Findings revealed: How haul truck plunged 26m at Central Queensland mine site

An investigation has determined what caused a haul truck to roll side-over-side down a dump face at a Central Queensland mine, resulting in the driver being taken to hospital. See the ‘five key issues’ the safety regulator found.

The truck at the bottom of the dump and (inset) where the bund was breached. Images courtesy of Resources Safety & Health Queensland.

An investigation has revealed how a haul truck plunged more than 26m down a dump face at a Central Queensland mine, resulting in the driver being injured and taken to hospital.

A document released by Resources Safety and Health Queensland details what happened when a CAT 789 haul truck backed position five and six wheels through a safety berm on an overburden dump during a night shift.

The RSHQ report does not state where the incident happened nor when, but this publication has confirmed it occurred at Middlemount Coal’s Middlemount Mine on June 18, 2022.

The RSHQ report states: “After teetering for a brief period at the tip head, the truck rolled side-over-side for two complete revolutions, before finally coming to rest 26.7m below on its wheels. The driver sustained injuries that required hospitalisation overnight.”

In relation to how the incident happened, the RSHQ report states that between the supervisor inspection at the start of the shift and the time of the incident, the standard of the tip head had deteriorated significantly.

“It had narrowed up, not been maintained in a straight edge, and the berm had reduced in height and width to such an extent that it was no longer a critical control to the mine standard which would prevent the truck from breaching the tip head,” the report states.

The truck at the bottom of the dump. Photo courtesy of Resources Safety & Health Queensland.

The report identified five “key issues”:

• The tip head was not to standard, being too narrow and misaligned, resulting in the truck backing up at an angle to the edge;
• The height of the berm was well below the half wheel height of the truck involved;
• The width of the berm was below the mine standard;
• The height of the dump had exceeded the maximum mine standard;
• The position of lighting was inadequate, resulting in shadows on the off-driver’s side of the truck where the berm was first breached.

Where the bund was breached. Photo courtesy of Resources Safety & Health Queensland.

The RSHQ report outlined six recommendations for “all site senior executives”.

They were:

– Review Risk Assessment and SOP for dumping on overburden dumps, minimising the frequency of narrow dumps. Where this can’t be achieved, ensure the design and operational parameters are clearly defined in the SHMS. Operators and supervisors must be trained and assessed in their understanding of the SOP;

– Include a competent geotechnical engineer in the risk assessment team as well the cross section of the workforce involved in the activity;

– Ensure Supervisors, Open Cut Examiners and Dump Dozer operators have an accurate means of continually checking that advancing dumps are always within their design parameters;

– Ensure all dump dozer operators are aware of the requirements for maintaining a tip head in a safe state;

– Ensure the SHMS contains a mechanism to monitor the effectiveness of the Supervisor and Open Cut Examiner inspections, auditing, and reporting on dump design compliance;

– Review lighting standards at tip head areas.

The RSHQ report also made three recommendations for “all operators.”

They were:

– Not use the safety berm as a stop for the rear wheels of the truck in dumping operations;

– Be aware that they have a responsibility to assess the tip head each time they approach it, to ensure it is safe to discharge their load in the normal manner. If not safe, then dump short;

– Be aware that the extent of the injuries sustained to the coal mine worker, while serious, were limited by the operator wearing their seatbelt.

The RSHQ report states that investigations are ongoing and further information may be published as it becomes available.

Since the release of the report, RSHQ confirmed this incident happened at Middlemount Coal’s Middlemount Mine on June 18, 2022.