EPA ID# WA0002329803
EPA Region 10

09 Congressional District

Other Names:
Last Update: April, 2010

Hide details for Site DescriptionSite Description

Sediments in the Lower Duwamish Waterway are contaminated with polychlorinated biphenyls (PCBs), polynuclear aromatic hydrocarbons (PAHs), phthalates, and inorganics. To address the long-term threat these contaminants pose to the human food chain and sensitive river environments, the site was added to EPA's National Priorities or "Superfund" List on September 13, 2001. The Lower Duwamish Waterway Superfund site is located south of Elliot Bay, near downtown Seattle, Washington. The waterway is maintained by the U.S. Army Corps of Engineers as a federal navigation channel. Most of the shoreline along the Duwamish Waterway is industrialized or developed for commercial purposes; however, the residential community of South Park also abuts the shoreline. In addition, over 200 storm drains, combined sewer overflows, and other outfalls discharge to this reach of the river. Historical or current commercial and industrial operations on the waterway include cargo handling and storage; marine construction; boat manufacturing; marina operations; paper and metals fabrication; food processing; and airplane parts manufacturing. Contaminants may have entered the river via spills during product shipping and handling, direct disposal or discharge, contaminated groundwater discharge, surface water runoff, storm water discharge, or contaminated soil erosion.

Site Responsibility: This site is being addressed through an administrative order on consent with potentially responsible parties.

NPL Listing HistoryDates
Proposed Date:12/01/2000
Removed Date:
Withdrawal Date:
Final Date:09/13/2001
Deleted Date:

Hide details for Threats and ContaminantsThreats and Contaminants

Media Affected: sediments
A number of investigations within the Duwamish Waterway prior to EPA's NPL listing have documented sediment contamination with PCBs, PAHs, phthalates, and inorganics. In 1997, the natural resource trustees for the Duwamish River collected 328 sediment samples to evaluate the extent and severity of PCB and polychlorinated terphenyl contamination in the sediments of the waterway. Concentrations of PCBs at many sample points in the middle portion of the waterway were 10 to 100 times the Washington State Sediment Management standards. The report also concluded that the quantity and concentrations of PCBs found in Duwamish Waterway sediments could potentially injure natural resources.

In 1997, King County's Department of Natural Resources performed a combined sewer overflow water quality assessment for the Duwamish River and Elliott Bay to better understand the risk to aquatic life, wildlife, and people who use the resources of the estuary. King County concluded that there is clear evidence that conditions in the estuary pose potential risks to aquatic life, wildlife, and people. There are nine City of Seattle or King County combined sewer overflows in the Lower Duwamish Waterway. Seven of these outfalls discharge 318 million gallons of untreated sewage annually.

In October 1997, The Boeing Company took samples in the waterway to generate information that could be used as a first step in evaluating potential chemical releases to the Duwamish Waterway attributable exclusively to Boeing. A total of 88 surface (0 to 10 centimeters) sediment samples were collected from locations adjacent to Boeing facilities. Sample results indicated the presence of PCBs, mercury, and semivolatile organic compound contamination of surface sediment throughout this waterway segment.

In August and September 1998, consultants for EPA conducted site inspection sampling in the Lower Duwamish Waterway. Sampling included the collection of 312 surface (0 to 10 centimeters) sediment samples and 35 subsurface sediment samples from the waterway. Surface sediment sample results documented polynuclear aromatic hydrocarbon, phthalate, PCB, and inorganic, contamination in both surface and subsurface sediments.

The Lower Duwamish Waterway is fished for recreational, commercial, and subsistence purposes. Three salmon hatcheries within the Green-Duwamish River system release approximately 10 million juvenile salmon each year. The Duwamish River is part of the traditional fishing grounds for the Muckleshoot and Suquamish Indian tribes.

For several species of Pacific salmon, the Lower Duwamish River serves as a nursery, migratory route, and transition zone from freshwater to saltwater. Puget Sound Chinook salmon, federally listed as a threatened species, use the Lower Duwamish Waterway during a critical stage of their migration from a freshwater to a saltwater environment. The federal candidate species Coho salmon also occurs in this area, as does a nesting territory for ospreys and bald eagles, and a wetland. The National Marine Fisheries Service has conducted numerous studies on the effects of contaminated sediments on biotic resources in the Duwamish River and elsewhere in Puget Sound. This research has shown that juvenile salmon from the river have reduced growth and immune system function relative to salmon from uncontaminated areas.

Hide details for Cleanup ProgressCleanup Progress

On December 20, 2000, EPA and the Washington State Department of Ecology signed an agreement called an administrative order on consent with four parties to investigate the nature and extent of chemical contamination in Lower Duwamish Waterway sediments. The four parties are the City of Seattle, King County, the Port of Seattle, and The Boeing Company. Under the agreement, the parties are collecting information, evaluating potential risks to human health and the environment, and recommending areas that warrant early cleanup action. The four parties will prepare a final investigation report and an evaluation of options for long-term cleanup.

The first phase of the investigation was completed in 2003. In this phase, the parties compiled data from past studies of the waterway and prepared a Phase 1 Remedial Investigation Report. This report includes a preliminary assessment of human health and ecological risks based on existing data. Phase 2 of the investigation was completed in 2009. It includes collection of fish, shellfish, and benthic invertebrate tissue samples, as well as sediment samples and toxicity tests. These new data have been used to revise the human health and ecological risk assessments. The risk assessments were completed in 2007 after being reviewed by the agencies and stakeholders, including members of the public and the Muckleshoot and Suquamish Indian Tribes. The risk assessments were revised to address reviewers' comments. The risk assessments concluded that contaminants pose a risk to people who would consume large amounts of resident fish and shellfish, and that contaminants in sediments are harming resident fish, worms and clams living in river sediments as well as other animals such river otters which eat the resident fish. EPA and Ecology will use the risk assessments tor determine what long-term cleanup action is needed in the river. The Washington Department of Health has issued and posted fish advisories in a variety of languages along the river warning people not to eat resident fish and shellfish. EPA is currently reviewing a draft Remedial Investigation and Feasibility Study submitted by the City of Seattle, King County, the Port of Seattle, and The Boeing Company. A second draft of the Feasibility Study is expected in fall 2010.

Phase 1 also included identification of candidate areas for early cleanup actions. Partial cleanups have been completed at two of these areas under a Natural Resource Damage Assessment consent decree. Other cleanups are taking place or are planned under the oversight of EPA's Resource Conservation and Recovery Act program, including the Boeing Plant 2, Jorgensen Forge, and Rhone-Poulenc sites. Two additional early cleanup actions, Terminal 117 and Slip 4, are being pursued under EPA Superfund oversight.

The Terminal 117/Malarkey Asphalt Early Action Area has been studied by the Port of Seattle and City of Seattle with EPA oversight. In July 2005, EPA selected a cleanup option that involved removal of PCB-contaminated sediments and replacement with clean fill. Following this decision, high concentrations of PCBs in soils were discovered in the upland area. EPA completed a time-critical removal action in October 2006 to remove isolated areas of high PCB contamination. EPA, Washington State Department of Ecology, the City of Seattle and the Port of Seattle have tested a large number of soil samples from streets and yards adjacent to Terminal 117. The City and the Port tested soil from streets and yards for PCBs in 2008 and 2009. The City and Ecology also tested some of these soil samples for dioxins/furans in 2009. In 2009, additional soil samples were collected from streets and yards in the area of South Cloverdale Street, South Donovan Street and 16th Avenue South. These samples were analyzed for PCBs and dioxin/furans. PCB concentrations were found from 0 to 8.1 parts per million (ppm). Dioxin/furan concentrations were found from 1.81 to 395 parts per trillion (ppt). The City saved a portion of the samples they collected from the streets and yards along South Cloverdale Avenue, 16th Avenue South and South Donovan Street, for future dioxin/furan testing if needed. Based on the PCB contamination here, EPA has delineated a Removal Study Area for the streets and yards between Dallas Avenue South and South Donovan Street and T-117 and 14th Avenue South. EPA expects to issue a draft Engineering Evaluation and Cost Analysis for public comment in June 2010. Once a removal plan is completed, cleanup could begin as early as 2012.

The Slip 4 Early Action Area has been studied by the City of Seattle and King County with EPA oversight. Sediments are contaminated primarily with PCBs. Cleanup options were presented to EPA in December 2005, with public comment on the selected cleanup option occurring in early 2006. In May 2006, EPA selected the remedy -- a combination of removing contaminated sediments and placing clean sand and gravel over remaining contamination. Project design documents were approved in February 2007. Cleanup was scheduled to occur in fall 2007, but was delayed due to uncertainties on whether sources of PCB contamination to Slip 4 had been adequately controlled. In August 2008, Ecology entered into an Agreed Order (under the state Model Toxics Control Act) for a comprehensive RI/FS on the North Boeing Field, while The Boeing Company, King County Airport and the City of Seattle continue to investigate, clean, and sample storm drains across and around the airfield. In 2009, the City of Seattle replaced the Georgetown Steam Plant flume, which discharges to Slip 4, and signed an Agreed Order with Ecology with Crowley Marine Services for development of a Remedial Investigation and Feasibility Study of their parcels. Sediment cleanup is currently scheduled to begin in 2011.

EPA and Ecology are also working to ensure that upland sources of contamination are adequately addressed prior to sediment cleanup. In 2001, the two agencies signed a memorandum of agreement, which describes how EPA will manage and lead remedial investigation of waterway sediments, while Ecology will manage and lead source control efforts to protect sediment quality. The agreement requires Ecology to develop a strategic approach for controlling sources of sediment contamination. In January 2004, Ecology issued the Final Source Control Strategy for the Lower Duwamish Waterway. It describes the process of source control, the roles of various regulators responsible for providing source control, and the methods Ecology uses to track and document the progress of source control. The physical extent of the source area for this Superfund sediment site is approximately 32 square miles. There are all types of urban land use, including interstate highways and airports, which reflect much of Seattle’s industrial and commercial history.

Based on interviews with community members, EPA and Ecology prepared a community involvement plan for the site and a Hispanic community involvement supplement. EPA awarded a technical assistance grant to a member of the community advisory group (CAG) for the site, and a subsequent grant to a subgroup of the CAG. The grants have helped the group review information about the site and share it with community members. Draft documents are being shared with the Citizens Advisory Group (Duwamish River Cleanup Coalition), the Muckleshoot and Suquamish Tribes, Natural Resource Damages Trustees, and other interested members of the public as part of EPA's commitment of early public involvement.

Hide details for Regional ContactsRegional Contacts

SITE MANAGER(S):Allison Hiltner (site investigation)
E-MAIL ADDRESS:hiltner.allison@epa.gov
PHONE NUMBER:206-553-2140

Piper Peterson Lee (Terminal 117 early action)

Karen Keeley (Slip 4 early action)
E-MAIL ADDRESSdagseth.renee@epa.gov, skadowski.suzanne@epa.gov
PHONE NUMBER:206-553-1889, 206-553-6689
Information pertaining to this site is housed at the following location(s):
South Park Branch, Seattle Public Library
8604 Eighth Ave. S., at S. Cloverdale St.
Seattle, WA 98108

EPA Region 10 Records Center
1200 Sixth Ave., Suite 900
Seattle, WA 98101

Washington Department of Ecology
3190 160th Ave. SE
Bellevue, WA 98008