PCB Cleanup: How Dredging Is Performed

GE is dredging the Hudson River in Upstate New York to remove PCBs in one of the largest and most successful environmental cleanup projects ever undertaken in the United States.

Dredging activities began in 2009 and continued from 2011-2014. Click here to view a map of where dredging activities have been performed. The sixth and final season of the project is currently being performed. At the end of this year’s  season, more than 2.7 million cubic yards of sediment from a 40-mile stretch of river between Fort Edward and Troy, N.Y. will have been removed and 100% of the PCBs that the U.S. Environmental Protection Agency targeted will have been addressed.

In order to get the work done, GE’s crews work 24/7, six days a week. Water is squeezed out of the sediment and PCBs are removed from the water at a specialized processing and dewatering facility GE built for the project. The sediment is shipped by train to federally permitted disposal facilities outside of New York State.

GE selected Cashman Dredging & Marine Construction Corp. and Great Lakes Dredge and Dock Co., both leading national dredging contractors, to perform the dredging work. CB&I Environment operates the processing facility and Finger Lakes Railway operates the rail yard.

Dredging is being performed in the river approximately 200 miles north of New York City. Dredging is generally proceeding from north to south in the main stem of the Hudson. Three to four dredges operate simultaneously.

Dredged material is loaded onto hopper barges that, when filled, are pushed by tugboats to a processing, treatment and transportation facility located on the Champlain Canal one mile upstream from the Hudson River. The 110-acre property where the facility is located is situated between the Champlain Canal and an existing rail line.

aerial image of PCB Processing Facility in Fort Edward, NYLoaded barges are moored at one of two unloading stations at the facility’s 1,600-foot unloading wharf. Prior to the start of dredging in 2009, this area of the canal was widened by 65 feet to ensure non-project vessels would be able to travel past the area despite the moored barges.

Free water is pumped from the barges, then large debris, such as tree trunks and boulders, is removed. One of two land-based material handlers then lift the sediment from the barges, where it moves through size separation equipment, which separates finer sediment from debris, gravel and rocks.

From there, the remaining finer sediment passes through additional steps to remove pea gravel, sand and grit. The remaining fine sediment slurry is pumped into one of two gravity thickeners for further processing, then is sent to one of 12 specially manufactured filter presses housed inside a 41,000-square-foot sediment dewatering building. Filter plates inside the presses push together to squeeze water from the slurry. When the presses open, the resulting cake-like substance falls into large bins stationed under each press.

Once filled, the bins are transported by truck to one of two enclosed staging areas. Inside these 365-foot-long, 50-foot-high structures, the filter cake waits to be loaded onto railcars for disposal at a permitted waste disposal facility. The debris, rock, gravel and sand removed from the material during dewatering is transported by truck to on-site staging bins where it, too, awaits being loaded onto railcars. A geomembrane liner installed under all areas where PCB-containing sediment is processed, managed or staged ensures PCBs do not migrate from the site.

Water removed during the dewatering process is treated inside a 27,000-square-foot water treatment building located next door to the sediment dewatering building. Larger than some municipal water treatment plants, the facility is capable of treating two million gallons of water a day. Once filtered and processed to meet New York State’s strict water quality standards, the water is discharged into the Champlain Canal.

Once dredging is completed, GE’s agreement with EPA requires GE to decommission the processing and transportation facility constructed to support the project. GE will meet this obligation just as it has met all of its other obligations.

If you have additional questions about the Hudson River PCB cleanup or dredging in the Hudson River, email info@hudsondredging.com or contact us at 518-792-4087, or toll-free at 1-888-596-3655.