Konkola Copper Mines (KCM) has said that the predicted caving-in (sloughing) of the ground at the Nchanga Open Pit (NOP) Cut 2 in Chingola following the recently highlighted ground instability has occurred without any threats to the safety of employees and people in communities near the mine area.
In a statement released to the media, the company said that the failure of the ground involved approximately 3 million tonnes of material spanning a distance of 370 metres around the epicenter of the failure zone, following a series of multiple tension cracks, which had opened up in the eastern part of the NOP.
Peak deformation rate at the time of the failure was 39 milimetres per hour against a threshold limit of 10 milimetres per hour. The KCM Geo-technical team had predicted that the fall of ground on the extreme ends of the unstable zone will continue until all loose ground attain a natural angle of repose. The failure is unlikely to occur beyond an area marked as a hazard exclusion zone, the company said.
The failure, which occurred around 08:30 hours, was controlled by planar sliding of the unstable ground above the Lower Banded Shale (LBS). The sloughing material settled against the north wall and was visibly wet.
There was also visible distortion of the original water pipeline by the moving ground, but no negative impact is expected on the newly installed re-routed water pipeline, used to carry water from the Kafue Pump Station to the KCM Smelter and eventually to Mulonga Water and Sanitation Company for onward community consumption.
According to the company, the safety of employees and people in surrounding communities remains their number one priority and the company reiterated its appeal to residents of Chingola, especially the Nchanga North area to continue staying away from the NOP area even though there is no threat to life.
“We commend the residents for their co-operation in implementing safety measures announced by the company thus far,” read the statement.
“We also encourage local residents to continue normally with their daily business activities, while school authorities in the area and parents should encourage their children in examination classes not to stay away from school,” the statement concluded