June 2022 G-14642.71-006-R-Rev0_FINAL 2 For the underground mine WSP’s agreed scope was to: Conduct the geotechnical review and gap analysis of the current design for the underground mine prepared by others. Make recommendations regarding the suitability of the current design and any additional work that needs to be completed for the next stages of mine design. The following tasks were carried out: 1) Review the available reports: a. SRK (2019): Wharekirauponga Mining Study. OGC008_WUG Scoping Study_Rev0. April 2019 b. WUG PFS - Geotechnical Section. PEX-000-PLN-046-A. Prepared by OGC Studies Group. undated. 2) Gap analysis. 3) Additional work for the next stage of the design. 1.4 Site Visits A site visit to the Willows Road Farm was completed by Tim McMorran (WSP Principal Engineering Geologist) on 20 July 2020. Tim accompanied Dan Calderwood (OGNZL), Fergus Mcarthur (OGNZL) and Holly Janssen (GHD) on the visit and observed rock and soil outcrops and geomorphology visible from farm tracks around the proposed portal site, rock stack site, silt pond and other infrastructure. Tim visited the site a second time on 22 September 2020 accompanied by Sue Bonham-Carter (WSP Principal Mining Engineer) and Holly Janssen and on 20 September 2021, accompanied by Rory McNeill (for OGNZL). Rock mass permeability testing has been completed in bore holes at the Wharekirauponga deposit during several site visits by Logan McLean (WSP Hydrogeologist) and Florian Buech (WSP Senior Engineering Geologist). 1.5 Co-ordinate System and Units of Measure Various reduced levels are used throughout this report: NZGD2000 – current New Zealand coordinate system. NZGD1949 – previously applied coordinate system, the datum of which is around 0.5m lower that NZVD2000. Mine datum – which is set at 1000m below a pre-1949 geodetic datum. The current datum at NZVD2000 is about 1,002m above mine datum. Each applicable datum is referenced in a footnote. All measurements are metric.
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