Cadia mine closed, tailings dam wall breach under close scrutiny

Work has been been suspended indefinitely at the mine south of Orange following the collapse of the wall between Cadia mine’s northern and southern tailings dams.

The collapse came less than a day after two small earthquakes just five and 10 kilometres away.

The Australian Workers Union said mine workers were concerned about a possible link between the events.

A spokeswoman for Newcrest said it was not known what caused the breach and said there had been no signs of further damage.

“The release has been contained within the southern tailings dam. We are monitoring the impact carefully, and have observed no environmental damage,” she said.

“We have engaged in continuous visual remote monitoring, as well as commissioning a remote radar system, which is providing real-time monitoring.

MAP: Where the earthquakes occurred ...

“An initial geotechnical inspection of the southern tailings storage facility embankment has been completed [on Sunday] and does not indicate any change in stability of the structure.

“Laser monitoring indicates there has been no further instability and no significant movement of tailings since the initial event on Friday evening.”

She said the tailings was not wholly liquid and it was unknown at this point what volume of tailings had seeped into the lower dam.

“The tailings is semi-solid and does not flow like water. The tailings material is a slurry of finely ground rock, water and a low level of benign processing re-agents.”

Mining work was progressively shutdown following the break and it remains unclear how long mining operations would be shut down at the site.

“We are assessing the impact on our operations and will provide an update when further information is available,” she said.

The spokeswoman said they were keeping in contact with local residents who could contact Cadia’s Community Hotline on 1800 063 043 if they had any concerns.

A spokesman for the NSW Resources Regulator said inspectors had been sent to the site.

“A range of technical specialists are currently onsite assessing the situation,” he said.

“Inspectors from the Resources Regulator are also onsite monitoring the situation and working closely with other agencies, including the NSW State Emergency Service, NSW Police and the Dam Safety Committee.”

Immediately after the breach was discovered residents in two nearby houses were evacuated and the families were provided with accommodation in Orange

Panuara Road, which is adjacent to the collapse site and tailings dams, was closed before being reopened to local traffic on Sunday afternoon, while nearby Angullong Wines had to find a detour route for its trucks.

Blayney Shire Council general manager Rebecca Ryan said they were in contact with the mine management.

“We have complete confidence in the processes being put in place at Cadia and will wait on their advice,” she said.

Orange City Council mayor Reg Kidd said stopping work at the mine was a concern for workers and businesses in the city.

“When the mine is closed for a time it affects everybody,” he said.

NSW Farmers branch chair Bruce Reynolds said farmers in the affected area had been notified by mine management about the partial wall collapse.

“Communication has been very good from Cadia. There has been lots of community consultation,” he said.

Angullong Wines vineyard manager James Crossing said its trucks had to make a detour with the road closure.

“It’s an inconvenience but it hasn’t really affected us. They are taking all the precautions,” he said.

The vinyeard is on Four Mile Creek Road, near the mine site.

Mr Crossing said he did not sense the earthquakes on Thursday night.

“We didn’t feel anything over here,” he said.

The NSW Environmental Protection Authority said it was investigating the incident.

“NSW EPA understand the tailing had been contained,” it said in a statement.

Last year Cadia mine production was shut down for several months after damage was caused by an earthquake of 4.3 magnitude occurred nearby.