Logistical and safety factors combine to make underground mine infrastructure decommissioning a technically demanding challenge.
Adding to the complexity is Western Australia’s strict regulatory and environmental landscape. Workers, surrounding ecosystems, and future land use must be protected both during decommissioning and long after.
Achieving all this requires detailed planning and disciplined execution.
In our experience over the last 50 years, it means close collaboration between operators who care about safety and regulatory compliance and contractors with expertise in underground environments.
What Is Underground Mine Infrastructure Decommissioning?
Underground mine infrastructure decommissioning refers to the controlled removal, dismantling, securing or permanent sealing of underground assets once mining operations have ceased or sections of a mine are no longer required.
It is fundamentally different from surface mine site demolition.
In underground mine infrastructure decommissioning, we are dealing with confined access, complex safety risks, ageing ground support, hazardous materials, and water management issues.
Typical Underground Infrastructure Can Include:
- Conveyor systems and transfer stations
- Electrical reticulation, switchboards and cabling
- Ventilation fans, raises and ducting
- Pumping stations, sumps and pipelines
- Rail tracks and haulage systems
- Workshops and underground maintenance areas
- Storage bays and magazines
- Shafts, declines, portals and access points
Decommissioning and removing these assets is complex enough on the surface. But in tightly confined environments, often hundreds of meters below ground, the challenge is amplified.
Access, ventilation, and stability must be carefully managed within an integrated decommissioning plan.
Key Challenges in Underground Mine Decommissioning
Underground mining is an exciting industry driven by innovation. And with Western Australia home to many of the country’s ~70 underground sites – including Gwalia Gold, Australia’s deepest underground mine and the world’s deepest trucking mine – most of these innovations are truly home-grown.
Whether it’s ventilating tunnels more than 1km underground or reinforcing roofs to extract load-bearing assets, many challenges in underground mine decommissioning are unique to the sector.
Restricted Access and Confined Conditions
Underground environments limit equipment movement and personnel access. Tunnels and declines impose strict constraints on the size of equipment we can deploy.
As a result, heavy machinery is often broken down into smaller components, while manual handling and specialised confined-space tools enable us to safely extract infrastructure.
Ventilation and Air Quality
Poor ventilation is a well-documented risk in underground operations and remains a priority through closure activities.
Dust, diesel particulates, and hazardous gases like methane are often present during decommissioning. Airflow patterns can also change as infrastructure is removed, requiring constant monitoring and adjustment to maintain safe working conditions.
Water Ingress and Flooding
Underground mines that sit below the water table are prone to flooding once dewatering systems cease operating. Without proper containment and management, this water can compromise ground stability, delay works, or contaminate surrounding strata.
Structural Stability
Ground support systems such as rock bolts, mesh, and shotcrete deteriorate over time. Unsupported voids and ageing tunnels increase the risk of rockfalls, and removing infrastructure can alter load paths.
Systematic hazard assessments, reinforcement, and careful sequencing of activity are essential.
Hazardous Materials
Underground equipment may contain all kinds of hazards:
- Oils
- Hydraulic fluids
- Batteries
- Lead-based paints
- Asbestos insulation
- Hydrocarbon residues
These hazardous materials must be identified, isolated and removed in accordance with environmental and safety regulations to prevent exposure and contamination.
Regulatory Requirements in Western Australia
All mine decommissioning in WA is governed by the Department of Mining, Petroleum and Exploration (DMPE, previously DMIRS), alongside broader environmental and safety frameworks.
Closure requirements vary by site. However, key obligations in underground mine infrastructure decommissioning typically include:
DMPE Mine Closure Obligations
- Approved mine closure plans
- Demonstrated risk-based closure outcomes
- Worker safety and ground control considerations
- Inspections and reporting throughout the project
Environmental Protection Act (WA)
- Management of contaminated materials
- Lawful transport and disposal of waste
- Protection of groundwater and surrounding ecosystems
National and International Standards
- ISO 45001 for occupational health and safety
- ISO 14001 for environmental management
DMPE guidance emphasises that mine closure is not a single event. It is a staged, risk-based process that must be integrated into operational planning well before final shutdown.
Step-by-Step Best Practices for Effective Underground Decommissioning
1. Conduct a Comprehensive Site Assessment
Underground decommissioning projects begin with a detailed assessment, including:
- Reviewing the structural integrity of tunnels, shafts, and supports
- Identifying hazardous materials and energy sources
- Characterising waste potential recyclables
- Water ingress and drainage risks
This informs safe work methods, equipment selection and sequencing. It also identifies unseen hazards, as well as potentially valuable recyclable materials.
Underground decommissioning generates significant volumes of recoverable material, including steel, copper and aluminium. Thinking ahead about scrap metal recycling allows valuable materials to be processed responsibly rather than treated as waste.
2. Develop a Detailed Decommissioning Plan
Underground mine infrastructure decommissioning plans often run longer than 100 pages. There are core elements found in almost all plans:
- Logical work sequencing
- Stability and ventilation requirements
- Site-specific safety management system
- Emergency response and evacuation procedures
- Equipment removal workflows
Beyond these fundamentals, the plan should provide details around infrastructure removal, waste containment and handling, and water management.
Every environment requires different solutions. This is why it’s important to engage a specialist mine decommissioning partner early in the process, so nothing is missed.
3. Backfilling, Sealing and Stabilisation
Once infrastructure is removed, remaining voids and access points must be secured. This happens in a number of ways:
- Shaft and decline plugging
- Barricading or permanent sealing of portals
- Measures to prevent future unauthorised access
Backfilling may also be required to maintain long-term ground stability. Surface markers and signage should be installed to identify former underground workings.
4. Final Cleanup and Site Rehabilitation
The final phase focuses on getting the site ready for its next life:
- Removing residual debris
- Recovering valuable scrap metal and vehicle batteries
- Transporting waste to approved facilities
- Creating documentation for mine closure certification
Surface rehabilitation should integrate with broader mine closure objectives, supporting the pathway to relinquishment and final certification.
Why Work With a Specialist Underground Mine Infrastructure Decommissioning Contractor
Underground decommissioning is not simply demolition work in a different space. It demands specialised knowledge and equipment, rigorous safety management systems, and the ability to respond to changing conditions safely.
Proper handling reduces risk and lowers project costs through metal recovery. It also positions operators for successful closure certification.
With over 50 years of mine site decommissioning experience across Western Australia, C.D. Dodd has completed large-scale projects in underground, remote, and offshore environments.
Our capabilities include full site rehabilitation support, metal recovery operations, and hazardous material management. We are certified to ISO 45001 and ISO 14001, and our impeccable safety record reflects our uncompromising commitment to protecting people and the environment.
Contact C.D. Dodd today to discuss your underground mine infrastructure decommissioning requirements.