Analysing Slope Change at Globe Progress Open Pit, Reefton

Airborne LiDAR and photogrammetry data collected across 2014 and 2015 was used to develop detailed digital terrain models and produce slope change models at the Globe Progress open pit mine in Reefton, New Zealand. Coupling of these slope change models with existing geotechnical data from the last eight years of mining allowed the north-east pit wall to be subdivided into four geotechnical domains, to understand the mechanism of failure and quantify the movement along the pit wall. The models were created in Leapfrog software developed by ARANZ Geo, allowing for data processing, measurements and models to be created in a single effective program. The range of maximum slope movement between the four domains is 1.6 m – 3.9 m with the volume of material loss from the pit wall in the order of 1800 m3 – 4900 m3. The failure across the domains is controlled by complex geology associated with the footwall of the major gold bearing shear zone. Asymmetric folds displaced by shears across the pit wall cause unfavourable bedding dip orientations, leading to the observed topple and planar failure within each domain.