NORTH BONNEVILLE — In 1969, Bonneville Dam workers disposed of three old electrical capacitors by simply shoving them into the Columbia River.
Now, almost four decades later, the Army Corps of Engineers finds itself in the midst of a complex, expensive and time-consuming cleanup of a potentially cancer-causing compound. The latest aspect of the cleanup began earlier this month, with divers armed with a 4-inch suction pipe removing PCB-tainted sediment inch by meticulous inch.
Huang &Associates Inc. of Elk Grove, Calif., landed the $1.9 million contract and began work earlier this month. The corps expects it will take another month to finish removing sediment from hot spots of polychlorinated biphenyls covering a little less than an acre of river bottom.
The shoreline is adjacent to a landfill operated between 1942 and 1982.
Corps officials maintain the landfill was mainly used for household garbage generated by corps employees who lived at the dam, but they said some higher-level waste from operating the dam apparently found its way into the landfill. In 1999, workers surveying the shoreline for groundwater seepage spotted three electrical capacitors poking out of the river.
Each capacitor contained between 10 and 12 gallons of oil heavily laden with PCBs, said Mark Dasso, cleanup manager for the Army Corps of Engineers.
“The only way it could have gotten in the river is if it was purposefully put there,” Dasso said.
The corps pulled the junk out of the river shortly afterward, and now they’re carefully scooping PCB-tainted mud out of the river bottom.
Bubbles cut the smooth surface of the water, and Darth Vaderlike breathing could be heard over a public address system linked to each diver working 3½-hour shifts. The muddy water is piped into a treatment system that removes PCBs using several filters.
Ultimately, the filtered water is discharged back into the river.
The corps will conduct a long-term risk assessment at Bradford Island, looking for potential ways that the pollutant could affect fish and the people who eat them.
Health authorities have already discovered crayfish in the mud with enough PCBs in their tissue to be disposed of as hazardous waste. Rather than wait to develop the longer-term cleanup strategy, Col. Thomas O’Donovan, the Portland, Ore., district commander, pressed for the corps to get the hot spots out of the river quickly.
During a visit to Vancouver earlier this year, O’Donovan expressed his sense of personal responsibility for reversing the damage that his agency caused. The corps has so far spent $7 million on the cleanup, and Dasso expects it will cost $15 million by the time it’s finished.
“We did it. We dropped the PCBs,” O’Donovan said. “So we — me — have a personal responsibility to clean that up.”
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