Source: Jim Gordon Clearwater News & Bulletins
The completion of a PCB dredging project along Lake Champlain in Plattsburgh, NY, has demonstrated that PCBs can be safely dredged from the Hudson River. Along the Lake Champlain shoreline waterfront homes were undisturbed, swimming beaches and motels stayed open during the three-year process, and former skeptics of dredging are now praising the operation.
'I was not in favor of it initially. I was concerned about stirring stuff up. It did not make a lot of sense to me,' said Dr. Djell Dahlen, an eye surgeon whose expensive home is immediately adjacent to the 34-acre beachfront site on Cumberland Bay. 'But as an immediate neighbor, it has not bothered me a tiny bit.'
'Ducks sat on the dredge while the dredge was running,' said Bill Ebert, site supervisor for project engineer Earth Tech Inc. The site is near city and state beaches, as well as motels. 'The beaches stayed open. The motels were open. Everything went on normally,' he said. The dredging operation continued 24 hours a day, but received no complaints, Ebert said. 'Sometimes people on their patios in the motel would wave at you.'
The PCB cleanup in Lake Champlain encompassed many of the same challenges a dredging operation in the Hudson would entail, yet was completed on time, under budget, with no stirring up of contaminants. The operation removed 25,000 pounds of pure PCBs, reducing on-site contamination by more than 90 percent, while earning praise from neighbors.
That success would be easy to duplicate on the Hudson River, according to the project engineers who oversaw the dredging in Plattsburgh. 'The technology is there to do it right, you just have to set it up and control it,' said Lech Dolata, an engineer with the state Department of Environmental Conservation. 'The bottom line is, dredging works.'
Dolata showed a simple yet effective dredging method for removing PCB-laden sludge. A notably small dredge vessel, about 20 feet long, is positioned using global positioning satellite (GPS) links directly along the desired line, and the operation proceeds in grids using cables draped along the desired course to move the dredge. The operation is so smooth, wildlife and neighbors barely notice.
Beneath the surface, an eight-foot-wide roto-tiller-like device breaks up the sediment and forces it inward, where a vacuum pipe sucks it into a covered container onshore. Silk curtains and other barriers under water keep any turbidity enclosed, but in Plattsburgh there was little stirring up of solids in any case.
Georgia Pacific Corporation operates an intake valve within fifty feet of one dredging site, and required water clarity with no more than 2 parts per billion of suspended particles. Ebert said dredge operators tested constantly, but always kept within the tight requirements, and the valve was able to remain open throughout the dredging process.
Once ashore the sediment was dewatered to reduce its weight and tested for toxicity. Hazardous sediment from Plattsburgh was sent to Buffalo for burning, while less-contaminated sediment was trucked to a landfill in Quebec. The water was treated and returned to Lake Champlain. Tests showed that it was clean enough to rank as drinking water.
General Electric, the company responsible for the PCB contamination that makes the Hudson a federal Superfund site, claims dredging would disrupt the river ecosystem and dry up the local economy. GE is currently spending millions of dollars a week on television ads depicting huge mud-dripping clamshell dredges. But according to EPA and DEC officials, clamshells are navigational, not environmental dredges, and are not under consideration for cleaning the poison GE dumped in the river. Under federal law, the multinational giant is responsible for removing the toxin, a cost GE does not want to pay.
While General Electric dumped one million pounds or more of PCBs into the river, it is not all in one place, but spread over about 40 'hotspots' in the river between Glens Falls and Albany. The toxin migrates from those areas, getting into the food chain, the water column, mud along the shore, and the air. Dredging equipment would be scaled to the size requirements of each hot spot. The equipment for dewatering sediment and cleansing the water can be trucked in and out of sites where it is needed, duplicating the technique used in Plattsburgh. No permanent treatment facilities would be required.
The USEPA is poised to announce a decision regarding its remedies for the PCBs contamination that has turned the Hudson River into America's largest non-government toxic waste site.
The Cumberland Bay in Plattsburgh within Lake Champlain was a state Class Two Superfund site, posing imminent danger to human health and the environment. PCB concentrations averaged 2000 parts per million. 50 ppm concentration is officially deemed hazardous. The PCB cleanup on Lake Champlain reduced concentrations to an average of 10 ppm.
The site encompassed some eight acres of wetlands and 50 acres of underwater lake bottom, where PCBs had accumulated. As the work finishes and equipment is removed, Plattsburgh is deciding whether the site will be a boat ramp, or perhaps a park. Dr. Dahlen, who has gone pleasure boating with workers from the dredging operation, laughingly said he preferred a park to a boat ramp, but added either was preferable to a hazardous waste site.
Reprinted from Clearwater News & Bulletins Web Site