Design, construction, monitoring and numerical modeling of large-scale field trials: assessing cover performance for reclamation method selection

The selection of the reclamation method for tailings storage facilities (TSF) can pose significant challenges, necessitating innovative approaches to its comprehensive evaluation. Four large-scale field cells were constructed at Canadian Malartic Mine (Quebec, Canada) to address specific considerations for selection of the reclamation method, particularly in terms of the constructability and performance of the covers. Each cell was instrumented with a dense system of hydrogeological and oxygen probes. Two meteorological stations were installed to record local climate conditions. The index properties of the cover materials were used to estimate the hydrogeological properties. Field data, comprising thorough monitoring of climate conditions and hydrogeological evolution, were integrated into a 2D transient numerical model in SEEP/w. This paper presents the methodology and the calibration results of the numerical model of one low permeability cover cell. The numerical model calibration involved the estimation of the spatial distribution of the material properties such as porosity, hydraulic conductivity, and the water retention curve. The calibrated results were consistent with observed field data, highlighting the reliability of the numerical model when combined with extensive monitoring and characterization to accurately represent the complex hydrogeological dynamics in the multi-layer covers. This case study demonstrates the capacity of a numerical model to effectively represent the hydrological evolution of the covers, and how large-scale field trials combined with comprehensive data can enhance confidence in the selection of the reclamation method.