EPA is requiring additional testing at sites subject to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, or Superfund) five-year review based on PFAS standards issued under the Safe Drinking Water Act (SDWA).

In April 2024, EPA finalized a rule designating two of the most studied and prevalent PFAS,  Perfluorooctanoic acid (PFOA) and Perfluorooctane sulfonic acid (PFOS), as hazardous substances under CERCLA. The rule was published May 8, 2024, and became effective July 8, 2024. 40 CFR § 302.4(a). As a consequence of the designation, owners or operators of a facility or vessel where PFOA or PFOS are released are responsible for the reporting, investigation, remediation, and monitoring requirements under CERCLA.

An important issue raised by the designation is whether previously remediated sites will be reopened for testing of PFOA and PFOS. In a question and answer document EPA released with the finalized rule, EPA stated it would not require sampling from National Priority List (NPL) sites that are designated final or deleted. However, it left the door open to evaluating PFAS levels at sites subject to five-year reviews.

Five-year reviews are required when a remedial action results in any hazardous substances, pollutants, or contaminants remaining at the site “above levels that allow for unlimited use and unrestricted exposure.” 42 USC § 9621(c); 40 CFR § 300.430(f)(4)(ii). The purpose of the review is to “assure that human health and the environment are being protected by the remedial action being implemented.” 42 USC § 9621(c). As part of the review, EPA ultimately issues a “protectiveness statement” describing the extent to which the remedies are still protective and whether any additional remedies are needed.

EPA has indicated it may expand the risk assessment for a site when there is a new exposure pathway, a new potential contaminant of concern, or an unanticipated byproduct of the remedy. The risk assessment determines the risks to human health and the environment by contaminants at a site and informs the development of response actions. 40 CFR § 300.430(d)(1). By expanding the risk assessment, the agency would take a fresh look at the site to determine if any further remedial actions are necessary to protect human health and the environment.

EPA has required PFAS testing at many sites subject to five-year review in the past. However, recent EPA actions have changed the scope of the five-year review for PFAS contaminants in two major respects: (1) the designation of PFOA and PFOS as hazardous substances under CERCLA lowers the threshold finding EPA is required to make before initiating a removal action; and (2) the setting of maximum contaminant levels (MCLs) and maximum contaminant level goals (MCLGs) of certain PFAS under the SDWA has established a potential cleanup standard.

Threshold Finding

EPA’s authority to remedy a site depends on the nature of the contaminants and the threat to public health and the environment. Whereas a release or threatened release of a hazardous substance triggers a removal action when there is a “threat to public health or welfare of the United States or the environment,” a finding of “imminent and substantial danger to the public health or welfare” is required upon the release or threatened release of a pollutant or contaminant. 40 C.F.R. § 300.415(b)(1); 42 USC § 9604(a)(1). So, the threshold finding for hazardous substances requires only a “threat”, while pollutants or contaminants require “imminent and substantial danger”. Thus, the threshold finding for hazardous substances is much lower than for pollutants or contaminants.

Sites with PFOA and PFOS could be subject to removal actions at a much higher rate than before. Other PFAS chemicals could also be subject to removal actions, but EPA would have a higher bar to meet. Also, exceedances of the drinking water standards may serve to justify a finding of a “threat” or “imminent and substantial danger” to public health or welfare.

Cleanup Standards

Under CERCLA, the remedial action chosen for the site is required to attain the “legally applicable or relevant and appropriate standard, requirement, criteria, or limitation” (ARAR) under any federal environmental law, including the SDWA. 42 USC § 9621(d)(2). Where “appropriate under the circumstances,” the MCLG is required. Id. In April 2024, EPA finalized the National Primary Drinking Water Regulation (NPDWR) for PFOA, PFOS, Perfluorohexane sulfonate (PFHxS), Perfluorononanoic acid (PFNA), and Hexafluoropropylene Oxide Dimer Acid (HFPO-DA, or GenX) pursuant to the SDWA. This regulation set MCLs and MCLGs for each of the listed PFAS chemicals, as well as a hazard index for mixtures.

EPA now has cleanup standards for the five PFAS chemicals addressed in the NPDWR. Whether the MCLs or MCLGs are appropriate will depend on the unique circumstances of each site.

EPA Five-Year Reviews

In conducting five-year reviews since the CERCLA rule went into effect, EPA regional offices have cited the MCLs as a basis for further testing. For example, at the 57th and North Broadway Streets Superfund Site in Sedgwick County, Kan., additional sampling was recommended in light of the MCLs based on the site’s history of automotive salvage, oil refining, and production of industrial finishes and coatings.

Even where PFAS concentrations at a site are above the MCLs, a response action is not automatically triggered. At the Saco Tannery Waste Pits Superfund Site in York County, Maine, EPA noted that while groundwater PFAS concentrations were above the MCLs, EPA did not identify any of the PFAS as contaminants of concern. EPA indicated that it will conduct a remedial investigation to determine if a PFAS source exists on the site and if there is any migration to private wells. At the Baird & McGuire Superfund Site in Norfolk County, Mass., EPA noted that groundwater PFAS levels exceeded the MCLs but issued a short-term protective determination based on the groundwater controls in place at the site. EPA wanted to conduct further PFAS testing to determine the extent of PFAS contamination.

Based on the above sampling of five-year reviews, EPA is gathering more information to determine the extent and impact of PFAS contamination at various sites. It is unclear when and if exceedances of the MCLs will trigger additional remedies, and whether EPA will require sites to meet the MCLs. Generally, additional remedies will not be necessary if the current remedies are adequately addressing PFAS as well as other contaminants. However, additional remedies may be required if the current remedies are not sufficiently containing a PFAS source.

It is important to note that the MCLs will not be the appropriate standard in most circumstances. Whether the MCLs are appropriate depends on the circumstances at the site, but any remedy must at least assure “protection of human health and the environment.” 42 USC § 9621(d)(1). MCLs set the standard for PFAS levels in drinking water, so they would not properly apply to PFAS concentrations in soil. Similarly, the MCLs would not apply to water that is not going to be used as drinking water.

Past and current owners and operators of industrial properties should be aware that EPA may use the MCLs as the benchmark for PFAS concentrations at many sites, potentially leading to the reopening of previously remediated sites. For help navigating federal and state PFAS laws, contact a member of Taft’s Environmental group.