After years of mining operations, managers of an open pit mine were seeking new solutions to ensure the stability of their waste rock storage facilities throughout the life of mine, in compliance with current regulations.
First, our experts determined which sections of the waste rock storage facility were most critical for stability assessments using 3D simulations, and also relying on local team knowledge along with consideration of construction methodologies.
The proposed disposal sequence was designed to ensure overall stability, but also to delay water flow to the catchment areas, storage basins and the water treatment plant. In fact, upstream water retention reduces the risk of environmental spills, which can be significant given the size of the watersheds, which during the spring thaw, translates to some 40 million m3 of water requiring management over a 30-day period, at a flow rate of 14 m3/s.
In addition, several pits are being mined simultaneously at the mine, which produces two types of waste rock—fine and coarse—in volumes that vary over time. As such, our experts developed detailed short-, medium- and long-term disposal plans that factored in these considerations as well as other site activities, such as overall drainage during operation and closure, snow management and truck cycle times. Our plans also called for the construction of a berm to contain the waste rock within the designated storage area.
Eventually, the waste rock storage facilities designed by our experts will occupy an area of about 20 km² and contain about 2 billion m³ of waste rock. The staged waste rock piles will eventually reach heights of over 200 m in some areas.
In addition to meeting the initial stability goal, the design goes further by promoting upstream water retention and lessening impacts on the environment.
billion m³ of waste rock over a 20 km² area
million m³ of water managed over 30 days during the spring thaw
Water flow rate of 14 m3/s