August 19, 2008

Flooding halts remediation efforts at Cameco’s Cigar Lake mine

PRINCE ALBERT, Sask.

Cameco Corp. reports that remediation work at the flooded No. 1 shaft at its Cigar Lake uranium project was temporarily suspended last week after an increase in the rate of water inflow to the mine was observed.

“Remediation and dewatering of the No. 1 shaft had been progressing smoothly up to this point,” said Tim Gitzel, Cameco’s chief operating officer.

“An inflow at this rate is disappointing but our remediation plan, as approved by our joint venture partners, recognized the risk and included specific actions to be taken at various levels of inflow.”

Cameco said the shaft had been pumped down to 430 metres below surface when the increase in water flow was reported early Tuesday morning.

Work in the shaft was suspended a few hours later.

During the day, the inflow rate increased steadily to about 600 cubic metres per hour, which is beyond the range that can be managed while sustaining work in the shaft, said Cameco.

The mine has a total depth of 500 metres and the mine underground workings are at the 480-metre level.

Work in the shaft has been suspended while the situation is assessed to determine the source and characteristics of the inflow, implications for planned remediation work and the impact, if any, on the planned production date. Cameco had anticipated production startup in 2011.

Cameco said it will provide an update in its second quarter news release Thursday.

The project, located about 450 kilometres north of Prince Albert, flooded during construction in October 2006 due to a rock fall. The mine has been described as the second-richest uranium mine in the world, but uranium has yet to be extracted from the site.

In February, Cameco plugged the weakened section of the mine that caused the flood with a 5,000-cubic-metre concrete seal — an amount equal to 250 basement foundations for standard bungalows.

Also in the first quarter of this year, the company determined through an assessment of two areas of the mine that “no additional reinforcement or other precautionary measures were needed before de-watering,” according to a company release.

Cameco said its plan now is to allow the water level in the shaft to rise to about 100 metres below the surface.

This will provide information that can be analyzed to determine the next step, said the company.

The company has indicated previously that the remediation plan for Cigar Lake includes options to address excess inflows including additional grouting from surface and ground freezing if necessary.

Canadian Press

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