No injuries were sustained in the event and all personnel working in the underground mine moved to refuge chambers or safe areas as per protocol.

Newcrest geotechnical engineers then inspected the mine accesses and certified them safe before those workers were moved to the surface.

The underground mine is subject to a prohibition notice from the NSW Mining Inspectorate. The work needed to get the mine back in operation includes:

• Cleaning up the access drives and extraction level of Panel Cave 2;
• Completing the assessment of damage to the extraction level of Panel Cave 1;
• Testing all critical mine infrastructure and the materials handling system;
• Rehabilitating any necessary damaged ground support; and
• Finalising a restart management plan and getting it approved by the Inspectorate.

Newcrest is unsure how long all of that will take.

While mining in the underground area has stopped for now, surface operations have not been adversely affected and continue. 

Since the seismic event the plant has been processing Cadia East stockpile material. That is expected to be exhausted by the end of April 18. 

According to Newcrest there are low grade stockpiles the plant can start processing once the Cadia East stockpile is consumed.

Newcrest managing director and CEO Sandeep Biswas said he was thankful all the company’s miners were safe.

“There is an enormous amount of work underway to safely bring the mine back online,” he said.

“The safety of our people involved in the assessment of damage and remediation activity is paramount, as is the safety of our workforce generally as we decide when and how mining operations recommence.”

Newcrest has started investigating the seismic event, supported by several independent parties. 

The company is working Inspectorate, which approved access to the mine for the purpose of re-establishing critical services, conducting inspections and undertaking engineering assessments of existing ground support and other key infrastructure.

There appears to have been little damage done to the mine and associated infrastructure in the areas inspected so far.

Where damage to ground support has been observed rehabilitation of those areas has been approved by the Inspectorate and that work has started.

The assessment of Panel Cave 1 has not been completed and the final mine assessment remains subject to further verification.

Initial assessment of ground support within the Panel Cave 2 extraction level and crusher chambers is that the level of damage appears to be minimal. More work is needed to confirm the integrity of the visually-intact ground support.

PC1 appears to have sustained some damage to the access ways. A remote operated camera is being used to assess any damage to the PC1 extraction level before personnel will be allowed into the area.

This work is expected to occur over the next few days.

Assessment of fixed plant infrastructure such as crushers and the conveyor system is ongoing. Early indications are that minimal damage has been sustained to the PC2 crushers, conveyor system and transfer stations. The PC1 crusher station is still being assessed.

Cadia is not expected to meet its production guidance for the 2017 financial year and Newcrest says it is still too early to be definitive about the impact on its production guidance for the 2017 financial year. 

It will update the market once plans to restart of mining operations are finalised.