EGL Ref: 9215 23 June 2022 Page 74 This report shall only be read in its entirety. File: WAI-985-000-REP-LC-0002_Rev0.docx 11.0 PROPOSED WAIHI NORTH PROJECT TAILINGS STORAGE AND ROCK DISPOSAL STRATEGY The results indicate Option 1 scores highest and this is the company preferred option. The report considers natural hazards which can affect the site, best available tailings technologies, potential locations for tailings storage and rock disposal facilities, and a combination of storage and disposal options for the Waihi North Project. A summary of the features of Option 1 follows: 11.1. Mine Overburden Disposal • Storage 3 TSF downstream embankment RL155 constructed of overburden • GOP TSF backfill with overburden ready to line the pit to be a TSF • Northern Rock Stack – working stockpile with engineered landform in closure • Underground backfill with overburden material 11.2. Tailings Disposal • Conventional tailings slurry disposal to Storage 3 and GOP TSFs • Storage 3 TSF constructed from downstream embankment with crest at RL155 • GOP TSF comprising lined in-pit storage 11.3. Closure • Storage 3 o Embankment slopes in pasture with some vegetation. o Impoundment top surface comprising perimeter cap with wetland and pond. Perimeter cap surface planted in native vegetation. • GOP TSF o Dry capped with small wetland and pond. Capped surface planted in native vegetation.
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