3-AD006.00 SOCIAL IMPACT ASSESSMENT WAIHI NORTH PROJECT Oceana Gold New Zealand Limited WSP June 2022 60 Impact Description: WUG and associated tunnels: The discharges to air during the construction and operation of the WUG and tunnels are a permitted activity in the Waikato Regional Plan (Beca Limited, 2022). The following was identified as relevant to the construction and operational phase: • Effects of dust from project surface features on dwellings. • Effects of portal and ventilation raises. The Air Discharge Assessment identified that, without appropriate mitigation, there would be: • A moderate to high risk of infrequent, short duration adverse nuisance dust effects at 111 Willows Road. • A moderate risk from nuisance dust at 122 Willows Road from the topsoil stockpile construction. If mitigation measures are implemented, dust levels are not expected to exceed standard guideline values. Concentrations of contaminants within dust are not expected to exceed current and proposed guideline values beyond the boundary of the Willows Road SFA. The assessment concluded that with the implementation of mitigation and management measures, the risk of discharges to air creating adverse effects beyond the Willows Road site boundary is considered low. Waihi Surface Facilities (the components of WNP excluding WUG and associated tunnels): Air emissions from the proposed WNP surface mining activities will be similar to those from the existing mining operations. Ambient air quality monitoring and complaints history of the existing operations demonstrates that emissions are small and well below the relevant standards and guidelines (Beca Limited, 2022). The assessment undertaken by Beca Limited (2022) identified that there is a moderate to high risk of sensitive receptors within 200 m of the proposed activities being exposed to infrequent, short duration dust emissions during dry and windy conditions. With the implementation of mitigation, concentrations are not expected to exceed standard and guideline values. There are no sensitive receptors within 200 m of the GOP, Processing Plant, and TSF3. There are two privately owned dwellings located approximately 90 - 100 m to the east of the closest stockpile associated with the proposed NRS. It is recommended that additional mitigation and monitoring is undertaken when construction works are being undertaken. Particular care will need to be taken with earthworks and vehicle movements on exposed services, especially under dry windy weather conditions (Beca Limited, 2022). As there is a proposed increase in the ore processing rate, emissions to air from the Processing Plant will increase, with mercury emissions. The Processing Plant Air Discharge Assessment (Beca Limited, 2022) identifies that the high mercury content of the GOP ore (11 times higher than current ore) and WUG ore (2 times current ore) is expected to increase mercury emissions from the Processing Plant. Based on dispersion modelling it has been predicted that mercury emissions will not exceed industry recognised guidelines and health-based assessment criteria, and therefore will not have an adverse effect on nearby residential properties, provided the proposed emission control system (oven retort) is implemented.
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