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EPA planning to extend armored cap in Grasse River to contain PCBs after ice jam damaged original cap in 2022

Posted 9/9/24

MASSENA -- More work needs to be done to fix a cap on the bottom of the Grasse River which was damaged by an ice jam in 2022.

The Environmental Protection Agency will be hosting a public …

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EPA planning to extend armored cap in Grasse River to contain PCBs after ice jam damaged original cap in 2022

Posted

MASSENA -- More work needs to be done to fix a cap on the bottom of the Grasse River which was damaged by an ice jam in 2022.

The Environmental Protection Agency will be hosting a public information session from 6-7:30 p.m. on Sept. 11 at the Hawkins Point Visitors center to discuss the particulars of a planned project to place more capping material on the damaged areas of the river bed.

Officials say the work is expected to begin this month and will seek to replace the sediment that was moved as a result of the ice jam.

According to reports, the section immediately upstream of the Route 131 bridge in Massena is where the repair work is most needed. EPA officials say they will oversee the work, including monitoring air quality, noise and water quality throughout.

No overnight work is expected, with contractors working from 6 a.m. to 6 p.m., officials said.

The event is expected to include representatives from Arconic, the Department of Environmental Conservation, EPA, the state Department of Health and the St. Regis Mohawk Tribe Environmental Division.

Arconic and EPA officials will also address the expected repairs required and answer questions from the public, officials said.

The initial dredging began prior to the COVID-19 pandemic before being completed in the fall of 2021 after Arconic capped 7.2 miles of the Grasse River to remove and cover a portion of the river that was contained with high quantities of polychlorinated biphenyls (PCBs).

In total, the project successfully capped 257 acres in the river's main channel, however an ice jam damaged the cap over a 4.3 acre section of the river.

The scouring of the ice reopened the river bed, potentially releasing harmful PCBs again, officials previously said.

At the time the damage was discovered, EPA officials said the section of the river that was capped with sand and a modified armored cap was not designed to withstand potential scouring from ice jams, like those experienced in the early part of 2022.

Following the ice jam an investigation was carried out by Arconic that officials said showed the material removed by scouring was largely just capping material.

The material scoured by the ice was deposited downstream, officials previously said.

Following the assessment, Arconic undertook a short term cap repair to ensure PCBs and other potential contaminants would not be carried further downstream.

With the temporary fix in the works, Arconic also undertook a plan to permanently address the section scoured by ice, including hiring specialists to assess whether further dredging and capping would be needed.

Following the scouring event EPA officials signed off on an extension of the armored cap for the river, which included a six-inch layer of sand and activated carbon mix, along with a six-inch gravel filter layer and 13 inches of large stone to armor a larger section of the river up to the Route 131 bridge.

Work on the armored cap will carry into spring 2025 due to a need to allow each layer to properly settle before future layers can be brought in, EPA officials said.