Cameco Reports Remediation Progress at Flooded Cigar Lake

- Cameco reported in late January 2007 that it is making progress with a phased plan to restore the underground workings at its Cigar Lake uranium project in northern Saskatchewan after a water inflow on Oct. 23, 2006, flooded the development (E&MJ, Nov. 2006, p. 5, and Dec. 2006, p. 16). The first phase of the remediation plan involves drilling holes down to the source of the inflow and to a nearby tunnel where reinforcement may be needed, pumping concrete through the drill holes, sealing off the inflow with grout, and drilling dewatering holes.

Subsequent phases will include dewatering the mine, ground freezing in the area of the inflow, restoring underground areas, and resumption of mine development. Regulatory approval is required for each phase of the remediation plan.

As of late January, six of the 14 drill holes planned for reinforcing and sealing off the water inflow area were complete, and about 200 m3 of concrete had been poured in the reinforcement area. Concrete is being poured in two locations, one near the rock fall to seal off the inflow area and another in a nearby tunnel to provide reinforcement. The concrete mixture is designed to harden under water and is being poured in successive layers.

Experience gained during drilling of the initial holes is reducing the time required for subsequent holes. Assuming the two drill rigs on site maintain their current pace of drilling and the concrete hardens as planned, Cameco expects to complete the work necessary to seal off the water inflow in the second quarter of 2007.

A third drill rig was scheduled to begin drilling dewatering holes in February. An additional four drill holes are planned for dewatering the mine. About 280 people were working on site at Cigar Lake, including drilling personnel working on the remediation program. Work on the project’s surface facilities, including the water treatment plant, mine ventilation fan foundations, and an electrical substation, was ongoing.

The Cigar Lake project is a joint venture owned by Cameco, 50%; AREVA Resources Canada, 37%: Idemitsu Canada Resources, 8%; and TEPCO Resources, 5%.