The capital value of the expansion project is estimated to be $79.9 million and is expected to provide ongoing employment for 280 people.

The company has lodged an Environmental Assessment with the NSW Department of Planning and Environment that outlines its plan for increasing the amount of coal it can extract from the Integra lease it acquired from Brazilian giant Vale.

It wishes to expand three existing longwalls, numbers 15 to 17, and to gain approval for up to three new longwalls, 18 to 20.

The company also wants to build additional surface works including new electricity lines on the lease site, which lies immediately west of Glencore’s Mount Owen open-cut mine and underneath the Mount Owen rail loop.

Glencore commissioned a geotechnical report that found longwall mining “directly beneath the highwall of the [Mount Owen] north pit” had the potential to induce rockfalls ... and ... slope instability”.

The reports said impacts would be managed in consultation with Mount Owen.

Mine subsidence is expected to be in line with existing conditions, with vertical subsidence of between 300mm and 1900mm.

The NSW government’s Division of Resources and Geoscience put the value of the extra coal at $900 million over six years.