Guidance material for mine design

Identification and assessment of final (i.e. post-mining) land use options.

Identification and justification of the preferred final land use outcome(s), including a discussion of how the final land use(s) are aligned with relevant local and regional strategic land use objectives and surrounding land uses.

Identification of how the rehabilitation of the project will relate to the rehabilitation strategies of any neighbouring mines within the region, with a particular emphasis on the coordination of rehabilitation activities along common boundary areas.

Inclusion of a set of project rehabilitation objectives that clearly define the outcomes required to achieve the final (post-mining) land use for each mining domain. Each mining domain must have a stated final land use and rehabilitation objectives (which describe the desired features and/or characteristics of the final land use domain). Rehabilitation objectives must include, where relevant, target vegetation communities.

The expected time frames for progressive rehabilitation.
Mine layout and scheduling, including maximising opportunities for progressive final rehabilitation. The final rehabilitation schedule should be mapped against key production milestones (i.e. ROM tonnes) of the mine layout sequence before being translated to indicative timeframes for each stage of rehabilitation throughout the mine life. The mine plan should maximise opportunities for progressive rehabilitation.

Inclusion of drawings at appropriate scales identifying key attributes of the final landform, including final landform contours, section views, significant water management features/structures, the location of the proposed final land use(s) and integration with existing and surrounding landforms. 

Identification and description of those aspects of the site or operations that may present barriers or limitations to effective rehabilitation, including an assessment of high risk rehabilitation landforms (such as high walls, steep slopes, waste rock dumps, etc). This should include (as relevant): 

• an assessment and life of mine management strategy of the potential for geochemical constraints to rehabilitation (e.g. acid metalliferous drainage, spontaneous combustion etc.), particularly associated with the management of overburden/interburden and reject material. This assessment should utilise any relevant data from previous exploration programs to characterise the geochemical properties of the materials and identify appropriate management strategies. This should include any emplacement strategies (e.g. how materials are emplaced to minimise oxidation and leachate), capping strategies, the source of capping materials, associated volume of capping materials required, routine sampling and testing; 
• the processes that will be implemented throughout the mine life to design and ensure the long term stability of the rehabilitated landforms, including how characteristics of the existing and surrounding landform can be incorporated into the final landform design. This should include identifying and adopting geomorphic design principles to achieve a natural and stable landform outcome. It should also include a constraints and opportunities analysis of alternative final landforms giving consideration to geotechnical stability, geomorphic stability (soil types, soil erosion, etc), water management, integration with the characteristics of the surrounding natural landform and minimising sterilisation of land post-mining. For large and complex sites, there should be a commitment to undertake landform evolution modelling throughout the mine life to address long-term erosion and stability risks;
• a life of mine tailings management strategy, which details measures to be implemented to avoid the exposure of tailings material that may cause environmental risk, as well as to ensure the geotechnical and geomorphic stability of the rehabilitated landform of the tailings storage facility. This should include any capping strategies, the source of capping materials and associated volume of capping materials required. It should also include a constraints and opportunities analysis of different tailings management techniques (e.g. co-disposal, dewatering tailings, integrated landforms, etc) and of alternative techniques to reduce the amount of tailings and reliance on conventional tailing storage facilities. Justification of the proposed tailings management strategy should be provided to demonstrate that it is the most feasible and environmentally sustainable option;

Where a void, is proposed to remain as part of the final landform, include: 

• a constraints and opportunities analysis of final void options, including backfilling, to justify that the proposed design is the most feasible and environmentally sustainable option to minimise the sterilisation of land post-mining; 
• a preliminary geotechnical assessment to identify the likely long term stability risks associated with the proposed remaining high wall(s) and low wall(s) along with associated measures that will be required to minimise potential risks to public safety; and 
• outcomes of the surface and groundwater assessments in relation to the likely final water level in the void. This should include an assessment of the potential for fill and spill along with measures required be implemented to minimise associated impacts to the environment and downstream water users. 

Where the mine includes underground workings: 

• determine (with reference to the groundwater assessment) the likelihood and associated impacts of groundwater accumulating and subsequently discharging (e.g. acid or neutral mine drainage) from the underground workings post cessation of mining; and 
• consideration of the likely controls required to either prevent or mitigate against these risks as part of the closure plan for the site. 

Where an ecological land use is proposed, demonstrate how the revegetation strategy (e.g. seed mix, habitat features, corridor width, aspect, etc.) has been developed in consideration of the target vegetation community(s).

Where the intended land use is agriculture, demonstrate that the landscape, vegetation and soil is capable of supporting this land use. In addition, demonstrate that the proposed location of the rehabilitated agricultural area is not isolated within the landscape and that there is ready access to water and relevant infrastructure (e.g. power, roads etc.) to support agricultural activities.

Consider the following relevant policies and guidelines. 

• Mine Rehabilitation (Leading Practice Sustainable Development Program for the Mining Industry, Australian Government, 2016)
• Mine Closure (Leading Practice Sustainable Development Program for the Mining Industry, Australian Government, 2016)
• Strategic Framework for Mine Closure (ANZMEC-MCA, 2000)
• Guidelines on Tailings Dams – Planning, Design, Construction, Operation And Closure – Revision 1 (ANCOLD, July 2019)
• Integrated Mine Closure: Good Practice Guide (ICMM, 2019)