Environmental dredging resumed Tuesday on the upper Hudson River after the levels of PCBs resuspended in river water dropped to acceptable levels on two consecutive days.
The Environmental Protection Agency had stopped the large-scale dredging project on Friday after water samples taken at the Thompson Island Dam, which is about six miles below Fort Edward, spiked beyond 500 parts per trillion PCBs for two days in a row.
The EPA uses the federal drinking water standard of 500 parts per trillion PCBs as the upper cutoff level for resuspension during dredging.
General Electric Co. contractors are conducting the estimated $780 million dredge project on the upper Hudson between Fort Edward and Troy. The first phase of the project, which started May 15, is being done at the upper end of the river between Washington and Saratoga counties.
The restart of dredging will be gradual, according to an EPA statement.
On Tuesday, dredging was confined to three river locations, one of which is inside a sheet metal enclosure.
Water sample results over the weekend indicated that PCB resuspension in the water had dropped from above 500 parts per trillion to 206 ppt and to 111 ppt between Sunday and Monday morning, according to the EPA statement.
“Dredging will be re-started in stages over the course of the week,” read a statement from General Electric Co.
“This will enable EPA and GE to closely monitor river conditions and assess the impact of individual dredging operations on PCB levels in the water,” the GE statement says.
Last week, before dredging was stopped, 11 dredges were working on the upper Hudson in areas around Rogers Island in Fort Edward and near Griffin Island, which is halfway between Fort Edward and Schuylerville.
The first phase of dredging has been stopped several times because of unusually high and fast river water flows caused by heavy rains in the Adirondacks. The first phase of the project will be completed this fall.
The EPA ordered GE to pay for and conduct the environmental cleanup project in 2002. GE plants in Hudson Falls and Fort Edward discharged an estimated 1.3 million pounds of PCBs (polychlorinated biphenyls, a probable carcinogen) into the Hudson for 30 years, ending in 1977 when the practice was banned.
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