‘It’s cracking’: fear rare rock formations at risk from NSW coalmine

Subsidence from an underground coalmine is leading to extensive surface cracking in a supposedly protected region of New South Wales, stoking locals' fears that rare rock formations could end up as rubble.

Centennial Coal officials are scheduled to meet government regulators on Thursday to discuss remediation for the extensive fracturing of stunning weathered sandstone shapes and cliffs within the 3,650 hectare Mugii Murum-Ban state conservation area, near Capertee, north-west of Sydney. The miner concedes the cracks exceed permitted levels.

Repairing the damage "is very hard", said Mary Thirlwall, a resident involved in landcare who has helped raise the alarm. "You can't jack up a mountain, you know, or fill in the cracks really that easily."

Whether Centennial receives any penalty for breaching the terms of its planning approval for the Mount Airly mine is being watched closely by conservation groups. Its many unusual rocks have been described as the "three hundred sisters", echoing the more famous "three sisters" at Katoomba in the Blue Mountains.

The nearby Gardens of Stone, a larger area of the remarkable, pagoda-like structures, was granted similar state conservation status last November. It too has had coalmining underneath and faces other development threats if tourism projects take off.

Centennial has been approved to mine in the Mount Airly region out to 2037. The next stage within the Mugii Murum-Ban area would be to extract coal under the adjacent Genowlan mesa, an even larger rocky landscape that could be more vulnerable to cliff collapses if there is similar fracturing as that at Mount Airly, according to Thirlwall.

"Airly and Genowlan are just iconic mesas," she said. "It's just a very special area."