Abandoned mines are detrimental to the environment and to the communities that surround them. To be granted access to future resources the mining industry must demonstrate it can effectively and sustainably create, manage, and close a mine.
Sustainable completion and relinquishment of a mine should include the delivery of a clear Mine Closure Plan defined during the feasibility study phase and considered throughout the Life of Mine (LoM). A Mine Closure Plan should be carefully and considerately thought out, as it is a critical component of environmental management for the mining industry.
Leaving A Successful Resources Legacy
A mining company’s future is dependent on the legacy it leaves behind so the business needs to practice sustainable development, follow Government legislation, and ensure the local community is looked after.
Figure 1: The mineral resources legacy.
Source: Australian Government Mine Closure: Leading Practice Sustainable Development Program
How the three legacy rings (demonstrated in Figure 1) are tackled will determine what kind of legacy is left behind once a mine has closed. If poorly managed the legacy of a mining company would be negative, inviting disaster for the business. To leave a positive and successful legacy early planning, progressive rehabilitation during operations and effective execution of the decommissioning, rehabilitation and relinquishment phase is vital.
Appropriate Management of Environmental Impacts
The appropriate management of materials and the landscape is critical throughout the LoM. Many impacts on the environment need to be considered such as the permanent alteration of existing landforms, disturbance to flora and fauna, hydrological impacts, and contamination.
The removal of mining materials, infrastructure, and by-products post-mining is key. One emerging trend is the focus on a ‘circular economy’ (demonstrated in Figure 2), which explores ways to repurpose and reuse as much as possible. For example, existing structures could be moved to another mine.
Figure 2: The Circular Economy System.
Source: The Ellen Macarthur Foundation.
The development of infrastructure for a mine site interrupts natural drainage paths. Interference with drainage patterns can result in deprivation of water to vegetation that may rely on intermittent flows. Clearing of vegetation for the mine, waste rock landforms, processing plants, tailings storage facilities and associated infrastructure can also directly impact flora.
Impact on fauna is either primary or secondary. The direct destruction of habitats through land clearing and earthmoving are considered a primary impact. Secondary impacts relate to activities that create a disturbance, such as access and haul roads, powerlines, pipelines and transport corridors, other key infrastructure, and general workforce activities.
It has been well documented that chemical reactions in tailings have the potential to be detrimental to the environment and its rehabilitation. Contamination to surface soils, groundwater and surface water is a real concern. Mining and processing operations require the transport, storage and use of a range of hazardous materials including fuels, process reagents, lubricants, detergents, explosives, solvents, and paints. These materials must be properly managed and disposed of to avoid atmospheric, soil or water contamination and eliminate ongoing risk to human health and the environment.
Identification and Mitigation of Risk to the Environment
A risk management approach during the LoM is integral to mine closure planning, enabling an operation to identify risks and develop controls to achieve sustainable mine closure, rehabilitation, and relinquishment.
Any risks associated with the closure and post-closure phases are often long-term and cover both economic and non-economic consequences. A well-planned closure process must protect the community from these consequences well after the mining company has left the area. This in turn will protect the reputation of the company and leave a positive legacy.
Early identification of closure risks at the planning stage, will ensure control measures are put in place to mitigate these risks. AS ISO 31000: 2018 Risk Management Guidelines provides detailed instructions on how to implement a risk management process for assessing, treating, monitoring, reviewing, recording, and reporting risk (as demonstrated in Figure 3).
Figure 3: The Risk Management Process
Source: AS ISO 31000: 2018 Risk Management Guidelines
Early Stakeholder Engagement
Stakeholder engagement is vital to sustainable mine closure planning. Early and continuous engagement with stakeholders enables better management of expectations and any potential risks associated with closure. Failure to undertake a stakeholder engagement program may compromise the approval process and mine closure outcomes.
Due to the importance of early stakeholder engagement, a Mine Closure Plan must therefore demonstrate that an effective engagement strategy has been developed and implemented. All stakeholders must have their interests and concerns considered and addressed.
When we talk about stakeholders this includes the local community, which must be engaged throughout all stages of mine development. Community programs, organised and implemented by the mining company, should be aimed at strengthening a community over the long-term. The Australian Government’s Community Engagement and Development handbook contains further information and case studies on best practice for effective community engagement and development programs.
Financial Assurance, Provisioning and Environmental Liability
Early recognition of mine closure costs promotes improved strategies. Processes for estimation of these costs help to reduce potential environmental liability as they ensure investment, development and operating decisions are made today in full recognition of the potential financial impacts of future closure.
Under sustainable development mining companies are required to consider mine closure planning and associated cost estimates across the LoM for financial reporting and provisioning purposes, environmental bonding and long-term LoM planning and budgeting.
For LoM or asset planning purposes, organisations should develop a closure cost estimate for asset valuation, business planning and budgeting. Recognition of rehabilitation and closure costs promotes improved strategies for operations to plan additional mitigation strategies and anticipate progressive closure and reclamation activities.
Figure 4: Closure Cost Estimate Types
Source: ICMM Integrated Mine Closure Good Practice Guide
Several types of cost estimates are used to characterise the financial aspects of closure (demonstrated in Figure 4). Mining companies need to make clear distinctions between the different types of cost estimates as they serve different purposes.
Making Sure You Get It Right
To meet the mining industry’s principles of sustainability and to maintain your businesses right to access resources for the benefit of all, effective mine closure planning is required. Engenium has a team of professionals who can assist with your mine closure planning requirements at the feasibility study stage. We have extensive experience in feasibility study management, which started 17 years ago when our business was established. If you are serious about sustainable mine closure and want to leave a positive legacy behind, please contact us for an informal chat.
National Marketing Coordinator, Perth WA
Engenium Pty Ltd