Item 7a Memo

PORT OF SEATTLE 
MEMORANDUM 
COMMISSION AGENDA  POLICY AND STAFF BRIEFING 

Item No.        7a 
Date of Meeting    May 5, 2009 
DATE:    March 20, 2009 
TO:      Tay Yoshitani, Chief Executive Officer 
FROM:    Stephanie Jones Stebbins, Senior Manager Seaport Environmental Programs 
Kathy Bahnick, Environmental Program Supervisor, Seaport Environmental
Programs 
SUBJECT:  Briefing on the Lower Duwamish Waterway Feasibility Study 
The purpose of this briefing is to present an update on the Lower Duwamish Waterway (LDW)
Feasibility Study (FS) being performed by the Lower Duwamish Waterway Group (LDWG).
The LDWG consist of the Port of Seattle, City of Seattle, King County and the Boeing
Company. The regulatory oversight for this study is being performed by the United States
Environmental Protection Agency (EPA) and the Washington State Department of Ecology
(Ecology). This briefing will include a brief site background and history, a status and schedule
of the study, and information on the draft cleanup alternatives that were developed as part of the
study. 
BACKGROUND 
In 2000, the City of Seattle, King County, the Port of Seattle, and The Boeing Company,
working collectively as the LDWG, signed an Agreed Order on Consent to conduct a Remedial
Investigation and Feasibility Study for the LDW with oversight by the US Environmental
Protection Agency (EPA) and the Washington State Department of Ecology (Ecology). The
LDW sediment site stretches from the south end of Harbor Island to the Norfolk CSO area just 
south of Turning Basin 3. This section of river was straightened and widened by the Army
Corps of Engineers in 1911 to create an industrial river for navigation. In September 2001, the
LDW was formally listed as a Superfund site, and in February 2002, the LDW was formally
listed as a Washington Model Toxics Control Act (MTCA) site. The draft RI was submitted to
EPA and Ecology on November 5, 2007, and a revised draft addressing EPA, Ecology and
stakeholder comments is due to the agencies in July 2009 and is expected to be finalized by
September 2009. The RI describes what is known about the LDW including the history of the
LDW; the environmental setting, habitat, and uses; the deposition and transport of sediment
within the LDW; the distribution of contamination in the LDW, including concentrations of
chemicals in sediment, water, and tissues; and information regarding potential historical and
ongoing sources of chemicals to LDW as well as the source control and identification strategy.

COMMISSION AGENDA 
T. Yoshitani, Chief Executive Officer 
March 20, 2009 
Page 2 of 2 

The draft Feasibility Study which has been worked on concurrent with the RI, is scheduled for
submittal to the agencies on April 24th. The FS will evaluate multiple alternatives for cleanup of
the LDW and will evaluate those alternatives for their effectiveness at meeting the risk
objectives. These documents will allow EPA and Ecology to make final cleanup decisions for
the LDW.

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