Gregory, S, Mackenzie, S & Bow, B 2019, 'The Pardoo mine: closure planning, implementation and five years of performance monitoring data', in AB Fourie & M Tibbett (eds), Proceedings of the 13th International Conference on Mine Closure
, Australian Centre for Geomechanics, Perth, pp. 457-470, https://doi.org/10.36487/ACG_rep/1915_38_Gregory
The Pardoo mine, located in the Pilbara region of Western Australia, is owned by Atlas Iron Pty Ltd. Mining commenced in October 2008 and reserves were depleted in 2013. The Project consisted of 11 open pits, six waste rock landforms and mining infrastructure.
This paper describes the risks to closure that were identified for the Project and the investigations and stakeholder engagement that Atlas undertook to mitigate these risks. The closure works that were undertaken and the results of five years of performance monitoring data, along with a comparison of rehabilitation performance against agreed closure criteria are also described. This represents the halfway mark of the planned 10-year monitoring period.
Detailed closure planning commenced in 2010 and was initiated using a risk assessment workshop to identify all closure risks. The highest risk events for closure of the Project included; a poor revegetation outcome, and failure of engineered structures. To mitigate these risks, and others, Atlas undertook a series of targeted closure investigations to ensure that knowledge gaps were filled, and appropriate control mechanisms were implemented. This work facilitated the development of the detailed mine closure plan (MCP), which was submitted and approved in 2013.
Closure works were implemented according to the MCP between late 2013 and early 2014. Closure performance has now been assessed for five years and closure criteria developed for the Project have already been met in some areas.
The early success of closure works at the Project was attributed to the identification of key risks, investigations which closed key knowledge gaps, stakeholder engagement being conducted early in the closure planning process and high-quality closure works.
Closure planning at the Project was initiated with the development of a conceptual mine closure plan in 2008 and detailed closure planning started during 2010. The closure planning process adopted by Atlas commenced with a closure risk assessment from which multiple knowledge gaps were identified. Atlas subsequently undertook a program of investigations and studies to fill these knowledge gaps and an extensive stakeholder engagement program. All information collected during the closure planning process was fed into the development of a detailed MCP (Atlas 2013).
A series of mine closure risk assessment workshops were undertaken for the Project. The objectives of the risk assessment were to identify, rank and prioritise risks, to develop management options for risk events that could compromise closure objectives, and to assist with managing uncertainty. The risk assessment process aligned with the Australian and New Zealand Risk Management Standard (AS/NZ 31000:2009) (International Organization for Standardization 2009). Key risk associated with vegetation and surface water/erosion are presented in Table 1.
Atlas 2013, Pardoo Mine Closure Plan, October 2013, prepared by Mine Earth.
International Organization for Standardization 2009, Risk Management – Principles and Guidelines (ISO31000:20090), Geneva.
Mine Earth 2012, Closure Recommendations for Waste Rock Landforms, November 2012, internal report for Atlas Iron Pty Ltd.
Mine Earth 2019, Pardoo DSO Project, Mine Waste Landform Erosion Assessment, February 2019, internal report for Atlas Iron Limited.
MWH 2013, Pardoo Mine Closure Hydrological Investigation, January 2013, prepared for Atlas Iron Limited.
Outback Ecology Services (OES) 2012, Pardoo DSO Project, Soil Resource Assessment, November 2012, internal report for Atlas Iron Pty Ltd by Outback Ecology Services.
Stantec 2018, Rehabilitation Assessment of the Pardoo Mine, November 2018, prepared for Atlas Iron Limited.
Trajectory 2013, Pardoo Mine Rehabilitation Plan, January 2013, internal report for Atlas Iron Pty Ltd.