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Toxics Cleanup Program

Lower Duwamish Waterway
Source Control Investigation

KC Lease Parcels
River Mile (RM) 1.0-1.2 East

Site Background Please click on map for larger view.

The KC Lease Parcels Source Control Area is located along the eastern side of the Lower Duwamish Waterway (LDW) Superfund Site between 1.0-1.2 miles from the southern end of Harbor Island.  The aerial photograph shows the area of interest which is bordered on the east by East Marginal Way South.  King County owns the property adjacent to the Lower Duwamish Waterway within this source control area and leases it to several facilities.  From north to south, these facilities are:

  • Manson Construction Company (Manson Construction),
  • Cadman Seattle Inc. (Cadman) and Lehigh Northwest,
  • United Western Supply (UWS), and
  • J.A. Jack & Sons (J.A. Jack).

The upland areas in this source control area have been heavily industrialized for decades.  Historical and current commercial and industrial operations in the area of the KC Lease Parcels include cement and limestone production facilities, boiler shops and construction services.  Seattle Boiler Works and I.F. Laucks (a paint and glue factory) historically operated in the KC Lease Parcels area.  


Sediments in the KC Lease Parcels portion of the LDW have been impacted by chemical contaminants from various sources. Before reaching the LDW sediments the contaminants first affected upland media including surface water, groundwater, soil, and air.

The following chemicals are considered to be contaminants of concern in the KC Lease Parcels source control area because they could possibly recontaminate Lower Duwamish Waterway sediments once it has been cleaned up.

Metals Organics
Mercury PCBs (polychlorinated biphenyls)
  Polynuclear Aromatic Hydrocarbons (PAHs)
  Bis (2ethylhexyl) phthalate 

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 as much as possible releases of pollution to the river.  Ecology looks at the drainage for the King County Lease Parcels source control area in order to determine what source control work needs to be done.  The KC Lease Parcels drainage basin outlines the area where sources need to be controlled (see picture).  The way contaminants enter Lower Duwamish Waterway sediments from 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.  This plan describes the source control actions that are necessary to prevent sediment 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.

Related Information

Additional Resources