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Lower Duwamish Waterway Site Cleanup Agreement Signed

Release Date: 09/29/2006
Contact Information: Karen Keeley (206) 553-2141, Mark MacIntyre (206)-553-7302,

(Seattle, WA – September 29, 2006) – The U.S. Environmental Protection Agency signed an agreement with the City of Seattle and King County under which these two parties will clean up the approximately 3.6-acre Slip 4 Early Action Area on the Lower Duwamish Waterway. The slip, located on the east side of the waterway about 2.8 miles south of Harbor Island, is contaminated with polychlorinated biphenyls (PCBs).

According to Dan Opalski, EPA Superfund Office Director: “Today’s agreement is an important step forward in the cleanup of the Lower Duwamish Waterway. The Slip 4 cleanup will significantly reduce risks that the waterway poses to people and the environment. EPA appreciates the continuing cooperation by the City and the County.”

Following design work, the actual cleanup is planned to begin in October 2007.
The cleanup is estimated to cost about $7.4 million and will include this work:

  • Dredge approximately 4,300 cubic yards of contaminated sediment (mud). This generally includes material that has the highest PCB concentrations.
  • Excavate approximately 9,700 cubic yards of contaminated sediment and soil along the shore. This work will expand and improve fish habitat.
  • Capping the entire 3.6 acres to isolate contaminated sediment not removed.
  • Dispose of removed material in a landfill that meets state and federal requirements for disposal of such materials.
  • Remove an estimated 500 tons of asphalt, creosote-treated timbers and piles, and other debris within the cleanup area.

In addition, the agreement calls for the City and the County to initiate land use controls to protect the cap from damage, and monitor to ensure that the cleanup continues to protect people and the environment.
For more about the Lower Duwamish Waterway cleanup: