Our Ref: 9215 23 June 2022 This report shall only be read in its entirety. File: WAI-985-000-REP-LC-0002_Rev0.docx TABLE A4. SCORING FOR OPTION 4 Option 4: Storage 2 Raise to RL176 Tailings Slurry TSF Category Subcategory Category Weighting Subcategory Weighting Score Weighted score Category Score Final Score Comments Technical Future ore resource 0.25 0.1 3 0.3 Small risk that GOP Lake may affect future underground mining Geotechnical 0.15 3 0.45 No detailed geotechnical investigations to west of current footprint, so some uncertainty about performance Geochemistry 0.15 3 0.45 Storage 2 and Northern Rock Stack will have controls for potential geochemistry effects that have worked to date and have been adopted and proven to work at other projects. GOP is a lake and so will not store tailings, but has partial backfill with some PAF rock as for GOP TSF. Constructability 0.1 5 0.5 Experience with existing TSFs indicates that they can be constructed to meet Specifications. Similar materials will be used for raising Storage 2 and the NRS. Will need to construct new site access road and maintain existing surface and subsurface collection systems while constructing new systems. Will need new Collection Pond. Operability 0.1 5 0.5 Storage 2 and GOP TSF can be operated in all conditions and without interference from other site functions. Assumes haul road from Northern stockpile to GOP TSF will be independent of existing access road/bridge to Process Plant. Storage capacity and expansion potential 0.15 5 0.75 Limited opportunity for expansion of Storage 2 for tailings storage. GOP TSF could be expanded as a mine open pit overburden disposal area with rock placed above tailings. Storage 3 could be developed as a new TSF in the future. Project schedule 0.25 0 0 Assessment indicates maybe tight to raise Storage 2 to meet tailings storage requirements. 2.95 0.7375 Environmental Terrestrial ecosystem 0.25 0.2 3 0.6 Some short term impact on on-site terrestrial ecosystem associated with construction and operation of Storage 3 and GOP TSF. Biodiversity associated with closure plan would provide long-term mitigation. Aquatic ecosystem 0.2 3 0.6 Minor impact on aquatic ecosystem No known historical impact Groundwater 0.15 5 0.75 Potential groundwater impacts expected to be controlled with proposed design for facilities and considering performance of existing facilities Surface water 0.15 5 0.75 Potential surface water impacts expected to be controlled with proposed design for facilities and considering performance of existing facilities Impact on SNA 0.1 5 0.5 Avoids SNA Dust 0.1 5 0.5 Control measure required and operating history indicates that air discharge standards will be met. Noise 0.1 3 0.3 Storage 2 is existing TSF. Construction at higher elevation may have some noise implications, but unlikely to be significant. 4 1 Socio-economic and permitting Social impact 0.25 0.15 5 0.75 Low social impact Mana Whenua 0.25 3 0.75 Consultation undertaken, but Mana Whenua prefer backfilling to recreate maunga rather than use as a TSF. Economic 0.1 5 0.5 Project has considerable economic benefit to community and other parties Recreation 0.1 5 0.5 No impact on recreational users Regulatory approval 0.2 0 0 Backfill of GOP with water may not get regulatory approval Archaeological/heritage 0.1 5 0.5 Some remnants of historical mining activities at GOP TSF, but not significant Landscape and visual 0.1 3 0.3 Some visual impact from raising of Storage 2, but rehabilitation provides long-term mitigation 3.3 0.825 Project Economics Land ownership 0.25 0.1 5 0.5 OGNZL owns all the land required Capital cost 0.35 3 1.05 Ranks in middle third Operating cost 0.35 5 1.75 Ranks in top third Closure and post-closure cost 0.2 4 0.8 Ranks 2 = and score reflects this 4.1 1.025 TOTAL WEIGHTED SCORE: 3.588
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