GHD | Oceana Gold NZ Ltd | 12552081 | Geochemical Assessment Wharekirauponga Underground Mine (WAI985-000-REP-LC-0013) 8 4. Spoil Geochemistry The geochemistry of the Willows Access Tunnel and spoil from the WUG Mine has been assessed using multi-element and acid-base accounting (ABA) analysis of drill core material thought to best represent the likely spoil material. At the time of writing the available data is sourced from the following locations: The Willows Access Tunnel at Willows Road Farm, and the T-Stream and EG-Vein orebodies at Wharekirauponga. It should be noted that there is no data available along the majority of Willows Access Tunnel. However, data from the Willows Road Farm area in the vicinity between the tunnel portal to the DOC reserve border is considered to be representative of the majority of the tunnel spoil material based on the conceptual model of the geology (as shown in Appendix A). In addition, field columns utilising material from the WUG Mine, and leachate data collected from them, will further inform the assessment when available. As with past OceanaGold Waihi mining projects, geochemical analyses will continue for a period beyond the start of the physical works. This will ensure that spoil management practises can be refined and updated if required and that they are suitable based on the waste geochemical properties. 4.1 Data Sources 4.1.1 Willows Access Tunnel Two drill cores (WNDD005 and WNDD006) located approximately 300-500m south and southeast of the proposed Willows Access Tunnel route, drill core material from the location of the proposed vent shaft located within the Willows Road Farm (WNDD007) and a drill core (WNDD008) running parallel to the proposed Access Tunnel within the Willows Road Farm area, have been utilised to characterise the Willows Access Tunnel spoil beneath the Willows Road Farm area extending into the adjacent DOC estate. Spoil from the far end of the Willows Access Tunnel is considered to be reflective of the orebody characterisation (Section 4.1.2), however based on the conceptual geological understanding, it is considered that the majority of the tunnel spoil material is likely represented by samples from the Willows Road Farm area. The location of the drill cores in relation to the Willows Access Tunnel alignment is indicated on Figure 3 and Figure 4. The vent shaft (from which core and analytical data exists) is located near the border of the Willows Road Farm and DOC estate on the Willows Access Tunnel alignment, due north of the surface of drill core WNDD006.
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