2017 – Tailing Dams – How Do We Make Them Safer?

Dr Andy Hughes

Tailings dams continue to undergo failures at an unacceptable rate compared to water storage dams, including failures at operations owned by high profile mining companies.Tailings dams have often a different form and method of construction than water storage dams in that tailings dams continue to be raised over time as part of the mine operations and rise to considerable heights. These failures are often the result of a combination of design, construction and operations actions that are controlled by humans and must be better coordinated and managed in the future. The consequence of failure can be widespread flows of tailings and water over the landscape and water courses. This can have extreme consequences in terms of life loss, environmental damage, social license to operate, company value, and mining industry sustainability. Therefore,it is necessary that the mining industry strive for zero failures of tailings facilities. Any additional technology and information that enables an owner of a tailings dam to be more certain of its condition and thereby reduce the risk of failure is of tremendous value to reliable tailings and mine water management.The Willowstick method uses low voltage, low amperage, and alternating electrical current to directly energise the groundwater by way of electrodes placed in wells or in contact with seepage or leaks. This approach has been successfully used to identify water flow paths through, under and around tailings dam in plan and elevation.The Willowstick technology provides additional information to supplement the geological, geotechnical and hydrological, evaluations analyses and designs, and to further improve tailings dam safety by more robust designs if necessary. This paper, using several tailings dam case studies, illustrates the procedure, findings, and the benefits of the Willowstick methodology. The findings of many Willowstick surveys range from tailings dams where the methodology has confirmed the design evaluations, to tailings dams where new groundwater and leakage flow paths were identified. In the latter case, the dam designers were able to update the designs, based on the new information,to mitigate the identified risks and to improve the overall safety of the tailings dams in accordance with the goal of zero failure.

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