Favorable river conditions have allowed General Electric Co. contractors to exceed their PCB dredging goal by more than 115,000 cubic yards so far this year on the upper Hudson River, a company official said Thursday.
The federal Environmental Protection Agency set a goal of 350,000 cubic yards of PCB-contaminated river-bottom sediment to be dredged between May and November this year.
The tainted dredge material is loaded onto barges and taken through Champlain Canal Lock 7 to a large treatment and dewatering complex in Fort Edward. Then it is loaded onto railroad cars and transported to hazardous waste landfills in Ohio, Michigan and Oklahoma.
As of this week a total of 466,000 cubic yards of sediment have been dredged along an area about two miles south of Fort Edward between Saratoga and Washington counties, said Tim Kruppenbacher, a GE Hudson River project manager. There is still a month of dredging left this year, he said.
“We were able to get started early in May,” he said at a meeting of the EPA’s Community Advisory Group in the Fort Edward firehouse.
Hudson River water volume was much lower than normal most of the summer, making dredging easier in some locations but more difficult in others, he said.
The EPA in 2002 ordered GE to conduct and pay for what is described as the largest environmental dredging project in the country. The company is spending at least $850 million on the multiyear project to remove polychlorinated biphenyls, a probable carcinogen, from the Hudson River between Fort Edward and the Federal Dam in Troy.
GE capacitor plants in Hudson Falls and Fort Edward discharged PCBs into the Hudson for 30 years, ending in 1977 when the practice was forbidden by the government.
Kruppenbacher said the river was so low a good portion of the summer that dredging in the Three Sisters Island portion of the river became difficult.
“This is a very shallow area,” he said. Contractors had to use a backhoe to gain water access into areas to be dredged.
“It’s been a long haul back there,” Kruppenbacher said.
In 2009, the first year of dredging, problems with the resuspension of PCBs into the river water were an issue, with the entire project being shut down at least four times because PCB levels exceeded drinking water standards and project guidelines.
There was no dredging in 2010 while the entire operation was reviewed and management techniques improved.
Resuspension has not been a major problem in 2011 and 2012.
The level of PCBs resuspended in the water never exceeded guidelines at the Waterford test station and no five-out-of-seven-day PCB resuspensions were recorded at the Schuylerville test station, according to GE officials.
Kruppenbacher said there were four times when single-day water levels exceeded 500 parts per trillion PCBs (the federal water standard) at the Schuylerville test station in August and September.
Air testing in the dredge areas this season showed “occasional” readings above the residential air standards for PCBs. The dredging in the shallow Three Sisters Island was an area where air levels of PCBs exceeded standards on occasion, the GE official said.
Manna Jo Greene, a community advisory group member and environmental director for Hudson River Sloop Clearwater, asked if the dredge teams found anything unexpected in the depth of PCB contamination, like they did in 2009.
Kruppenbacher said there were some surprises, especially in areas where debris covered the river bottom.
The dredge management plan calls for two swipes of the dredge in highly contaminated areas.
“We were getting a good hit on the first pass,” he said. Much less contamination was found in the second pass of the dredge than in past years, possibly because GE did extensive river bottom core sampling over the past two years to determine the depth and extent of contamination.
The river dredging will end in November when the state Canal Corporation closes the system for the winter.
Dredging will resume in May. Another five or six years of seasonal dredging will be done as the work progresses downriver toward Troy.