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 2018.

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.

The CHPP produces both semi soft coking coal and thermal coal. The CHPP operates 24 hours a day, seven days a week, with the exception of downtime due to maintenance (generally 10 to 12 hours each fortnight). The CHPP has a processing capacity of 8 Mtpa.

The total ROM coal processed at Liddell’s CHPP during the 2018 reporting period was 5,933,351 tonnes. The total product coal produced was 4,123,866 tonnes with 1,719,540 tonnes of coarse and 175,366 tonnes of fine rejects generated.

Coal is transported from open cut areas by trucks along internal haul roads to the ROM coal receival facility located to the northwest of the existing CHPP. ROM coal is reclaimed off the stockpile or fed directly into a ROM bin, onto a feeder conveyor, through a rotary breaker or sizer and then onto a conveyor, which transfers the ROM coal to the CHPP.

At the CHPP the coal is sized, washed, screened, rinsed, crushed, dewatered and placed on the product stockpile. The product coal is then reclaimed from the product stockpile, loaded into trains and transported to Newcastle via the Hunter Valley Rail Loop and Main Northern Railway Line.