Regulator releases update on Endeavor mine explosion

The NSW Resources Regulator has released new details on its investigation into last month’s fatal blast at the Endeavor mine near Cobar, expanding its focus to the systems, equipment and conditions surrounding the use of ballistic disc explosives underground.

The October 28 incident occurred around 3.30am on level 500 of the mine, where three workers were preparing a BD260 ballistic disc to clear a hang-up in a drawpoint. Ballistic discs, like the one used in the Polymetals’ owned mine, are used to break up unfragmented ore that blocks stopes during stoping operations.

According to the regulator, the disc detonated while the workers were still underground, well before the scheduled 5.45–6.00am surface-initiated blast window. The connecting wire used to link the electric instantaneous detonator assembly to the mains firing line was later found in the shot firer’s vehicle, indicating it had not been connected at the time. The unintentional detonation killed two workers and seriously injured a third.

The new investigation update confirms that inspectors are examining the mine’s procedures for handling and preparing ballistic discs and electric instantaneous detonator assemblies, including the instructions, training and supervision provided to workers involved in the task.

Investigators are also assessing whether radio frequency interference from underground communication systems – such as two-way radios, mobile phones, smart watches and signal amplifiers — may have played a role. Additionally, the regulator will review risk assessments, safe-work instructions, and the guidance issued by designers and manufacturers of the explosive devices.

A technical assessment of the ballistic disc and detonator is underway to verify compliance with manufacturer specifications. The use of electric instantaneous detonators to initiate ballistic discs is also under scrutiny.

The update follows the regulator’s alert urging mine operators to reassess the use of ballistic discs and consider alternative methods for clearing blockages while the investigation continues.