Frequently Asked Questions

A remedial or cleanup action reduces or removes contamination found at a site to ensure it’s safe for humans and the environment.  

At the Terminal 115 Plant 1 Site, remedial actions are overseen by the Washington State Department of Ecology under the Model Toxics Control Act (MTCA). 

A remedial investigation (also called RI) involves collecting soil and groundwater chemical data to understand the types, volumes, and severity of contamination at a site and where that contamination is located. 

A feasibility study (also called FS) explores options for removing or containing contamination and compares the outcomes, costs, and impacts of each cleanup alternative.  

The final remedial investigation/feasibility study document is used by the Washington State Department of Ecology to create a draft Cleanup Action Plan, which identifies the selected cleanup alternative and describes the plan for cleanup. 

For this phase of fieldwork, crews collect soil and groundwater samples by drilling steel rods into the ground. Soil and water samples are then tested by a certified analytical laboratory to determine chemical concentrations.

Fish and wildlife are not impacted by this type of fieldwork.

There is a possibility of discovery of historical or cultural artifacts during fieldwork given the historical presence of village sites and seasonal gathering areas of the Coast Salish Tribes as well as of historical industrial activities across areas of the Duwamish River valley. An inadvertent discovery plan has been developed in coordination with the Department of Ecology. As material is removed from the ground, the field team screens for any items that may be cultural resources. 

The contamination data are compared to chemical specific screening levels (e.g., levels that are protective of humans and the environment) developed by the Washington State Department of Ecology. Any soil or water samples that contain contaminants less than those screening levels are generally considered safe, and those found with concentrations greater than the screening levels are remediated.

This information will be presented in a figure or map that displays the distribution of each contaminant throughout the site. This figure is called the Conceptual Site Model (CSM).

The results of the remedial investigation will indicate if cleanup is needed. The Port of Seattle and Boeing will work together and with the Washington State Department of Ecology to determine the appropriate cleanup actions, if any.

Depending on the specific situation at the site, cleanup actions might include excavation to remove contaminated soil, capping or covering the contamination to create a barrier, or injecting the groundwater to break down or degrade the contamination.

The Terminal 115 Plant 1 Site is located at the boundary between the middle and the lower section or reach of the Lower Duwamish Waterway, which is a U.S. Environmental Protection Agency (EPA)-designated Superfund Site.

Remedial actions on the Terminal 115 Plant 1 Site align with cleanup work in the Lower Duwamish Waterway because they include efforts to control sources of pollution from potentially draining to the river. This source control effort is part of Washington State Department of Ecology’s Lower Duwamish Waterway Source Control Strategy.

Both the Port of Seattle and Boeing are supporting the EPA and Washington State Department of Ecology with cleanup efforts along the Duwamish Waterway.

The goal of source control is to minimize or stop the spread or transport of contamination from upland sites into the river. This is done through the remedial investigation/feasibility study process by locating and remediating upland contamination and creating management and safety standards to reduce the potential for new contamination.

The formal cleanup project is currently funded by the Port of Seattle and Boeing. The Washington State Department of Ecology is also providing grant funding through the Remedial Action Grant Program. 

Yes. The Washington State Department of Ecology will hold public comment periods for the public to review and comment on the draft remedial investigation/feasibility study and draft Cleanup Action Plan before documents are finalized. The Washington State Department of Ecology will share all public comments submitted during these comment periods.

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