Surface soils in the Wangi area and proximate to the surface facilities are classified as part of the Awaba erosional landscape on the Lake Macquarie to Gosford. The Awaba soil landscape is associated with the Munmorah Conglomerate Formation of the Narrabeen Group, and the Newcastle Coal Measures. The topography of this landscape typically comprises low hills with short side slopes and numerous closely spaced drainage lines. Rock outcrops are usually absent and lenses of mudstone and tuff may occur. This soil landscape generally has a high erosion hazard.

Myuna Colliery has extensive workings in the Wallarah, Great Northern and Fassifern seams and has been extracting coal for over 30 years. The area covered by the Colliery is located in the centre of the Newcastle coalfield, a geological sub-division of the North Eastern Sydney basin. The coal deposits of this area are contained within sedimentary rocks of the late Permian age Newcastle Measures. The coal seams typically extend deeper to the south, therefore a higher depth of cover is observed.

Mining activities are concentrated in the Great Northern and Fassifern seams, but could include workings in the Wallarah seam.

Myuna is an underground mine using a continuous mining method.

Myuna is located 25 km south west of Newcastle NSW in the Lake Macquarie and Wyong Local Government Areas. Myuna Colliery’s Surface Facilities Area is on the western side of Lake Macquarie, at Wangi Wangi.

Underground coal miming has been conducted at Myuna Colliery since 1982. Coal has been recovered from three seams (Wallarah, Great Northern and Fassifern) within the Project Application area and Development Consent mining area. The majority of the mining has been conducted under Lake Macquarie.

The method of extraction for these areas is by conventional underground bord and pillar mining methods. The mining system includes:
- Multiple seam mining – first workings or non caving partial pillar extraction systems where multiple seams are to be mined; and
- Single seam mining – first workings, partial pillar extraction or wide panel full extraction.

Two subsidence zones have been established at Myuna Colliery in accordance with the PA10_0080 (Project Approval).
- Zone A – long term stable mining systems generating up to 20 millimetres surface subsidence (i.e. no measurable or discernible surface impacts) on sensitive surface features including land and seagrass beds; and
- Zone B – Mining Systems generating up to 650 millimetres surface subsidence (under Lake Macquarie).

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