www.valenza-engineering.com 381_R_04_Rev 0 OGNZL_WUG_Phase1_Conceptual_Mitigation 10 means there is little or no hydraulic connection between these perched aquifers and the deeper groundwater system except where structures are present. 3.2.2. HYDRAULIC PARAMETERS Lithologically generic groundwater hydraulic parameters have been established according to rock type from experience elsewhere at Waihi according to Table 3-1. Table 3-1:Aquifer Hydraulic Properties (GWS) Hydraulic Conductivity Storativity Material Max (m/s) Min (m/s) Geomean (m/s) Max Min Shallow Aquifers Ash / Alluvium 1 x 10-4 1 x 10-7 0.3 0.1 Ignimbrite 1 x 10-5 1 x 10-8 0.01 0.001 Rhyolitic Tephra 1 x 10-6 1 x 10-7 0.1 0.05 Deep Aquifer Andesite Surface 3 x 10-5 2 x 10-6 5 x 10-6 0.3 0.1 Andesite to 50 m Depth 7 x 10-9 6 x 10-9 0.01 0.005 Andesite to 100 m Depth 6 x 10-7 6 x 10-9 3 x 10-8 0.01 0.005 Andesite (>100 m depth) 1 x 10-5 1 x 10-8 0.05 0.001 Early geological and resource information was collected from fully cored inclined drillholes within the WUG by OGNZL, with four holes intersecting the EG Vein and one the T-Stream Vein used for hydrogeological characterisation. Hydrogeological observations during drilling were limited to the recording of voids and drilling fluid circulation losses. Packer testing was completed by Golder in July 2021 (ref 11) in all these drillholes across test intervals within, and on either side (hanging wall and footwall), of the veins to determine the range of hydraulic parameters. Within this work package, the objective was to determine the typical higher permeability of the veins compared to the expected low permeability of the host formations and to characterise the lower permeabilities expected in the weathered and altered rocks. Multi-level, three-sensor, vibrating wire piezometers (VWP) were installed in three of these boreholes (WUG-P03D, WUG-P04D and WUG-P05D). The packer test program completed 38 hydraulic tests, 35 of which are considered valid (12 constant rate injection, 23 Lugeon) in both single and double (straddle) packer arrays. The two FHTs completed in WUG-P03D did not produce a valid test result due to hole collapse during the test, however, it was possible to derive an approximation of the transmissivity of the T-Stream Vein at this location of 0.129m2/day. The packer test results overall indicate a moderate to high permeability (mean 1.3 x 105m/s) for both the rhyolite host rocks and the veins. The shallow weathered rhyolite, andesite cap, ignimbrite and tuff units indicate lower permeability (mean 3.0 x 10-7m/s) consistent with the presence of alteration and weathering products (clay minerals and silicification).
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