Dugald River Sinkhole: what have Australian miners learned?

MMG’s Dugald River zinc mine. Credit: MMG Limited

On 15 February, 2023, Dylan Langridge and Trevor Davis, two mine workers at the Dugald River mine in Queensland, Australia, were declared missing after the ground collapsed beneath the vehicle they were driving, sending them plummeting 125m into a stope.

A little over 24 hours after the incident, the men were found dead. Another worker barely escaped the same fate, as his drill rig also fell into the stope; he was recused and treated for minor injuries. 

Tributes poured in for the two men, both in their thirties and one a father of two. An investigation involving police from three different forces, as well as several government bodies, immediately started. Eight months later, what has the Australian industry learned in response to this tragedy?

The Dugald River mine primarily processes zinc and is one of the top ten zinc operations worldwide. The site is estimated to have a mine life of over two decades and processes an average of 1.7 million tonnes of ore per year. While the majority of this is zinc concentrate, the project has also produced lead and silver ore since it was fully commissioned in November 2017.

Dugald River is fully owned by MMG Limited, a major mining operation, and its 500 contractors and employees are a mix of fly-in, fly-out (FIFO) workers and local residents. 

Detailed investigations of the incident appear to still be ongoing, but a safety alert published by Resources Safety and Health Queensland (RSHQ) in the days following the incident stated: “Early investigations suggest that the stope void had been caused due to bogging operations on the level below the area where the light vehicle and drill rig had been operating.”

Bogging – the process of removing either waste material or ore-bearing rock from a stope – can create voids in a stope if it is not correctly filled in, leading to a dangerous decline in structural integrity. Notably, the report added that “It is unknown at this stage why those bogging operations were being carried out”.

As such, it seems like this tragedy may have been preventable. In his introduction to the January – April 2023 High Potential Incidents and Serious Accident Summary report published by RSHQ, Chief Inspector for Mineral Mines and Quarries Hermann Fasching said of the deaths: “Disappointingly, the hazards that contributed to this fatal accident are well known and understood as are the controls necessary for prevention”.  

The mine was declared safe to reopen on 21 March 2023, a little over a month after the accident occurred.

While not speaking specifically of the Dugald River mine, Dr Elise Crawford, a workplace health and safety expert at CQ University in Rockhampton, theorises that many mine accidents could be a result of insufficient training among staff.

“[Workers] are not always aware of the hazards," she said, "they just know if they do the job this way [and follow procedures] it'll be safe. When work is prescribed and has to be done a particular way and the people who are doing the work aren't involved in the design of that work, then they're not always aware of the hazards.”

While avoiding loose speculation in matters such as these is important, it is not unreasonable to assume that, given the RSHQ’s earlier remark about the reason for bogging operations being “unknown”, poor communication practices at the site could have contributed to the events that took the lives of two workers.

Professor Michael Quinlan, from the University of New South Wales' Industrial Relations Research Centre, also highlighted the risks of complacency in mine safety procedures, noting: "When the system corrodes over time, because everything's worked, people get a bit too casual about it and then you can find that your systems are not working”. 

While some have questioned MMG’s own safety procedures after news emerged that the Dugald River mine had been visited by safety inspectors 27 times in the two years preceding the accident, with three safety directives put in place by the mine inspectorate as a result, MMG clarified that these were “routine inspections by the regulator”, adding:

"These three safety directives issued to Dugald River that required suspension of activities since July 2020 were related to single pieces of machinery, tyre handling and an underground truck fire. In all cases, remediation was undertaken swiftly and inspected with return to safe work conditions.”

Mine safety rules and regulations are written in blood. To put it more delicately, almost every rule and safety standard in the industry is the result of a tragedy that has been unpicked and examined to prevent the next one.

Many mining safety standards in Australia came about after a series of mine disasters in New South Wales and Queensland in the 1990s provided a wakeup call to the industry.  

So the question is: have improvements to mine safety standards been implemented since this accident? So far, no changes to standards have been made, but it is still relatively soon after the incident and legal safety standards take time to implement.

Contractor and site operator Barminco employed the two workers who died. Parent company Perenti launched a "safety transformation taskforce" in the wake of the incident, bringing on board two world-renowned safety experts to help investigate and prevent further tragedy. 

One of these experts, Peter Wilkinson, was the principal author of the International Council of Mining and Metals' guide on implementing critical controls, while the other, Professor Sidney Dekker, is among the world’s top two percent of “most influential scientists”, according to Stanford University, and worked with Boeing following the 737-Max aircraft accidents.

Perenti aims to share the results of the Taskforce’s investigation with the wider mining industry as well as use it to improve its own safety procedures.  

Eight months on, the full future impact of the Dugald River Mine tragedy remains to be seen, but we must remain hopeful that the industry will learn lessons and implement better standards to ensure the deaths of Dylan Langridge and Trevor Davis do not go unheeded.

The industry must not accept fatalities as the cost of doing business, and as more details will inevitably be revealed in the coming months and years, the true value of the industry will be seen in the changes it makes to prevent the next loss of life.