Mine Pit Lake Assessment and Management: A National Initiative to Support Mine Closure and Regional Opportunities

The Challenge 

Most recent estimates suggest that 92 per cent of Western Australia’s ~26,500 mines are inactive, with only 12 per cent of inactive mines classified as rehabilitated. This mimics national and global trends. There is a need to reverse these statistics. Changing closure ambitions from rehabilitation to beneficial post-mining reuse creates new opportunities for mining regions. However, there are numerous regulatory, technical and economic hurdles that can undermine the likelihood of reuse success. A significant challenge is quantifying residual risks and the reuse value of open pit mines that extend below the natural water table and are dewatered during mining operations. While the primary concern for mine closure is ensuring that mine voids are geologically stable and safe to the public, the pit lakes that form when dewatering ceases could provide a valuable resource for regional communities. Quantifying post-closure risks and realising the potential for this water resource will support mine relinquishment and sustainable post-mining economies. 

Proposed Solution 

There is a need for transformational research that links stakeholder preferences to state-of-the-art computational platforms, underpinned by the latest data and understanding of pits in mining environments. This project will develop guidance that can be used to assess risks and potential end-uses for pit lakes across Australia, as well as recommendations for the technical data and approach required for fit-for-purpose pit lake modelling. These tools will be informed by state-of-science approaches to pit lake assessment and management, and consultation to understand stakeholder views of risk and opportunity. In addition, case studies representing priority mine pit lake scenarios for Australia will be developed to explore the post-mining value of pit lakes. These case studies will particularly focus on whether management options for improving water quality for post-closure reuse can match stakeholder aspirations. 

Proposed Benefits to WA 

This research will increase the likelihood that open cut mines are managed for alternative reuse purposes, ensuring mines are closed and formally relinquished rather than abandoned. Like many other jurisdictions, Western Australia’s regulatory framework for mine closure currently recommends a risk-based assessment of pit lakes, focussed on environmental and public safety. This research will help address the current environmental legacy of WA mining and support better planning and a reduced environmental footprint for future WA mines. It also supports WA regional communities in deriving economic and social amenity value from end-state mine voids