Corps Releases Report on Pollution at Dam
by Erik Robinson
The Columbian, January 21, 2011
The Army Corps of Engineers has released a voluminous investigation of contamination at an old landfill that had been leaching pollution into the Columbia River from Bonneville Dam.
The corps is soliciting public comment, then will formulate long-term cleanup plan.
The landfill, at the upriver tip of Bradford Island, had been used for household waste as well as project-related debris between 1942 and 1982.
Materials dumped in the landfill include household garbage, petroleum products such as oil and grease from dam turbines, paint, solvents, insulators, mercury vapor lamps, sealed buckets of grease, blast grit, scrap metal, switch gear and cables.
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 polychlorinated biphenyls, or PCBs.
Subsequent testing of fish tissue revealed extremely high levels of pollution, to the point that public health officials warn fishermen to avoid consuming smallmouth bass caught in the pool above the dam. Crayfish in the area carried even greater levels of PCBs -- up to 75,600 parts per billion, compared to "safe" levels of 5 ppb. Not only would it be an extremely bad idea to eat crayfish in the area, a PCB level that high qualifies as hazardous waste.
The corps removed items from the river in 2000 and 2002. Then, in 2007, the corps hired a contractor for $1.9 million to send down divers who meticulously vacuumed PCB-laden soil from an area of river bottom a little smaller than an acre.
"Testing of crayfish in 2008 revealed PCB levels several orders of magnitude lower than 2002 and 2007, corps spokesman Scott Clemans said Thursday.
The new report concludes that the remaining contaminants on land and in the water exceed risk-screening levels. It proposes a feasibility study to identify remedial actions that would reduce contamination in the water.
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