Sediment Management Program

King County's Wastewater Treatment Division is carrying out a Sediment Management Plan developed in the late 1990s to remediate sediment contamination near county outfalls for combined sewer overflows, or CSOs, in Seattle. Those areas are contaminated with variety heavy metals (lead, copper, zinc), phthalates, polychlorinated biphenyls (PCBs), and hydrocarbons. Correcting those identified errors of the past will cost the county $26 million to $36 million.

During the past 20 years, industrial discharges, stormwater discharges, and CSOs to Elliott Bay and the Duwamish River were reduced substantially. Despite that achievement, however, historical, persistent chemical contaminants in sediment continue to pose a risk to aquatic life, wildlife and human health.

Areas with contaminated sediment exist near some CSOs now operated by King County. Most of that contamination is historical--from the first half of the 20th century. Since the 1960s, the county's Industrial Waste Program and CSO Control Program have dramatically reduced pollutants from CSOs.

Sediment remediations projects

To deal with sediment issues, King County is collaborating with other agencies and organizations to clean up the following contaminated sites in Elliott Bay and Duwamish Waterway:

• Norfolk CSO Sediment Remediation Project
• Duwamish/Diagonal Sediment Remediation Project
• Denny Way CSO Sediment Remediation Project
• King Street CSO Sediment Remediation Project
• Lander/Hanford CSO Sediment Remediation Project
• Brandon CSO Sediment Remediation Project

View the program library for available documents on these projects.

News releases

• Nov. 20, 2007 -- Contaminated Elliott Bay sediment clean-up begins
• Sept. 6, 2007 (WSDOE) -- Cleanup planned for contaminated area on Elliott Bay
• Dec. 15, 2004 -- King County planning follow-up sediment cleanup in lower Duwamish River
• Nov. 10, 2003 -- Contaminated sediment cleanup begins in Duwamish River
• Sept. 10, 2003 -- Cleanup of contaminated sediment to begin in Lower Duwamish

For more information

• Please contact Doug Marsano by e-mail or at 206-684-1235.
• Read the history of local sediment clean up and view documents available on the program library.

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For questions about the Wastewater Treatment Division Web site, please send an e-mail message. For general information about the division, contact us at:

Department of Natural Resources and Parks
Wastewater Treatment Division
201 S. Jackson St., Suite 505
Seattle, WA 98104-3855
Phone: 206-684-1280
Fax: 206-684-1741
Telecommunication device for the deaf (TTY): 711

Updated: Jan. 25, 2008
 

Related Information:

Lower Duwamish Waterway Programs

WA State Dept. of Ecology Sediment Management Unit

Elliott Bay/Duwamish River Restoration Program

US Army Corps of Engineers Center for Contaminated Sediments

Regional Wastewater Services Plan