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


Updated October 2019

Contaminated groundwater is not impacting the Indoor air quality at the 5005 3rd Avenue South Building.

Ecology reviewed air quality samples taken in January and August 2019 from inside a building located at 5005 3rd Ave. South Seattle, WA 98108 to determine if there are unsafe levels of contaminants in the air. None of the samples indicated that the air inside the building was unsafe. You can view the sampling work plan and indoor air sample data to see the location and results of the indoor air sampling.

Solvent spills and leaks of Trichloroethylene (TCE) contaminated soil and gas nearby on the 220 Dawson St. property. We required GE to sample in the 5005 3rd Ave. building because it is close to the location where the contamination occurred.

TCE is a human-made, colorless liquid solvent used to remove grease from metal parts. When TCE is underground in soil or groundwater, it can vaporize and contaminate the air space between grains of soil. This “soil gas” can pollute the indoor air by moving through cracks in building foundations and openings used for utility lines.

We will continue to monitor groundwater and soil but do not anticipate more indoor air sampling in this building unless:

  • There is an increase in TCE or other volatile contaminants 

  • OR if we discover that vapors could get into the building via previously unknown vapor intrusion pathways

  • OR as a result of building renovations.

We sample indoor air to ensure that people are not exposed to TCE

According to the Environmental Protection Agency, potential health effects from breathing TCE depend on levels in indoor air, length of exposure, and whether and when a person is exposed. TCE has the potential to increase the risk of heart malformations in the developing fetus. Women in the first 8 weeks of pregnancy, before some may even be aware they are pregnant, are most sensitive to TCE exposure.

Breathing TCE over a long period of time may affect individuals’ immune system and increase susceptibility to infections. Long-term exposure may also increase the risk of cancers of the kidney, liver, and non-Hodgkin’s’ lymphoma. For more information about the potential health effects from TCE see the DRAFT “Important Information about Trichloroethylene (TCE) in Residential Indoor Air.”

Contingent Groundwater Treatment Injections at the 220 S. Dawson Street Property

GE has tried three different methods to cleanup Trichloroethylene (TCE) and other contamination in the groundwater under the property. Most recently in 2019, GE injected zero valent iron particles mixed with organic plant material (eZVI) into the contaminated groundwater. This treatment has been slow to work in some areas and is not yet working in other areas.

We will continue to review the monitoring results and are considering other cleanup methods. One method we might consider is injecting emulsified vegetable oil to increase the population of naturally-occurring bacteria in the groundwater to break down the contaminant. (This is called in-situ bioremediation.) . If a new method is needed, we will hold a public comment period. GE still plans to use eZVI injections to clean up contaminated groundwater that has moved off the property.


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.

2019: Ecology approved and GE injected a mixture of zero-valent iron and organic plant material (also known as eZVI) into groundwater. Sampling during February, May and August showed that the eZVI broke down some TCE at the west end of the injection area. It did not work near the east end of the injection area.

2019: GE collected indoor air samples and samples below the building. All air samples taken at four locations were below the short-term acute indoor air toxicity levels that would require action.

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

Cleanup Site Details Report

Facility Site ID: # 2522

Cleanup Site ID: 2446

Seattle, King County

Status: Cleanup Started   Get definitions of Status terminology

Paul Bianco
Site Manager
(425) 649-7253

Janelle Anderson
Public Involvement Coordinator
(425) 649-7286