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Toxics Cleanup Program

Lower Duwamish Waterway
Source Control Investigation

Spokane St to Ash Grove Cement
River Mile (RM) 0.0-0.1 East

Site Background
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The map shows the River Mile 0.0-0.1 East (Spokane St to Ash Grove Cement) source control area. Unlike other source control areas on the LDW, River Mile 0.0-0.1 East includes two different upland areas that are separated by a narrow stretch of the waterway itself.  The Harbor Marina Corporate Center is located on Harbor Island which lies in the middle of the LDW channel.  The Port of Seattle Terminal 104 and the Ash Grove Cement facility are both located on the east bank of the LDW.

Three facilities of concern are identified for inclusion in this source control area: Harbor Marina Corporate Center, Port of Seattle Terminal 104, and Ash Grove Cement. These facilities have confirmed or suspected contamination of various upland media, or conduct activities that threaten LDW sediments.


Sediments in the portion of the LDW adjacent to the RM 0.0-0.1 East source control area 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
Lead Dibenz(a,h)anthracene
Arsenic Phthalates (butyl benzyl phthalate)
Tin Poly Aromatic Hydrocarbons
Zinc Semivolatile Organic Compounds (SVOCs)

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 source control area drainage basin to determine what sources need to be controlled (see map).  The routes for contaminants to LDW sediments in this source control area 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 RM 0.0-0.9 East (Spokane St to Ash Grove Cement) which describes what source control actions are necessary.  As part of the Source Control Action Plan, Ecology hired a contractor to develop a Summary of Existing Information and Data Gaps report.