Tailings impoundments continue to undergo failures at an unacceptably high rate, including failures at operations owned by high profile mining companies. These failures are often the result of a combination of design, construction and operation actions that are controlled by humans and must be better coordinated and managed in the future. The consequence of failure can be the widespread flow of tailings, environmental damage, social license to operate, company value and mining industry sustainability. Any additional technology and information that enables an owner of a tailings impoundment to be more certain of its condition, and thereby reduce the risk of failure is of tremendous value to tailings and mine water management. One method that can provide valuable information involves the injection of a low frequency electrical current in the ground between two electrodes generates a magnetic field that can be measured at the ground surface with sensitive magnetic sensors. The map of the magnetic field, measured at the frequency of the injected current, can be used in turn to determine the position of the current paths in the ground. When the current is channeled in conductive paths, the Magnetometric Resistivity (MMR) method can be used to detect these paths. Conductive current paths are then interpreted as preferential seepage flow paths. A case study, from a tailings impoundment at a Zinc Mine in Tennessee, USA, is also shown. Several preferential paths of electric current were identified and interpreted as preferential seepage flow paths out of the impoundment. One in particular, identified the source and path of a spring downgradient of the impoundment (referred to as the “Big Seep”) that appeared decades ago without any explanation. This method has been shown to be an effective tool to model preferential seepage flow paths and assist in targeted remedial works.
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