Mine - Partial Closure, Order of Magnitude Study

Undisclosed Client

Western Australia

The Client engaged Calibre in 2021 to deliver engineering services for Mine X Partial Closure Order of Magnitude (OoM) Study, schedule, estimate, abandonment strategy and design.

The Calibre Delivery team identified the key OoM Study milestones as being the completion of the Basis of Design criteria set; OoM options analysis; OoM Non mine landform MTO production, OoM estimate, engineering services deliverables; General Manager review and development of the OoM Study Report.

The project was unique as the closure requires a progressive rehabilitation. The six mine pits will be progressively closed such that the pit floors are rehabilitated and access to rehabilitated areas is restricted to prevent inadvertent trafficking post rehabilitation.

Mine X will continue to mine low grade stockpile while Calibre rehabilitates the mine pits that have been exhausted.

Project need

The original project scope was a partial closure of Mine X. After a series of reviews and the Life of Mine Ore Body Effectiveness Study, the client decided that they would continue to mine at site X. The delivery strategy changed from partial closure to progressive rehabilitation once the Mine Pit and low-grade stockpiles are exhausted.

Project solution

Calibre coordinated and managed the engineering works and collated results for developing the master OoM Report, estimate and schedules. Calibre was accountable for delivering engineering services for the following:

  • Non-mined landforms.
  • Drafting/visualisations.
  • Identifying technology opportunities.
  • Engineering study scoping
  • Technical assurance planning.
  • A health, safety, environment and community (HSEC) focused design.


Calibre has delivered the following outcomes to date:

  • Development of General Arrangement drawings.
  • Delivery of the abandonment and catchment bund alignment and design including in-pit catch bunds, internal progressive safety bunds and external progressive abandonment bunds.
  • Pit floor rehabilitation including ripping and seeding to a maximum of 300mm and medium growth spread.
  • Completion of the Basis of Design Criteria set.
  • Completion of the OoM Options Analysis.
  • Completion of the OoM Technical Scope.
  • Completion of the OoM Study Report.
  • Completion of the Abandonment Bund Strategy in the Technical Memo.
  • Preparation of the volume calculation and material movement required to prepare the estimate.



Key Services:

Specialist Services:

  • Mine Closure


Jacqui Davitt



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