to several milligrams per liter. PFOS and PFHxS from ECF-derived AFFF dominate many military site profiles, while 6:2 FTSA and its transformation products (particularly PFHxA and PFBA) are prominent at sites where fluorotelomer AFFF was the primary formulation. Treatment systems serving community water supplies affected by these plumes have needed to address both compound classes simultaneously.
Canadian training area contamination investigations near air force bases in Ontario and Alberta have produced similar findings, with PFOS and PFHxS as dominant compounds at older ECF-AFFF sites and a broader suite of fluorotelomer-derived compounds at more recently operated facilities. The Canadian Drinking Water Guidelines for PFAS, which established a health-based guideline of 200 ng/L for total of measured PFAS, have driven investment in treatment at several affected community water systems, with PFAS-selective media deployed at sites where short-chain compound removal was identified as a critical requirement.
European Site Experience
European firefighting training area investigations have been particularly extensive in Scandinavia, where groundwater is a dominant drinking water source and environmental monitoring networks are well-developed. Norwegian Civil Aviation Authority investigations at airports with AFFF training histories identified PFAS plumes with diverse compound profiles including PFSAs, PFCAs, and FTSAs. Swedish military training area investigations have produced detailed compound inventories that document the evolution of groundwater PFAS profiles as longer-chain compounds attenuate and shorter-chain transformation products become relatively more abundant over time.
The temporal evolution of compound profiles at Swedish and Norwegian sites provides a longitudinal perspective that is valuable for treatment system planning. Older, well-monitored sites show a clear pattern: PFOS and PFOA concentrations declining as plumes disperse and attenuate, while PFBS, PFHxA, and PFPeA persist or even increase as transformation products accumulate. This trajectory means that treatment systems installed based on early monitoring data dominated by long-chain PFAS may find their performance increasingly inadequate as compound profiles shift toward short-chain dominance over the treatment system’s operational lifetime.
Asia-Pacific Findings
Firefighting training area contamination investigations in Australia have produced some of the most comprehensive public PFAS datasets available globally, driven by Australian Defence Force site investigations and associated community health programs. Investigations at air bases in Queensland, New South Wales, and Victoria documented PFAS profiles similar to those at North American military sites — PFOS and PFHxS dominant in source zones, with a longer tail of fluorotelomer-derived compounds. The Australian findings influenced the development of PFAS drinking water guidance values and drove investment in treatment at communities served by affected groundwater sources.
Japanese training area and airfield investigations have produced findings consistent with the global pattern, with PFAS contamination documented near both US military installations and Japanese Self-Defense Force facilities. Japanese drinking water quality standards for PFAS, established in 2020, have driven remediation and treatment programs at affected sites, with continued monitoring revealing the complex compound mixtures that characterize AFFF-impacted groundwater globally.
Treatment Implications from the Cross-Continental Record
The cross-continental body of firefighting training area case studies converges on a common treatment design implication: the compound profiles at these sites are broad, temporally variable, and shifting over time toward shorter-chain dominance. Treatment infrastructure with a 20- to 30-year operational horizon that is selected based only on the compound profile present at installation risks becoming inadequate as the profile evolves. PFAS-selective media with demonstrated broad-compound-class removal capability provides a more resilient treatment investment for the long operational timescales that characterize groundwater contamination remediation.