A quantitative and practical method for prioritising contaminated sites to support mine closure planning

Authors: Hari, E; Brabham, P; Mason, R; Holland, M Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2615_82

Cite As:
Hari, E, Brabham, P, Mason, R & Holland, M 2026, 'A quantitative and practical method for prioritising contaminated sites to support mine closure planning', in AB Fourie, G Boggs, J Heyes & M Tibbett (eds), Mine Closure 2026: Proceedings of the 19th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-16, https://doi.org/10.36487/ACG_repo/2615_82



Abstract:
Mining operations typically contain hundreds of potential contaminant sources that differ in size, complexity and risk. As mine plans evolve, rehabilitation progresses, and regulatory expectations increase, mining companies need a consistent way to identify which contaminated areas require action first. Without a structured method, prioritisation often depends on expert opinion, which can be inconsistent, difficult to explain, and difficult to align across large operations. To address this challenge, we developed the risk assessment and prioritisation tool (RAPT), a quantitative, multi-criteria approach that evaluates all contaminated areas against a common set of measures. The method brings together environmental, operational, regulatory and social factors, including geological and hydrogeological considerations, within the scoring criteria and converts them into a transparent risk score. This allows contaminated areas to be compared on a like-for-like basis, even when the risks are very different in nature. It also highlights where early action reduces long-term risk, where investigation adds the most value, and where issues can be safely managed through routine controls. The approach supports adaptive decision-making by allowing priorities to shift as site conditions, mine plans or regulatory requirements change, while still keeping the contaminated sites program aligned with key milestones such as progressive rehabilitation, closure strategies and approvals. This helps reduce program bottlenecks, improves sequencing and allows limited resources to be directed where they have the greatest impact. The paper explains how the method evaluates each area, how the criteria are weighted, and how the tool calculates risk scores to create a clear and defensible prioritised list. This includes examples of how contaminant type, exposure pathways, proximity to sensitive receptors, operational constraints and closure dependencies influence the final ranking. The work demonstrates how a structured, quantitative approach improves the way contaminated sites are identified, compared and prioritised, ultimately supporting safer operations, better environmental outcomes, and more efficient mine closure planning.

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