MASSENA — A milestone has been reached in the cleanup of the Grasse River Superfund site, according to U.S. Environmental Protection Agency officials.
They said Thursday that dredging and capping work, which began in 2019, has been completed, with nearly a quarter million cubic yards of sediment contaminated with polychlorinated biphenyls, PCBs, removed and more than 200 acres of river bottom capped.
During the cleanup, contaminated soil was also removed from two areas along the north shore of the river near the Alcoa Bridge.
With that work completed, dredging and capping equipment has been removed from the river and from two shoreline support areas on Route 131 and Haverstock Road. EPA officials said the Haverstock Road staging area, which was used for storing capping material, has been fully restored, and the Route 131 staging area will continue to be used for river monitoring activities over the next few years.
“This is an important milestone at the Grasse River Superfund site,” Acting Regional Administrator Walter Mugdan said in a statement. “We have removed forever about 220,000 cubic yards of PCB-contaminated sediment, which will allow for the recovery of this vital and culturally important river system. This success could not have been achieved without the work of our partners, the St. Regis Mohawk Tribe and New York State.”
EPA selected a cleanup plan in 2013 that called for removing contaminated sediment from near-shore areas along a 7.2-mile stretch of the lower Grasse River and placing a cap on the river bottom in the main channel.
Capping material included sand and powdered carbon, which works to capture and chemically bind pollutants in place, as well as some stone and gravel.
Construction began in 2017 on a land-based staging area to support dredging and capping operations. Capping resumed in April and was ongoing downstream of the Route 131 bridge to the Grasse River mouth.
Additional capping materials were placed over portions of the 2020 armed cap areas, upstream of Route 131.
Dredging was performed from May to June in a small area just downstream of Snug Harbor in coordination with the St. Lawrence Seaway Development Corp. to support the use of a new tugboat.
Dredged materials were processed at the staging area near Route 131 and disposed in a secure landfill.
Placement of backfill material over portions of the dredged areas on Snug Harbor was ongoing.
The project’s long-term monitoring plan requires fish, water and habitat monitoring to track the recovery of the river over time.
Capped areas of the river bottom will also be monitored to ensure that the caps remain intact.
EPA officials said work to reconstruct habitat areas impacted by the project will continue in 2022.
Arconic is conducting the cleanup and the associated monitoring and habitat restoration work under a 1989 administrative order with the EPA.