SECTION 1 Introduction 3 pumped by electric pumps through poly pipe installed as part of mine services to the surface holding tank before treatment through the water treatment plant. Where significant quantities of water are encountered in tunnelling, the ground in the immediate vicinity will be shotcreted and/or grouted to provide an effective seal and prevent any significant and/or sustained drainage of local aquifers.” Simply put, the tunnel will be designed to limit the potential for groundwater effects to develop as it is constructed and this premise sits behind this effects assessment. All level information in this report is based on a mine datum set at 1,000m below a pre-1949 geodetic datum. The current standard, New Zealand Vertical Datum 2016 (NZVD2016), is approximately 1,002m above the mine datum. That is, reduced levels stated in this report can be reduced by 1,002m to approximate the same level to NZGD2000/NZVD2016. 1.3 Scope of Report This document describes the groundwater conditions and potential effects on groundwater associated with the development of the proposed tunnels that will be driven from Waihi to Willows Farm and from Willows Farm to the WUG ore deposit. The groundwater effects assessment associated with the development of the WUG resource itself is included in a separate report prepared by GWS (WAI-985-000-REP-LC-0030A). We note that this report does not include any effects on groundwater associated with the Willows Farm surface infrastructure (e.g. waste rock stacks, silt ponds, etc.) other than that associated with the tunnel elements. Surface infrastructure effects are included in the GHD hydrogeology report (WAI-985-000-REP-LC-0012). This assessment of effects on groundwater relates to the development of the portals, shafts and the tunnels. The purposes of this assessment are to determine: • Groundwater inflows to the tunnel elements. • Drawdown effects related to the tunnel elements. • Potential for effects on aquifers. • Potential for effects on surface waters. • Potential for effects on other groundwater users. • Potential for effects on plant growth. This report has been prepared based on recent and historical information from adjacent areas that provides an understanding based on a long association with groundwater systems in the area. This understanding has been taken forward alongside the project scope and has included further technical analysis to enable potential associated effects to be quantified.
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