Abstract

The phreatic surface and seepage field are key factors causing instability in tailings storage facilities (TSFs). In this study, electrical resistivity tomography (ERT) was used to determine the internal structure and phreatic surface of the TSF of Husab Mine. The seepage pathways at the southeast and northwest corners of the TSF were identified and the seepage mechanisms were analyzed. In order to discharge the slurry, outlets equipped with valves were installed on the tailings embankment. During the deposition process, time-lapse electrical resistivity tomography (TL-ERT) was conducted to monitor the infiltration of water around the W13 outlet. The results show that the tailings sediments were divided into three layers based on resistivity values. The top layer consisted of shallow, unsaturated tailings material, while the middle layer comprised saturated tailings material. The thickness of the saturated zone gradually increased from the dam toward the decant pool. The bottom layer consisted of the geomembrane liner and natural sediments. Two seepage locations, named the Lebusa corner and Alister corner, were located at the southeast and northwest corners of the TSF, respectively. Seepage occurred because clarified water originating from the decant pool migrated through the saturated zone of the tailings pond, along the base of the tailings embankment. Upon encountering the starter dam, the water was impeded and subsequently emerged as seepage at the junction between the starter dam and the tailings embankment. TL-ERT monitoring shows that the extent of increased moisture was approximately 60 m horizontally and roughly 10 m vertically due to deposition at the W13 outlet.

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