Effective closure planning and site rehabilitation are important priorities for MMG. We have an integrated approach to planning the closure and relinquishment of our assets, commencing from the development stage and continuing throughout the asset life cycle. We have a Progressive Rehabilitation and Closure Standard with supporting Work Quality Requirements that provide a consistent approach to closure and progressive rehabilitation across all of our global operations.
In alignment with the 2019 ICMM Closure Good Practice Guide, Rosebery is advancing mine closure planning activities from the ‘conceptual’ to the ‘detailed design’ phase. In 2019, Rosebery commenced a mine closure prefeasibility level of design study that aims to identify and evaluate all credible mine closure scenarios before recommending a preferred mine closure pathway. This study will also involve discussions with regulatory organisations, the community and other key stakeholders to identify suitable site relinquishment criteria for the mine.
A key part of the project is the identification of potential opportunities to progressively rehabilitate landforms and infrastructure during the operational life of the mine. This will help minimise final closure costs, efficiently utilise onsite personnel and assets and, wherever possible, restoration of the site can be commenced well before production ends. Two full-time employees have been employed to help run this prefeasibility closure study, along with the use of external consultant experts.
An example of this is the commencement of technical investigations into the rehabilitation options for the Bobadil tailings storage facility (TSF), which is approaching the end of its operational life. Simulation modelling was completed in early 2019 to assess several TSF closure designs and their relative performance on minimising potential influences on the downstream receiving environment of Lake Pieman. Two preferred closure capping systems have now been identified and these will be tested via instrumented field scale trials, planned to be installed in 2020. Performance data for each of the trial plots will be collected over the next two to three years, allowing refinement of the TSF closure model with site specific data. This key project enables location specific closure capping methodologies to be developed for the Bobadil TSF well before the end of tailings deposition so that long-term geotechnical and geochemical risks are managed.
