Mine closure plans assumptions and optimism
Proceedings of the 13th International Conference on Mine Closure
Because planned closure is often many years into the future many closure plans have a set of underlying assumptions. Sometimes these are well documented, but more often they are inferred within the framework of the closure concept and do not always receive appropriate focus. Even when closure plans document assumptions the list is often incomplete. It is entirely appropriate for closure plans to be based on assumptions. Indeed, assumptions will need to be made regarding the feasibility of the
... easibility of the closure concept, regulatory regime, schedules, criteria achievement, mine life etc. Sometimes assumptions are conservative although often, however, assumptions are based on an optimism bias, in which case these assumptions really equate to risks if the assumptions do not come to fruition. It is therefore imperative that all underlying assumptions in a closure plan that can potentially have a material impact on outcomes and cost are identified and documented. However, the closure plan cannot simply just list and thereafter ignore them. The risks of the assumption not eventuating need to be assessed and incorporated into the closure risk register and possibly into a revision of the closure plan itself. Those risks will also need to be analysed and quantified in terms of the potential impact to closure costs. This paper discusses a framework for capturing the assumptions that underlie many closure plans, their transition into closure risks and how they should be addressed by the closure plan and associated closure cost estimates. The paper also discusses examples of typical closure plan assumptions and cases where optimism has not been realised.