After decades of industrial use, the Boeing Isaacson Thompson site is undergoing significant remediation as part of the broader Lower Duwamish Waterway cleanup initiative. This effort aims to keep further pollution from leaving the site and entering the Duwamish.

Historically, the site was contaminated due to various industrial activities, including wood treatment and the disposal of hazardous materials. Previous cleanup attempts, such as the application of concrete to stabilize soil, inadvertently worsened the situation by increasing groundwater pH, contributing to arsenic leaching into the waterway. (See our previous blog post for more information.)

Our environmental recovery plan

To address these issues, Ecology has proposed a Draft Cleanup Action Plan, which includes several key strategies:

• Installing a Permeable Reactive Barrier (PRB) to treat contaminated groundwater
• Excavating polluted soil from targeted areas
• Maintaining a containment cap (pavement) to prevent exposure to remaining contaminants
• Monitoring groundwater and environmental factors to ensure the effectiveness of the cleanup measures over time

While the site does not present an immediate threat, our objective is to effectively manage contamination to ensure the long-term protection of public health and the environment.

We want to hear from you

Before proceeding with our plans, we invite community members to review and provide feedback on the documents related to the site's future. The following documents are available for public review:

Your input on these documents is essential in ensuring that the cleanup reflects the community’s concerns and priorities. We will carefully review all comments received during this public comment period. If significant revisions are warranted, another public comment period will be held to ensure that all voices are heard. If there are no major modifications, we will finalize the documents, allowing Boeing to move forward with the design of the cleanup. Any new or updated legal agreements will also be made available for review in future comment periods.

How to share your feedback

Starting Oct. 21, 2024, at 12:00 a.m., you can submit your public comments through the following options:

Visit our online form to submit your comments online.

Comment Period: Oct. 21, 2024, 12:00 a.m. – Nov. 19, 2024, 11:59 p.m.

You can also send your comments via mail to:

Beau Johnson, Site Manager
PO Box 330316
Shoreline, WA 98133-9716

Phone: (206) 638-0816
Email: beau.johnson@ecy.wa.gov

Join us for a community conversation

In addition to online submissions, we are also hosting a two-hour community event with food and conversation about this cleanup site on Thursday, Oct. 24, 2024, from 4:30 – 6:30 p.m.

In-person location:

Duwamish River Community Hub
8600 14th Ave. South
Seattle, WA 98108

To request an ADA accommodation, contact Ecology by phone at 425-229-3683 or email LDW@ecy.wa.gov, or visit ecology.wa.gov/Accessibility. For Relay Service or TTY call 711 or 877-833-6341.