One cleanup shapes another

Lessons learned from the partial cleanup of one of the Willamette River's most toxic spots are being applied to planning for work on a heavily contaminated site nearby.

This week, the U.S. Environmental Protection Agency unveiled its blueprint for designing cleanup of Arkema Inc. The 54 acres in North Portland, home for decades to the chemical manufacturer and its predecessors, are steeped in DDT, rocket propellant, hydrochloric acid, ammonia and other pollutants.

The EPA, frustrated by a lack of progress by Arkema and its agents, took over planning an initial cleanup last fall as part of a Superfund action spanning six miles of the river. The resulting work plan made public this week doesn't dictate precisely how Arkema should proceed, but does signal that the agency will take a harder line to prevent river contamination during cleanup.

In 2005, during dredging of a tar body by Northwest Natural Gas Co., highly toxic levels of benzo(a)pyrene were released into the river. The chemical can quickly kill aquatic life and cause cancer in humans.

NW Natural's use of a dredge bucket stirred up the chemicals, which escaped into the river through an experimental silt curtain. Delays in lab results from water testing allowed the danger to go unnoticed for days.

The Arkema work plan suggests a harder look at more expensive dredging alternatives such as a hydraulic dredge, which cuts into the riverbed and pumps sediment through a pipe.

Sean Sheldrake, an EPA project manager, said Arkema also will need to consider installing an expensive and rigid system of steel sheets in the river -- a coffer dam -- to better contain dredged chemicals.

"Given the high levels of DDT at the Arkema site, all of those options are going to be on the table, and the bias is going to be heavily toward higher levels of containment," Sheldrake said.

more from the Oregonian