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Update on a 2016 fatality at an underground gold mine in New Zealand

By Les McCracken, AusIMM Health and Safety Society Committee Member

Introduction

On 28 July 2016 a serious incident at OceanaGold’s Waihi underground operations resulted in the death of a loader operator. The loader operator was tasked with building a waste rock bund at the brow of an open stope prior to carrying out backfilling operations when the loader entered the open stope and fell to the floor below.

The investigation resulted in the development of a system using high level controls to prevent the recurrence of such an incident and these were the subject of a presentation at the AusIMM NZ Branch conference in September 2018 entitled Managing the Hazards Associated with Open Stopes by Charles Gawith, Underground Mine Manager OceanaGold Waihi Operations

This report summarises that presentation in order to share what was learned to prevent a recurrence of the event that occurred during a routine activity carried out at many other similar underground operations. The full presentation can be found here.

What have we learned?

Waste rock bunds are still widely used as part of the controls to prevent a loader from entering the stope below during backfilling operations. Unless the rock bund or other physical barrier such as a steel stop log or similar can be placed prior to the creation of the stope void and remain in place during the stoping cycle then there can be significant risks associated with the construction or placement of these physical barricades around the open stope.

Research following the Waihi incident brought to light seven incidents since 1996 involving loaders unintentionally entering a stope as part of backfilling operation. Like most other mines the operators at Waihi were aware of these tragic incidents through the initial safety bulletins, however in these previous incidents much of the critical detail is not available until many years later.

The fact that all of these previous incidents could have or did result in a fatality then this gives rise to the first issue:

  • In mining, historically the time taken to release a level of information so that others may carefully analyse and act to prevent such incidents occurring at their mines can be too long.

Why is this the case?

In the case of a serious injury or fatality, a major reason for the restriction on sharing such information is that the matter is often subject to an investigation by the regulator (liability). This process usually involves legal privilege and requires a very detailed investigation and a coronial enquiry. This process can take years to complete then release detailed information to industry so that others can review their operations to determine if they face similar hazards and assess whether they can apply similar controls.

  • Is there potential for the critical information on serious mining incidents to be disseminated in a timelier manner to those best placed to use the information – other mine operators?

Another point to consider is that currently we have in Australasia, eight separate sets of Australian and New Zealand regulations governing safety in mining operations. Whilst these bodies are all working hard to share the learnings from such serious events within their various jurisdictions as well as across the wider industry there may be an opportunity in having a single repository for such critical safety information. This body could help play a pivotal role in reinvigorating the incident within the industry when the legal process is complete. It could share the main contributing factors and key learnings from these serious incidents, knowledge that due to long elapses in time can be lost to other mine operators that are not directly involved in the incident.

Generally, mine operators are not looking for lengthy coronial reports, perhaps it would be more beneficial to have a clear statement of facts. This would enable them to look at their operation and see if they face the same hazard and if they are using the same controls to manage the risk. If the answer to both questions is yes, then clearly, they need to reassess their risk in the light of the facts arising from the reported incident.

  • Is there a need for a co-ordinated approach to the dissemination of critical health and safety information arising out of incidents such as this?

Bearing the above in mind it is then not surprising that even in today’s modern high-tech society that an almost identical incident occurred at an Australian mine just two years after the Waihi incident. Although this most recent incident did not result in any injury to the operator it could easily have resulted in another fatality.

Finally, what has OceanaGold done to prevent a reoccurrence of the incident?

  • The process of using a loader to place the waste rock bund at an open stope brow has been replaced with a system that places this rock bund using an Integrated Tool carrier that is fully protected from the open stope hazard by steel bollards.

Acknowledgments

Thanks to Charles Gawith for his original presentation and his review of this article.

 

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