image:filtered light in the forest

Toxics Cleanup Program

Lower Duwamish Waterway
Source Control Investigation

Slip 3 to Seattle Boiler Works
River Mile (RM) 2.0-2.3 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..

Slip 3 Source Control Area is located on the eastern side of the LDW Superfund Site.  It is located between river miles 2.0 and 2.1 as measured from the southern end of Harbor Island.  The map shows industrial facilities within the drainage basin that discharge into Slip 3 that Ecology identified as facilities of concern.  These properties include: Big John’s Truck Repair, Inc.; Fox Avenue Building; Northland Services, Inc.; Shultz Distributing, Inc.; and V. Van Dyke, Inc.

In addition, there is a combined sewer basin/storm drain (CSO/SD) owned by the city of Seattle located within this area.  The Brighton Street CSO/SD system discharges stormwater and untreated sewage during periods of heavy rainfall when the sewer system is overwhelmed with water.

The upland areas next to Slip 3 have been industrialized for decades. 


Sediments in the Slip 3 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: benzyl alcohol and arsenic. 

Fox Avenue Building LLC Site

This site is located at 7900 Fox Avenue, in Seattle, Washington on the east bank of the Lower Duwamish Waterway.  The site boundaries are defined by the extent of the contamination at and migrating from the Fox Avenue Building property.  Currently there are chlorinated solvents in the groundwater.  This plume is thought to extend beyond the Fox Avenue Building property boundaries.

Ecology and the currently property owner are entering into an Agreed Order to perform interim actions to control the discharge of the plume on the Lower Duwamish Waterway.  More information related to controlling sources from this site are in the Source Control Action Plan for this source control area (see link below).

Click here for more information on the Fox Avenue Building LLC site.

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 3 drainage basin to determine what sources need to be controlled (see map).  The routes for contaminants to Slip 3 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 developed a Source Control Action Plan for Slip 3.  This plan describes what source control actions are necessary to prevent recontamination .  As part of the Source Control Action Plan, Ecology hired a contractor to put together a Summary of Existing Information and Data Gaps report.