Rehabilitation of tailings impoundments for final closure is one of the most challenging aspects facing engineers, as not only does the potential for producing leachate pose a challenge to the rehabilitation designer, but also other aspects such as stability and settlement must be considered. The water balance of a tailings impoundment is unique in the sense that it usually hosts a pond that in turn causes a phreatic surface in the impoundment. The position of the phreatic surface defines the saturated and unsaturated zones in the impoundment, which of course varies spatially and temporally. Predictive modeling for this hydrologic system becomes difficult, as numerical models capable of analyzing the combined saturated/unsaturated zones are not adequately refined to accurately solve the flux boundary problem for infiltration at the surface of the tailings..