State orders BHP investigation

The state mining engineer has ordered BHP Billiton to carry out an independent engineering study at its Perseverance nickel operation following the second rock-fall incident in less than a month.

Earlier this week, BHP confirmed around 25 tonnes of rock had fallen near a worker, dispelling claims a worker had been trapped in the incident.

The rock-fall is said to have been caused by small tremor that registered 2.3 on the Richter scale.

It follows another rock-fall at the underground mine near Leinster, where a worker was trapped for around 16 hours.

Yesterday Mines Minister Norman Moore said the government was considering closing the mine but was seeking urgent advice from state mining engineer Martin Knee on the matter.

Late yesterday, Mr Knee directed BHP Billiton Nickel West to undertake an independent engineering study at the mine in order to ensure a continued safe operation.

"It is extremely important to clearly identify all factors involved in the recent incidents with as much information as possible in order to ensure that there is not a similar occurrence with adverse consequences," Mr Knee said.

"Inspectors of Mines are conducting an investigation into the first incident and given this second incident, it is evident that the range of issues and factors leading to and associated with the rock-falls may be extensive and complex."

Mr Knee added the study would have to assess the risk of any future seismic events and methods to deal with that.

BHP has been given eight weeks to conduct the study.

Earlier this year, the state government took the unprecedented step that it would order BHP to halt operations following a string of safety issues at the miner's WA sites, including the death of five workers in the Pilbara.