Sonnekus, K & Ochocinski, C 2025, 'Slope stability design acceptance criteria for closure of the Victorian Latrobe Valley coal mines', in S Knutsson, AB Fourie & M Tibbett (eds), Mine Closure 2025: Proceedings of the 18th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-7, https://doi.org/10.36487/ACG_repo/2515_05
(https://papers.acg.uwa.edu.au/p/2515_05_Sonnekus/)
Abstract: Design acceptance criteria (DAC) for the stability of open pit mines are often based on widely accepted industry standards, such as those quoted in renowned literature like Read & Stacey (2009) or Hawley & Cunning (2017). However, these standards are only applicable to the operational phase of the mine life cycle and may not reflect the increased long-term uncertainty and lower degree of operator management associated with the closure phase. They also may not be applicable for complex geological environments, namely lignite mines. A desktop review of timely and relevant technical guidance was undertaken to examine the feasibility of developing stability DAC for open pit mine closure, with a focus on the Victorian Latrobe Valley coal mines. After consideration of critical issues during and after closure, as well as published literature around design confidence during the mine lifecycle, the concept of data reliability was included as a measure for determining appropriate DAC. This paper proposes a set of stability DAC, in terms of Factor of Safety and/or Probability of Failure, which is contingent upon the level of data reliability, in terms of coefficient of variation that can be achieved for open pit mine closure. It is recommended that these criteria, if adopted, are reviewed and adjusted so that they are made site-specific to the project of interest.
This paper is designed to address the aforementioned issue via the use of conventional and published metrics. It is acknowledged that further work has recently been published, such as CSIRO’s Guidelines for Open Pit and Waste Dump Closure (eds de Graaf et al. 2025), which establishes new means of quantifying closure objectives and performance. This paper does not aim to supersede or contest those works but presents a potential solution as an alternative approach while uptake by industry is underway.

Keywords: mine closure, design acceptance criteria, Latrobe Valley coal mines, data reliability, coefficient of variation