Canadian diversified miner Teck Resources expects copper production at its Highland Valley Copper project in British Columbia to be down by about 35 million pounds in the second half of 2009 because of recently identified geotechnical issues.
Mining has been suspended in the affected area and access to some of the ore in the valley pit could be limited for the next 18 months, Teck said.
Production in 2010 is expected to produce 115 million pounds less than expected.
The announced cuts will bring down total production at Teck mines to about 755 million pounds from the expected 870 million pounds.
Lower grade ore from the Lornex and Highmont pits will be used to compensate the shortfall.
Teck has hired geotechnical consultants to assess the extent of the issue, which is expected to be completed by the end of 2009.
Remedial actions would include at least 40 million tonnes of additional stripping and placement of an additional buttress.
Preliminary estimates suggest the mine ore reserves are expected to be reduced by about 2% depending on the remedial actions, Teck said.