Coal Inspectorate | Alert | No.396 V 1 | 21 September 2021

Fatality resulting from a fall of ground at an underground coal mine

What happened?

At approximately 11:00 pm on 14 September 2021 three coal mine workers were conducting work in a conveyor drift at Crinum underground coal mine when a significant fall of ground from the roof area of the drift occurred. This resulted in one worker being fatally injured and a second worker being seriously injured.

How did it happen?

Initial indications are that two coal mine workers were drilling Rocsil application holes into the roof of the drift using a QDS Bolter. Whilst drilling the application holes, a large quantity of roof material has dislodged from the roof and fallen onto two of the workers. A third coal mine worker, who was working in the adjacent area, initiated the emergency response.

Key issues

The incident is under investigation. The underground part of the coal mine has been evacuated and secured to prevent unauthorised persons entering the mine until it can be determined that it is safe to do so.

Recommendations

The recommendations contained in this alert are general in nature, relating to the management of strata hazards in underground coal mines, and are not direct findings relating to the cause of the accident at the Crinum mine.

The Mine Operator should ensure that the Site Senior Executive and Underground Mine Manager at their underground coal mines review their Principal Hazard Management Plan for Strata Control to ensure this is effective to prevent any potential for a similar incident. Consideration should be given to the following:

• Having sufficient geological and geotechnical information to adequately assess the requirements for the strata at your mine.
• The design of the strata support system, based on relevant geological and geotechnical data, being implemented provides a factor of safety appropriate to the life cycle of the strata support for the excavation.
• The minimum design considerations of the support system must consider strata properties, the properties of the support system, potential failure surfaces and appropriate factors of safety.
• Strata support has been installed as per design specifications and detailed in the approved support plan.
• The strata monitoring system is adequate to provide effective monitoring to ensure the integrity of strata support over time in all circumstances.
• Mine management must develop and implement a suitable quality control process to ensure that the standard of installation meets that required by the design criteria for ground conditions at the mine.
• The integrity of the strata support system has not been compromised due to the life span of the components originally installed for providing effective strata support and monitoring.
• The changes of any other factors, particularly relating to but not limited to, shallow depth underground excavations associated with mine entries with a long life cycle that may impact on the installed strata support such as changes in surface topography, water control and catchment, erosion, weathering, and the potential for water ingress.
• Ensure that the assessment and review of the strata PHMP is conducted by a suitably qualified, independent and competent geotechnical engineer.