Terminal 115 Plant 1

Updated July 2020

Please note: the Northwest Regional Office, the document repository for this Site, is temporarily closed to the public.  Please access documents online through the links below.

Ecology negotiated a legal agreement called an Agreed Order with the Port of Seattle and the Boeing Company, the Potentially Liable Parties (PLPs) for the Terminal 115 Plant 1 Site (Site). The order requires them to investigate environmental conditions and develop a draft cleanup plan.

Ecology hosted a public comment period from April 27 - May 26, 2020 to get input on the Agreed Order and other documents for the Site. This comment period is now closed.

Ecology did not receive any comments that warranted significant changes to the documents, so they were finalized.  The Agreed Order was signed on July 6, 2020, and the cleanup process is now moving forward.




• Agreed Order – requires the PLP to investigate contamination, complete a Remedial Investigation (RI), Feasibility Study (FS) and draft Cleanup Action Plan (dCAP) for the Site. 

• Public Participation Plan – describes how Ecology will inform the community about Site activities and opportunities to be involved in the cleanup process. 






Fact sheets
Terminal 115 Plant 1 Fact sheet - English
Terminal 115 Plant 1 Fact sheet - Español
Terminal 115 Plant 1 Fact sheet - Tiếng Việt


Why this cleanup matters 

This site is part of Ecology’s Lower Duwamish Waterway source control efforts, because it is contributing pollution the Lower Duwamish Waterway (LDW) Superfund Site. The 5-mile stretch of the Duwamish River that flows north into Elliot Bay was added to the Superfund National Priorities List by the U.S. Environmental Protection Agency (EPA) in 2001. The sediments (mud) in the river contain a wide range of contaminants due to decades of industrial activity and runoff from urban areas. EPA is leading efforts to clean up the river sediments. Ecology is leading efforts to control sources of contamination from the surrounding land area. The long-term goal is to minimize recontamination of the river sediment and restore water quality in the river. The Site is one of several sites that will be cleaned up as part of Ecology’s Source Control Strategy – controlling sources of pollution to the river. Contaminants in the soil and groundwater around the river pose a risk to human health and the environment. They can also find their way into the river through storm runoff and other pathways. For more information, visit our Source Control page.

Site location and history

The Site is located on the western shore of the Lower Duwamish Waterway, between Port
of Seattle N Terminal 115 and Glacier Northwest Inc. cleanup sites to the north and Highland Park Way SW to the south.  It occupies an area of approximately 99.5 acres and is owned by the Port of Seattle. 


 Between 1916 and 1970, a portion of the southern end of the site was the location of the former Boeing Plant 1 facility, used for the manufacture of wood and metal airplanes.  Other historic uses of the property included retail gasoline service stations, gravel and cement production, salvage yard, storage of log booms (former river portions), and a smelter. 


 Until approximately 1969, large areas of the Site were part of the waterway and were under water.  In 1969-1970, a large portion of the Site was filled to create usable land.


 Since then, the Site has been used for Port-related functions including cargo storage, loading and off-loading, gasoline sales and associated storage in underground storage tanks (USTs), seafood processing, retail sales and vehicle and shipping container maintenance.









 Contamination

Previous investigations at the Site found the following in soil and/or groundwater:

• Diesel range petroleum hydrocarbons
• Vinyl chloride
• Benzene
• Lead

All of these contaminants have been found at levels that exceed allowable standards under the state’s cleanup law, the Model Toxics Control Act (MTCA), and therefore must be addressed.


Previous investigations and cleanup work

Since 1990 several investigations have been conducted at the Site, primarily in response to
petroleum releases from former USTs. Investigations have also been done to evaluate catch basin solids, the presence of fill, and other former operations at the property. Sediment quality was also evaluated on the eastern portion of Terminal 115. Cleanup at the Site to date has included removal of visibly impacted soil and groundwater during removal of USTs.  In addition, free-phase petroleum was removed from extraction wells in the southwest portion of the Site.  The current Agreed Order may lead to additional cleanup.

The Model Toxics Control Act (MTCA; Chapter 70.105D RCW is Washington’s environmental cleanup law). It provides requirements for contaminated site cleanup and sets standards that protect human health and the environment. Ecology enacts the MTCA and oversees cleanups. The MTCA site cleanup process is completed in steps (see graphic below) over a variable timeline.