Liddell Colliery is located in the Hunter Coalfield, within the north-eastern portion of the Sydney Basin. The north-eastern boundary of the basin is the New England Block and is marked by the Hunter–Mooki thrust.

The coal seams currently mined at the Liddell Colliery include the Lemington, Pikes Gully, Arties, Liddell and Barrett seams.

The coal seams targeted by current and future mining operations range from 0.7 metres to 9.5 metres in thickness and include semi-soft and thermal coal types.

Liddell currently has approval to utilise three mining methods, truck and excavator, dragline and highwall mining (utilising an auger or continuous miner). Truck and excavator mining method is the primary method currently utilised.

The open cut mining sequence at LCO includes:
- Land preparation including vegetation removal and pre-stripping topsoil;
- Removal of overburden;
- Coal extraction, predominantly using excavators-and tucks;
- Coal processing and transport.

Mining will continue in accordance with the MOP (Mining Operations Plan) targeting coal from the Lemington, Pikes Gully, Arties, Liddell, Barrett and Hebden seams. These seams range from 0.7 metres (m) to 9.5 m in thickness, and include semi-soft and thermal coal types. Mining will generally utilise hydraulic excavators and trucks which are suitable for working in the South Pit and Entrance Pit to recover coal from multiple seams.

No mining was undertaken using dragline or highwall extraction methods during 2020.

During the reporting period there was no noncompliance with the sites approved production limits.

Coal is transported from the open cut areas by truck to a ROM stockpile with an approximate capacity of 200,000 tonnes for storage prior to processing in the CHPP.

Coal is trucked from the open cut areas via internal haul roads to an (approximate) 200,000 tonne ROM stockpile prior to processing in the CHPP. Coal with a low propensity to spontaneously heat may also be stockpiled in a 450,000 tonne supplementary stockpile adjacent to the ROM stockpile.

Loaders or dozers load coal from the stockpiles into the adjacent ROM dump bin that gravity feeds the coal onto a feed conveyor, through a primary sizer, and then onto the transfer conveyor to transfer the ROM coal to the CHPP for processing. At the CHPP ROM coal is crushed, sized, washed, screened, rinsed and dewatered. The ROM coal yields approximately 70% product. Rejects comprise approximately 21% coarse rejects and 9% fines (tailings).

Semi-soft and thermal coal products are stockpiled separately in product stockpiles that have an approximate combined capacity of 400,000 tonnes. The product coal stockpiles are formed by dumping coal off an overhead conveyor belt and coal i ........