A high-resolution 4D groundwater flow model for transient pit wall pore pressure and mine inflow estimates was developed for the large open pit mine. The model capitalises on FEFLOW advances, including the application of a fully unstructured mesh that honours the complex geologic model including the explicit incorporation of 56 faults in the pit area. The model, calibrated to historical flow and head measurements, was used to predict pit wall pore pressures through time and identify sectors that will require additional effort to depressurise.