Early actions moving cleanup forward

Several sites in the Lower Duwamish Waterway (LDW) have been cleaned up. These early action area (EAA) cleanups are designed to leave clean surfaces that will protect the river environment (i.e., small animals, shellfish, crabs and fish) and reduce health risks to people. In total, EAA cleanups addressed approximately 29 acres, and reduced the site-wide average Polychlorinated biphenyl (PCB) contamination in the waterway sediment by about one-half, a significant step forward in the cleanup of the LDW.

Boeing Plant 2

In 1936, Boeing purchased 28 acres along the Lower Duwamish as an assembly site for its new B-17 Flying Fortress bomber to accommodate the federal government’s growing need for military aircraft. By the end of World War II, Plant 2, also known as Air Force Plant 17, had expanded to almost 1.7 million square feet and produced nearly 7,000 B-17s. In December 2011, the Plant 2 facility was demolished to clear the way for Boeing’s cleanup and habitat restoration efforts along the Lower Duwamish Waterway. Boeing recycled or reused over 85 percent of the building materials, including steel and wood beams, copper wiring and concrete.

In-water work - In 2013, Boeing began excavating sediment that contains Polychlorinated biphenyls (PCBs) and other chemicals from the waterway. In 2015, Boeing completed its work to dredge and remove a total of 165,000 cubic yards of contaminated sediments in the waterway next to the Plant 2 site. In addition to removing contamination, Boeing transformed nearly one mile of mile of former industrial waterfront into an award-winning new habitat areas. Boeing continues to monitor the quality of the mud, or sediment, at the site.

Upland - Boeing has completed the majority of interim soil cleanups and installed stormwater treatment systems to control contaminants from entering the waterway. EPA will provide public notice and an opportunity to comment on a proposed Final Cleanup Plan, known as a Statement of Basis, for the upland area of the site in 2018.

Additional early action efforts conducted by Boeing include: the remediation of sediment hot spots, the removal of nearly a mile of joint caulk compound (caulk) containing PCBs at North Boeing Field, the cleanup or replacement of storm drains to reduce metals and PCBs in stormwater, and the treatment of solvent-contaminated groundwater.

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Jorgensen forge

The 22-acre Jorgensen Forge facility is located south (upstream) of Boeing Plant 2. In 2007, Ecology and the Jorgensen Forge Corporation (the current owner of Jorgensen Forge) negotiated an agreed order to conduct a source control investigation at the facility. Underground storage tank removals and some upland soil investigations have occurred (Ecology 2007). Also, in 2003, EPA issued an Administrative Order on Consent (AOC) to the Earle M. Jorgensen Company (a former owner of Jorgensen Forge) for investigation and preparation of an Engineering Evaluation/Cost Analysis (EE/CA) for a non-time-critical removal action for sediments and associated shoreline bank soils. The EE/CA was completed in 2011, and an Administrative Settlement Agreement and Order on Consent (Settlement Agreement) was issued in late 2012 for the sediment and bank removal action.

Some of the PCB-contaminated sediments and river bank dirt were removed in 2014. However, samples collected after the excavation found that some sediments were still contaminated. EPA is requiring EMJ to evaluate additional cleanup work to address this sediment contamination. This evaluation will be described in a Supplemental Engineering Evaluation and Cost Analysis, which will evaluate ways to clean up the remaining PCB contamination.

Terminal 117

Terminal 117 is located on the west bank of the LDW in South Park. Beginning in the late 1930s, this site was used for asphalt materials manufacturing, which left behind considerable soil and adjacent sediment contamination. The cleanup work was a joint cleanup project by the Port of Seattle and City of Seattle. From 2012 to 2015, they replaced soil and sediment and updated the storm drainage system. Final site modifications, including permanent stormwater controls and regrading the Dallas and Donovan streets, were completed in 2017. The Port is developing habitat restoration plans.

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Duwamish/Diagonal Site

The Duwamish/Diagonal Site is located on the east side of the LDW, one-half mile south of Harbor Island. It was identified as a priority cleanup area by the Elliott Bay/Duwamish Restoration Program (EBDRP) because of sediment contamination associated with the Duwamish/Diagonal combined sewer overflow (CSO)/storm drain outfalls. In 2003, King County dredged 66,000 cubic yards of contaminated sediments to an average depth of 5 feet near 4 storm drain and CSO pipes. The project isolated any remaining contaminated sediment from the environment by capping the area with clean sand. The cap surface was also designed to provide beneficial foraging habitat for salmon. In 2005, a thin layer of sand was placed around a portion of the dredged area as a follow-up, reducing the concentrations of contaminants stirred up from earlier dredging.

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Norfolk Area

This site is on the east side of the LDW, just offshore of the Norfolk CSO/storm drain outfall. It was identified as a priority cleanup area in 1992 by the Elliott Bay/Duwamish Restoration Program (EBDRP) because of sediment contamination associated with the Norfolk CSO/storm drain discharge. In 1999, King County excavated 5,190 cubic yards of contaminated sediment as deep as 9 feet in portions of the site, and then backfilled the excavations with 6,700 cubic yards of clean material. In 2003, The Boeing Company (Boeing) excavated contaminated sediment from a small area immediately offshore of a Boeing Developmental Center storm drain outfall, and then backfilled that area with clean sand to reduce the potential for PCBs recontamination of the Norfolk CSO/storm drain cap. Subsequent monitoring of surface sediment on both caps showed that PCB concentrations remained relatively low.

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Slip 4

Located about three miles upstream from Harbor Island, near the Georgetown community, Slip 4 is a 6.4-acre navigational slip on the east side of the waterway. The City of Seattle worked with The Boeing Company and King County to control sources to Slip 4 and clean up the sediments.

For many years, nearby industries used the slip as a berthing area for vessels and for various industrial activities. Storm drains and emergency sewer overflows were also historically routed into the water. The slip was full of debris, including logs, pilings, bulkheads and other derelict material. As a result, about 3.5 acres of the slip's sediments were contaminated with Polychlorinated biphenyls (PCBs), along with some metals, organic compounds, and petroleum products.

The first step in cleaning Slip 4 was controlling the ongoing pollution sources. Actions led by the Washington State Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA) have been completed at a number of sites along the slip, and other efforts will continue to ensure that Slip 4 is not recontaminated. These efforts include:

  • In 2009, the City of Seattle demolished and removed the wooden sections of the existing Georgetown Steam Plant flume structure, plugged all existing input connections from adjacent properties, removed contaminated sediment from within the flume and contaminated soil adjacent to the flume, and constructed a new drainage system and outfall to Slip 4.
  • In 2011, Boeing and the City of Seattle jointly completed cleanup of contaminated soils on the Georgetown Steam Plant property and the northern portion of the adjoining North Boeing Field (NBF). Approximately 10,000 cubic yards of contaminated soil were removed from this area.
  • Boeing has conducted numerous source control actions at North Boeing Field, including: the removal of PCB-containing joint compounds, the abatement of PCB-containing paint, the cleanout of storm drain systems, and the replacement of storm drain lines.
  • During 2010, Boeing installed a temporary stormwater treatment system at the north end of North Boeing Field. A permanent stormwater treatment system was subsequently installed to treat runoff from the North Boeing Field and a portion of the King County International Airport (KCIA). Approximately 66 million gallons of stormwater were treated in the first four months of operation of the final stormwater treatment system. This system treated approximately 176 million gallons of stormwater in its first year of operation.
  • Ecology and Boeing continue to sample and test stormwater and storm drain sediments to monitor the effectiveness of source control actions at North Boeing Field.
  • KCIA performs source tracing, catch basin cleaning, and line cleaning within its Slip 4 stormwater drainage basin. Oil-water separators within this basin are cleaned as part of ongoing maintenance.

With the source control complete and continued monitoring in place, the City of Seattle, partnered with King County, purchased the cleanup area within the slip to convert it to wildlife and fish habitat.

A combination of proven technologies was used to remediate the sediments and improve the habitat. The most contaminated sediments – approximately 14,000 tons – were removed from the slip bottom, and the banks were excavated. To permanently isolate the remaining contamination, the remaining sediments and banks were covered with an engineered cap of clean sand, gravel, and rock. The old concrete pier on the northwest bank was also removed, resulting in an additional 0.44 acres of unshaded habitat, which is preferred by juvenile salmonids. The sediment cleanup and removal project took place between October 2011 and February 2012. Construction was completed ahead of schedule and under budget.

The cleanup includes a net gain of more than an acre of shallow intertidal and riparian habitat for threatened Puget Sound Chinook and Coastal/Puget Sound bull trout, as well as habitat on the banks of the slip for wildlife. The City of Seattle improved the habitat by planting native plants along the slip shorelines. The City continues to monitor the quality of the sediment at Slip 4.

Slip 4 Status Updates:

Slip 4
Slip 4
Slip 4
Before Remediation
Slip 4
After Remediation
Boeing Plant 2
Boeing Plant 2 and Bridge from Above
Boeing Plant 2
Boeing Plant 2 - Sediment and Bridge Looking North
Boeing Plant 2
Boeing Plant 2 - Sediment and Bridge Looking South
Boeing Plant 2
Boeing Plant 2 - View from Southpark

Terminal 117