Lower Duwamish Waterway
Source Control Investigation
Slip 3 to Seattle Boiler Works
River Mile (RM) 2.0-2.3 East
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
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
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.
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.