Numerical Modelling for Mine Closure and Pumped Hydro Feasibility

A pumped hydro energy storage system was the proposed use of a mine pit and adjacent tailings pond after mine closure. As the mine was located in an arid climate, it was important to understand whether groundwater inflow into the pit would balance the evaporative losses from the surface water in the pit lake. Available observation data included water level fluctuations during the thirty years of historical mining activity. A model simulating the historic mining activity was constructed in FEFLOW using time varying boundary conditions and material properties to simulate the advancement of mining activity.

An Iterative Ensemble Smoother (IES) approach was used for calibration and uncertainty analysis. This approach allowed for a high degree of parameterization and the use of geostatistical realizations of potential hydraulic conductivity distributions that were oriented along the direction of regional tectonic stress.

This approach successfully enabled predictive uncertainty to be quantified with 150 alternative “calibrated” parameter sets available