Mount Thorley Warkworth (MTW) is located within the Sydney Basin of New South Wales (NSW), a world–class export thermal coal mining district.

The Sydney Basin is a north-south trending basin, containing generally flat lying Permian Triassic sequences, approximately 250 km long, averages 100 km in width, ranges from 2km to 4km in depth and covers an area of approximately 37,000 km2 onshore and 15,000 km2 offshore.

Sedimentation in the Sydney Basin can be divided into many distinct depositional episodes, related to marine transgression and regression an terrestrial sedimentation. In the Sydney Basin the total thickness of the sedimentary package ranges on average from 2 to 3 km over much of the basin, based primarily on drill-hole records and deep seismic profiles.

Coal bearing formations in Permian aged sediments are extensive in the Sydney Basin and range in depth from near the surface to over 1 km. The Sydney Basin is divided into five major coalfields; Southern, Central, Newcastle, Hunter and Western, and comprised of black anthracite coal bed of a few centimetres to several meters, interbedded with sandstones, shales, tuffs and claystone. During coal bore drilling in the late 19th Century a number of bores encountered flows of natural gas.

The Late Permian coal measures show sources of both oil and gas, with the offshore basin possibility more prone to oil Fine grained sediments deposited during the brief marine incursions that took place during the Late Permian may also have some potential as oil sources.

The proposed mining method within MTW is the same as that currently employed. Large electric face shovels, hydraulic excavators and front-end loaders are utilised to load haul trucks to remove pre-strip and parting material. Draglines are used to expose lowest coal seams. Ancillary equipment in the form of drills, graders, rubber-tyred dozers and water carts will provide the mining equipment with support as required. Coal is extracted by front-end loaders and/or excavators loading haul trucks.

The current mining equipment will continue to be used. In general, changes may occur due to replacement or as technology changes.

Coal will be washed in both the North CPP and South CPP in accordance with market requirements.