Coal of Maules Creek associated with the early Permian age Maules Creek Formation of the Maules Creek Sub-basin.

The basement of the Maules Creek Sub-basin is formed by the Boggabri Volcanics. The rhyolitic volcanics are overlain by the Leard Formation, a thin unit comprised of black claystone and rare, thin coal seams. The Maules Creek Formation is up to 800 m thick within Aston’s mining authorities and sits conformably on the Leard Formation.

Within CL 375, the Maules Creek Formation contains 15 named coal seam groups, which exhibit splitting towards the north-east. This seam splitting has resulted in the recognition of up to 39 individual seam plies resulting in complex geological modelling. The identified coal measures generally dip towards the south- east with a flattening of dip occurring in the far south-eastern corner of CL 375 (coal lease).

Dips range from 1 to 7 degrees but are within the range of comfortable open cut mining operations. Dip direction is generally consistent across the deposit.

Coal will be extracted from all 15 defined seams, via open cut methods down to the Templemore seam. All seam groups situated stratigraphically below the Braymont Seam lap onto the basement volcanics. The depth of weathering across the modelled area varies from 6 m to 113 m with the average depth of around 25 m.

The Maules Creek Coal Mine (MCCM) is an open cut coal mine with an approved maximum ROM coal production rate of 13 Mtpa to December 2034. Pre- mining clearance activities including ecological, archaeological and soil analysis were undertaken in line with the relevant approvals and management plans. The 2018 vegetation clearing activities were completed during the approved annual clearing period (15th February to the 30th April each year).

Topsoil was reclaimed from the area to be mined and stockpiled for later use on rehabilitation areas. Overburden is blasted prior to being removed by loader and / or excavator and trucks before proceeding with coal extraction.

Coal mined from the open cut is delivered directly or from temporary storage in pit to the ROM pad area, where it is either fed directly into the ROM coal hopper from the rear dump trucks or stockpiled for later feeding to the ROM coal hopper via front end loader and/or rear dump trucks. From the hopper the ROM coal is fed through various sizing stations and either bypassed to the product coal stockpiles or fed via a surge bin to the CHPP for washing.

Product coal generated by the MCCM includes bypass coal (i.e. ROM coal that is crushed and screened but not washed in the CHPP) and washed coal that is processed in the CHPP.