The borehole QC135 in the West Sub-pit has been installed casing with totaling 50 m-depth, the slope movement in the North Pit wall at the West Sub-pit has been monitored from this borehole by dropping plummet method. This method can indicate weak layer or layer of movements. The location of borehole QC135 is shown in Figure 1. and the process of installation casing is shown in Figure 2.