Washington State Department of Ecology

Ecology home > Toxics Cleanup Program  >  Site Information   >  Lower Duwamish Waterway  >   Sites   >  Slip 6  RM 3.7-3.9 East

Lower Duwamish Waterway
Source Control Investigation

Slip 6  RM 3.9-4.4 East

Site Background

Please cllick on map above, then click on the small gold square in the bottom right hand corner to view a larger size..
The former Slip 6 Source Control Area is located along the eastern side of the LDW Superfund Site.  It sits 3.9 to 4.4 miles from the southern end of Harbor Island.  The map shows the areas of interest which include: the former Paccar site, the former Rhone-Poulenc site, the Museum of Flight, a portion of the Boeing Developmental Center, and a portion of the King County International Airport.
 
The upland areas next to Slip 6 have been heavily industrialized for decades.  Historical and current commercial and industrial operations in the area of Slip 6 include cargo handling and storage, auto storage lots, truck manufacturing, chemical processing, aviation operations, and airplane parts manufacturing.  The nearest residential area is about one-half mile to the southwest across the LDW.

Contamination

Sediments in the Slip 6 portion of the LDW have been contaminated by various sources and chemicals.  The contaminants first affected upland media including surface water, groundwater, soil, and air before reaching the LDW sediments.

The following chemicals are considered to be contaminants of concern with regard to potential sediment recontamination.
 

Metals Organics
Mercury PCBs
Copper Dibenz(a,h)anthracene
Lead Phthalates (butyl benzyl phthalate)
Tin Volatile Organic Compounds (VOCs)
Arsenic Semivolatile Organic Compounds (SVOCs)
Chromium Petroleum Hydrocarbons
Nickel  
Zinc  

Source Control

Ecology is the lead for source control for the LDW Superfund site.  Source control is the process of finding and then stopping or reducing releases of pollution to the river.  Ecology looks at the Slip 6 drainage basin to determine what sources need to be controlled (see map).  The routes for contaminants to Slip 6 sediments include: direct discharges via piped outfalls, bank erosion from adjacent properties, surface runoff from adjacent properties, groundwater discharge, air deposition, and spills directly to the inlet.

Source Control Action Plan

Ecology is in the process of developing a Source Control Action Plan for Slip 6.  This plan will describe what source control actions are necessary.  As part of the Source Control Action Plan, Ecology hired a contractor to put together a Summary of Existing Information and Data Gaps report.

Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.

Access Washington, Official State Government Web site Copyright © Washington State Department of Ecology
Contact Us | Privacy Notice | Site Info 		Information for Ecology staff