Silver Lake Resources Ltd has been fined $30,000 after a worker drove his loader into an exclusion zone at the company's Daisy Milano underground gold mine around 50 km south east of Kalgoorlie.
No workers were injured in the incident.
Silver Lake Resources pleaded guilty in the Kalgoorlie Magistrates Court on 19 October 2023 for failing to provide and maintain a working environment where employees and contractors were not exposed to hazards.
In February 2018, a loader operator was instructed to enter a stope to build a rock embankment (bund) at the edge of an open void. A stope is an excavated space that contains the ore being mined.
At the time of the incident, the stope was subject to a mandatory period excluding workers from entering the area due to seismic risks from the recent detonation of explosives at a nearby section of the mine. The company had not assessed the stope as seismically safe to enter which meant there was a risk of rock fall.
The recent detonations also created a risk of unsafe gas levels in the area where the loader operator was working.
A sign that restricted unauthorised access to the stope and surrounding area had been removed prior to the loader operator entering the space.
WorkSafe Chief Inspector of Mines Christina Folley said Silver Lake Resources did not have adequate controls to manage the risks of working in the area.
"There were a number of contributing factors, and this incident could have easily resulted in a fatality," she said.
"The explosives used in firing a stope emit noxious fumes that at certain levels can be hazardous to the health of workers.
"Exposure to those fumes at unsafe levels can cause nausea, breathing difficulties, rapid heart rate and loss of consciousness.
"In serious cases this can lead to asphyxiation and death."
Ms Folley said ground instability and the possibility of rock fall are major hazards at any mine.
"Managers and front-line supervisors must develop safe systems of work and implement the appropriate controls, particularly after firing explosives in underground mines."
