This report shall only be read in its entirety. File: WAI-985-000-REP-LC-0002_Rev0.docx 1.0 INTRODUCTION Engineering Geology Ltd (EGL) has been appointed by Oceana Gold (New Zealand) Limited (OGNZL) to prepare a series of technical reports for resource consent for tailings storage and rock disposal for the Waihi North Project. This report is Volume 1 of a 4-part series of reports on tailings storage and rock disposal for the Waihi North Project. This report documents a review of natural hazards, and the locations and best available technologies for tailings storage and rock disposal for the Waihi Operation. Volume 2 is a technical report on the use of the proposed Gladstone Open Pit (GOP) as a Tailings Storage Facility (TSF). This will involve partial backfilling of GOP with rock, so the GOP TSF provides for both tailings storage and rock disposal for the Waihi North Project. The technical report for GOP TSF is prepared by GHD (Ref. 1). Volume 3 is a technical report on a new TSF named Storage 3, located east of Storage 1A. It provides for both tailings storage and rock disposal for the Waihi North Project. Volume 4 is a technical report on the Northern Rock Stack (NRS). It provides for disposal of rock and is located north of the existing TSF Storage 2. These preferred facilities are compared against a range of options. This report covers: • Waihi Operation location and site description. • An overview of the climate, geology, hydrology, hydrogeology, and seismicity of the Waihi area. • An overview of the Waihi Operation existing storage facilities which have performed well geotechnically and environmentally. • A comparison of the Waihi TSFs with practices seen globally. • Waihi North Project tailing storage and rock disposal requirements. • Locations for tailings storage and rock disposal. • Tailings storage best available technologies. • Rock disposal best available technologies. • Assessment of options. • Proposed Waihi North Project tailings and rock disposal strategy. The chosen options for tailings storage and rock disposal take into consideration a wide range of inputs to result in designs that provide: long term security for the disposal or rock and 23 June 2022 OCEANA GOLD (NEW ZEALAND) LTD WAIHI OPERATION WAIHI NORTH PROJECT TAILINGS STORAGE AND ROCK DISPOSAL VOLUME 1 NATURAL HAZARDS AND OPTIONS ASSESSMENT TECHNICAL REPORT EGL Ref: 9215
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