Glacial recession is exposing previously hidden ore deposits around the world. Developing facilities in the areas left by receding glaciers requires an understanding of the surface and sub-surface hydrology of glaciers in order to route melt waters and storm runoff around mine workings.
The proposed KSM Project (named for the Kerr, Sulphurets and Mitchell deposits), owned by Seabridge Gold Inc., is located in Northwest British Columbia and includes both open pits and block cave workings, in steep, mountainous, glaciated terrain. The Mitchell deposit, in close proximity to the retreating Mitchell glacier, will be mined via open pit followed by block cave methods, and will require diversion of contact and non-contact water flows from the glacier. Most of the annual precipitation occurs either as snow in the winter, or rain on snow during the freshet and rain during the fall storms. Extensive investigations of sub-ice conditions, water levels and water quality were completed for the Mitchell glacier using ice penetrating radar, and both diamond core and hot water drilling. Design of diversions considers snow avalanche blockages and large peak freshet flows, with subsequent reduced effectiveness and reliability of surface diversions in avalanche areas as compared to tunnels. The advantages of single and twinned diversion tunnels paired with subglacial diversion inlets were examined and alternatives considered. Tunnels and surface diversions were designed to route contact water by gravity to a single mine area contact water containment system for treatment prior to release to the environment and to route non-contact water away from the mine area.
Parkinson, G., H. McLeod, G. Stevenson, A. Morrison, A. Dalpatram, K. Norlund, C. Pelletier, et al. 2015. “Snow, rain and ice – management of mine area glacial water at the KSM Project,” in Mine Water Solutions in Extreme Environments 2015, Vancouver, BC, April 12-15, 2015.