Denison Environmental Services : Decommissioning projects : Denison Mines

Elliot Lake Reclamation
The majority of the decommissioning and rehabilitation of the Elliot Lake properties Denison Mines and Stanrock/ Canmet was completed in 1998. Dam construction and cleanup commenced on the Stanrock Tailings Management Area (TMA3) was the final project in the reclamation program.

In 1997 the tailings located in the area downstream of TMA3 were cleaned up and removed to permanent storage. Dam structures were raised and reinforced to increase settling capacity and to provide one meter of water cover over the tailings and effluent residues. Permanent spillways and monitoring flumes were installed.

On the western perimeter of the tailing storage basin for TMA3, three temporary dams were replaced with engineered, till core, permanent structures designed to confine the tailings over the very long term. Dam A, the final dam on the south flank is now complete.

After several years nearly the whole surface area of the Stanrock Tailings Management Area has been revegetated. Several test programs involving biosolids from St. Mary's Paper have been very successful in encouragaging growth on the tailings material.

The recovery of the main tailings basin at Denison has also been remarkable. The water cover has so significantly reduced the acid generation of the tailings that treatment that was a major 24 hour per day operation during the mines operating days has been nearly eliminated.

Expenditures on decommissioning and rehabilitation of the Denison Sites in Elliot Lake have topped $55 million. Monitoring and reporting activities with continue for the foreseeable future. Denison In 1997, Denison Mines formed an Environmental Division to deal with this work and also to explore the opportunities for similar work with other mining companies with closed properties.

Denison Mine

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