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City of Seattle
Ed Murray, Mayor

SUBJECT: Major Duwamish Waterway hotspot cleanup effort begins this week

10/6/2011  11:00:00 AM
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Major Duwamish Waterway hotspot cleanup effort begins this week
Slip 4 work is “a serious shot of adrenaline” for Duwamish River cleanup

SEATTLE — The decade-long effort to clean up the Lower Duwamish Waterway takes a major step forward this week as the City of Seattle begins work on one of the hotspots on the Superfund mega-site.

The cleanup of Slip 4, about three miles upstream from Harbor Island, near the Georgetown community, comes as the U.S. Environmental Protection Agency considers how to clean up the rest of the five-mile portion of the river. EPA’s cleanup plan is expected to be issued next year.

Lower Duwamish Waterway early cleanup areas. Source: U.S. Environmental Protection Agency  One of five major lower Duwamish hotspots, which collectively account for about half the chemical contamination on the river, Slip 4 is a 6.4-acre navigational slip on the east bank of the waterway, about 1400 feet long and 200 feet wide.

“The Lower Duwamish is the heart of our thriving industrial corridor,” said Seattle Mayor Mike McGinn. “It provides 80,000 jobs a year with an annual economic output of $13.5 billion — we want it to keep on thriving.”

McGinn said the effort to clean up the river will begin to restore a part of Seattle that needs help to once again provide healthy habitat for fish, birds, and people.

“The salmon that swim in the Duwamish are symbolic and important, but there is much more in the  Lower Duwamish Waterway that  also matters — bottom fish, shellfish, animals, and most importantly the people who live, work, fish, and recreate there.  We owe it to them, and especially our tribal partners, to clean up Slip 4’s legacy of contamination,” McGinn said.

“This is just the beginning of the river cleanup, but a very important step,” said Duwamish River Cleanup Coalition Coordinator James Rasmussen. The DRCC is an alliance of community, environmental and small business groups affected by ongoing pollution and cleanup plans for the Duwamish River.

“Cleaning up Slip 4 will eliminate some of the greatest environmental and health risks to the river, its fish and its neighboring communities,” Rasmussen said.

“Tackling Slip 4 gives the Duwamish River cleanup a serious shot of adrenaline,” said Dennis McLerran, U.S. Environmental Protection Agency regional administrator. “Today, we mark major progress not only on the Duwamish, but in protecting Puget Sound downstream. The City of Seattle and The Boeing Company deserve a lot of credit for cleaning up a serious problem in the heart of the City.”

“We invest in our future with every step we take in this cleanup process,” said Washington state Ecology Director Ted Sturdevant. “Through this cleanup — and related work to guard against re-contamination here — we advance our commitment to protect the quality of life for local residents. This investment to restore and preserve this important resource will pay returns right away and for future generations.”

Working with its partners — The Boeing Company, the Port of Seattle, and King County — Seattle is making cleanup progress on Slip 4 and the other hot spots in advance of the main Superfund process which will address cleanup of the entire river.

A pier and berthing area for industrial vessels at Slip 4 have been used over the years, and storm drains and emergency sewer overflows historically were routed into the slip. The slip is full of debris — logs, piling, bulkheads, and other derelict material. About 3.5 acres of the slip’s sediment is contaminated with polychlorinated biphenyls or PCBs, along with some metals, organic compounds, and petroleum products.

Controlling ongoing pollution sources to Slip 4 has been an important part of planning the cleanup. Source control actions led by Ecology and EPA have been completed at a number of properties and other efforts will continue to ensure that the cleanup of Slip 4 is not re-contaminated.

An important part of the cleanup is restoring habitat for fish and wildlife; this cleanup will add habitat in shallow water and the intertidal area. New aquatic habitat on the banks will also be created. The cleanup will include a net gain of over an acre of shallow and riparian habitat for threatened Puget Sound Chinook and Coastal/Puget Sound bull trout.

The City purchased the land in the cleanup area so the land use could be converted from industrial vessel berthing to habitat; and in-water cleanup work is only allowed between October and mid-February to protect migrating juvenile salmon.

A combination of proven technologies is being used to clean the sediments while improving habitat. The project includes stringent requirements for best management practices and monitoring of water quality. About 800 tons of debris will be removed from the slip. The most contaminated sediments will be removed from the slip bottom, and the banks will be excavated back to create stable slopes and expand habitat.

The removed sediments and soils will be drained and shipped by barge and rail, for disposal in a permitted landfill. Engineered multi-layer caps of clean sand, gravel, and rock will then be placed to cover the sediments and banks. The old concrete pier on the northwest bank will be demolished to improve habitat. Both land-based excavators and floating equipment will be used for the cleanup work.

Total costs for Slip 4 cleanup are about $8 million. The project is expected to be completed in early 2012.

View detailed information on Slip 4

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