Washington State Issues Draft Guidance for PFAS Investigation and Remediation

In mid-December 2022, the Washington Department of Ecology (Ecology) released Draft Guidance for Investigating and Remediating PFAS Contamination in Washington State.

The Draft Guidance would apply to independent cleanups and those that Ecology supervised or conducted. It follows Ecology’s decision last year to include per- and polyfluoroalkyl substances (PFAS) as hazardous substances under Washington’s Model Toxics Control Act (MTCA), the Washington Department of Health’s establishment of State Action Levels for five PFAS compounds in drinking water, and the publication over the summer of preliminary cleanup levels for soil and groundwater for six PFAS compounds, including the five with State Action Levels. The Draft Guidance identifies preliminary cleanup levels for six PFAS compounds and signals that Ecology intends to develop additional standards to reflect new federal and/or state PFAS regulations and the availability of new scientific information.

Comments on the Draft Guidance are due by January 27, 2023.

Preliminary Cleanup Levels

The Draft Guidance summarizes Ecology’s preliminary numeric cleanup levels in soil and groundwater for six PFAS compounds based on human health protection goals. Ecology indicates that it developed these preliminary levels based on existing methods in the MTCA regulations, including risk-based calculations and other applicable or relevant and appropriate requirements.[1]

The Draft Guidance also explains how Ecology may determine cleanup levels for air and surface water. Ecology has not yet set cleanup levels for air because chemical-specific inhalation reference doses (RfDs) are unavailable. Ecology intends to establish inhalation toxicity criteria as new data become available.

Ecology also has not calculated default cleanup levels for surface water due to data limitations and the lack of surface water quality criteria for PFAS. However, for potable groundwater and surface water that may be used as drinking water, Ecology relies on State Action Levels that the Department of Health established for drinking water.

There are two sets of MTCA soil cleanup levels for PFAS. They are based on direct human contact through incidental ingestion and protection of groundwater as a potable drinking water source.

The Draft Guidance also includes protective concentrations for ecological receptors for ten PFAS compounds in surface waters (marine and freshwater) and/or upland soil based on concentrations determined by methods in the MTCA regulations to protect against adverse effects on wildlife, fish, and other biota.[2]

The Draft Guidance does not identify cleanup levels for sediments.

Investigation and Sampling

Ecology recognizes that PFAS sampling methods are still evolving and are not available for all PFAS compounds. Ecology recommends analyzing for a “comprehensive set of PFAS compounds consistent with current, available analytical methods and laboratory capabilities … to allow for future assessment of the site once additional screening and cleanup levels are established.”[3]

The Draft Guidance identifies general resources and specific recommendations regarding use of accredited methods, minimization of cross-contamination, and collection of quality-controlled samples. It incorporates the Interstate Technology and Regulatory Council (ITRC) PFAS Guidance for general PFAS sampling protocols as well as site characterization, sampling precautions, and laboratory analytical methods. For drinking water sampling, Ecology favors EPA’s currently approved methods.

Notably, the Draft Guidance states that the potential presence of PFAS compounds should be considered during all Phase I investigations in Washington.

Treatment Technologies

The Draft Guidance also describes several “field demonstrated” treatment technologies for addressing PFAS in water and solids. Ecology expresses no preference for specific technologies but notes that additional testing and documentation will be necessary to use an unproven treatment option. Remedy selection at sites involving PFAS will still need to satisfy the disproportionate cost analysis requirements under MTCA.


The Draft Guidance provides insights into regulators’ expectations for PFAS investigation and cleanup in Washington. However, final cleanup levels will be based on site-specific determinations. In addition, as reflected in the qualifications throughout the Draft Guidance, the framework for addressing PFAS compounds at MTCA sites in Washington is expected to evolve rapidly. Even once the guidance is final, parties responsible for work at PFAS sites should be alert to changes and coordinate with Ecology to confirm cleanup plans that will provide as much finality as possible, especially in light of rapid technological and analytical developments, ongoing regulatory actions, and potential for site re-openers.

Beveridge & Diamond’s Superfund, Site Remediation, and Natural Resources Damages practice group counsels clients on developing case-law and requirements under CERCLA and similar state laws. With an office in Seattle, we closely track MTCA developments and their impacts on stakeholders. For more information on CERCLA, MTCA, or contaminated site issues in general, please contact the authors.

[1] The six PFAS compounds include perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), perfluorobutane sulfonic acid (PFBS), and hexafluoropropylene oxide – dimer acid (HFPO-DA) (a GenX chemical).

[2] These include five PFAS compounds with human health-based cleanup levels and perfluorohexanoic acid (PFHxA), perfluorobutanoic acid (PFBA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), and perfluorododecanoic acid (PFDoA).

[3] This broad screening requirement may place performing parties in a quandary, given Ecology’s acknowledgment that it would consider the new data once additional regulatory levels have been established for other PFAS compounds.