image:filtered light in the forest

Toxics Cleanup Program

Lower Duwamish Waterway
Source Control Investigation

Seattle Boiler Works to Slip 4
River Mile 2.3-2.8 East

Site Background Please click on map above, then click on the small gold square in the bottom right hand corner to view a larger size..

The river mile (RM) 2.3-2.8 East Source Control Area is on the eastern side of the Lower Duwamish Waterway (LDW) Superfund Site between 2.3 and 2.8 miles from the southern end of Harbor Island.

The upland areas next to this portion of the waterway have been industrialized for decades.  Historical and current operations in the vicinity of RM 2.3-2.8 East include food products manufacturing and distribution, metal products fabrication and recycling, cargo handling and storage, chemical repackaging and distribution, coffee roasting, heavy equipment storage, and truck interior manufacturing.

The map shows the facilities located within this source control area.


Sediments in this portion of the LDW have been contaminated by various sources and chemicals.

The following chemicals are considered to be contaminants of concern at RM 2.3-2.8 East with regard to potential sediment recontamination:

  • Mercury
  • PCBs (polychlorinated biphenyls)
  • PAHs (polynuclear aromatic hydrocarbons)
  • Dioxins/furans
  • Organo-tin compounds

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 this sub-drainage basin to determine what sources need to be controlled (see map).  The routes for contaminants to the Lower Duwamish 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 waterway.

Source Control Action Plan

Ecology developed a Source Control Action Plan for RM 2.3-2.8 East (Seattle Boiler Works to Slip 4) which describes 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.

Cleanup Sites in RM 2.3-2.8 East Seattle Boiler Works to Slip 4