PORT OF SEATTLE 
MEMORANDUM 
COMMISSION AGENDA  POLICY AND STAFF BRIEFING 
Item No.            7b 
Date of Meeting       October 12, 2010 

DATE:      September 23, 2010 
TO:       Port of Seattle Commissioners 
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 

BACKGROUND: 
The purpose of this briefing is to provide an update on the Lower Duwamish Waterway
(LDW) Feasibility Study (FS) being performed by the Lower Duwamish Waterway
Group (LDWG). The LDWG consists of the Port of Seattle, City of Seattle, King County
and the Boeing Company. A briefing of the first draft of the FS was presented to the
Commission on May 5, 2009.
The LDW is a sediment site that stretches from the south end of Harbor Island to the
Norfolk Combined Sewer Overflow 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
Federal Superfund site, and in February 2002, the LDW was formally listed as a
Washington Model Toxics Control Act (MTCA) site.
In 2000, the LDWG members signed a joint 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 draft RI was submitted to EPA and Ecology on November 5,
2007, and the RI was given final approval on July 7, 2010.  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 
Tay Yoshitani, Chief Executive Officer 
September 23, 2010 
Page 2 of 2 

The first draft of the Feasibility Study which has been worked on concurrently with the
RI was submitted to the regulatory agencies and the public on April 24, 2010. The draft
FS  evaluated  multiple alternatives for cleanup  of the LDW  and evaluated  those
alternatives  for  their  effectiveness  in  meeting  the  risk  objectives.  A  revised  draft
addressing EPA, Ecology and stakeholder comments is scheduled for submittal on
October 12, 2010. An EPA public meeting is schedul ed for December 12, 2010. The 
combined RI/FS  documents will enable EPA and Ecology to make final cleanup
decisions for the LDW. 
BRIEFING OUTLINE: 
This briefing will include a brief site background and history, a status and schedule of the
study, information on the draft cleanup alternatives that were developed as part of the
study and layout the EPA process moving forward. 
PREVIOUS COMMISSION ACTIONS OR BRIEFINGS: 
May 5, 2009  Briefing on the Draft Lower Duwamish Waterway Feasibility Study 
December 6, 2007  Briefing on the Draft Lower Duwamish Waterway Remedial
Investigation