The U.S. Environmental Protection Agency (EPA) announced yesterday that dredging will begin in April to clean up sediment contaminated with polychlorinated biphenyls (PCBs) at the Grasse River Superfund Site (aka Alcoa Aggregation) in Massena, New York.
PCB contamination is the result of past waste disposal practices at the Alcoa West (now Arconic) facility.
In 2013, EPA selected a cleanup plan for the site that called for dredging and capping of PCB-contaminated sediment in a 7.2-mile stretch of river.
Since that time, Arconic has been working out the details of how the dredging and capping work will be carried out, under EPA oversight. Arconic is performing the work, estimated at $243 million, under an EPA order.
“EPA continues to work collaboratively with New York State and the Saint Regis Mohawk Tribe on the oversight and coordination of this critically important cleanup of the Grasse River, including engagement in recent months to ensure a full understanding of their perspectives,” said EPA Regional Administrator Pete Lopez. “The removal of over 100,000 cubic yards of contaminated sediment along the shores of the Grasse River, along with thoughtful attention to habitat reconstruction, will go a long way toward achieving the ultimate restoration of the river’s health.”
The dredging portion of the cleanup is expected to be completed by late fall. Beginning in 2020, clean material will be placed in the river’s main channel to encapsulate PCB contamination in the river bottom. The dredging, capping and habitat reconstruction work is expected to take approximately 4 years to complete.
The EPA will hold public meetings on April 3 in Massena and April 4 in Akwesasne to discuss the details of the work to be performed in 2019.
During the 2019 dredging season, mechanical dredges will be used to remove PCB-contaminated sediment from near-shore areas of the project using environmental buckets.
Excavated sediment will be transported by barge to a staging area located next to the river, near the intersection of County Route 42 and Route 131 in Massena, for offloading, processing and dewatering.
As EPA reported, the dredging will generally be performed upstream to downstream, except for a few upstream areas which have been identified as lake sturgeon spawning areas. Work will not begin in these upstream areas until the middle of June.
Dredges are expected to work on the river 12 hours a day, Monday through Saturday, through the fall. Project activities will be conducted through the night time hours at the staging area.
Contaminated sediment water will be collected and pretreated at the staging area before being sent to the Arconic West plant for additional treatment and subsequent discharge into the Grasse River. Processed sediment will be loaded into dump trucks for transport to the permitted landfill at the Arconic West plant. Trucks leaving the staging area will be thoroughly cleaned before exiting the site.
In 2019, an additional shoreline support area will be constructed near Haverstock Road. Clean capping material, needed for work in the main channel in 2020, will be brought to this area by truck and transported by pipeline to the cap placement equipment on the river. Other work to be conducted in 2019 includes the removal of an estimated 7,500 cubic yards of contaminated soil from the floodplain and areas along the north shore of the river near the Alcoa Bridge.