The dozer was being used to prepare the tailings dam area for a remote dozer push.

That work involved building a tip head at the dozer sighter peg line and then filling in the void area before the sighter pegs. 

The NSW Resources Regulator said mine operators must have safe systems of work in place to inspect highwalls, low walls and dumps, with inspections to consider weathering effects, ground water and conditions that affect ground stability.

The regulator said there were significant health and safety risks around highwalls, low walls and dumps failing, and people and equipment had been exposed to harm as a result.

The frequency of this type of incident increased during and after wet weather events.

"The adequacy of control measures, including survey controls, should be verified and operators working in the vicinity of geotechnical hazards should be trained and deemed competent to do so," the regulator said.