The company blamed “abnormal geological conditions” for damage that was tracked over more than 2km within the conservation area adjacent to the mine's Longwall 41.

“Glencore’s underground mining operations within the SSCA are undertaken in accordance with a Part 3A Project Approval received from the NSW Department of Planning and Infrastructure and its approved extraction plan/subsidence management plan,” a spokesman told ILN.

“While subsidence occurs as a consequence of all underground longwall mining, despite extensive planning and geotechnical studies prior to mining in this area the subsidence impacts were greater than originally predicted as a result of abnormal geological conditions.

“The subsidence impacts, the magnitude of which is a rare occurrence in longwall mining, were identified and reported to authorities.”

The remediation plan to address these impacts will be implemented in consultation with the NSW Department of Planning & Industries, the Office of Environment & Heritage and the NSW Division of Resources & Energy, according to Glencore.

A grouting spill in the same area, which has also been identified and reported to authorities, will be removed in accordance with a remediation direction issued by the OEH.

Grouting is a recognised method for subsidence management in the SSCA and the “grout” used is an aerated cement material approved for such use.

“We are deeply disappointed and regret that these incidents have occurred despite our careful and comprehensive management plans, and we are fully committed to remediating these areas,” the spokesman said.

“As remediation is carried out to address these issues, Glencore will continue to monitor the active subsidence zone to ensure the ground is stable enough for this work to be safely carried out.”

Glencore asked the public to be aware of the dangers present in active subsidence zones and observe safety warnings that are marked, sign-posted, and attended by security personnel to manage and protect public safety in the area.