River Mile (RM) 0.9-1.0 East
The Slip 1 Source Control Area is located along the eastern side of the Lower
Duwamish Waterway (LDW) Superfund Site between 0.9 and 1.0 miles from the
southern end of Harbor Island. The map shows the area of interest which is
bordered on the east by East Marginal Way South. The facilities located
within this source control area are:
- U.S. General Services Administration (GSA)-Federal Center South (commonly known
as Federal Center South),
- Snopac Products, Inc., and
- Manson Construction Company
The upland areas near the Slip have been heavily industrialized for decades.
Historical and current commercial and industrial operations in the area of Slip
1 include automobile manufacturing, missile manufacturing, food products
manufacturing and distribution, and construction services.
Sediments in the Slip 1 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 at Slip
1 because they could possibly recontaminate sediment once it’s cleaned up.
||Polynuclear Aromatic Hydrocarbons (PAHs)
|Bis (2ethylhexyl) phthalate
||Semivolatile Organic Compounds
(SVOCs) (1,2,4-trichlorobenzene, benzoic acid, dibenzofuran)
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
Slip 1 in order to determine what work needs to be done for source control. The
Slip 1 drainage basin outlines the area where sources need to be controlled (see
map). The way contaminants enter Slip 1 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 1. 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