LOWER DUWAMISH SITE WASHINGTON EPA ID# WA0002329803

EPA Region 10 King Seattle 09 Congressional District Other Names:

Last Update: November, 2009

Site 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 History	Dates
Proposed Date:	12/01/2000
Removed Date:
Withdrawal Date:
Final Date:	09/13/2001
Deleted Date:

Threats 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.


Cleanup 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 due to the contamination, and recommending areas that warrant early cleanup action. They will do any necessary additional sampling, and 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 additional 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 affected Native American Tribes. The risk assessments were revised to address feedback from reviewers. The conclusions of the risk assessments are that contaminants would pose a risk to humans consuming large amounts of resident fish and shellfish, and that contamiants in sediments are harming resident fish, worms and clams living in Duwamish sediments as well as other animals such river otters which eat the resident fish in the Waterway. EPA and Ecology will use the risk assessments as a basis for determining what long-term cleanup action is needed in the waterway. The Washington Department of Health has posted fish advisories in a variety of languages along the river warning people not to eat resident fish and shellfish.

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 in the design phase under the oversight of EPA's Resource Conservation and Recovery Act program. Two additional early cleanup actions, Terminal 117 and Slip 4, are being pursued under EPA Superfund oversight.

The Terminal 117 Early Action Area was studied by the Port of Seattle and City of Seattle in order to determine the extent of contamination requiring cleanup. 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 PCB contamination identified upon further investigation. It is anticipated that the remaining upland soils and the sediments will be cleaned up in 2010.

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. Additionally 2009, the City of Seattle replaced the Georgetown Steam Plant flume 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 bein 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 Mucleshoot and Suquamish Tribes, Natural Resource Damages Trustees, and other interested members of the public as part of EPA's commitment ot early public involvement.


Regional 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) peterson-lee.piper@epa.gov 206-553-4951 Karen Keeley (Slip 4 early action) keeley.karen@epa.gov 206-553-2141
COMMUNITY INVOLVEMENT COORDINATOR:	Renee Dagseth
E-MAIL ADDRESS	dagseth.renee@epa.gov
PHONE NUMBER:	206-553-1889

Information pertaining to this site is housed at the following location(s):
South Park Branch, Seattle Public Library
8604 Eighth Avenue South, at South Cloverdale Street
Seattle, WA 98108
206-615-1688

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

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