The Project is located on the western limb of the Bowen Basin, a north-south trending Early Permian to Middle Triassic geological basin. Comprised of a sedimentary sequence of Permo-Triassic clastics, which attain a maximum thickness of 9,000 metres (m) in the depocentre of the basin, the Taroom Trough, the Bowen Basin is vast and covers an area of approximately 200,000 square kilometres, from Collinsville in the north to Rolleston in the south.

Divided into a number of tectonic units which comprise north-north-west to south-south-east trending platforms/shelves, separated by sedimentary troughs, the major structural features of the Project area include the Collinsville Shelf to the north and the Nebo Synclinorium 2 to the east.

Folds within the Basin are gentle and generally the results of drag on thrust faults along the eastern boundary of the basin. The boundary between the Collinsville Shelf and the adjoining major axis of deposition, the Nebo Synclinorium of the Taroom Trough, is indicated by a major thrust fault, the Jellibah Thrust Fault (URS, 2012). Limited regionally significant fault zones or structures differentiate the sediments of the Collinsville Shelf from the tightly folded and intruded sediments of the Nebo Synclinorium (Elliot, 1989). Summarised, the sequence comprises:
- Middle Permian Back Creek Group (basement);
- the Late Permian Blackwater Group sediments (and coal measures);
- unconsolidated Tertiary sediments;

Saraji is open-cut, using dragline and truck and shovel fleets for overburden removal.

BHP Mitsubishi Alliance (BMA) proposes to develop the Project, a greenfield single-seam underground. The Project incorporates a 20 year production schedule. Coal will be mined by longwall methods consisting of a northern region of panels and a southern region of panels separated by a portal which will be progressively mined out and developed as mining progresses. Mining will commence from the western end within ML 1775, adjacent to the existing Saraji open-cut operations, and progressing towards the east into MLA 70383.

The current approved Saraji open-cut mine plan is expected to continue until around 2031 (in some pits reaching the ML boundary). This means that the proposed underground mining and approved open-cut mining will occur concurrently between 2023 and 2031 i.e. an eight-year overlap. As a portion of the Project covers an area currently approved for open cut mining (ML 1775), BMA are seeking the flexibility to mine coal within this area using the most effective and economic mining method. It is noted that in areas where there are both open-cut mining and underground mining proposed, only one type of mining activity will be carried out. During the time of overlap between the proposed underground and approved open-cut mining an offset distance will be maintained between the two operations to ensure safe working distances and minimise geotechnical risks.
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