Old Channel Sediments to Be Removed from the Clark Fork River 

September 9, 2009

Starting this week, Envirocon will begin excavating additional contaminated sediments from Clark Fork River at the Milltown Superfund site.

After lengthy negotiations, the state of Montana, Envirocon, and ARCO's insurer, AIG, reached an agreement in August on the price and scope of work for the removal of an additional 250,000 cubic yards of contaminated sediments from the Milltown Reservoir site.

In December of 2007 the Clark Fork Coalition secured grant funding from the Montana's Natural Resources Damage Program (NRDP) to pay for sediment removal, but the ultimate stay-or-go decision was dependent on negotiating a fair price.

Known as the Area III-b sediments, this contaminated river mud lies in the former channel of the Clark Fork River, extending from the dam site about a third of a mile upstream. Without this agreement, and without grant funding from the NRDP, these sediments would have remained adjacent to the confluence as an armored repository. Since this material is just as contaminated as the reservoir sediment, removal is considered critical for permanent restoration success at Milltown.

The sediment was left in place in the remediation plan, now nearly complete, because the EPA and state believe that location of the sediments, though toxic, had little effect on the Milltown aquifer recovery, the primary goal of the Milltown Superfund cleanup.

Under the terms of the agreement, the state will contract with Envirocon to excavate the sediment and place it in the Tunnel Pond repository, located behind the former Milwaukee Road rail grade. This location is up and away from the river and floodplain, where the sediments will not pose a hazard to human health or the environment. Originally, it was proposed to haul sediments to BP-ARCO's repository at the Anaconda Superfund site, but the state's staff felt that the price for that was about $1 million dollars too high.

For the project, the State of Montana will pay roughly $1.65 million dollars from the NRDP grant funds, and AIG will contribute $1.1 million dollars.

Excavation began on August 31st and will continue until the end of October. It will take an additional month to shore up the railroad buttress, and cap and reclaim the tunnel pond repository. It should all be finished by the end of November.

"We're glad to see these sediments go, and we're thankful for the efforts of the State NRD Program, Envirocon, and AIG, in negotiating this agreement," says Chris Brick, the coalition's science director and a CFRTAC advisor. "Ultimately, this makes an already good cleanup just that much better."


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