MASSENA — The St. Regis Mohawk Tribal Council said the U.S. Environmental Protection Agency’s chosen remedy to remediate the Grasse River was a “devastating failure.”
Tribal Council members said in a press release that they had sent a letter to the EPA this week to share their ongoing objection to the remedy that was prescribed for the remediation, which was completed last October.
The letter, addressed to EPA Region 2 Administrator Lisa Garcia, said that most recently hazardous waste was reintroduced into the environment following an ice jam in March.
“A portion of the cap system approved by EPA to cover the significant contamination in the sediment was torn apart by a March 2022 ice jam scouring event, which exposed and introduced hazardous waste with concentrations up to 1,500 mg/kg (parts per million) of PCBs (polychlorinated biphenyls) in the river, and unknown concentrations released downstream into the St. Lawrence River,” said Tony David, the tribe’s Environment Division director.
EPA had 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.
EPA announced in November that dredging and capping work, which began in 2019, had 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 was 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, was fully restored, and the Route 131 staging area will continue to be used for river monitoring activities over the next few years.
Tribal officials said they had expressed concerns to the EPA several times over the years about ice jam scour in the main channel. They said the EPA’s first five-year review of the remediation effort noted the occurrence of severe ice jam events over the course of 40 to 50 years, causing measurable scouring of the river bottom. The report is available on EPA’s website at wdt.me/mWS3nA.
They said that, following a March 2003 ice jam, the EPA’s Record of Decision noted that a section of the main channel continued to be prone to potential scouring of sediment from ice jam events.
“In 2012 and 2013, prior to EPA’s issuance of the 2013 Record of Decision, the tribe stated to the EPA that the Grasse River is prone to frequent and significant ice scour events in known locations that dig up the banks and sediment in the river in the early spring. EPA rejected our scientific and technical investigations and instead relied upon Arconic’s computer-generated modeling, which has proven to be grossly flawed,” Tribal Chief Michael Conners said.
Tribal officials said they had repeatedly voiced objections to the approved remedy to cap, rather than remove hazardous materials from the river.
“The tribe never supported the EPA’s capping remedy and continually insisted upon a dredging remedy for PCBs. Dredging was successfully completed for near-shore removal of hazardous contaminants, and in the lower Grasse River to accommodate a tug boat,” they said.
“The EPA rejected the tribe’s historical knowledge and wrongly concluded that failure of the armored cap was an unlikely event,” Tribal Chief Ron LaFrance said. “Environmental justice is not achieved by, once again, turning a deaf ear to our knowledge and returning to a flawed remedy that has set us back years. The tribe continues to advocate for a permanent remedy that entails dredging and completely removing all hazardous materials from the Grasse River.”
Tribal officials said their Environment Division conducted real-time monitoring of the March ice jam event.
“But it was not immediately investigated by Arconic until June 2022. Arconic’s website states the ice jam resulted in ‘limited scouring and damage,’ however, Arconic reported scour depths up to 4- to 5-feet deep into the contaminated sediment — on a section of the modified armor cap and releasing hazardous materials downstream,” they said.
“It is highly alarming that PCBs 900 to 1500 mg/kg (ppm) were detected in areas that were previously not exposed in the main channel. These are new PCB-concentrations and are extremely harmful, exceeding the limit of 500 ppm (for hazardous waste) and posing a substantial threat to human health and the environment,” Tribal Chief Beverly Cook said.
EPA officials did not respond to a request for comment by press time.