Phillip Jones Reference No. G-01483.84-008-LR-Rev0_FINAL OceanaGold Corporation 17 June 2022 5 Conclusions and Recommendations Options 3, Bottom-up concrete backfilling of the vent shaft, although more expensive and difficult to construct, is considered to have the lowest risk of failure for the purposes of permanent closure. Before selecting this option, additional studies are required to confirm the availability and suitability of the concrete pump and confirm that the pump selected will fit in the final constructed drift development openings. Closure Should you have any queries, please do not hesitate to contact the undersigned. Yours sincerely WSP NEW ZEALAND LIMITED Tim McMorran Technical Director Engineering Geology CMENGNZ (PENGGEOL) 176867 Attachments:Attachment A – Report Limitations Attachment B – WKP Mine Development – Sketches -Concept Shaft Closure Options Attachment C – Example Specifications High Pressure Concrete Pump https://wsponline-my.sharepoint.com/personal/joanna_black_wsp_com/documents/sharepoint_temp folder/waihi/r006/appendices/appendix e shaft closure/rev0_final/g-01483.84-008-lr-rev0-capping of shaft_final.docx
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