Waihi North Project Preliminary Site Investigation (Ground Contamination) Williamson Water & Land Advisory Limited 2 • A new TSF named “TSF3”. This will have a height of 155 m RL. • Upgrades to the existing Processing Plant and Water Treatment Plant (“WTP”) to increase capacity; and • Reconsenting of the existing WTP discharge to the Ohinemuri River (Section 3.3). The project will involve ground disturbance, ranging from minor to significant, on land where activities listed on the Ministry for Environment Hazardous Activities and Industries List (“HAIL”) have been, or are, undertaken. Due to the existing and/or historic presence of HAIL activities within the project footprint and the proposed scale of ground disturbance and land use change associated with the WNP, resource consent is required pursuant to Regulation 11 of the Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations 2011 (“NESCS”). As it is not feasible to complete a full Detailed Site Investigation (“DSI” - soil sampling) prior to consent lodgement, this PSI has been designed to support a discretionary consent application under the NESCS and inform the sampling plan. 1.2 Objectives and scope of this report This PSI has been undertaken to identify the potential presence of ground contamination within the footprint of the WNP and the likely implications of contamination for project planning, design and approval processes. The scope of this report included: • Review of historical site data including aerial photographs, OGNZL records and Waikato Regional Council files. • Site walkover inspection by a Contaminated Land Specialist. • Assessment of the potential presence of contamination in the project footprint, based on an evaluation of current and historical land uses against the HAIL. • Development of a preliminary Conceptual Site Model (“CSM”) including geological and expected ground conditions to assess contaminant risks and mitigation requirements during the establishment of the new mine facilities and upgrade of existing facilities. • Evaluation of DSI requirements, resource consenting pathways and likely ground contamination-related earthworks and construction implications for earthworks to facilitate the WNP objectives. • This report does not assess remediation or other mine closure operations at the end of the WNP. The potential for contamination at that stage of the project is currently unknown, as there may be many variables between what is currently being proposed and what is ultimately consented and constructed. We have assumed that mine closure/remediation will be addressed through specific reporting and management plans prepared at an appropriate future date. Note: A Plant Access Tunnel will facilitate the transport of ore from, and rock to the WUG mine/Processing Plant/WTP site. It will run beneath a range of properties but is not expected to intercept the surface at any point between Willows Road and the Processing Plant/WTP site. HAIL assessments of overlying properties have therefore not been made. In addition, the Services Trench between the Willows Road Property and Waihi facilities will generally follow the alignments of Willows Road and the highway, before diverting south at the highway bridge to the Processing Plant/WTP via farmland. This route has not yet been confirmed but some assumptions can be made. Roads are not considered a HAIL and it is highly unlikely that HAIL activities will be present in the areas of farmland that the trench will cross. The service trench alignment has therefore been excluded from this investigation, but it is expected that any contamination within this route can easily be identified and managed through implementation of the Site Management Plan (SMP) that has been prepared under separate cover.
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