Alcoa Will Dredge Columbia River for Toxic Sediments

The agreement will be finalized when the cleanup action plan, being developed this winter, is complete.

The agreement calls for Alcoa to dredge up to 95 percent of known polychlorinated biphenyls, PCBs, that are contaminating the river bed at its former aluminum smelter site near Vancouver, Washington.

When the dredging is finished and the ecosystem has had time to restore itself, the residual contamination should not exceed 98 parts per billion (ppb) PCBs.

The Columbia River near Vancouver, Washington (Photo courtesy USGS)

The state agency and Alcoa agree that dredging is the best option for reducing the level of contamination. The cleanup goal represents the residual level of contamination that will remain after dredging is complete, sand is brought in to fill holes and the site returns to equilibrium.

"This will be a very aggressive cleanup to remove as much contamination as physically possible," said Carol Kraege, whose Ecology team oversees the Alcoa site. "Unfortunately, the Columbia River is besieged with contamination from many sources. This cleanup is just one of many important steps in the long-term efforts to restore the river's health."

Alcoa started operating a primary aluminum smelter in 1940 on a site of several hundred acres adjacent to the Columbia River in Vancouver. About 56,000 tons of waste potlinings containing cyanide, fluoride, and heavy metals were piled on bare ground on the site during 1973-80.

PCBs can cause a variety of health effects and have been linked to cancer. The dredging will lessen the risk to human health and will be protective of wildlife.

High levels of PCBs were found in clam tissue collected around the Alcoa property and throughout the river. Alcoa recently announced its intention to dig and dispose of all clams on its site as soon as feasible.

While harvesting freshwater clams in the Columbia is illegal, some have expressed concern that people may ignore the prohibition and dig for clams.

The Alcoa Vancouver site is located in Clark County on the north bank of the Columbia River three miles northwest of downtown Vancouver. Alcoa constructed an aluminum smelter on the western portion of the site in 1940.

Between 1944 and 1970, a number of fabrication operations were added to the facility to form aluminum into finished goods such as wire, rod, and extrusions. Alcoa operated the entire facility for 45 years, until its closure in 1985.

To date, Alcoa has spent approximately $42 million on cleanup at the Vancouver site, including $34 million on cleanup of PCBs.

Alcoa will complete the remedial investigation and a feasibility study report for the entire site by the end of December. In early January, Alcoa is expected to submit the sediment cleanup engineering plans for Ecology review and approval. Ecology will also begin work on a cleanup action plan for the site, including the sediments. The public will have an opportunity to comment on the cleanup action plan when the draft is published in early spring.

Copyright Environment News Service (ENS) 2007. All rights reserved.