June 2022 G-01483.84-017-R-Rev0 Because the 1 1.0 INTRODUCTION 1.1 Overview Oceana Gold (New Zealand) Limited (OGNZL) engaged Golder Associates (NZ) Limited (Golder) [now WSP New Zealand Limited (WSP)] to provide geotechnical assessment of various elements of the proposed Wharekirauponga Underground Mine (WUG) tunnel portal and infrastructure at the Willows Road property located north of the township of Waihi, New Zealand. The assessment, undertaken to support a prefeasibility study and resource consent application, is part of the wider Waihi North Project. The Waihi North Project integrates the proposed underground mine development of the Wharekirauponga ore body located approximately 10 km north of Waihi with OGNZL’s existing operations at Waihi. The WUG Mine is accessed initially by tunnelling from the Willows Road farm property approximately 3 km from Waihi. The proposed Willows Road project elements include the Wharekirauponga Underground Portal (“WUG Portal”), Surface Facilities Area (SFA) and a Services Trench joining the existing Waihi plantsite area to the Willows Road developments (Figure 1). Geomorphological mapping, subsurface investigations, in situ and laboratory testing have been completed as part of the assessment. All field investigations have been supervised by OGNZL personnel, in consultation with WSP-Golder. The results of the field investigations have been used by WSP-Golder to complete this assessment. This report summarises the findings of the geotechnical assessment of various elements described in the "the Assessment of Environmental Effects prepared by Mitchell Daysh Limited, dated June 2022 (Mitchell Daysh Limited, 2022) based on the available geotechnical information as at 30 September 2021 and the design and staged development of the Willows Rock Stack (WRS), Services Trench and various SFA elements. The objective of the study is to evaluate the available geotechnical information to assess the geotechnical issues affecting the project, inform the element designs and development and to identify any potential issues affecting the viability of the project. This assessment includes the following project elements: ▪ Willows WUG Portal ▪ Willows Rock Stack including drainage works ▪ Haul road ▪ Supporting surface infrastructure located within the SFA and an access road to the portal ▪ Services Trench between OGNZL’s Waihi Processing Plant and the Willows Road SFA for power, water and telecommunications.
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