Proposed Grasse River Superfund Site Clean Up Remedy

A Public Information Session was held on May 7th at the St. Regis Mohawk School to discuss the ‘Selected Remedy’ to deal with the polluted 7.2 mile stretch of the Grasse River. Mr. Walter Mugdan, Director of Emergency & Remedial Response Division of the Environmental Protection Agency (EPA) explained the pilot studies and the EPA proposed plan. It was based on studying, testing and monitoring the river since 2003. Because of man-made changes to the river, two types of capping were explained. Near the Alcoa site, an armored cap will be used to cover the PCB polluted sediment, which is much more contaminated where it enters the river from the Alcoa site. The armored capping consists of 13 inches of armored stone, 6 inches of gravel, then 6 inches of sand and top soil over the polluted sediment on the river bottom. Further along the river towards Akwesasne, EPA proposed only capping with 12 inches of sand and topsoil over the polluted sediment.

They will dredge near-shore sediment where PCB concentration equals or exceeds 1 parts per million. The sediment will be stored on Alcoa property, cleaned on site and capped.

Walter Mugdan promised a long-term EPA commitment with this selected remedy by continuous testing and monitoring. He also stated it will take two years to design the remedy. Then the dredging will take four to six years to complete. He stated Alcoa is responsible for all continuous clean up costs, with EPA Superfund funds also available.

After all the scientific reasons for capping were presented, the community in attendance spoke on concerns relating to the health and well being of Akwesasne. Questions were asked about why just armored capping would be used in the Massena area and not near Akwesasne. Also questions like, why doesn’t the EPA just dredge the river and remove the polluted sediments so this issue doesn’t have to be revisited in future generations? Concerns of ice jams damaging the caps were discussed and the failure of the capping that took place at the GM landfill site. There were comments on how promises from the federal government mean nothing to native people and how this remedy will affect the next seven generations. The scientists were invited by Dana Leigh Thompson to join the hospice program to witness and help with end of life deaths related to cancer caused by the pollution. Also in attendance were Saint Regis Mohawk Tribal Chief Ron LaFrance and the Tribe’s environment program staff, along with the Haudenosaunee Environmental Task Force as well as community members.

GRASSE RIVER SUPERFUND SITE

Selected Remedy

• Dredge all near-shore sediments where PCB concentrations equal or exceed 1 part per million (ppm)

• Approx. 109,000 cubic yards will be dredged

• Dredged areas will be backfilled to pre-dredging depths

• Cap all main channel sediments where PCB concentrations equal or exceed 1 ppm

• Armored cap in upper 2 miles where either the “segment length weighted average” or the maximum surface sediment PCB concentrations equal or exceed 1 ppm (59 acres)

• Sand & topsoil cap in lower 5 miles where maximum surface sediment PCB concentrations equal or exceed 1 ppm (225 acres)

•Dewater dredged sediment and dispose in the on-site permitted landfill

•Reconstruct habitat

•Long-term monitoring and maintenance

WHY NOT DREDGE IN MAIN CHANNEL TOO?

• Site-specific conditions not conducive to dredging main channel. Dredging main channel results in high residual concentration still requiring capping after extensive dredging.

•Most highly contaminated sediment buried towards the bottom of sediment column

•Irregular, uneven river bottom

•Boulders and rock debris

CAN ARMORED CAP WITHSTAND ICE JAM SCOURING?

• Armored cap designed and implemented during 2005 ROPS.

• Models used to design armored cap address turbulent flow, velocity and ice thickness. Designed to protect against scouring forces created under the toe of the ice jam.

• In-river armored cap has been used at contaminated sediment sites to address erosional and scouring forces for which sand/topsoil caps are insufficient.

WHAT HAPPENS IF THE CAP FAILS?

• EPA has confidence in the cap.

• Monitoring will identify areas in need of repair as a result of localized erosion by manmade actions or by nature.

• If at any time EPA determines that the cleanup is no longer protective of human health or the environment then EPA may direct Alcoa to implement further response actions for the Site.

For information on this clean up remedy, check out

http://www.epa.gov/region02/superfun/mpl/aluminumcompany