Early cleanup of Seattle's only river moving ahead

SEATTLE — Ten years after the U.S. Environmental Protection Agency listed the lower five miles of Seattle's only river as a Superfund site, cleanup work on some of the most toxic sections of the Duwamish River is moving forward.

On Monday, the city of Seattle will begin dredging and removing over 10,000 cubic yards of sediment in a navigational slip that is contaminated with polychlorinated biphenyls, or PCBs. The $8 million project at Slip 4 is part of a larger, decades-long effort to reduce toxic waste from a century of heavy industrial use along the waterway.

Slip 4 is one of several identified as the worst areas requiring accelerated cleanup. Another is Boeing's Plant 2, the factory that turned out B-17 bombers and was home to "Rosie the Riveter," women who built thousands of World War II planes. Earlier this month, Boeing tore down the last remaining steel structures at the plant to prepare for a large cleanup and habitat restoration project. Dredging and soil cleanup is expected to begin in 2012.

"We're at a point now where in the next several years, there's going to be a lot of progress," said David Schuchardt, the city of Seattle's Duwamish program manager. "It's very visible."

About $66 million being spent on these hotspots will reduce contamination by half, EPA officials say. The EPA is overseeing early cleanup work, which will take place over the next few years. Two sites were completed in the early 2000s.

Meanwhile, the EPA is considering options for the larger, long-term cleanup of the rest of the Duwamish that could take anywhere from four years to four decades, and cost from $220 million to $1.3 billion. The EPA will release its cleanup plan in March. A decision is expected in 2013.

The options include dredging to remove the sediment, capping it with rock and sand, or letting sediment from upriver naturally bury the toxic material, though it's likely going to be a combination of options depending on the site, said Allison Hiltner, EPA's manager for the Duwamish cleanup. Each option could potentially reduce contamination by 90 percent.

The Duwamish, once a meandering river before it was straightened and deepened into a navigation channel, runs through Seattle's industrial core and two residential neighborhoods before emptying into Elliott Bay. Decades of industrial use left behind pollution that's mixed into the mud at the river bottom and banks. Pollutants include long-lasting PCBs, dioxins, cancer-causing polycyclic aromatic hydrocarbons (PAHs) and arsenic.