Resume/ Abstract
The Canadian Malartic Mine (CMM) is one of the largest gold mines in Canada. Conventionally, waste rock and tailings (WR&T) have been disposed into two separate storage facilities. Since 2022, waste management has undergone a complete transformation into an open-pit backfilling operation. Co-placement WR&T into a pit reduces the disturbance of natural surfaces and the environmental impacts. First, a central berm of dumped WR is built to divide the pit into two sections. Then, tailings are poured into their separate section but remain in contact with the central WR dump. Tailings drainage water flows through the WR and is captured in the lowest point to be recycled. The water collection is protected by a granular filter to avoid clogging. However, the main structure of WR is subjected to tailings migration upon infiltration, and its hydraulic conductivity could be affected. WR&T interactions are crucial to an efficient co-placement operation; however, they are poorly understood and not sufficiently documented. The main objective of this study is to assess tailings migration through the structure of WR in the backfilling project at CMM. A large strain consolidation model and multiple steady-state-flow models are used to calibrate field observations, allowing the estimation of tailings migration through decreasing hydraulic conductivity of the WR. The results indicate a significant migration of tailings over time, which accurately correlates with field monitoring data. The results contribute to a better understanding of co-placement facilities and provide insights about potential challenges.