GHD | Oceana Gold (New Zealand) Ltd | 12552081 | Waihi North 69 . 3.7.3 Monitoring recommendations Monitoring is recommended as a condition of consent, as per other mining activities at Waihi. This section provides only a high-level overview of monitoring recommendations. Specific requirements should be detailed in an overarching Gladstone Water Monitoring and Contingency Plan. The plan should include requirements for baseline monitoring (for comparative analysis to provide a degree of confidence in the assessment), trigger levels, and contingency measures to manage any potential exceedances. – GOP excavation: Pit inflow: Monitoring of pit inflow rates should be undertaken during the excavation and dewatering works. This will assist with understanding the potential connection of the shallow groundwater system and the current degree of dewatering within the deep groundwater system as a result of existing mine dewatering. Water quality: Monitoring of groundwater and surface water should be undertaken to assess potential impacts to the receiving environment during excavation and dewatering of the pit. It is recommended that this includes the nearest private bore users, if amenable to the owners. In addition, discharges from the excavated pit should be monitored to inform treatment requirements at the WTP. Groundwater levels: Monitoring of shallow and deep groundwater levels should be undertaken at selected monitoring wells, including a network of piezometers installed around the perimeter of the pit. Monitoring of groundwater in wells connected to the Gladstone vein and adjacent to it, southwest of the site, is also recommended to confirm the extent of drawdown along strike of the vein. Flow monitoring: Surface water flow gauging of the Ohinemuri River and its tributaries should be undertaken prior to and during the pit excavation and dewatering works. – TSF development: Water quality: Monitoring of groundwater and surface water should be undertaken to assess potential impacts to the receiving environment during and after development of the TSF. Groundwater levels: Monitoring of shallow and deep groundwater levels should be undertaken at selected monitoring wells during development of the TSF and rewatering of the deep groundwater system. Flow monitoring: Surface water flow gauging of the Ohinemuri River and its tributaries should be undertaken prior to, during and after development of the TSF, and prior to, during and after rewatering of the deep groundwater system.
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