During the first two years of its existence, the Office of the Queensland Mine Rehabilitation Commissioner has visited over 80 mines, held hundreds of stakeholder consultation meetings, and commissioned a range of technical papers on aspects of progressive mine rehabilitation and closure.

This keynote presentation will reflect on the work of the QMRC in its formative years – what we have learned, what we are seeing and what might contribute towards a more enduring model of stewardship of our precious mineral resources.

Many aspects of the mine rehabilitation and closure task have vexed researchers and practitioners alike for decades. Decisions that may have implications for many years into the future must be made in an external environment that is constantly evolving, as a diverse range of stakeholders bring their aspirations to bear on the industry. Deciding what rehabilitation occurs and when, how we avoid sterilising future resources while ensuring we protect environmental values now, suggest the mine rehabilitation and closure task is a “wicked problem”. As such, there’s no right or wrong, “solutions” are highly contestable, and a path forward must involve all parties which benefit from or are affected by, the resources industry.
The presentation will look at the early works commissioned by the QMRC, in ecosystem rehabilitation, regional biodiversity corridor modelling, mine void modelling, options for post-mining land uses of voids, cover systems design and grazing as a post-mining land use.

Some of the trends and performance of the industry in progressive rehabilitation will be presented, focusing on strip mining operations and the challenges emerging from historical practices in metalliferous mining. The growth in rehabilitation ‘backlog’ and the pathways to successful mine ‘closure’ under contemporary environmental regulation will be discussed, and overall trends emerging from ESG-related pressures and the “two speed” industry emerging as some sectors see capital and sentiment exiting, while others see exponential demand growth. These reflections also signal huge opportunity for the industry to continue to be pivotal to regional and national economies despite inevitable transitions in the coming decades.

Coal mining in Queensland has resulted in around 90 Environmental Authorities (EAs) associated with large scale operational mines. Many of these mines will leave one or more residual voids in place at the end of mining. These structures typically fill with water after mining, and evapoconcentration can lead to poor water quality with limited practical use. However, under Queensland’s Environmental Protection Act (1994), the goal for rehabilitation of residual mine voids is to achieve a safe, stable, and non-polluting landform which can sustain a Post-Mining Land Use (PMLU). To work towards robust mine void rehabilitation, it is important to understand both the historic and current planning practices, identify possible PMLUs and the constraints that may limit their implementation. To understand how approaches to planning for voids are changing in Queensland, mine void rehabilitation commitments in existing EAs were compared to those in Progressive Rehabilitation and Closure (PRC) plans. This comparison highlighted that many historic approvals did not clearly describe a PMLU for voids, but that there is a trend towards greater clarity in PRC plans. A review of water quality data submitted to Queensland government showed that the water held in coal mine voids would typically be unsuitable for common PMLUs such as irrigation and stock watering without water treatment. In particular, elevated salinity is likely to limit common PMLUs for many voids in Queensland. Alternatives to water-filled void uses involve backfilling a void, which provides flexibility to achieve a range of PMLUs such as grazing or native ecosystems. Backfilling can also help to minimise risks associated with an open water body and avoid leaving an undesirable landform to the local community and future generations.

The Mine Land Rehabilitation Authority is the independent overseer of Victoria’s declared mine rehabilitation. Currently, only the Latrobe Valley’s three brown coal mines are declared, with each mine at a different stage of rehabilitation and closure planning: Hazelwood ceased mining in 2017, Yallourn is scheduled to end mining in 2028 and Loy Yang in 2035.
The three declared mines are very large, close together and present significant environmental risks that must be mitigated during rehabilitation and post closure. In addition to fire risks, the brown coal mines are inherently unstable and require continuous monitoring and management of ground movements and groundwater pressures.
The Authority has a number of roles including:
o Overseeing Mine rehabilitation
o The requirement to create a register of rehabilitated mine land that defines the controls to be implemented by future landowners post closure
o Possible ownership of high-risk land
o Assisting with the assessment of post-closure funds
o working with, listening to and involving the community in all matters related to mine rehabilitation and its long-term use
The Authority is but one example of several models that have been or are being implemented around the world that are all predicated on the specific conditions that prevail in the different regions. The different models present common themes that highlight the complexity of transitioning away from mining to future land uses that deliver positive outcomes for affected communities. Meeting in perpetuity obligations underpin all models.