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 Se ........

Wambo is 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.

The South Bates Extension Underground Mine includes nine longwalls in the Whybrow Seam (Longwalls 17 to 25). The Extraction Plan Application Area for Longwalls 21 to 24 (Longwalls 21 to 24 Application Area) is based on a 26.5 degree (°) angle of draw.

Mine Plan
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 extraction of LWs 21 to 24 would recover approximately 6.6 million tonnes of run-of-mine coal from the Whybrow Seam.

LWs 21 to 24 would be 261 m wide, with chain pillars between 21 m and 37.2 m wide and lengths ranging from 1505 m to 1870 m. The height of mining is expected to range between 2.3 m and 3.0 m, with a depth of cover ranging between 60 m and 290 m.

Mine Schedule
The proposed sequence of mining for Longwalls 21 to 24 at the South Bates Extension Underground Mine:
- Longwall 21: April 20 ........

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