EPA officials addressing remediation concerns from St. Regis Mohawk Tribe

The St. Regis Mohawk Tribal Council had called the EPA’s remedy to remediate the Grasse River a “devastating failure.” The council said in a press release that it had sent a letter to the EPA this week to share its 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 the 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 officials said they updated the community “and our important partners in the St. Regis Mohawk Tribe” in June after the responsible party began its EPA-required investigation.

“This investigation, which will identify actions that need to be taken, is still underway. We anticipate that work will begin on an interim measure to address in the immediate the damage to the cap in late summer and will likely be completed before the end of the year,” they said. “Furthermore, these investigations will allow EPA to evaluate the performance of the cap in the section of the river where the failure occurred, to determine what sort of possible changes to the cleanup plan might be needed.”

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. They said a March ice jam event resulted in some scouring, which damaged the cap and sediment immediately upstream of the Route 131 bridge in Massena.

“The portion of the cap damaged was small — more than 98% of the capped area held up as designed and was not damaged during the 2022 ice jam,” EPA officials said. “EPA is overseeing the repair of the damaged portion. River sections downstream of the damaged section are also being tested to ensure that contamination did not flow downriver. This was a very unusual ice jam. Historically, ice jams have not occurred this far down river and the construction of the cap in the damaged area was not designed for the forces resulting from the ice jam. The armored cap constructed in the river upstream of the area, which was designed to withstand ice jam forces, was not damaged.”

EPA officials said plans that were developed to monitor the site after cleanup and after ice jams required water samplings and measurements of the river bottom to identify areas that had eroded, or where the eroded capping material and sediment deposited, and to evaluate the extent of impact.

“Under EPA oversight, Arconic began its investigation in April and will develop a workplan that details next steps. This is anticipated to include installation of a more robust cap in the area where erosion has occurred; though this is dependent upon the outcome of the investigations,” they said.

“Work to address the damaged cap area is expected to begin in late summer and be completed this year. EPA issued a Community Update in June 2022, which discusses the ongoing ice jam investigation and anticipated in-river work. The results of the investigation and details of the planned work will be shared with the community before the start of any in-river work. EPA will continue to consult with the Saint Regis Mohawk Tribe and coordinate with project stakeholders to address their concerns,” EPA officials said.

Alcoa’s presence in the town of Massena dates back to 1903, and for decades, the company released hazardous materials onto its properties and into the Grasse River through four industrial outfalls. When the EPA stepped in at the end of September 1989 to investigate the contamination’s extent, an arduous organizing and cleanup process began.

The remediation involved dredging roughly 190,000 cubic yards of sediment contaminated by polychlorinated biphenyls, or PCBs. With no taste or smell and highly toxic when uncontained, PCBs were banned from commercial use in 1979.