General Electric Aviation Div
220 S Dawson St, Seattle, WA 98108


Updated October 2018

We held a public comment period from August 30 - September 28, 2018 about  a new proposed method to cleanup groundwater at the former General Electric Aviation (GE) site at 220 S. Dawson St., Seattle, WA 98108.

You can still view the documents that were available for your comments:

We are requiring GE to develop new cleanup (remediation) actions because the current methods are not working sufficiently. GE has submitted the following documents to us regarding new actions:

What happens next?

Under our oversight, GE is proposing a new groundwater cleanup method. If we approve the methods, GE will inject a mixture of iron particles (called zero valent iron or ZVI) and organic plant material.  The mixture of these two substances is expected to destroy TCE and other groundwater contaminants. This method works through a different chemical pathway than the previous method that used the persulfate solution.

GE will also continue to follow other cleanup actions as directed in 2014 CD and CAP. The actions are:

  • Preventing contaminated groundwater that is above cleanup levels from moving beyond the 220 S. Dawson Street property. They will do this by extracting groundwater and relocating one of the groundwater extraction wells to a better location father west and continuing to extract groundwater.
  • Continuing to protect indoor air quality by operating the air quality mitigation system (vapor intrusion system  or VIM) in the 220 S. Dawson St. buildings.

  • Under our oversight, GE will also continue non-engineering measures that help to reduce the potential for human exposure to contamination and/or to protect current cleanup actions.  The actions are:

  • Restricting withdrawal of groundwater at the Site.
  • Preventing subsurface activities that mix the contamination in the intermediate.
  • Preventing deeper zone groundwater with contamination from getting into the shallow zone groundwater.
  • Restricting future activities which could increase the likelihood that vapor intrusion could occur.
  • Restricting subsurface activities in areas where the soil or groundwater is contaminated.
  • Monitoring groundwater on the site.
  • Why this cleanup matters

    This site is part of our Lower Duwamish Waterway source control efforts because it has had the potential to contribute pollution in the Lower Duwamish Waterway (LDW) Superfund Site.  We required an interim action (partial cleanup) to prevent the contamination from reaching the river. 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.

    We are 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 General Electric-Dawson Plant Site is one of several sites that will be cleaned up under EPA’s Resource Conservation and Recovery Act (RCRA) and as part of Ecology’s Source Control Strategy to control 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.


    The cleanup site and the source of the contamination is located at 220 S. Dawson Street in Seattle, Washington.  The groundwater contamination extends approximately 1,100 feet west from this property.  The cleanup site is located in an industrial zoned area in the Lower Duwamish Waterway.


    The main site contaminants include:

    • trichloroethylene (TCE)
    • tetrachloride-ethylene (PCE)
    •  1,1,1 - trichloroethane (1,1,1-TCA)
    • Metals and oils

    Some or all of these contaminants are in the indoor air, soil, and groundwater beneath the 220 South Dawson Street building. TCE in soil and groundwater beneath the building has vaporized and moved upwards through the soil, into the building workspaces. (A process known as vapor intrusion.) Some groundwater contaminants moved west at least as far as Utah Avenue South.


    GE produced and serviced aircraft parts during most of the years it occupied the building at 220 S. Dawson St. between 1949 and 1996. Other tenants have since occupied the building, using it for various warehousing operations.

    During GE’s occupancy, solvent spills and leaks contaminated underlying soil and groundwater. The main contaminants include solvents used to clean metal parts trichloroethylene (TCE), tetrachloroethylene (PCE), and 1,1,1 - trichloroethane (1,1,1-TCA ) as well as fuels and oils.

    These contaminants are found in the indoor air, soil, and groundwater beneath the 220 South Dawson Street building. The contaminants have also migrated in the groundwater to the west near Colorado Avenue South.  Some TCE in the soils and groundwater below the 220 South Dawson Street building changed to a gas and moved upwards through the soil, into the building workspaces


    We required GE to install a mitigation system to prevent people in the buildings from contaminated air from beneath the 220 S. Dawson St. building. (A process known as vapor intrusion). The system pulls contaminated vapors from under the building so that they do not enter, and redirects them to a roof vent. Outdoors, the vapors quickly dissipate to acceptable levels. This was done under a legal agreement (Agreed Order or AO

    2008: We required GE to review possible cleanup methods and actions to clean up the site in a focused feasibility study (FFS). Ecology modified and approved the FFS report in late 2009. Done under a new AO.

    2014: We required GE to implement Ecology’s selected method to clean up  contaminated soils, groundwater and indoor air that were above the necessary cleanup standards. Done under a legal Consent Decree.

    2017: GE injected a cleanup chemical (aqueous persulfate chemical oxidant) into the contaminated groundwater below the 220 S. Dawson Street property.  The results did not show that the actions adequately destroyed the TCE and other groundwater contaminants.

    2018: GE tried a different cleanup method.  They installed persulfate slow diffusion release bags into several groundwater wells on the same property.  These actions also did not adequately destroy the TCE and other groundwater contaminants.

    Please click on the photo for a larger view


    We are in the cleanup action plan phase of cleanup.


    The Environmental Protection Agency (EPA) has developed a new environmental justice (EJ) mapping and screening tool called EJSCREEN. It is based on nationally consistent data and an approach that combines environmental and demographic indicators in maps and reports. See below for information about demographics in the area of General Electric Aviation, Seattle.

    EJSCREEN ACS Summary Report GE Aviation– This shows the demographic information about the population of the area.

    EJSCREEN Report GE Aviation – This report shows the values for environmental and demographic indicators and EJSCREEN indexes. These percentiles provide perspective on how the selected block group or buffer area compares to the entire state, EPA region, or nation.

    You can also check What’s in My Neighborhood to find out about other cleanups in your area.


    Map showing site location as King County, WA SITE INFORMATION


    View Electronic Documents

    Site Summary Report

    Facility Site ID: # 2522

    Cleanup Site ID: 2446

    Seattle, King County

    Status: Cleanup Started   Get definitions of Status terminology

    Dean Yasuda
    Site Manager

    Thea Levkovitz
    Public Involvement Coordinator