Spokane International Airport PFAS

Homes already connected to city water are excluded, as that water is regularly tested and safe. We notified the responsible parties Feb. 10, and included a scope of work and schedule for providing:

• Bottled water and/or point-of use (POU) filtration systems (short-term interim action)
• Private well testing and treatment system maintenance
• Point-of-entry treatment (POET) systems or connection to city water where possible (long-term interim action)

Short-term plan to provide POU filters and offer private well testing

We received the draft work plan on March 20 and provided our comments on March 27. The responsible parties submitted a revised plan that did not incorporate all our comments on April 3. After considering our options, we accepted the revised plan as final to keep the work progressing because it meets the minimum requirements for the interim action. The final Short-term Interim Action Work Plan was submitted April 20. Our acceptance of the plan starts the schedule of deadlines for work:

• Begin providing drinking water by May 13
• Send letters about how to get filters and sign up for well testing by May 28

See our April 15 West Plains PFAS email list message for more information.

Long-term plan to provide POETs or city water, periodic private well testing, and treatment system maintenance due in May

The responsible parties will submit a draft long-term interim action work plan by May 11. This plan will detail how the responsible parties will supply POETs to people with contaminated private wells or connect them to city water where possible. The work will include maintaining the treatment systems and periodically testing private wells and filtered water.

We expect the work to begin later this year. We will hold a 60-day public comment period and public meeting for the long-term interim action work plan.

What if I'm not in the affected area?

For now, the work will be limited to the area in the map above, excluding homes already connected to city water. However, Washington's cleanup law requires responsible parties to find the full extent of contamination. As the investigation continues, the area may expand based on groundwater sampling results.

We based the current boundaries of the affected area on:

• Data in the draft Initial PFAS Investigation Report
• Historical data from the airport property
• Well-established and published characteristics of regional geology and hydrogeology
• Very low to non-detect levels of PFAS in groundwater upgradient of the airport's property
• High levels of PFAS in groundwater immediately downgradient of the airport's property
• Documented PFAS impacts to drinking water wells further downgradient from the airport's property

On March 13, the responsible parties submitted the revised Initial PFAS Investigation Report, which incorporated some of our comments. We approved the report on March 19, noting parts we still disagree with in a letter. The appendices are split into multiple files:

• Appendices A–C: Field and Chain of Custody Forms (A) | Investigation Derived Waste (B) | Data Usability Summary (C)
• Appendix D: Analytical Laboratory Reports, Part 1 | Part 2
• Appendices E–F: Monitoring Well Survey Report (E) | Lithologic Logs of Soil Borings (F)

Groundwater samples were collected from 50 monitoring wells. Soil samples were collected from 57 locations at multiple depths below the ground surface. The report includes maps and preliminary analyses of soil and groundwater data. The results will be used to develop a Remedial Investigation Work Plan.

• Learn more in our report summary.

We held a comment period Feb. 6 to Mar. 9 for the Agreed Order for a remedial investigation, feasibility study, and potential interim cleanup actions with the City of Spokane and Spokane County and the updated Public Participation Plan. We responded to 27 comments. Thank you for your comments and questions! We have shared them with the responsible parties.

On Feb. 25, we presented an update on the airport's investigation into PFAS and the upcoming interim actions to provide safe drinking water (see below for more details). We appreciated the thoughtful questions and comments from the 90+ attendees and were pleased to see many new faces. We added 46 people to our West Plains PFAS updates email list as a result. Please continue to share information with your neighbors, as we heard loud and clear that some residents in the West Plains are still unaware of potential PFAS in their private wells. We welcome suggestions for reaching new people.

The remedial investigation will determine the full extent of PFAS and other contamination in soil and groundwater, and the feasibility study will assess cleanup options. The order includes a scope of work and schedule for completing the work, excluding any work Spokane International Airport (SIA) will do or has already done. Because SIA is already in progress on the work under the March 2024 Enforcement Order, it continued during the comment period.

In June 2025, Ecology provided preliminary notification to the city and county of their responsibility involving contamination at SIA. The airport is jointly owned by the two local governments. We finalized the decision in August. We negotiated the Agreed Order in late 2025.

On July 31, Ecology received a request from SIA to modify the schedule by extending the deadline for submitting the Remedial Investigation Work Plan by 120 days. This extension affects all the other deliverables, as they are based on the submittal of the previous one.

Ecology compromised by granting a 60-day extension, and we amended the order. We will share the draft Remedial Investigation Work Plan when it's final.

As part of the schedule modification, we are requiring quarterly groundwater monitoring and the submittal of groundwater monitoring reports to occur sooner than the Enforcement Order originally required. Quarterly groundwater monitoring was going to start after the Remedial Investigation Work Plan was finalized; however, SIA and Ecology agreed to change the schedule, and monitoring should start by the end of the year.

SIA submitted the final Initial PFAS Investigation Work Plan, Sampling and Analysis Plan, Health and Safety Plan, and Inadvertent Discovery Plan on December 13, 2024. Ecology reviewed and commented on a draft submitted September 19. Following SIA's revision, we approved it noting a few of our comments were not fully incorporated in a cover letter attached to the work plan. SIA responded to our conditional approval letter.

Work plan summary

The Initial PFAS Investigation Work Plan explains where and how preliminary groundwater and soil samples will be collected on SIA's property, focusing on areas with potential or known PFAS releases (click image above to enlarge and view the areas). The field work detailed in this work plan was completed in January 2025. 

March 2024 groundwater sampling results

Appendix A of the work plan is the results of groundwater samples taken in March 2024. Based on Ecology’s review, the results are generally consistent with SIA’s past sampling and indicate several areas within the airport property had PFAS. Highest concentrations were observed in the Joint Fire Training Area, with one type of PFAS (PFHxS) at 16,000 parts per trillion (ppt), which is 1,600 times the drinking water standard of 10 ppt.

Learn more

• Download the Initial PFAS Investigation Work Plan, includes Ecology's conditional approval letter (read SIA's response) and figures showing March 2024 and planned sampling locations
• Download the work plan appendices, which are as follows:
1.  March 2024 Groundwater Sampling Data
2. Quality Assurance Project Plan / Sampling and Analysis Plan
3. Health and Safety Plan
4. Inadvertent Discovery Plan (for if historical artifacts are found during the investigation)
5. Groundwater Monitoring Well Boring Logs
• Read Ecology's summary

After Ecology review and comment, SIA made revisions and the Site Assessment Report for PFAS was approved as final in August 2024. The report includes the following sections:

• SIA description (current and past operations and land use, geology and hydrogeology, groundwater and surface water) 
• Records review (personnel interviews, incident records)
• Fire emergency training response system information
• Waste related to SIA operations
• Other potential sources of PFAS
• SIA's historical PFAS data

The report lists areas that could be PFAS sources where firefighting foam was stored or used, and areas where PFAS was previously found in groundwater:

• Airplane crash that resulted in a fire – 1994
• Joint Fire Training Area and Military Burn Pit, Air Force, SIA, and Air National Guard training with firefighting foam
• Triangle Ramp training area
• Historical SIA Fire House, previous firefighting foam storage and firefighting training area
• Current SIA Fire House, firefighting foam storage and firefighting training area
• FAA inspections and testing (Taxiway K)
• Hanger 725, firefighting foam storage
• Field Maintenance Building, firefighting foam storage and equipment maintenance
• Air National Guard Operations Area, previous firefighting foam training
• Park Drive waste disposal area and Waste-to-Energy Plant borrow pit, unknown source
• Stormwater recovery area, collects stormwater that may contain PFAS
• Southeast area of business park, no known firefighting foam activities in the area, further investigation needed

In addition to reading the report, you can learn more in Ecology's summary.

The Enforcement Order and Public Participation Plan were open for public comment March 29 through May 27, 2024. We held a public meeting May 6 (download the slides) that was attended by more than 100 people. We appreciate the community’s input and interest and thank the 21 people who submitted comments. We considered and responded to all the comments we received. 

The order requires SIA to complete a remedial investigation and feasibility study. The remedial investigation will determine the full extent PFAS and other contamination in soil and groundwater, and the feasibility study will assess cleanup options. The order includes a scope of work and schedule for completing the investigation and study. The Public Participation Plan describes how you will be informed and can comment during the cleanup process. You can learn more in the public notice that was mailed to the community and by reviewing the order and plan.

If you would like to be added to the postal mailing list, please send your mailing address to Erika Beresovoy at erika.beresovoy@ecy.wa.gov or call her at 509-385-2290. The postal mailing list will notify you about open public comment periods for the Spokane International Airport PFAS site.

To join the West Plains PFAS updates email list, you can subscribe online, or email or call Erika to request to be added. The email list will notify you about open public comment periods for the Spokane International Airport PFAS site, as well as other PFAS-related topics relevant to the West Plains, including the Area-wide Groundwater Investigation we're funding. You can also find more information on our PFAS in West Plains private wells webpage.

In October 2017, SIA hired an environmental consultant to drill two new groundwater monitoring wells in the northeast part of the airport property. In November, these wells and an existing well were sampled to determine if PFAS were in groundwater. Sample results for all three wells had levels of PFAS above Washington’s recommended health safety levels.

PFAS contamination had been identified in wells in and around the nearby Fairchild Air Force Base earlier in 2017. PFAS, a known human health hazard, are in firefighting foam used to control petroleum fires at airports and military installations.

In March 2019, SIA hired another consultant to sample groundwater monitoring wells for PFAS in an area that had been used for fire training drills in the southwest portion of the airport property. Sample results for three wells had levels of PFAS above Washington’s recommended health safety levels.

Ecology received the 2017 and 2019 sampling results in early 2023 from a third party who had obtained them through a public records request. Ecology completed an initial investigation, and then added the airport to the Contaminated Sites List.