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Using Technology to Identify Seepage Flow Paths Through, Under and Around Tailings Impoundments

Tailings and Mine Waste Conference (2019 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

Tailings impoundments continue to undergo failures at an unacceptably high rate, including failures at operations owned by high profile mining companies, for example the Brumadinho Dam failure in Brazil. 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 discharge of tailings, environmental damage and loss of life. 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. The Magnetometric Resistivity (MMR) method can provide valuable information, and it involves the injection of a low frequency electrical current in the ground between two electrodes generating a magnetic field that can be measured at the ground’s 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 electric current paths in the ground. When the electric current is channelled in conductive paths, the MMR method can be used to identify the location of these paths. Conductive current paths are then interpreted as preferential seepage flow paths. A case study from Recycle Tailings Pond (RTP) at a gold mine in Alaska, USA is also presented. This dam had known seepage problems at the downstream toe of the dam. One grout curtain along the upstream toe of the dam and three smaller curtains that ran parallel to one another near the south abutment were installed to mitigate the seepage. Unfortunately, the seepage issues continued after the grout curtains were installed. A MMR investigation was performed on the tailings dam and the results showed the exact location of a preferential seepage flow path that bypassed the toe grout curtain and flowed through the dam. The remainder of the dam was performing as designed. With this information the client was able to make additional repairs and mitigate the seepage issues.

Text

2024-02-15

Attribution-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87434

Unreviewed

http://creativecommons.org/licenses/by-nd/4.0/