Authors: Narendranathan, S; Patel, N; Mok, T; Stipcevich, J; Symonds, A

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Narendranathan, S, Patel, N, Mok, T, Stipcevich, J & Symonds, A 2022, 'A case study: conceptual rehabilitation and closure planning for the Loy Yang mine using the risk-based probabilistic approach employing the Mine Geotechnical Risk Index methodology', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 449-462,

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In the mining industry, risk is conventionally evaluated under absolute conditions – that is, operational scenarios or, say, a completed rehabilitated scenario. However, challenges arise when applying these methods to a mine that is in a transient state – that is, transitioning from operation to final rehabilitated conditions. Risk-based approaches, such as the Mine Geotechnical Risk Index (MGRI) developed by Narendranathan et al. (2019), may be adopted to quantify the geotechnical risks associated with lake filling, and are useful tools for assessing transient risk profiles. AGL’s Loy Yang mine, located in Victoria, Australia, is in the process of rehabilitation and closure planning and is considering a full lake option as part of their final landform. This paper demonstrates how the MGRI approach was successfully employed to assess the batter stability implications during proposed lake filling so as to determine slope supplementation requirements under varying pit lake levels, to conceptualise transient slope supplementation measures to manage slope stability–related risks during this phase.

Keywords: rehabilitation and closure, post-closure, large open cut coal mine, risk-based stability assessment

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