Signed off on Friday, the operation received approval for a layout of seven 400m-wide longwall panels instead of 12 at 265m widths.

As part of its assessment report, the Planning and Infrastructure Department says the proposed layout uses a “newer, wider longwall miner that has been deployed in the Blakefield South mine”.

Other key modifications were developing main heading instead of access adits off the Whybrow pit highwall to better integrate the mine with the proposed Bulga optimisation project, plus a lot more gas drainage and ventilation infrastructure including 6-20 drainage wells per panel.

Approval was also sought for additional coal seam gas-run electricity generators of up to 32 megawatts each.

Despite the changes in longwall layouts, subsidence was predicted to be a little less than under the previous layout.

Out of the various conditions on the approval, the department requires an extraction plan to be prepared for all the longwalls not covered by approved subsidence management plans by the start of 2014.

The revised mine plan will not result in changes to the existing coal production rates for the Blakefield seam in the underground mine.