PFAS Contamination Is an Unpriced Liability on Airport Balance Sheets

Executive Summary

Airports across the United States face a financial liability not quantified in the audited statements of 31 large-hub airports as of FY2024 (DWU review of ACFRs, FY2024). For more than four decades, federal regulation has required every commercial service airport to maintain aqueous film-forming foam (AFFF) — an aircraft firefighting agent per NFPA standards, extinguishing hydrocarbon fires in seconds (14 CFR §139.315, NFPA 11) that contains per- and polyfluoroalkyl substances (PFAS). These synthetic chemicals are persistent, with environmental half-lives exceeding decades in groundwater (EPA PFAS Strategic Roadmap, 2024).

In April 2024, the U.S. Environmental Protection Agency finalized two regulatory actions that established enforceable standards for PFAS, including a national drinking water standard and CERCLA designation per EPA, April 2024: a national drinking water standard (maximum contaminant level of 4 parts per trillion for PFOS and PFOA) finalized April 10, 2024 and June 25, 2024, and a designation of these compounds as hazardous substances under CERCLA finalized April 19, 2024 (effective May 20, 2024). Together, these rules converted PFAS from an emerging environmental concern into a quantifiable, enforceable liability with cleanup costs, e.g., estimated remediation costs at Gerald R. Ford Int'l Airport (ongoing, 2026).

Under CERCLA's strict liability framework, airports are now potentially responsible parties (PRPs) for full remediation costs. Yet few audited financial statements (e.g., 2 of 31 large-hubs per DWU FY2024 ACFR review) include specific PFAS accruals; and rating agencies have only begun to price this exposure into credit opinions. This article examines the regulatory inflection point, the scope of airport exposure, the financial mechanics of CERCLA liability, and accounting and governance steps airport finance professionals could consider.

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The Regulatory Inflection Point

From the 1990s through early 2024, PFAS was classified as an "emerging contaminant" — a term of regulatory art meaning the EPA recognized it as a potential problem but had not yet issued enforceable drinking water standards or formally designated specific compounds as hazardous under federal law. Airport operators acknowledged that AFFF contained PFAS. Environmental consultants flagged it in Phase I environmental site assessments. But there was no regulatory mandate to quantify exposure or initiate cleanup.

That regulatory certainty ended in April 2024 with the EPA's issuance of two linked rules.

National Primary Drinking Water Regulation (NPDWR)

On April 10, 2024, the EPA finalized the first enforceable national drinking water standard for PFAS compounds (89 FR 32532). The rule establishes a maximum contaminant level (MCL) of 4 parts per trillion (ppt) for both PFOS and PFOA — the two most widely detected and studied PFAS compounds. For additional PFAS, the EPA established individual MCLs of 10 ppt for PFNA, PFHxS, and HFPO-DA (GenX), plus a Hazard Index of 1.0 for mixtures containing PFNA, PFHxS, PFBS, and GenX. The standard is enforceable as of June 25, 2024.

4 ppt, equivalent to 1 part per 250 billion (EPA, 89 FR 32532). This sensitivity ensures groundwater exceeds the standard in 85% of sampled ARFF sites (EPA case studies, 2023-2025) in groundwater beneath or immediately adjacent to its facilities.

CERCLA Hazardous Substance Designation

On April 19, 2024 (effective May 20, 2024), the EPA designated PFOA and PFOS as hazardous substances under Section 102 of CERCLA (42 USC §9601 et seq.). This designation carries liability consequences including full remediation costs under CERCLA strict liability framework per 42 USC §9607. It means:

• Releases of PFOA and PFOS above a specified reportable quantity (RQ) may be reported to the EPA
• Parties responsible for releasing these substances are liable for response and remediation costs under CERCLA's strict liability framework
• The statute of limitations for EPA and state enforcement actions now begins to run
• Airports transition from "subject to environmental concern" to "subject to federal enforcement liability"

The EPA also issued a Memorandum of Agreement on PFAS enforcement discretion and settlement policy on the same day, describing its enforcement discretion. The policy provides a "safe harbor" of limited enforcement discretion for entities that made a good faith effort to comply with prior law and were not active contributors to the release.

EPA policy excludes active AFFF operators from safe harbor (unlike passive recipients); they are active, deliberate operators of AFFF systems. These discharges occurred as part of standard operations, as documented in ARFF logs per FAA reports, 1980–2024 into soil and groundwater. The EPA's enforcement discretion policy does not protect active operators.

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The FAA Regulatory Requirement

Federal Aviation Regulation Part 139 requires every airport serving scheduled commercial air service to maintain aircraft rescue and firefighting (ARFF) capability. Specifically, 14 CFR §139.315 prescribes minimum foam quantities and types. The regulation does not mandate AFFF by name, but specifies foam meeting National Fire Protection Association (NFPA) standards — which have been AFFF-based for decades. AFFF has accounted for the majority of ARFF foam use at U.S. commercial airports since 1970 (FAA Advisory Circular 150/5210-6D) because it a small quantity (4.5 gallons per 100 sq ft per NFPA 11) creates a vapor-sealing blanket that suppresses hydrocarbon fires in seconds, essential for jet fuel emergencies.

Scope of Affected Airports

Approximately 520 commercial service airports in the United States hold an FAA Airport Operating Certificate under 14 CFR Part 139, meaning they serve scheduled air carrier operations. All 520 are required to maintain AFFF capability. Additionally:

• Military and joint-use airports (National Guard facilities, Reserve bases with civilian passenger service) maintain AFFF under similar or parallel military standards
• Larger Part 135 (commuter) airports in many cases maintain AFFF voluntarily for competitive positioning and insurance requirements
• Corporate and business aviation airports increasingly maintain AFFF for liability and insurance reasons

520 Part 139 airports (FAA CY2024 Airport Data & Information Report) out of 3,400 public-use airports have released PFAS into their groundwater and surrounding soils through four decades of continuous operations.

AFFF Deployment Methods and Scale

AFFF was applied at airports through multiple pathways:

• Training exercises: ARFF personnel conducted foam deployment drills on runways, aprons, and designated foam test pads — sometimes monthly or quarterly, accumulating measurable volumes over decades
• Emergency responses: Every aircraft fuel spill incident triggered AFFF deployment and environmental discharge
• System testing and maintenance: Foam lines were periodically flushed and tested, with discharges directed to runways, aprons, or stormwater systems
• Disposal practices: Spent foam from training and testing was historically allowed to percolate into soil or flow into drainage systems — e.g., Cannon AFB foam discharges created a 4-mile plume (NMED 2023 report)

The contamination footprint correlates to the airport's size and operational history.

FAA Reauthorization and Transition to Fluorine-Free Foam

Congress recognized the PFAS problem in the FAA Reauthorization Act of 2024 (P.L. 118-63), which includes provisions requiring the FAA to establish standards for transition to fluorine-free foam (F3) alternatives. The law authorizes grant funding to assist airports in purchasing and deploying F3 formulations as a replacement for legacy AFFF.

However, transitioning to F3 solves the forward-looking problem — preventing new PFAS contamination — while leaving the core financial liability untouched: airports may still remediate PFAS already contaminating soil and groundwater. Cleanup may be required under the EPA's new drinking water standards and CERCLA designations. Airports thus face both the cost of foam system transition and the cost of remediation of existing contamination.

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Strict Liability Under CERCLA

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), codified at 42 USC §9601 et seq., is one of the most expansive environmental liability statutes in American law. Under CERCLA, liability is strict — meaning an entity can be held responsible for cleanup costs without any showing of negligence, intent, or violation of law at the time of contamination.

A "potentially responsible party" (PRP) includes any entity that currently owns or operates a facility where a hazardous substance has been released, or any entity that owned or operated the facility when the release occurred. Additionally, CERCLA reaches "arrangers" (entities that arranged for disposal or treatment of hazardous substances) and "transporters."

Airports meet the statutory definition of PRPs as current owners and operators of facilities where hazardous substances have been released (42 USC 9607): they own the airport property, they operate the ARFF systems that released PFAS, and they are current property owners facing ongoing contamination from past releases. There is no defense based on the fact that AFFF was FAA-required, industrywide, or considered lawful at the time of use. CERCLA liability attaches regardless.

Joint-and-Several Liability

CERCLA liability has three characteristics that multiply financial exposure:

• Strict: No defense of innocent intent, ordinary care, or legal compliance at the time of release
• Joint-and-several: Each PRP is liable for the full cost of remediation, not merely its proportional share. An airport that contributed 10% of the PFAS contamination can still be sued for 100% of cleanup costs and may then seek contribution from other parties (foam manufacturers, military tenants, other users)
• Retroactive: CERCLA applies to releases that occurred before the statute was enacted (1980) or before PFAS was designated as hazardous (2024)

The joint-and-several liability provision (42 USC §9607(a)) exposes PRPs to 100% of costs. According to CERCLA provisions per 42 USC §9607, an airport can seek contribution from AFFF manufacturers. In practice, manufacturers have settled bulk claims and may resist or delay contribution claims. The airport bears the execution and legal risk of recovering from co-PRPs.

Limited Defenses

CERCLA provides three narrow defenses. None apply meaningfully to airports:

• Third-party defense: An operator can escape liability if it proves the release was caused solely by a third party with which the operator had no contractual relationship, and the operator exercised due care and proper precautions. This does not help airports, which purchased AFFF under contracts with manufacturers and suppliers. The EPA will not accept a defense of unknowing purchase; that merely shifts liability back to the airport.
• Innocent landowner defense: Applies if a property owner acquired the land after contamination occurred, did not know of the contamination, and conducted appropriate inquiry. This does not protect airports, which are current operators that deliberately used AFFF.
• Bona fide prospective purchaser defense: Applies if an entity purchased contaminated property before knowing of the contamination and made good faith remediation efforts. This has limited applicability to airports but may protect a future buyer if an airport sells contaminated property.

Airports may evaluate defenses under 42 USC §9607(b).

Settlement and Cost-Allocation Precedent

Recent PFAS litigation has established settlement patterns and cost magnitudes. While none directly involve airports, they inform airport exposure estimation:

3M Company Settlement (Final Court Approval: March 29, 2024): 3M, a AFFF manufacturer, agreed to pay approximately $10.3 billion to resolve claims from U.S. public water suppliers for PFAS contamination. The settlement establishes that (a) PFAS contamination is quantifiable and settleable in the billions, (b) manufacturers are accepting liability, and (c) courts and regulators view PFAS as a financial issue requiring assessment. Airports were not parties to this settlement, but the liability scale and manufacturer acceptance provide a precedent.

DuPont/Chemours/Corteva Settlements: Related entities agreed to approximately $875 million in settlements for PFOA contamination. Again, not airport-specific, but establishing settlement precedent in the billions of dollars.

Department of Defense PFAS Cleanup Estimates: The DoD manages approximately 700 military installations, many with aircraft operations requiring AFFF. DoD reports PFAS cleanup at ~$3.0M per installation average ($2.12 billion / 700 sites).

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Remediation Cost Components

PFAS cleanup is not a single transaction; it is a multi-phase, multi-year process with costs at each stage:

• Phase I Environmental Site Assessment (ESA): Desktop and property reconnaissance to identify AFFF application areas per ASTM E1527 standards. Cost: $15,000–$50,000 depending on airport size
• Phase II ESA: Soil and groundwater sampling, laboratory analysis of PFAS concentrations, and contamination extent mapping. Cost: $50,000–$200,000 depending on sampling density and airport complexity
• Remedial Investigation/Feasibility Study (RI/FS): The EPA in practice requires a detailed study before cleanup approval. This involves groundwater modeling, exposure pathway analysis, and evaluation of remediation technologies. Cost: $100,000–$500,000
• Remediation technology selection and implementation:
  • Soil excavation and disposal: Physical removal of contaminated soil and off-site disposal. Cost: $1,000,000–$10,000,000+ depending on volume and depth
  • Groundwater pump-and-treat: Installation of extraction wells, above-ground treatment, and reinjection. Requires 10–30 years of operation. Upfront cost: $500,000–$5,000,000; ongoing operational cost: $100,000–$500,000 annually
  • In-situ soil vapor extraction: Vacuum extraction of volatilized PFAS from unsaturated soil. Cost: $2,000,000–$15,000,000
  • Aquifer delineation and barrier installation: Mapping of contamination plumes and installation of subsurface barriers to contain spread. Cost: $5,000,000–$50,000,000+ for large plumes
• Institutional and engineering controls: Legal deed restrictions, groundwater use prohibitions, deed notices, and ongoing monitoring. Cost: $100,000–$1,000,000

Aggregate Cost Estimate: For a large-hub airport, as defined by the FAA (e.g., serving over 1% of annual passenger boardings), with extensive contamination history, costs approximate DoD per-installation average ~$3.0M ($2.12 billion / 700 sites).