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Plan keeps sediment at dam cleanup site

Project removing tons of mine waste buildup

BUTTE – Officials say some sediment from the Milltown Dam cleanup may stay on site rather than being shipped to Anaconda.

The issue is part of a recently proposed amendment to a $2.8 million grant approved last year by Gov. Brian Schweitzer.

Originally, the sediment would have been shipped by rail to a remediation site.

The proposed change would allow the state to negotiate with contractors working on the project to store some at the Milltown Dam site if they thought it would be best.

A repository in the area is covered with water and sediment could be used for a cap material to stop water from collecting, said Robert Collins, supervising assistant attorney general.

“I think it would be an environmental benefit to fill that up,” he said.

The proposal would allow the state to store as much as 700,000 cubic yards of Milltown Dam sediment to fill existing waste repositories at the site.

That’s in addition to the more than 2 million cubic yards being shipped to the BP-Arco Waste Repository, where the sediment is being used to cap old mine waste at the Superfund site.

The plan must be approved by Schweitzer.

Work continues to remove tons of mine waste that had settled behind the dam after more than a century of mining and smelting in the Butte area.

The dam was breached earlier this year, allowing the Clark Fork and Blackfoot rivers to flow unimpeded.

Biologists say the fishery will eventually recover and the trout will be stronger, allowed to migrate and spawn upstream into traditional habitat in the two rivers.

Most of the $120 million cleanup is being paid for by Atlantic Richfield Co., which assumed financial responsibility for the Milltown Dam site after a merger with Anaconda Co.