The Pilbara bioregion, where the South Flank is located, is situated in the south-eastern comer of the Pilbara Craton. The cratonic basement comprises Archaean granite-greenstone and is unconformably overlain by the late Archaean to Early Proterozoic deposits of the Hamersley Basin. The Hamersley Basin can be divided into three stratigraphic groups: the Fortescue, Hamersley and Turee Creek groups. Of these groups, the Fortescue and Hamersley groups outcrop in the immediate area Mining Area C.

The Hamersley Group is seen throughout the Hamersley Basin and forms the outcrop of Mining Area C. It is a sedimentary sequence comprising banded iron formations (BIFs), shales and dolomites with minor felsic volcanics and intrusive dolerite dykes and sills. The group contains both the Brockman and Marra Mamba Iron formations, which together host most of the known major iron ore deposits in the Pilbara region. The six lowermost formations of the Hamersley Group that exist within the area are listed below in order of increasing age:

1. Weeli Wolli Formation.

2. Brockman Iron Formation. Ore mineralisation from the Packsaddle Range deposits is contained within the Brockman Iron Formation, composed of a sequence of interbedded Banded Iron Formation, shales, siltstones and cherts. The four members comprising of the formation are:
- Yandicoogina Shale Member (shale and BIF);
- Joffre Member (BIF with minor shale bands);
- Whaleback Shale Member (interbedded shale, chert and BIF); and
- Dales Gorge Member (interbedded BIF and shale).

3. Mount McRae Shale (graphitic and chloritic shales interbedded with BIF). The Mount McRae Shale (~30 m thick) consists of alternating bands of black carbonaceous shale and chert and is commonly capped with pyritic chert bands. The Mount McRae Shale forms the basal unit to the ore horizons in the Brockman Iron Formation and contains a limited enriched ore zone. BHP Billiton Iron Ore informally subdivides this lithology into five units based on lithology and pyrite content. Several zones within the unit contain abundant pyrite nodules, thus, the formation is commonly regarded as a significant AMD risk throughout the Pilbara region.

4. Mount Sylvia Formation (shale, dolomite and BlF bands).The Mount Sylvia Formation (~2.5 Ma) has a thickness of ~50 m in the vicinity of the town of Newman, WA, and consists of three BIFs separated by interlayered shale and dolomite as well as small amounts of chert.

5. Wittenoom Formation. The Wittenoom formation is located stratigraphically above and is younger than (2.6 – 2.5 Ma) the Marra Mamba Formation. The Wittenoom Formation has been deeply eroded in the development area and is mostly covered by Tertiary Detritals. The formation is predominantly comprised of calcareous and manganiferous shales, cherts and dolomite and includes the following members comprising:
- Bee Gorge Member (calcareous shale and dolomite);
- Paraburdoo Member (dolomite – karstic in part); and
- West Angela Member (manganese-rich shale with minor BIF and chert bands).

6. The Marra Mamba Iron Formation consists of:
· The lowermost Nammuldi Member (approximately 80 m thick) which includes thick bedded, poddy cherty BIF interbedded with thin shales.
· The MacLeod Member (approximately 75 m thick) which includes BIF, cherts and carbonates with numerous interbedded shales.
· The upper Mount Newman Member (approximately 65 m thick) which includes podded BIF with interbedded carbonates and shales. The Member has been sub-divided by BHP into three sub- members based upon shale band content to allow for detailed modelling and estimation; lower N1, central N2 and upper N3. Iron ore mineralisation within Marra Mamba hosted deposits occurs as either martite-goethite or martite-ochrous goethite formed primarily by supergene enrichment processes. The Mount Newman Member is the main mineralised horizon within the formation although lesser amounts of mineralisation can be found in the Nammuldi and MacLeod Members and within the overlying West Angela Member shales of the Wittenoom Formation.

Mining at South Flank will be undertaken utilising conventional open-cut mining for iron ore. Campaign mining involves drilling, blasting, and categorisation of blasted material into iron ore or waste rock. Iron ore will be extracted from the three South Flank deposits - Highway, Vista Oriental and Grand Central.

BHP is seeking a works approval to construct processing and support infrastructure at Mining Area C -South Flank. Primary crushing will occur at South Flank, and overland conveyors will transport crushed ore to the Mining Area C hub. The existing Mining Area C hub infrastructure and facilities will be expanded with a a new ore handling plant (OHP) to achieve a nominal combined processing rate of 150 Mtpa of blended ore.

Ore from the South Flank via Vista Oriental (PC1) and Grand Central North (PC2) will be processed through two primary crushing (PC) facilities, each with a nameplate capacity of 40Mtpa. The two primary crushing stations (PC1 and PC2) will have a dual truck dump apron located at the top of a mechanically stabilised earth wall designed to accept ultra-class mining trucks of up to 363t capacity. Each primary crusher will have a nameplate capacity of 40Mtpa. The mining trucks will feed into the Run of Mine (ROM) bin located over a gyratory crusher that will crush the iron ore to a -250mm top size. The crusher will discharge to a surge vault directly beneath. An apron feeder draws ore from the surge vault and loads the discharge conveyor, which feeds onto the overland conveyor (OLC) system.

Each the primary crushing facility includes:
- Rock catchers, truck dump slabs and anchor blocks;
- Primary crushing building including rock breakers;
- Dust suppression (foggers and cannons);
- Primary crushing discharge conveyor; and
- Transfer stations, onto the overland conveyor circuit.

Three new overland conveyors will transport primary crushed ore from the primary crushing facilities at South Flank to the new coarse ore stockpile (COS) at Mining Area C. The discharge conveyors CV402 and CV404 will transfer ore from PC1 and PC2 onto the overland conveyors CV411and CV412 via Transfer Stations TS402 and TS404. The discharge conveyors will each include a magnet, metal detector, Bulk ore conditioning sprays (BOC) sprays, moisture analyser and belt weigher. The overland conveyors CV411 and CV412 have a design capacity of 7,500 tonnes per hour (tph). The third conveyor CV413 will be loaded with ore by overland conveyor CV412 at Transfer Station TS411. Conveyor CV411 and CV413 will discharge onto the COS and has a capacity of 15,000tph. All three overland conveyors will be fitted with BOC sprays to ensure the ore is above the DEM moisture content prior to being fed onto the COS.

The coarse ore stockpile (COS) will be located inside the rail loop and will receive and store primary crushed ore from South Flank. It will consist of a conical stockpile above a concrete vault and tunnel containing two apron feeders for reclaim of the primary crushed ore for loading onto the scalping screen feed conveyor for transfer to Ore Handling Plant (OHP) 3. The nameplate production rate for OHP3 is 80Mtpa. The key components of the OHP3 comprising of:

- Scalping screening building containing five scalping screening bays (Scheck SLD4385s);
- Secondary crushing building containing four secondary crusher bays (Metso MP1250s);
- Product screening building containing six product screening bays (Scheck SLD4385s);
- Interconnection conveyors; and
- Lump and fines product conveyors.

The material from the COS feeds the scalping screening building. The scalping screening building arrangement includes with five screening bays and large screens (Schenck SLD4385DX.). The belt feeders transfer material from the bins onto the double deck screens. Material separates into three streams:
- The oversize is conveyed to the Secondary Crushing Building;
- The middlings is directed to the Product Screening Building; and
- The undersize Fines Product is conveyed to the stockyard.

The Secondary Crushing Building includes four Metso MP1250 cone crushers. Ore will be delivered into the secondary crusher feed bins and transferred to the crusher feed conveyor via a vibrating feeder. The feed conveyor incorporates a metal detector to protect the cone crusher from tramp metal damage. Once crushed, the undersized ore will be discharged onto the product screening feed conveyor. Oversize material will be recirculated through the crushing and screening circuit.

The secondary crushed ore and the mid-size ore from the scalping screening building will be conveyed into the product screening building surge bins. Vibrating feeders will transfer material onto the double deck screens which will again separate the ore into three streams. The oversize is recirculated to the Secondary Crushing Building for processing. The mid-size reports to the Lump Product Conveyor and undersize to the Fines Product Conveyor. The lump and fines ore streams are sampled en-route to the stockyard.