Serious mining incident – Rock fall hits employee during development heading charging
WorkSafe is issuing a reminder about the importance of managing the risks associated with rock fall whilst charging development headings in underground mines.
An underground development heading was being charged (loaded with explosives) by two employees. The first employee was at ground level close to the development heading face and was loading explosives into drill holes. The second employee was several metres back from the face operating a pneumatic trigger. The development drive was fully ground supported up to the face through a combination of shotcrete, mesh, spilling bars, friction bolts and mechanical lock bolts. The face had been mechanically scaled by a jumbo drill post face drilling and manually checked scaled prior to charging. Approximately 75% of the face was charged 'top-down'.
The first employee was struck by a rock on the helmet that fell approximately 3.5m from the centre of the development face.
The employee was knocked backwards receiving injuries to their shoulder and neck, requiring admission to hospital.
Upon investigation, several pieces of rock were located within the drop zone and had an accumulated weight of approximately 80kg.
Common safety issues associated with charging underground development headings include:
- exclusion zones not being maintained
- batter stability / ground failure / rock fall
- fire and/or explosion (including plant fire, misfires)
Recommended ways to control risks
To reduce the risk of ground failure, mine operators must:
- Identify all potential hazards during risk assessments and assess the adequacy and benefits of existing control measures
- Consider additional control measures, such as:
- ground support for securing development faces (e.g. partial or full face meshing further to mechanical and manual scaling).
- exclusion zones and separating distances from unsupported ground.
- Include a broad range of expertise and personnel when developing risk assessment teams to ensure all aspects of risk are considered.
Under the Occupational Health and Safety Act 2004, employers must, so far as is reasonably practicable, provide and maintain a working environment that is safe and without risks to the health of employees (this includes contractors and labour hire employees).
Under the Occupational Health and Safety Regulations 2017 (OHS Regulations), mine operators must:
- identify all mining hazards at their mine and assess associated risks, so far as is reasonably practicable
- implement risk controls that eliminate or reduce risks, so far as is reasonably practicable
- establish and implement a safety management system for the mine, which provides a comprehensive and integrated management system for all identified risks.