Parties to Plan for Persistent PCBs in Duwamish Waterway Inlet

The city of Seattle, King County, and the Boeing Co. have signed an agreement with the Washington Department of Ecology to investigate and propose solutions for soil, stormwater, and groundwater contamination in the North Boeing Field/Georgetown Steam Plant area of south Seattle.

A public review and comment period on the agreement runs through Sept. 26. The state agency will host a public meeting on the proposed site investigation on Sept. 18 at the South Seattle Community College Duwamish Campus. Representatives of the state, the city, the county, Boeing, and the U.S. Environmental Protection Agency will be available to answer questions.

The effort will pave the way for a cleanup of contaminated sediment at the bottom of Slip 4, a nearby inlet of the Duwamish Waterway. A cleanup in the 137-acre North Boeing Field/Georgetown Steam Plant area will help prevent re-contamination of the inlet. Polychlorinated biphenyls (PCBs) and other pollutants have been found in storm drains that empty to Slip 4 from city, county, and Boeing property in the study area.

The Department of Ecology will conduct an investigation and work with the three property owners, who will pay the estimated $2.5 million cost of the study and analysis. The area to be studied includes northern portions of King County International Airport (Boeing Field), property owned by King County, and leased by Boeing to the west, and the city-owned Georgetown Steam Plant site to the north.

The three parties have conducted several clean-up and storm-drain improvement projects over the past 25 years, all aimed at cleaning up soil and groundwater contamination from past industrial activities. PCBs and other contaminants continue to appear in storm drain sediments.

"Before cleaning Slip 4, we must find how to prevent its re-contamination," said Jim Pendowski, who leads Ecology's toxic cleanup program. "The agreement by Seattle, King County and Boeing to undertake a single, unified investigation makes sense, given the area's complex contamination problems. This approach may serve as an effective model for other challenging parts of the Lower Duwamish."

An Agreed Order between Ecology and the city, county, and Boeing can be viewed at

A five-mile reach of the river -- upstream of Harbor Island -- is the federal Lower Duwamish Superfund cleanup site, jointly administered by EPA and Ecology. Slip 4 is part of that larger sediment cleanup effort. The Duwamish flows to Puget Sound.

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