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. The coal-bearing rocks of the Sydney Basin are Permian in age and are typically associated with low-lying gentle topography.

The overlying rocks of Triassic age cover large parts of the Sydney Basin and tend to form prominent escarpments where they outcrop. 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.

Wittingham Coal Measures are divided into the Jerrys Plains Subgroup, Vane Subgroup, Denman Formation and Archerfield Sandstone. The Jerrys Plains Subgroup contains eight formations with 15 named coal seams. The Jerrys Plains Subgroup is up to 800 metres (m) thick and generally consists of relatively coarse clastic sediments. 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.

These seams dip gently to the south-west at approximately 2 to 3 degrees, with minor local variations due to varying thicknesses of inter seam sediments and fault zones. Faulting usually trends north or north-east to south-west with normal throws of up to 10 m, with some low angle thrusts.

WCPL 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 is scheduled to commence in Longwall 17 in September 2018 and involves extraction of coal by longwall mining methods.

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.

Run-of-mine (ROM) coal will be crushed and washed at the Wambo Coal Mine Coal Handling and Preparation Plant.

CHPP capable of processing approximately 1,800 tonnes per hour.

Coarse rejects and tailings would be incorporated, encapsulated and/or capped within open cut voids (that would comprise part of United’s operations during Phase 2).