As part of the scope to investigate the stability of and remediation options for a large underground open void (stope) complex at the Giant Mine Remediation Project (an inactive underground gold mine in the Northwest Territories), Golder's project team built and flew a custom unmanned aerial vehicle (UAV) in order to inspect inaccessible areas of the stope and connected development workings. The UAV surveys supplemented traditional investigation techniques including borehole-based camera surveys and LIDAR scanning (cavity monitoring system, CMS) and was successful in filling information and data gaps while reducing overall investigation costs. 3D geometry models built from UAV flight video were found to accurately reproduce the shape of the excavation when compared to incomplete CMS data collected from boreholes that intersected the void.

Steel ground support elements installed in underground excavations are exposed to groundwater and atmospheres that can cause corrosion of the steel and thus a loss of support capacity over time. For high tonnage mines, where in some cases, hundreds of kilometres of drifts may be excavated, the ground support must be maintained for long periods of the mine life. Ground support corrosion must therefore be considered early in the planning process and this paper discusses an approach to classify the possible corrosive conditions in a mine, estimate ranges of possible corrosion rates and develop hazard maps that can be used to develop forecasts of loss of support capacity and timing of rehabilitation. Currently available corrosion protection technologies are also discussed and compared qualitatively. Better understanding of ground support corrosion can improve health and safety, reduce costly delays to production due to the ability to schedule support replacement in the mine plan and provide mine managers with more realistic forecasts of ground support costs and equipment needs over the life-of-mine.