Authors: Gregory, SJ; Mackenzie, SP; Sprenkels, TJ; Slabber, AG

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DOI https://doi.org/10.36487/ACG_repo/2215_63

Cite As:
Gregory, SJ, Mackenzie, SP, Sprenkels, TJ & Slabber, AG 2022, 'Applying monitoring data to measure and improve rehabilitation performance at four mine sites in the Pilbara region of Western Australia ', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 869-882, https://doi.org/10.36487/ACG_repo/2215_63

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Abstract:
Atlas Iron Pty Ltd (Atlas) rehabilitated four iron ore projects in the Pilbara region of Western Australia between 2013 and 2017. Rehabilitation works at each project have involved reshaping and revegetation works on waste rock landforms (WRLs), construction of abandonment bunds and removal of non-essential infrastructure. Atlas has set a target to demonstrate the achievement of completion criteria for all WRLs within 10 years of completing the rehabilitation works. This paper explores the temporal trends in rehabilitation monitoring data across the four projects and how the monitoring data has been used to inform remedial works that have been undertaken to improve rehabilitation performance. Uncontrolled surface water/erosion and poor revegetation were identified as key closure risks for the projects and, as such, the emphasis in this paper is on vegetation and erosion performance on the rehabilitated WRLs. Vegetation performance has been assessed using traditional methods including plots and transects, along with visual spectrum and multispectral imagery. Erosion performance has been assessed using orthophoto and digital elevation model (DEM) data. Rehabilitation performance has been compared against the completion criteria, which have been agreed upon with regulators and other stakeholders and have been derived using data collected from a combination of rehabilitated areas and natural analogue areas. Rehabilitation performance has been variable across the projects but has generally been successful, and multiple rehabilitated areas are already meeting the agreed completion criteria. The monitoring data has indicated that a small number of rehabilitated areas are unlikely to meet the completion criteria. Atlas uses the annual monitoring data to determine their priorities for remedial works in rehabilitated areas. Remedial works have consisted of implementing drainage controls, stabilising slopes and repairing erosion gullies, reseeding, weed management, and constructing fences to exclude livestock.

Keywords: rehabilitation, completion criteria, monitoring, erosion, vegetation, remedial works

References:
Atlas Iron 2013, Pardoo DSO Project, Mine Closure Plan, prepared by Mine Earth, Perth.
BOM 2022, Climate Data Online, retrieved from Australian Government, Bureau of Meteorology,
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Mine Earth 2020, Wodgina Mine Closure Plan, prepared for Atlas Iron, Perth.
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Woodman Environmental 2019a, 2019 Rehabilitation Monitoring, Abydos Iron Ore Project, prepared for Atlas Iron, Perth.
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