The WA State Mining Engineer Martin Knee has stopped short of closing BHP Billiton Nickel West’s Perseverance mine as a result of two rock-fall incidents within the past three weeks, instead directing the company to undertake an independent engineering study of its operations.
The requisition order for an engineering study of what may have contributed to the seismic events on June 10 and June 29, 2009 was issued on July 1 in accordance with the provisions of section 45(1) (b) of the Mines Safety and Inspection Act 1994.
BHP Billiton has been given eight weeks to conduct the study and provide the report.
Knee said an independent engineering study was required to ensure the continued safe operation of Perseverance mine by identifying the potential for further similar events.
“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,” he 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.”
Issues to be addressed and matters that must form part of the report will include detailed study of the geological structure of the mine and influences on rock stability, particularly the area affected by the seismic events.
The effects of extraction of ore and the design, installation and quality control of rock support and reinforcement in the area affected by the seismic events will also have to be considered.
The State Engineer said the independent study would also have to provide an assessment of the risk of an emergency occurring as a result of a seismic event in the future and consideration of ways in which emergency events may be prevented or mitigated.
A Department of Mines and Petroleum Resources Safety Mines inspector is currently on site to begin an investigation into the latest incident on June 29 and a geotechnical engineer will examine the site on Monday, July 6.