Building Better Water Balance Models to Proactively Manage Water Quality for Mine Rock Stockpiles and Tailings Storage Facilities

In mining operations, seepage from mine rock stockpiles and tailings storage facilities often constitutes a small proportion of the overall site-wide water balance. However, its effect on downstream water quality can be disproportionately significant. Many water balance models developed during the permitting stage rely on simplified, empirical assumptions about the hydrology of these facilities, which frequently overlook critical source-control measures such as construction sequencing and progressive cover placement. The common justification for using simplified empirical assumptions in water balance models is the uncertainty and limited data regarding the internal processes in stockpiles. Despite these uncertainties, we propose shifting toward explicitly representing the physical processes of mine rock stockpiles and tailings storage facilities in water balance models, as they offer significant advantages. These models integrate detailed hydrological mechanisms and provide robust tools for scenario simulation and sensitivity analysis. By embracing an “open-box” modelling approach, we can transparently communicate key processes and uncertainties, fostering trust and improving stakeholder understanding, particularly during the permitting phase. Physically based models create opportunities to refine water management strategies by simulating different scenarios and identifying proactive measures to mitigate risks. This approach enhances confidence in water balance outputs while supporting better decision-making, aligning with the mining sector's increasing focus on sustainability and environmental responsibility. This paper presents a mining case study that demonstrates the benefits of adopting physically based models for mine rock stockpiles and tailings storage facilities. It provides actionable insights for addressing uncertainties while developing defensible, stakeholder-focused models that better reflect real-world conditions. By leveraging these innovative methods, mining operations can proactively tackle water quality challenges with greater confidence and clarity.