Introduction
MEC Case Study: Reducing Geotechnical Uncertainty Before Final Investment Decision
Project Stream: Feasibility / Bankable / Definitive
Project Stage: Due Diligence
Type of Mine: Underground
Region: Queensland, Australia
Commodity: Hard Coking Coal
The Challenge
A brownfields longwall underground development was being assessed to extend the life of an existing coal operation by transitioning from open cut to underground mining. The project targeted approximately 4.5–5 Mtpa of saleable hard coking coal production across an estimated 23-year mine life.
The key challenge was assessing geotechnical risk associated with dual-seam longwall mining in conditions that differed from comparable operations. Uncertainty existed around in-situ stress conditions, pillar sizing, seam interaction, and long-term ground behaviour.
Additional complexity included:
- Drift and shaft access design
- Ground support requirements
- Subsidence impacts
- Structural variability and geological complexity
- Ventilation and long-term operational stability
These assumptions had direct implications for mine safety, coal recovery, capital costs, operational productivity, and overall project economics.
The Approach
- Independent Geotechnical Due Diligence: MEC completed a detailed review of available geotechnical and mining design documentation to identify key areas of technical uncertainty and project risk.
- Benchmarking Against Comparable Operations: The team benchmarked the project against comparable longwall and dual-seam underground operations, validating assumptions related to pillar sizing, seam interaction, and mining access strategies.
- Scenario Testing & Design Review: MEC reviewed modelling methodologies, support standards, and empirical design parameters, challenging assumptions against industry experience and operational practicality.
- Multidisciplinary Technical Assessment: A multidisciplinary team of geotechnical, mining, ventilation, and underground operations specialists collaborated to assess both technical robustness and commercial implications. Geotechnical risks and opportunities were directly aligned with the project economic model and risk framework.
The Outcome
- Key geotechnical risks and uncertainties clearly identified and prioritised.
- Recommendations developed for targeted infill drilling, additional modelling, and staged design optimisation.
- Improved understanding of the implications of dual-seam mining on safety, recoveries, capital costs, and long-term productivity.
- Geotechnical findings integrated into the project risk framework and updated economic model.
- Strengthened confidence in the project development pathway ahead of final investment decision.
Key Impact: Independent technical due diligence provided the client with greater clarity around geotechnical risk, enabling more informed investment decisions and a structured pathway for staged project de-risking.
Next Steps
MEC’s current work program has been completed, with the client progressing targeted technical refinement activities to support final investment decision processes. Recommended follow-up work includes focused drilling programs, further modelling, and progressive optimisation to reduce remaining uncertainty and strengthen long-term operational confidence.
Conclusion
Turning technical complexity into practical, commercially informed decisions across the full mining lifecycle.