MASSENA -- As expected, the U.S. Environmental Protection Agency has announced its final plan to clean up contaminated river sediment at the Grasse River Superfund site at Alcoa near Massena.

Details of the plan will be laid out over the next two years, the design phase of the plan.

The plan calls for an armored cap on part of the channel in an attempt to prevent ice scouring from re-exposing the toxic materials.

From the 1950's until the mid-1970's, the Alcoa West facility near Massena released waste including PCBs from its aluminum production and fabrication activities, onto their property and into the Grasse River. As a result, sediment in the waters near the Alcoa West facility and extending approximately seven miles downstream has been contaminated.

In 1989, the EPA issued an administrative order that requires Alcoa to investigate the extent of contamination in that portion of the river, to evaluate cleanup options, and to design and implement a cleanup plan to be selected by the EPA. The EPA says it expects that Alcoa will perform the $243 million cleanup announced today.

The details of the plan include dredging and filling in the near-shore portion of the Grasse River with clean material. In addition, the plan calls for the placement of a thick armored cap in the upper two miles of the river’s main channel, where the sediment is susceptible to ice scouring during severe weather, according to the EPA announcement.

Past industrial activities have contaminated the river sediment with polychlorinated biphenyls, the EPA says. PCBs are probable human carcinogens that build up in the fat of fish and mammals, increasing in concentration as they move up the food chain. The primary risk to people is the accumulation of PCBs in the body from eating contaminated fish.

The EPA says it has been engaged in the cleanup of the Grasse River for several decades.

The plan requires dredging and capping of contaminated sediment in a 7.2 mile stretch of the river. Approximately 109,000 cubic yards of contaminated sediment will be dredged from near-shore areas of the river, which will then be filled in with clean material. Dredged sediment will be disposed of at a permitted, secure landfill at the site.

In the river’s main channel, approximately 59 acres of contaminated sediment will be covered with an armored cap and another approximately 225 acres of contaminated sediment will be capped with a mix of clean sand and topsoil to isolate the contamination from the surrounding environment.

The remaining five-mile stretch of the main channel will be capped with sand and topsoil mix, under the EPA’s plan. Habitat that is impacted by the cleanup will be reconstructed, the environmental agency says.

The EPA says it finalized the plan after reviewing and considering all comments received during the 60-day public comment period, and after consultation with the New York State Department of Environmental Conservation and the St. Regis Mohawk Tribe.

The plan requires long-term monitoring of the capped areas to ensure that the caps remain intact, and monitoring of fish, water and habitat. Details of this work will be defined during the estimated two-year design phase of the project, and will include plans for worker and community health and safety.

A cultural resources survey will also be conducted prior to the start of in-river work.

Based on current estimates, dredging, filling, and capping will take approximately four years to complete and will cost approximately $243 million. The fish consumption advisories established by the New York State Department of Health will remain in effect until PCB concentrations in fish are reduced to the point where they can be relaxed or lifted by the state.

In 1995, Alcoa dredged about 3,000 cubic yards of highly contaminated sediment from an area near the Alcoa facility. Since that time, a number of studies have been conducted by Alcoa to evaluate cleanup options for the site. In 2001, Alcoa tested a variety of materials to be used as a cap over the contaminated sediments and also a variety of methods of placing a cap over the sediment. This testing took place in a 7-acre area of the Grasse River. Subsequent monitoring in 2003 showed that part of the cap placed during the study was lost and some underlying river sediment had eroded as a result of hydraulic scouring caused by ice. As a result, the EPA directed Alcoa to re-evaluate cleanup options for the site to account for scouring caused by future severe ice events, as well as other options to address the sediment contamination. The results of the studies were carefully examined and were used to develop the cleanup plan, the EPA announcement says.

The announcement said the EPA has post its plan at http://www.epa.gov/region2/superfund/npl/aluminumcompany/.