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EPA releases cleanup plan for lower Duwamish Superfund site
The U.S. Environmental Protection Agency released a proposed plan to clean up the Lower Duwamish Waterway Superfund Site, Seattle's chief industrial waterway located on the south end of Elliott Bay. The release of the sediment cleanup plan marks the beginning of a public comment period.
“The Duwamish is Seattle’s river. This plan is the product of our close coordination among the governments and businesses responsible for cleanup, and the communities and tribes who use the river for their food and livelihood,” said Dennis McLerran, Regional Administrator for EPA Region 10. “This cleanup will ensure that the Duwamish will be healthier and safer for the people and communities who rely on it, while also keeping the river open for business.”
The proposed plan calls for cleanup of the most contaminated sediment and would reduce PCB contamination in the Duwamish River by at least 90 percent in conjunction with cleanups already underway at early action sites. The plan also includes an environmental justice analysis that examines the impacts of contamination on minority and low-income populations around the Superfund site. In addition, the plan has a source control strategy to minimize the release of pollutants that could re-contaminate waterway sediments.
EPA manages the cleanup of contaminated sediment and the Washington State Department of Ecology oversees pollution source control under a 2002 agreement to share management of the five-mile site.
“Source control targets pollutants both past and present, and represents a continuing commitment to protect against re-contamination of Duwamish sediments after the EPA cleanup,” said Jim Pendowski, Ecology’s toxics cleanup program manager. “It takes broad involvement – including public agencies, businesses, and local residents – to sustain this effort. We’re all responsible for the health of the Duwamish.”
Industry, storm drains, and combined sewer overflows have polluted the Lower Duwamish Waterway surface water and sediments over the past 100 years. Over 40 hazardous substances were found in sediments at concentrations that pose a risk to people and marine life. Resident Duwamish fish and shellfish, which are consumed by local communities, accumulate contaminants that are harmful to human health.
The primary contaminants of concern are PCBs, dioxins, arsenic and carcinogenic polycyclic aromatic hydrocarbons. EPA used scientific studies completed by the City of Seattle, King County, the Port of Seattle and Boeing to determine the extent of contamination and evaluate cleanup options. These parties recognized the need for cleanup measures and stepped up to do the work in areas of the river that contained the most contamination. The early action areas for cleanup are Slip 4, Terminal 117, Boeing Plant 2, Jorgensen Forge, Duwamish Diagonal and the Norfolk combined sewer overflow.
The proposed cleanup would address 156 acres of contaminated sediments through dredging, capping or enhanced natural recovery, including removal of nearly 800,000 cubic yards of contaminated sediments from the waterway. Enhanced natural recovery refers to the application of a thin layer of clean sand that would reduce contaminant levels more quickly than natural recovery, where natural sedimentation from the river creates a cleaner surface over time. An additional 256 acres with lower levels of contamination would benefit from monitored natural recovery.
Since 2002, Ecology, the City of Seattle and King County have worked to investigate and reduce pollution sources in the waterway’s 32-square-mile drainage area with a series of targeted initiatives:
- Conducted 3,100 inspections at over 1,300 businesses
- Performed 421 combined hazardous waste and water quality inspections under the state’s Urban Waters Initiative
- Collected over 800 samples to track and identify sources
- Cleaned over 30,000 feet of storm drain lines
Ecology has overseen cleanups or investigations at 22 contaminated industrial sites along or near the Duwamish under the state’s cleanup law. EPA has managed the federal cleanup process at eight sites. Ecology’s proposed source control strategy will carry these efforts into the future, including monitoring to track the strategy’s effectiveness.
The proposed cleanup would take approximately seven years to implement, with an additional ten years to reduce contaminant concentrations to the lowest predicted concentrations through natural recovery. The estimated cost of the proposed cleanup is $305 million.
The release of the proposed plan marks the beginning of a 105-day public comment period. The public can submit comments through the EPA website and at three public meetings scheduled for April and May.
For more information on the proposed cleanup plan for the Lower Duwamish Waterway Superfund Site or to submit comments online, visit: