The Legacy of AFFF at Military Installations
Aqueous film-forming foam has been in operational use at military airfields and fire-training areas since the 1960s. AFFF formulations were developed to suppress hydrocarbon fuel fires rapidly, a capability that required surfactant chemistry capable of spreading across fuel surfaces and excluding oxygen. The perfluorochemicals that gave AFFF its fire-suppression effectiveness — particularly electrochemically fluorinated compounds and fluorotelomer-based surfactants — are now recognized as persistent environmental contaminants that resist natural degradation and bioaccumulate in living organisms.
Decades of AFFF use at military installations produced large-volume releases to soil and groundwater at and around airfields, crash sites, and dedicated fire-training areas. Those releases were not single-compound contamination events. AFFF formulations contained dozens of individual PFAS molecules, and the breakdown and transformation of those molecules over time has expanded the contamination profile further. Drinking water wells and municipal systems serving communities near military bases now frequently show PFAS compound mixtures containing 20 or more distinct compounds — a profile that fundamentally shapes the treatment challenge.
The Chemistry of AFFF-Derived PFAS Mixtures
Two broad manufacturing pathways produced the PFAS compounds found in legacy AFFF: electrochemical fluorination (ECF) and fluorotelomer chemistry. ECF-derived AFFF, primarily produced by one major manufacturer, generated a mixture of perfluoroalkyl sulfonic acids including PFOS and its precursors (PFOSA, perfluorooctane sulfonamides), along with a range of branched perfluoroalkyl isomers not present in fluorotelomer-based products. Fluorotelomer-based AFFF produced by other manufacturers generated fluorotelomer sulfonates (FTSAs), fluorotelomer alcohols (FTOHs), and related precursor compounds that can oxidize to PFCAs in the environment.
Military installations where both AFFF types were used — which includes many major airfields — show correspondingly complex groundwater PFAS profiles. PFOS and PFHxS from ECF-derived AFFF coexist with 4:2, 6:2, and 8:2 FTSAs from fluorotelomer AFFF, alongside their respective transformation products. This mixture complexity means that a treatment system selected primarily on the basis of PFOS removal performance may underperform for the full compound profile actually present.
Why GAC Alone Is Insufficient for AFFF-Impacted Sites
GAC treatment has been deployed at numerous AFFF-contaminated sites and has demonstrated good performance for PFOS and PFOA removal. However, military site groundwater chemistry differs from simple PFOS/PFOA contamination in ways that challenge GAC performance. The presence of FTSAs and sulfonamide precursors — compounds with more complex molecular structures and varying carbon chain lengths — means that a portion of the total PFAS load has poor GAC adsorption affinity. These precursor compounds can pass through GAC treatment and subsequently transform to PFCAs in distribution systems or in the human body after ingestion.
Short-chain PFAS compounds generated by environmental transformation of longer-chain AFFF components are a growing concern at aging military contamination sites. As PFOS and PFOA concentrations in source water gradually decline through natural attenuation and remediation, shorter-chain transformation products can become the numerically dominant PFAS compounds. Regulatory frameworks that focus remediation goals on PFOS and PFOA may inadvertently permit treatment system designs that leave short-chain transformation products unaddressed.
Next-Generation Media for Military Site Complexity
PFAS-selective adsorbent media designed to address a broad compound profile offers a more defensible treatment approach for AFFF-impacted source water. The ability to adsorb both ionic long-chain PFAS and ionic short-chain PFAS through selectivity mechanisms that go beyond simple hydrophobic partitioning means that the technology can adapt to the evolving compound profile as longer-chain compounds attenuate and shorter-chain transformation products persist.
Several Department of Defense-funded research programs have evaluated advanced adsorbent technologies specifically for AFFF site remediation applications. Results consistently show that PFAS-selective media outperforms GAC for the broad compound mixture typical of military site groundwater, with the performance advantage widening as the short-chain fraction of total PFAS increases. For potable water treatment serving base housing and adjacent communities, this broader removal capability translates directly to greater public health protection.
Community and Regulatory Implications
Communities near military installations have pursued regulatory relief, alternative water supplies, and treatment system upgrades through a combination of CERCLA cleanups, state action, and litigation. The complexity of AFFF-derived PFAS mixtures means that simple compliance with PFOS/PFOA MCLs may not address the full health risk posed by the contamination. Health-protective treatment design at military-impacted sites should target the full compound profile identified through comprehensive source water analysis, not the subset of compounds covered by initial regulatory standards.
As the EPA expands its PFAS regulatory framework and as states adopt more comprehensive PFAS monitoring requirements, the treatment gap between targeted PFOS/PFOA removal and genuine broad-spectrum PFAS removal will become increasingly visible in compliance reporting. Communities and utilities investing in treatment infrastructure now have the opportunity to select technology that will remain compliant as regulatory requirements evolve, avoiding costly mid-service-life upgrades.