Howard, EJ & Loch, RJ 2019, 'Acceptable erosion rates for mine waste landform rehabilitation modelling in the Pilbara, Western Australia', in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1545-1560, https://doi.org/10.36487/ACG_rep/1915_121_Howard
(https://papers.acg.uwa.edu.au/p/1915_121_Howard/)
Abstract: A major concern for rehabilitation and closure of waste landforms on mine sites is their long-term erosion stability. In Western Australia, regulators are requesting landforms remain ‘stable’ for hundreds of years or the ‘long-term’. Therefore, assessing a landform’s potential long-term erosion stability requires the use of erosion and/or landform evolution models and defensible erosion thresholds below which rehabilitation landform designs are considered acceptably erosion resistant or ‘stable’.
The Pilbara Rehabilitation Group, through four member companies—BHP, Fortescue Metals Group, Rio Tinto, and Roy Hill—initiated a project aimed at defining acceptable rates of erosion for rehabilitation landform design for the Pilbara region of Western Australia. As part of the project, a review of information relating to erosion rates on natural and man-made landforms was conducted. This review showed that a wide range of approaches have been used to define acceptable erosion rates, including linking them to rates of soil formation; maintenance of soil quality, which may include considerations of plant/crop productivity, effective soil depth, and soil organic matter and nutrient stores; rates of natural erosion in adjoining areas; potential for gully formation; and water quality impacts. Based on this review, a guideline was developed to define acceptable erosion rates for use in the design of stable mine waste landforms in the Pilbara region. The guideline uses a risk-based approach, with erosion thresholds being linked to the waste material’s physical properties and the adverse environmental impacts that may result from landform failure.

Keywords: landform design, erosion, acceptable rates, Pilbara