Nov. 20, 2007
Contaminated Elliott Bay sediment clean-up begins
King County is cleaning up Elliott Bay and improving habitat for
fish and wildlife by removing an estimated 4,000 dump truck loads of
contaminated material from the bottom.
Beginning Nov. 27, dredging barges working just offshore Myrtle Edwards
Park in Seattle will start to remove contamination from combined sewer
overflows (CSO) and restore habitat in local water bodies. Dredged
material will be disposed in an approved landfill.
The contaminated sediment accumulated over decades from stormwater and
sewage overflows discharged through an outfall pipe known as the Denny
Way CSO, at 3165 Alaskan Way.
variety of chemicals and metals washed out and collected in adjacent
sediments. The old outfall pipe has since been removed, and sewage and
stormwater overflows are now controlled by a $139 million King County
project that was completed in 2005.
stems from an agreement with the Washington State Department of Ecology
to remove sediments that do not meet state sediment quality limits.
20,000 cubic yards of material contaminated with PCBs and mercury will
be removed from the nearshore area. Future projects are also expected
farther offshore to remove a smaller amount of contamination.
County's contractor, American Civil Constructors, is using a mechanical
dredge on a barge to excavate the area and load a second barge with
contaminated sediment. The second barge will transfer the sediment to
trucks and trains for transport to a landfill.
excavated area will be backfilled with clean sand and gravel to match
the seabed's existing grade and improve the site as shallow-water
nearshore habitat for fish and wildlife.
County project managers will oversee contractor operations to ensure
careful dredging methods are used to limit sediment disturbances. King
County inspectors will regularly monitor water quality around the work
area to verify that the environment is protected. American Civil
Constructors' crew has years of experience in removing contaminated
County worked closely with the Department of Ecology, the Muckleshoot
Tribe, NOAA Fisheries and other agencies in planning the project.
Stakeholders also weighed in on best management practices, cleanup
methods and restoration.
Work is expected to last approximately 10 weeks at a cost of $3.6 million.
The project will require some minor construction staging near the King
County facilities and plaza in Myrtle Edwards Park. Although park users
are not expected to be significantly impacted by the cleanup, community
members can call the project's 24-hour construction hotline at
206-205-9305 to share comments or inquires about the project.
People enjoy clean water and a healthy environment because of King
County's wastewater treatment program. The county's Wastewater
Treatment Division protects public health and water quality by serving
17 cities, 17 local sewer districts and more than 1.4 million residents
in King, Snohomish and Pierce counties. Formerly called Metro, the
regional clean-water agency now operated by King County has been
preventing water pollution for more than 40 years.