Authors: Narendranathan, S; Faithful, J; Patel, N; Stipcevich, J

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Narendranathan, S, Faithful, J, Patel, N & Stipcevich, J 2021, 'A case study – from operation to closure, transient slope supplementation measures for the northern batters of the Hazelwood Mine, using the MGRI approach', in AB Fourie, M Tibbett & A Sharkuu (eds), Mine Closure 2021: Proceedings of the 14th International Conference on Mine Closure, QMC Group, Ulaanbaatar,

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In the mining industry risk is conventionally applied under absolute conditions (e.g., operational scenarios or say a rehabilitated scenario); However, challenges arise when applying these methods to a mine that is in a transient state (i.e., transitioning from operational to final rehabilitated conditions). The closure of Hazelwood Mine, Victoria, Australia, presents a number of unique challenges in this regard. The Mine is considering a full pit lake as part of their rehabilitation and closure plan. Extensive batter stability analyses have indicated that partial lake fill options can lead to a sub optimal outcome for long term mine batter stability. The Northern Batters of the Hazelwood Mine are within close proximity to the Princes Freeway and Morwell township and have been identified as a ‘critical’ mine batter within the Ground Control Management Plan (GCMP). As such, more stringent design acceptance criteria have been nominated for the Northern Batters during the transient state. It has been determined that during lake filling some sections of the Northern Batters would require slope supplementation measures to be installed to further improve the stability outcome. The design of temporary slope supplementation measures in such transient scenarios (lake filling) need to be carefully considered as there can be an elevated risk profile where adequate treatment is not applied. The Mine Geotechnical Risk Index (MGRI) was developed by Narendranathan et al. (2019) to propose a methodology for quantifying risk under such transient states with specific consideration to mining and geological conditions in the Latrobe Valley. This paper presents a case study on the design of transient state slope supplementation measures for the Northern Batters of the Hazelwood Mine using the MGRI approach. This ultimately resulted in the identification of critical slope sections which required supplementation. The slope supplementation measures identified through the MGRI process and the method by which these slope supplementation measures are to be installed will be outlined in the paper.

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