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Lower Duwamish Waterway
Source Control Investigation

North Boeing Field/Georgetown Steam Plant Site

Site Location

The North Boeing Field (NBF) and Georgetown Steam Plant (GTSP) are located at 7370 East E. Marginal Way S and 6700 13th Avenue S in Seattle, Washington.  They are on the East side of the Lower Duwamish Waterway.  The Sites are bordered to the Northwest by Ellis Avenue South, the Southwest by East Marginal Way South, and the East by King County International Airport.

Site Background

The GTSP was built by the Seattle Electric Company in 1906 to provide power during periods of high use. In 1912, Puget Sound Power and Light Company bought Seattle Electric Company. Use of the GTSP decreased after 1912. When built, the GTSP was next to the Duwamish River. When the river was straightened in 1916 to form the Duwamish Waterway, the GTSP flume was constructed to carry cooling water to Slip 4. A condenser pit under the powerhouse connects to an underground concrete tunnel that discharges into the GTSP flume (Flume). The Flume extends for about 0.4 miles into the head of Slip 4. Cooling water discharges ended in the 1960s when the GTSP was shut down. In 1951, the city of Seattle bought the GTSP and now owns the 7.29-acre property that contains the powerhouse and property next to the Flume. Seattle City Light will be demolishing the Flume and replacing it with a closed piping system in the summer of 2008.

Most of the 130-acre NBF property is leased by the Boeing Company from King County. The Boeing Company leases a few acres on either side of the Flume from the city of Seattle. The Boeing Company also owns a parcel that includes a NBF building and a lot next to it used for parking. The Boeing Company has operated at NBF since the 1940s; yet there are few historical records on site operations before the 1970s. Many buildings have been built and torn down over the years. This makes it hard to track operations in detail. Currently there are about 80 buildings on NBF. NBF has a complex storm drain system that includes over 400 catch basins, 400 manholes, up to 16 oil water separators and lift stations, parking lot ditches, and roof drains. The system connects with seven to eight miles of piping ranging from four to 48 inches in diameter. Stormwater from the Flume and NBF flows into Slip 4. Slip 4 is part of the Lower Duwamish Waterway (LDW) Superfund site.

Contamination

Contamination at the site is most likely the result of industrial operation and maintenance activities performed on this site since the 1940’s. The potential for sediment recontamination from site stormwater has delayed cleanup of sediments in Slip 4. Past studies have found pollutant concentrations above applicable cleanup standards.

• Polychlorinated biphenyls (PCBs).
• Total petroleum hydrocarbons (TPH).
• Polynuclear aromatic hydrocarbons (PAHs).
• Antimony, arsenic, cadmium, chromium, copper, lead, mercury, and zinc.

• Total petroleum hydrocarbons (TPH).
• Volatile and semi-volatile organic compounds (VOCs and SVOCs).
• Antimony, arsenic, chromium, and lead.

• Polychlorinated biphenyls (PCBs).
• Polynuclear aromatic hydrocarbons (PAHs).
• Semi-volatile organic compounds (SVOCs).
• Arsenic, copper, lead, mercury, and zinc.

• Polychlorinated biphenyls (PCBs).
• Semi-volatile organic compounds (SVOCs).

Agreed Order

Ecology, The Boeing Company, King County, and the city of Seattle are currently negotiating a legal agreement called an Agreed Order. This will address how to determine the nature and extent of contamination at the site and how to proceed with cleanup.

Related Information

• Slip 4 Early Action Area and GTSP Flume Removal Remedial Action
• More information on the Lower Duwamish Waterway
• Watershed Information for WRIA 9

Additional Resources

• Glossary and Acronyms used by the Toxic Cleanup Program
• Cleanup Process: Major Steps & Definitions
• Data Submittal Requirements for All Cleanup Sites
• Facility/Site Atlas
• Toxics Cleanup publications