EGL Ref: 9215 23 June 2022 Page 46 This report shall only be read in its entirety. File: WAI-985-000-REP-LC-0002_Rev0.docx. 8.6. Site east of Storage 1A A new TSF or rock stack could be constructed east of Storage 1A. The option for storage of tailings in this area has been investigated in detail and a feasibility study has been undertaken. This option is referred to as Storage 3. The land is owned by OGNZL. Geotechnical investigations indicate that ground conditions are suitable for a TSF subject to removal of weak ground that has been identified by the investigations. The Storage 3 TSF provides for efficient storage of tailings. The embankment construction program meets the current ore and mine pit overburden rock production schedule. The site would be suitable for storage of mine pit overburden rock. However, there are better options at the existing Development Site that avoid disturbing a new area and have better economics. Dry stacked filtered tailings could be located east of Storage 1A. However, this option is not suited to the climate at Waihi. Capital and operating costs are very high. 8.7. Beyond the current Development Site New TSFs or rock stacks beyond the Development Site other than discussed above have not been considered. Any options would be located more distant from existing mine infrastructure, result in disturbance and potential effects on new areas, and affect additional stakeholders. There would be significant consenting issues and capital and operating costs would be higher than other options at the Development Site. 8.8. Martha Open Pit Tailings associated with the Waihi North Project and overburden rock from Gladstone Open Pit and the north wall of Martha Open Pit could be stored in the bottom of Martha Open Pit. However, there would be several technical as well as health and safety challenges including stabilisation of the pit walls and construction and operation of the facility. It would complicate and possibly prevent the current closure plan to fill the Martha Open Pit with water and create a lake. The cost of constructing and operating a TSF in the Martha Open Pit would be greater than using and developing new TSFs at the Development Site. Storage of overburden rock in the base of the pit would be easier but there would still be technical and health and safety challenges. The cost of disposing of waste rock in Martha Open Pit would be significantly greater than associated with options at the Development Site due to the haul costs. A major disadvantage with storage of either tailings or overburden rock in the Martha Open Pit is that it would compromise future options for extending mining operations in the area. 8.9. Gladstone Open Pit The Gladstone Open Pit could be used for both disposal of tailings and mine pit overburden material. A TSF would require flattening of the pit walls to reduce the
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