Before the approval last week the Abel underground bord and pillar mine was permitted to extract up to 4.5 million tonnes per annum to 2028, with the coal processed at a preparation plant shared with the Donaldson open cut, the Tasman underground and Bloomfield colliery.

The successful modification plans were based on introducing five longwall panels and five shortwall panels on the Lower Donaldson seam, plus bord and pillar mining in the Upper Donaldson seam including total pillar extraction above the new longwall panels.

The plans to add another 10Mt to the mine also aimed to upgrade the shared Bloomfield coal preparation plant to accommodate the subsequently boosted 6.1Mtpa run of mine target, plus develop a ventilation shaft and create an alignment of the pit-top coal conveyor.

In its recommendation to approve the project, which was signed off on Wednesday, the Department of Planning and Infrastructure noted that the additional subsidence risks would be mitigated through its requirement for extraction plans that included consultation with the division of Resources and Energy.

Overall the department found the modifications generally decreased some of the environmental impacts of the previous plans, especially on fauna, with the proposed conveyor realignment.

The project also offered the prospect of creating 48 jobs, bringing in $A65 million of capital investment and an estimated $75 million in state royalties.

“On balance, the department believes that the proposed modification represents a more efficient use of a readily available coal resource and the existing processing and transportation infrastructure,” the Planning Department said.

“The department considers that the benefits of the proposed modification significantly outweigh any potential environmental costs.”

The mine is in the Newcastle coalfield about 23km northwest of Newcastle.