Ridgeway Mine is an underground mine using the block cave extraction method. The incident occurred at the 4786 level in Extraction Drive 10 at the East 6 draw point (10E6), about 1100 metres below the surface of the mine.
Rock and other unconsolidated material had hung-up in the 10E6 draw point. The Jacon was intended to be used to water blast the hung-up material in an attempt to cause it to fall into the draw point so that it could be removed by a LHD.
The Jacon was positioned facing into the draw point. The water cannon boom was extended toward the brow beam. During the task, it appears that there was a rapid movement of rock and material from the draw point into the extraction drive. The material impacted the front of the Jacon. For this or other reasons, the Jacon moved backwards trapping the worker between the Jacon and the side wall of the extraction drive.
The worker received fatal injuries.
Recommendations
This incident reinforces the risks associated with working in the vicinity of block cave draw points. When considering the recommendations below, mine operators are reminded of their obligation to take a combination of measures to minimise the risk, if no single measure is sufficient for that purpose.
Operators of metalliferous underground mines that contain draw points but are not block cave operations should consider the following recommendations as far as reasonably practicable.
When undertaking block cave mining and draw point production activities, mine operators should:
1. Use the hierarchy of controls when developing critical controls, with a focus on hard controls (e.g. elimination, substitution or engineering).
2. Consider remote technology, taking workers out of the line of fire from draw points.
3. Prohibit mine workers from undertaking work on foot in the vicinity of underground draw points without appropriate controls in place.
4. Eliminate or minimise worker exposure to pinch points between mobile plant and mine workings.
5. Construct bunds to consistent standards in appropriate areas such as open draw points and maximise bund size taking into consideration rock fragmentation and material type.
6. Consider the potential for rock material (whether dry or wet) to flow into extraction drives and place workers at risk.
7. Ensure inrush control plans identify and control rock flows from draw points.
8. Undertake regular reviews of the inrush principal hazard management plan and map against the codes of practices and guidelines, including the NSW code of practice for inundation and inrush hazard management.
9. Ensure appropriately trained personnel inspect active draw points to identify hazards and eliminate or minimise risks to health and safety.
10. Ensure human factors and working environment are considered during the development of critical control measures.
11. Ensure monitoring arrangements are developed and implemented to minimise dust exposure.