June 2022 G-14642.71-006-R-Rev0_FINAL 7 4.2 Geomorphology The proposed project lies at the southern end of the Coromandel Range. The Wharekirauponga ore body is located beneath the upper catchment of the Wharekirauponga Stream catchment, which flows east to the coast via the Otahu River. The catchment comprises heavily bush covered terrain with northeast trending ridges rising to between 300 m and 500 m elevation above sea level that are separated by incised northeast flowing streams. Slopes are typically steep. Willows Road Farm lies on the south side of Mataura Stream, which flows east into Ohinemuri River. Figure 3 depicts the key geomorphological features of the Willows Road Farm site. The Ohinemuri River occupies a wide flat valley south east of Willows Road Farm and the WUG access tunnel portal is proposed for a site on the western side of the valley on the outskirts of Waihi town. 4.3 Groundwater The assessment of groundwater effects for the project estimates that groundwater levels are about 10 m below existing ground (GWS 2020) throughout the project site. The estimated assumed average rock mass hydraulic conductivity is approximately 2.5 x 10-8 m/s and fault zones are indicated to have hydraulic conductivity of 1.0 x 10-5 m/s. Rock mass permeability testing has been completed in boreholes at the Wharekirauponga deposit and vibrating wire piezometers have been installed at various elevations. The results of this work are presented in a separate report (Golder 2021). 4.4 In-situ Stress Conditions In situ stress measurements were conducted in about 2010 for OGNZL by the West Australian School of Mines (WASM) using the Acoustic Emission (AE) method and the results were provided to WSP. Results from two drillholes at Trio Underground Mine at Waihi were broadly in agreement and are presented in Table 1.
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