40 The GOP aspect of the WNP involves open pit mining from development and production through to closing of the pit as a tailings storage facility. The pit will be mined over a period of approximately six years and conversion of GOP into a TSF will commence thereafter. No tailings will be discharged into the GOP until the production from the Martha Underground (MUG) operation has ceased. 9.2 Gladstone Open Pit Project Activities Mining of GOP comprises: • Pre-stripping of topsoil from the pit footprint and storage at Southern stockpile (capacity: 52,500 m3); • Relocating the existing Favona portal and associated infrastructure within GOP or north of the conveyor adjacent to the proposed WUG Portal; • Installing a new crusher and interconnecting conveyor for transporting rock to the NRS; • Establishing a new Portal “WUG Portal”; • Hauling and storing ore and/or rock at the existing polishing pond stockpile, if required; and • Construction of noise bunds or screens around the pit rim, where required. The pit comprises 2.6Mt of ore and 18.7Mt of waste rock. Selected topsoil material will be stockpiled adjacent to the pit at the Southern Stockpile. Waste rock from the GOP will be removed from this location and stored initially at the existing central and eastern stockpile areas adjacent to the existing TSFs. For closure, approximately 5.0Mt of rock will be required for partial backfilling of the pit. The rock required for backfilling will be transported across the Ohinemuri River from the NRS by reversing the existing overland conveyor. The remaining void will be used for tailings storage. All discharges will be directed either to the mine dewatering ponds located close to the Favona amenities buildings or direct to the WTP. Clean water diversion drains will be installed around the pit perimeter, lined either with HDPE or shotcrete if necessary and these will discharge directly to the nearby minor water courses to which surface runoff is currently reporting. It may also be possible to direct discharge clean water to the Ohinemuri River from dewatering holes in the upper parts of Gladstone pit provided that they do not have elevated metals or high TSS or TDS levels. 9.3 Ecological Values 9.3.1 Headwater Gully 9.3.1.1 Gully Characteristics The area of the proposed pit encompasses the headwaters of a tributary gully of the Ohinemuri River, which leads to a restored wetland in the lower reaches (Gladstone Wetland). We note that the Gladstone wetland downstream is largely fed by the water table at that location, rather than from the tributary gullies feeding into it (see below). Nevertheless, during intensive rain
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