Achieving Successful Mine Closure

With the commodity price recovery and an optimistic medium term outlook in the mining sector it means that Mine Closure Planning can now cease and we should start focussing on operations again.....WRONG! There has never been a better time to start (or finish) planning for Mine Closure. Our experience has been that detailed mine closure planning is often left too late into an assets life-cycle to enable it to be well planned and cost-effective. Unlike any time before, mining and associated land use conflicts  have come under increased scrutiny from key stakeholders and the sectors Social Licence to Operate is now dependent on  demonstrating quality mine rehabilitation.  External stakeholders identify rehabilitation and ultimately mine closure as a key performance indicator for responsible mining.

This figure shows the typical lifecycle (our Life of Mine (LOM)) of a mining project from exploration through to the disposal of the asset.  Mine closure planning should really be undertaken throughout all phases of the Life of Mine, however as the mine nears the end of its economic life there is a need to update and review the plan.

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There are 5 key phases for closure planning through the LOM, each with varying levels of detail, but all focussed on achieving the goal of successful mine closure.

Phase 1- Exploration Concept and Pre-Feasibility

Prior to the commencement of an exploration program there us a need to develop an Exploration Closure Plan (or rehabilitation plan). Exploration does not necessarily mean that a mine will follow and often this phase of the lifecycle is undertaken on land that is not owned by the mining company.  Careful planning and a commitment to the rehabilitation and closure of bore holes, drill pads, sumps and roads is a fundamental step long after the geologist has taken the core logs.

Phase 2- Feasibility and Front End Engineering and Design (FEED)

A Conceptual Closure Plan would typically be required by the end of the feasibility phase for inclusion within the Environmental and Social Impact Assessment (ESIA). The government and determination authorities are looking for a commitment to post mining land uses, detail on landforms, rehabilitation outcomes and the minimisation of any final voids.  As a minimum, the Conceptual Closure Plan should be developed based on the assumption that all mine related disturbed lands are to be returned to the pre-disturbance land-use or some other pre-determined land use. In addition to the plan it would be expected that a rehabilitation/closure estimate to +/- 30% would also be required at this stage.

Phase 3 Execution- Construction and Operations with a reserve Life of Mine (LOM) greater than five years

If a Conceptual Closure Plan has not already been prepared as part of the EIS, then it is at this point that a Conceptual Closure Plan and subsequent estimate  would be developed. It would be carried into the construction and operations phase of the project.  If the Conceptual Closure Plan has been prepared as part of the EIS, then it may need to be peer reviewed and updated when planning approval is received from the relevant regulatory authority to make sure it is applicable.  During the life of the facility, the content of the Conceptual Closure Plan and closure cost estimates would typically be reviewed annually and updated to ensure it adequately reflects the changing requirements for the operation. It is the intention that the level of detail to be included in the Conceptual Closure Plan will increase as the mine moves toward closure.  A rehabilitation  / closure estimate to +/- 20% would typically be required at this stage.

Phase 4- Detailed Closure Planning- Operations with a reserve LOM less than five years; and

The detailed closure planning process should have commenced once a reserve has a LOM of less than 5 years. It is not uncommon for the LOM to be shortened due to mine economics or swings in commodity price so during this phase of the LOM sudden or unplanned closure must also be a key planning consideration.  The process would typically require undertaking a suite of detailed investigations to ensure that the full scope of closure issues are identified and that  appropriate solutions (e.g. engineering) are developed and adequate provisions are accrued to ensure that the nominated post mining land use objectives can be met. A rehabilitation  / closure estimate to +/- 10% would typically be required at this stage.

Phase 5- Post Closure Maintenance, Monitoring and Relinquishment

Prior to the completion of the closure and rehabilitation Phase, a Post-Closure Care and Maintenance Plan should be developed and implemented until successful close-out and lease relinquishment is achieved. This plan would also would typically include information on the rehabilitation monitoring requirements and the ongoing maintenance required.  Close out and then lease relinquishment is generally achieved where the monitoring demonstrates that all rehabilitation objectives have been meet and sustained for a number of years.


Key Contacts:

Andrew Hutton

Asia-Pacific