The Wambo Coal Mine is situated within the Hunter Coalfield subdivision of the Sydney Basin, which forms the southern part of the Sydney-Gunnedah-Bowen Basin (WCPL, 2003). The coal-bearing rocks of the Sydney Basin are Permian in age and are typically associated with low-lying gentle topography (WCPL, 2003). The overlying rocks of Triassic age cover large parts of the Sydney Basin and tend to form prominent escarpments where they outcrop (WCPL, 2003). Mining activities at the Wambo Coal Mine include both open cut and underground mining of several coal seams from the Wittingham Coal Measures, which combine with the Newcastle Coal Measures to form the Singleton Supergroup. The Wittingham Coal Measures are divided into the Jerrys Plains Subgroup, Vane Subgroup, Denman Formation and Archerfield Sandstone (WCPL, 2003). The Jerrys Plains Subgroup contains eight formations with 15 named coal seams (WCPL, 2003). The Jerrys Plains Subgroup is up to 800 m thick and generally consists of relatively coarse clastic sediments (NSW Department of Mineral Resources [DMR], 1993). The sedimentary rock layers above and between coal seams are typically lithic sandstone, siltstone and conglomerate, while minor carbonaceous claystone and tuff occurs throughout the sequence (WCPL, 2003). Coal seams previously, currently and approved to be mined at the Wambo Coal Mine include: • Whybrow Seam; • Redbank Creek Seam; • Wambo Seam; • Whynot Seam; • Woodlands Hill Seam; and • Arrowfield Seam. These seams dip gently to the south-west at approximately 2° to 3°, with minor local variations due to varying thicknesses of inter-seam sediments and fault zones (WCPL, 2003). Faulting usually trends north or north-east to south-west with normal throws of up to 10 m, with some low angle thrusts (i.e. reverse faults) of variable throw (MineConsult, 2001). There is a series of north-northeast to south-southwest trending faults within and adjacent to the mining area with throws between 0.5 m and 1 m. Some larger faults have been identified to the north-west and to the south-east of the longwalls with throws between 3 m and 12 m. The South Bates Extension Underground Mine mines the Whybrow Seam, which produces a low ash thermal coal. ROM coal is crushed and washed at the Wambo coal handling and preparation plant. Product coal from the South Bates Extension Underground Mine will be considered suitable for export and domestic markets. The overburden of the Longwalls 21 to 24 Application Area consists predominately of interbedded sandstone and siltstone layers, with minor claystone, mudstone, shale, tuffaceous and coal layers.

Wambo is currently mining Longwall 20j at the South Bates Extension Underground Mine.

The South Bates Extension Underground Mine is a component of the approved Wambo Coal Mine.

The South Bates Extension Underground Mine commenced in Longwall 17 in December 2018 and involves extraction of coal by longwall mining methods from the Whybrow Seam.

Longwalls 21 to 24 will be extracted using retreating longwall mining methods for secondary extraction of panels with approximately 261 m void width (extraction face of approximately 250 m). Construction of development main headings, maingates and tailgates will be undertaken using continuous miners.

The South Bates Extension Underground Mine mines the Whybrow Seam, which produces a low ash thermal coal. ROM coal is crushed and washed at the Wambo coal handling and preparation plant. Product coal from the South Bates Extension Underground Mine will be considered suitable for export and domestic markets.