An employee was recently struck in the head by a rock whilst developing headings in an underground mine. The employee sustained serious injuries to the head and shoulder, including a depression to the skull, requiring hospitalisation.
The injury occurred during an inspection of a stripping cut (i.e. 'drag cut') that was being made to an underground heading along the sidewall of an existing development.
The initial cut had been fired, bogged and scaled. Shotcrete was being applied as the first means of ground support within the development cycle. Approximately 80% of the shotcrete (i.e. surface support) had been applied, however the immediate left hand pillar and a small area within the backs were yet to be shotcreted. Ground penetrating support (such as rock bolts or split-sets) had not yet been installed.
Shotcrete application was stopped to carry out an inspection. Whilst standing close to the transition line between supported and un-supported ground, the employee was struck by rock(s) that fell approximately 4.5 metres from the wall or backs. The exact source location of the fallen rock is unknown.
Upon investigation, several fragments of rock were located within the drop zone that had an accumulated weight of approximately 13kg.
Figure 1: Plan of Incident Location
Figure 2: Yet to be shotcreted wall (fallen rocks denoted in blue circle)
Figure 3: Fallen rocks
Entering or approaching areas that do not have ground support installed (unsupported ground) creates risks to the health and safety of employees, such as being struck by falling objects.
Recommended ways to control risks
To reduce the risk of falling objects mine operators must:
- perform a risk assessment to identify all potential hazards and assess the adequacy of all considered control measures, including exclusion zones and separating distances from unsupported ground
- review and, if necessary, revise the need for and adequacy of overhead fall protection, should employees be potentially exposed to falling objects. This includes working in shafts
Mine operators should 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 and independent contractors. Where the risk cannot be eliminated, it must be reduced so far as is reasonably practicable.
Under the Occupational Health and Safety Regulations 2017, 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