EGL Ref: 9018 22 June 2022 Page 19 WAI-985-000-REP-LC-0006_Rev0.docx This report shall only be read in its entirety. 9.10. Construction aspects The construction of the NRS will likely be undertaken in stages as the requirement for rock storage volume develops. Initially the working areas of the NRS will consist of converting the existing NAF Northern Stockpile into a PAF stockpile. This will require constructing a Zone A liner and leachate drains and utilising the existing Northern Collection Pond and Northern Stockpile Silt Pond. It will also need to avoid permanently covering any existing NAF material. The northern part of the site beyond the Northern Stockpile will then be developed along with the NRS Collection Pond. The perimeter infrastructure (road, surface water drain and seepage collection system) and uphill diversion drain will also be constructed. The estimated volumes of material to be excavated from the foundations of the NRS are summarised in Table 2. An initial estimate of fill volumes by NAF, PAF, and topsoil, and by NRS zonation has been made and is summarised in Table 3 and Table 4. Approximately 1,180,000 m3 of NAF is required. 504,000 m3 of NAF material is estimated to be cut from the existing site (Table 2). Not all this material will be suitable for construction. Assuming only half the alluvium is suitable it is estimated that 470,000 m3 can be obtained from the NRS foundation works and that 710,000 m3 of NAF mine overburden material will be required from GOP and MOP4. Management of NAF stockpile volumes and site preparation is required to ensure suitable quantities of ash, alluvium, and rhyolite is won from the Development Site prior to NRS construction. To initially establish the NRS site it is estimated that only 465,000 m3 of NAF material (i.e. Zone A and I volumes in Table 3) is required. This required volume is equal to the undercut NAF volume mentioned previously, however it is expected that material will still be required from GOP or MOP4, as materials stripped from the site that are better suited to rehabilitation layers Zones G and H may preferentially be stockpiled for use at a later date. Materials required to be sourced offsite from external suppliers, such as drainage metal, sand filter material, rockfill lining, pipes, sumps, concrete, and decants, are summarised in Table 5. Section 13.0 outlines the Erosion and Sediment Control Plan aspects.
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