The GM Central Foundry, Reynolds Metals, and Alcoa Superfund sites have been identified as sources of PCBs to the St. Lawrence River and major tributaries.

The General Motors Foundry site abuts the St. Lawrence River on the North, the Raquette River on the South and the Akwesasne Mohawk Nation on the North and East. The GM Central Foundry has been in operation die-casting aluminum automotive parts since 1958.

The GM Foundry Site on the St. Lawrence river.

From 1959 until 1974, the facility used heat and fire-resistant PCB-based hydraulic fluids in the die-casting machines. Leakage of the hydraulic fluids into the facilities wastewater treatment system produced PCB-contaminated sludge, which was disposed of at several sites near the plant. PCBs and other compounds disposed of on the plant's grounds have contaminated the St. Lawrence and Raquette Rivers and Turtle Creek, a small creek which drains from the GM site into the St. Lawrence River. In 1983 the GM facility was placed on the National Priorities List of Superfund Sites by the EPA and fined half a million dollars for illegal use and disposal of PCBs.

The EPA issued a consent order in 1985 requiring a Remedial Investigation and Feasibility Study (RI/FS) on the land based and river sediments. In June 1989, GM released the RI and in November of the same year it released the FS. Meanwhile, GM implemented interim remedial measures which included the closing, grading and temporary capping of the on-site hazardous waste landfill.

The EPA released its first Record of Decision (ROD) in 1990 regarding the cleanup of the GM site. In this ROD, the agency called for the excavation of contaminated sediments and soils on Mohawk land, the North Disposal Area and unlined lagoons. It also required the dredging of the St. Lawrence and Raquette Rivers and Turtle Creek, pumping and treating groundwater, control of surface water runoff and treatment of contaminated sludge and soils on the site. Any material containing greater than 10 parts per million (ppm) of PCBs would be treated on-site. All material less than 10 ppm would be disposed on-site and capped with a vegetative cover. The Mohawk Tribe agreed with this ROD. In 1992, a second ROD was proposed concerning the landfill, the East disposal area and groundwater flowing under these areas.

In 1994, GM requested that the EPA re-evaluate treatment levels, and in the 1995 Post Decision Proposed Plan, the treatment level for materials contaminated with PCBs was raised to 500 ppm. Materials containing less than 500 ppm and greater than 10 ppm of PCBs would be contained on-site. This plan was withdrawn due to strong opposition by the Mohawk Community.

While waiting for a final plan, dredging in the St. Lawrence River was completed in 1995 and sediment was stored on-site. The next Post Decision Proposed Plan was issued in 1998 and it modified the 1990 plan by requiring the removal and off-site disposal of materials having greater than 10 ppm of PCBs instead of treating them; solids at less than 10 ppm will be contained on-site. This plan was acceptable and removal to off-site facilities began in the summer of 1999.

The Reynolds Metals Aluminum Plant is located one-mile northeast of the Akwesasne Mohawk Nation. This plant started operations in 1959 and has been listed as a New York State Superfund site for improper disposal of hazardous wastes on the plant's property. Contaminants from Reynolds to the St. Lawrence River include PCBs, aluminum, furans and polychlorinated aromatic hydrocarbons (PAHs). Also, airborne fluoride in the 1970s from the aluminum production lead to fluorosis, which killed cattle on Cornwall Island.

In 1989, there was a Unilateral Order to Reynolds to investigate contamination in the St. Lawrence River system. This order also included the design and implementation of EPA's final remedy. In 1992, the New York State Department of Environmental Conservation (NYSDEC) issued a Record of Decision for the land-based portion. This ROD included the removal and/or treatment of contaminated sediment on land and the upgrading of the groundwater, surface water and leachate collection and treatment systems. Also it included the dewatering and capping of Black Mud Pond, the excavation, treatment and on-site disposal of all contaminated soils containing 25 ppm or more of PCBs from the North Yard, the capping of the remainder of the North Yard, and the removal of soil and sediments containing greater than 1 ppm in wetlands and 10 ppm of PCBs elsewhere.

In 1993, the EPA issued a second ROD for the remediation of approximately 50,000 cubic yards of contaminated sediment from the river. Sediment dredged from the river containing greater than 25 ppm of PCBs would be treated on site by thermal desorption and those materials with 25 ppm or less would be disposed on site in Black Mud Pond.

This plan was modified in the October 1998 Post Decision Proposed Plan. Sediments containing from 50 to 500 parts per million would be disposed of off-site in a landfill. Sediments containing less than 50 parts per million would be stored on-site and sediments containing greater than 500 parts per million would be treated off-site.

Alcoa Aluminum

The Alcoa Aluminum Plant is located in Massena, N.Y. on the Grasse River and has been in aluminum production since 1903. Contaminants at this state Superfund site included PCBs, cyanide, polychlorinated aromatic hydrocarbons (PAHs), fluoride, and arsenic. This Superfund site also includes 7 miles of Grasse River bottom sediments contaminated with PCBs.

In 1980 the EPA released a Unilateral Administrative Order that Alcoa investigate contamination in the river system. This included design and implementation of a final remedy once selected by the EPA.

The Alcoa property has 15 different disposal sites, with 9 considered priority sites. In 1991, the NYSDEC issued a Record of Decision (ROD) for 8 sites, and in 1992 a second ROD was issued for the remaining sites. Alcoa has created a state-of-the-art, four-cell secure landfill for disposal of treated wastes containing less than 25 ppm of PCBs.

In 1995 Alcoa completed dredging of the most highly contaminated river sediments located near the primary industrial outfall to the river and is now analyzing alternatives for completing the river remediation. There are plans for additional sediment removal and a contaminated sediment capping project in 1999. A complete full-scale cleanup plan is scheduled to be released in December 1999.