Cadia looks to use old open pit to reopen operations after dam wall collapse

Collapsed: Taken from Meribah lane, this image, which was contributed by a reader, shows the collapse of the tailings wall following an earthquake at the mine.
Collapsed: Taken from Meribah lane, this image, which was contributed by a reader, shows the collapse of the tailings wall following an earthquake at the mine.

Newcrest is considering reopening its old open pit as an alternative location for dumping tailings after the partial collapse of a wall between its two tailings dams.

NEW LEASE: Newcrest is considering pumping tailings into the old Cadia Hill open pit to allow the company's Cadia Valley Operations to reopen.

NEW LEASE: Newcrest is considering pumping tailings into the old Cadia Hill open pit to allow the company's Cadia Valley Operations to reopen.

Work at its Cadia Valley Operations south of Orange was suspended indefinitely after the collapse occurred at 6.30pm on Friday.

Two small earthquakes were recorded close by less than a day earlier but there has been no evidence to show they contributed to the collapse.

A statement from Newcrest said they were now looking at alternative locations to dump the tailings, the waste products from the mining operations.

“Geotechnical analysis has commenced on possible repair options of the failure zone,” it said.

“Work has also commenced on multiple recovery scenarios including alternative tailings locations such as the old Cadia Hill open pit, which is already the subject of a prefeasibility study to assess suitability for tailings disposal.”

The company also said the breach of the wall would affect its financial situation.

“This event will adversely impact guidance for FY18 [financial year 2017-18] given the contribution of Cadia to the overall outcomes of Newcrest.”

It said it was too early in the evaluation and recovery process to determine the extent to which production, capital and cost guidance would be affected by the event.

It said updates would be provided to the financial market when available.

The company has been monitoring the impacted site with radar and cameras and said there had been no further movement since Friday night.

It said the tailings spill had not damaged the environment.

“The tailings material is a slurry of finely ground rock, water and a low level of benign processing reagents,” it said.

“Cadia does not use a chemical reduction process to recover gold, that is, the gold extraction process does not involve the use of substances such as mercury, cyanide and arsenic.”

Managing director and chief executive officer Sandeep Biswas said safety was a company priority.

“The safety of our people and the community, together with the highest standards of environmental compliances, are paramount and remain our focus as we investigate this event and enact our forward work plan,” he said.