PITTSFIELD -- Work on one of the most visible PCB cleanups in the city since the first two miles of the Housatonic River is set to begin next week.
General Electric Co.’s contractor, Sevenson Environmental Services, will begin staging Silver Lake next week for a two-year remediation project to deal with PCB, or polychlorinated biphenyl, contamination released from the company’s former 250-acre Morningside plant.
The majority of the work this year will center on excavation of contaminated soil and sediment along the banks of the 26-acre water body. Roughly 12,500 cubic yards of sediment and soil will be removed from the banks of the lake, of which 1,600 cubic yards are highly contaminated with PCBs.
This will require the removal of trees and other vegetation around the lake and temporary drawdowns of the water. And while there will be two major staging areas at the northeast and southwest corners of the lake, access will be required through all adjacent properties.
The project will require periodic closures of Silver Lake Boulevard by August and possible, yet less frequent, lane closure on East Street.
Next year, a barge will placed in the lake to install a 14-inch cap of sand kept in place by stone armoring along the shoreline. The cap will include 0.5 percent organic carbon to sequester future inflow of PCBs.
"This one is going to be very visible," said Dean Tagiafarro of the EPA.
There are plans to replace much of the vegetation with native species of trees and shrubs, and picnic tables and a walking path will also be installed as well. All removed contaminants will be taken to an out-of-state landfill.
PCBs are probable cancer-causing chemicals used by GE in its transformer manufacturing until 1977, the same year most uses were banned by the federal government.
A variety of monitoring techniques will be used during work, including dust and water quality monitoring. Work will be stopped if PCB concentration in the air and nearby waterways becomes elevated above prescribed benchmarks.
GE expects the project to be finished by the fall of 2013, though EPA officials acknowledge that with the fits and starts leading to this point, it may not be completed until 2014.
The eventual goal is to make the lake fishable and swimmable, though advisories against such activities will remain in place until future testing shows the remedy has worked.
Some local environmental groups have been highly critical of the plan for Silver Lake. They say capping doesn’t go far enough to remove the long-term threat of PCBs, which have been found at depths more than five feet below the lake bottom.
David Dickerson, EPA’s project manager for the site, said capping is one of the fundamental remedy techniques for sediment contamination, and dredging isn’t always the best answer because of residual effects from resuspension.
"Each situation has to be judged on its own merits," said Dickerson. "There’s no magic remedy for sediments that’ll successfully clean any particular water body."
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