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Regulatory Updates

Washington State Establishes PFAS Cleanup Levels

Clint Miller & Keith Woodburne | September 21, 2022

Washington State continues on its path to developing and promulgating cleanup levels for per-and polyfluoroalkyl substances (PFAS compounds). The Washington State Department of Ecology (Ecology) recently published a list of 6 PFAS compounds that now have soil and groundwater cleanup levels under the Model Toxics Control Act (MTCA). The cleanup levels have been incorporated into the most recent update to the Ecology Cleanup Levels and Risk Calculation (CLARC, July 2022) database.

The Washington State Department of Health (DOH) had previously issued a final rule that included State Action Levels (SALs) for five of the six PFAS compounds.  The Ecology update builds on the DOH SALs using methods established under MTCA for cleanup level development.

The new Cleanup Levels apply to the following compounds:

  • Perfluorooctanonic acid (PFOA),
  • Perfluorooctane sulfonic acid (PFOS),
  • Perfluorononanoic acid (PFNA),
  • Perfluorohexane sulfonic acid (PFHxS),
  • Perfluorobutane sulfonic acid (PFBS), and
  • Hexafluoropropylene oxide dimer acid (HFPO-DA; GenX).

How were the Cleanup Levels Developed?

Effective January 1, 2022, soil and groundwater SALs were established by the DOH for five of these PFAS compounds (excluding HFPO-DA).  The DOH concluded that, since there is limited data available to support a quantitative assessment of cancer risk, SALs would be used based on the Environmental Protection Agency’s (EPA’s) non-cancer reference doses (RfDs).  Future SAL recommendations from DOH for surface water, sediment, air, and terrestrial/ecological exposures are pending.  Ecology adopted the SALs for the five compounds and developed cleanup levels for HFPO-DA using established MTCA equations, EPA non-cancer RfDs, and default exposure assumptions under the MTCA Cleanup Rule.

  • Soil cleanup levels (vadose and saturated) were established direct exposure via incidental ingestion, with values for unrestricted and industrial land use scenarios, and for protection of groundwater.
  • Ecology elected not to not use the June 15, 2022 EPA Health Advisory Levels (HALs) in establishing the cleanup levels for PFOS, PFOA, PFBS, and HFPO-DA.

The groundwater cleanup levels for the first five PFAS compounds are the DOH SALs.  The cleanup level for HFPO-DA was calculated using a standard MTCA equation and EPA RfDs. The MTCA preliminary cleanup levels are summarized below.

MTCA Preliminary Soil and Groundwater Cleanup Levels
MTCA Preliminary Soil and Groundwater Cleanup Levels

How will the Cleanup Levels be Applied?

Under the MTCA Cleanup Rule (WAC 173-340-710(4)), cleanup levels must comply with all relevant and appropriate requirements (ARARs). There is not a Federal ARAR to be considered under MTCA since Federal maximum contaminant levels (MCLs) have not yet been established.  The newly established cleanup levels for the PFAS compounds are based on the DOH ARARs and EPA research and data.  Ecology has indicated that they should be applied on a site-specific basis. Until a site-specific determination can be made by Ecology, these soil and groundwater screening levels should be considered preliminary. We are not yet aware of any sites where these cleanup levels have been applied under Ecology oversight. Generally, if a site has concentrations of PFAS compounds in soil or groundwater greater than the preliminary cleanup levels, then further investigation is likely warranted. While Ecology guidance indicates that these cleanup levels will be evaluated on a case-by-case basis they should be considered the functional cleanup levels. 

What are the Implications?

  • These six PFAS compounds should be considered contaminants of concern (i.e., they are no longer “emerging contaminants”). It is prudent to consider PFAS compounds when conducting All Appropriate Inquiry (AAI) for property acquisition/divestiture.
  • Given the EPA’s recent proposed rule designating PFOA and PFOS as “hazardous substances” under the Superfund law, it is likely that Ecology’s ability to order cleanups and recover costs will be strengthened.
  • Until PFAS compounds are regulated federally, Ecology will likely rely on these preliminary cleanup levels until newer values are developed or unless stricter Federal ARARs are developed.  We anticipate that Ecology will continue to refine its CULs as it has with other compounds and to expand the list of PFAS compounds for which it has CULs.
  • It is not yet clear how materials impacted with PFAS compounds can be disposed. The Washington Dangerous Waste Regulations have not been updated to include PFAS compounds and there has been no applicable guidance issued by Ecology on waste disposal. It appears likely that due to their chemical nature, PFAS compounds will initially be regulated as Washington State “Special Wastes” under WAC 173-303-100, although the specifics of how the regulation may be applied are not yet clear. We continue to explore this issue with our regulatory contacts.

What Happens Next?

  • Additional PFAS SALs are being developed by DOH for other media and for terrestrial and ecological exposures. These additional SALs may be used to develop preliminary cleanup levels under MTCA, and will likely result in more sites in Washington being investigated for PFAS.
  • The timeline for the EPA to establish water regulatory standards (MCLs and possibly secondary standards) includes a proposed rule in fall 2022 and a final rule in fall 2023.

What Can You Do?

  • The primary consideration is to understand that PFAS are no longer “emerging” contaminants but must be considered as a contaminant that should be assessed, where appropriate, at sites in Washington State. PFAS should be considered in AAI and if present should be considered when developing regulatory and closure strategies.
  • PFAS are not like other more commonly understood compounds. Specialized sampling techniques and trained personnel are necessary. The cleanup levels are extremely low (e.g., parts per trillion) and these compounds are pervasive in the environment. “False positives” are common when poor sampling methodology is used.
  • Due to the potentially pervasive nature of these compounds different sampling strategies may also be appropriate. Those strategies should be tied to known uses and releases versus a general screening for these compounds. Because these compounds are pervasive and long-lived and the cleanup levels and detection limits are exceedingly low, a general screening may identify compounds, which are actually a background condition rather than related to an on-site release.
  • Unlike other discontinued contaminants (e.g., PCBs, DDT), PFAS chemicals are still in common use. At operating facilities, consider conducting an audit of the processes and chemical formulations used on site.
    • Consider replacing PFAS materials with non-PFAS products.
    • Dispose PFAS materials appropriately and understand the potential for PFAS discharges in your process or waste streams.
    • Take actions to prevent further PFAS contamination/migration, including operational changes, removal and/or cleanup if necessary.

TRC is prepared to assist you with your PFAS-related environmental evaluation and regulatory screening questions. For more information, please contact Clint Miller at or Keith Woodburne at

Clint Miller

Dr. Clint Miller is an expert geochemist with over 11 years of experience in environmental consulting. He currently serves as the Advanced Characterization & In-Situ Remediation CORE Team Lead in the Engineering, Construction, and Remediation (ECR) practice. During his career, he has been involved in projects across the globe, including Arctic Siberia, Chile, Greece, Japan, Papua New Guinea, Philippines, Syria, Taiwan, and the United States. He has significant remediation experience with chlorinated solvents, coal combustion residuals (CCRs), metals, per- and polyfluoroalkyl substances (PFAS), pesticides and fertilizers, semi/volatile organic compounds, and many other contaminants in soils, groundwater, surface water, and sediments. Dr. Miller’s background includes extensive service to public and private-sector clientele including expert witness, remedy screen, and cost-to-closure estimates. Contact Clint at

Keith Woodburne

Keith Woodburne is a principal geologist with 24 years of experience in environmental consulting. Keith has served as a Program and Project Manager and Senior Technical Lead for a broad range of site characterization and remediation projects in the western United States, including in Washington, Oregon, Montana, California, Arizona, and Texas. He has extensive experience in project management, site characterization design and implementation, and regulatory liaison and stakeholder management. He has managed complex projects regulated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), and under a variety of State regulatory agencies and programs. During his career, Keith has managed projects for major industries including oil & gas, cement, tire, and fertilizer manufacturing, for residential and commercial developers, former dry-cleaning facilities, the Port of Seattle, and for a number of industrial class I railroads. He currently provides support in the Pacific Northwest to the TRC’s per- and polyfluoroalkyl substances (PFAS) CORE Team in the Engineering, Construction, and Remediation (ECR) practice. Contact Keith at

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