Mine Closure Risk and Decision Analysis
Abstract
Effective mine closure can be defined, in simple terms, as the creation of sustainable outcomes through the minimisation of environmental, social and economic impacts on host communities and the maximisation of positive legacies that contribute positively to future generations (Dowd & Slight, 2006). The identification and evaluation of potential environmental, social and economic outcomes associated with mine closure is therefore critical for effective closure planning.
Most ‘sustainability’ conscious companies now adopt closure planning processes which include objective decision making tools for the identification and evaluation of both higher level post closure land use options and more detailed closure configuration alternatives. While sustainable development assessment tools can offer sound decision making support for determining broad land use objectives (Moller et al, 2006) facilitated risk assessment workshops are proving to be the most effective methodology for identifying and assessing potential risks and opportunities associated with preliminary and detailed design configurations (Bentel et al, 2003).
This paper provides an overview of an evolving evaluation tool to balance the complex range of alternative configurations which builds upon the techniques of Multi-Criteria Analysis (Kepner Trego Analysis), Risk Analysis (AS/NZS4360) and Cost Benefit Analysis into a single integrated approach which can be applied to mine closure planning processes.
The key to the process is the identification and prioritisation of decision criteria. Such criteria provide a balanced scorecard of statutory requirements, corporate policies, potential risks, and desired objectives. Each alternative configuration is then assessed against these criteria using a process that is transparent and excludes bias. Relative merit is provided mathematically in the background based on weighting, relative rank and cost. The cost benefit analysis is the final parameter that distinguishes the best configuration option from the rest and provides the stakeholders with clear and justifiable reasoning for the mine closure plan.
In addition to traditional sustainable development criteria identified during higher level assessments (i.e. environmental, social and economic) (Moller et al, 2006) this process facilitates the development of criteria reflecting safety, technical achievability, compliance and commercial viability. The robustness of the tool allows for customisation of criteria weighting and incorporation of additional criteria to meet alternative closure scenarios or specific corporate and/or statutory requirements for a particular operation or company.
A specific advantage of this process is the ability to evaluate negative impacts and risks, as well as positive opportunities and legacies. The readily communicated, transparent and robust decision process also assists with the engagement of stakeholders. Consideration of innovation within the selection criteria also provides opportunity for best practice concepts and cost optimisation.
Once the preferred closure configuration is identified, the tool facilitates the extension of the decision making process to identify risk and opportunity management strategies that ensure the selected configuration reaches its full potential.
Author
R.B. Logan Sinclair Knight Merz, Perth, Australia
D.P. Murphy Sinclair Knight Merz, Perth, Australia
C.A. Beale Sinclair Knight Merz, Brisbane, Australia