June 2022 G-14642.71-006-R-Rev0_FINAL 1 1.0 INTRODUCTION Oceana Gold (New Zealand) Limited1 (OGNZL) engaged Golder Associates (NZ) Limited (Golder) [now WSP New Zealand Limited (WSP)] to provide preliminary geotechnical assessment for various elements of the proposed Wharekirauponga Underground Mine (WUG), which is located north of the township of Waihi, New Zealand. This report summarises the findings of the preliminary geotechnical assessment of the access tunnels and underground mine. The objective of the study is to evaluate the available geotechnical information to support a prefeasibility study (PFS) and consent application for the Waihi North Project (WNP), to assess the geotechnical issues affecting the project and to identify any potential issues affecting the viability of the project. 1.1 Project Outline The project comprises development of an underground mine in an epithermal gold deposit in the upper catchment of the Wharekirauponga Stream on the Coromandel Peninsula. The deposit is located approximately 10 km north of Waihi and will be accessed by tunnelling from a surface mine infrastructure site located on Willows Road Farm property approximately 3 km north of Waihi. The assessment of environmental effects (Mitchell Daysh 2022) describes twin parallel tunnels to provide access from the Willows Road Farm development to the WUG ore body. 1.2 Project Elements Assessed as Part of this Report This preliminary geotechnical assessment includes the following project elements: Willows Access Tunnel and portal First ventilation raise (vent shaft #1) Waihi Plant Access Tunnel and portal Twin access tunnels from vent shaft #1 to WUG Wharekirauponga underground mine design 1.3 Scope of Work WSP undertook the following scope of work: Data compilation and review of available geotechnical information, aerial imagery and LiDAR. Geomorphological mapping, subsurface investigations, in situ and laboratory testing. All field investigations have been supervised by OGC personnel, in consultation with WSP. The results of the field investigations have been used by WSP to complete this assessment. Complete a geotechnical assessment report for the access tunnels and underground mine that includes the information from the above points (i.e., this report). 1 References in this report to “OGC” includes OceanaGold Corporation, Oceana Gold (New Zealand) Limited.
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