GHD | Oceana Gold (New Zealand) Ltd | 12552081 | Waihi North 44 . Surface water quality Surface water quality data recorded at TB4 and its upstream headwaters, TB5 and the Ohinemuri River (OH6) between 2017 – 2020 is presented in tables and piper plots in Appendix E. The water chemistry is summarised as follows: – The chemical composition of the sample from the intermittent watercourse TB5 is similar to that of the intermittent watercourse at GLD A and the Ohinemuri River at OH6. These samples are likely to be representative of surface water runoff and interflow. – Concentrations of sulphate and calcium increase along the flow path of the intermittent watercourse at GLD B and C, suggesting the inflow of groundwater influenced by mineralisation. – Surface water within the wetland (GLD D) has a similar water chemistry to the Gladstone shallow groundwater system (GLD01a and GLD03), confirming that the intermittent watercourses and wetland receive shallow groundwater discharge. The water quality of the wetland also demonstrates an influence of mineralisation, with elevated trace element concentrations. – The TB4 water chemistry is similar to that of the wetland (GLD D), confirming that the wetland contributes to the downstream tributary flow. The water quality recorded in the Ohinemuri River at the location of OH6 complies with the RWQC throughout the available data set (excluding mercury due to the laboratory limit of detection being greater than the criteria). While the concentrations of some trace elements are naturally elevated in groundwater flowing from the Gladstone shallow system due to the natural geological setting, the influence on the Ohinemuri River quality is expected to be negligible owing to the relatively small contribution of local groundwater to baseflow of the river. 3.3.6 Water resource users A total of 48 registered bores are located within 3 km of the centre of the proposed Gladstone Pit (Figure 3.11); WRC, 2021c). Nine of the registered bores have consented groundwater takes, and there are an additional four consented surface water takes. A full list of these water users is provided in Appendix K. A summary is provided below and in Table 3.4: – The closest registered bores (Bore IDs 72_959 - 72_961) are located approximately 430-440 m south of the proposed GOP (Figure 3.8). – The closest consented groundwater take (AUTH139311, Bore ID 72_9798) is located at Black Hill Orchard approximately 820 metres south of the proposed GOP (Figure 3.8). – There are no registered bores or water takes located between the proposed GOP and the Ohinemuri River. – All registered bores presented in Figure 3.8 are interpreted to be installed within andesite to a maximum depth between 72-350 mbgl. – There are no surface water takes within 1 km of the proposed GOP. The nearest downstream Ohinemuri River take (AUTH141637 for frost protection) is located approximately 10 km downstream of the WNP area and is not shown on the report figures. Table 3.4 Groundwater takes and registered bores in the vicinity of the proposed Gladstone Pit Registered bore ID (Completion year) Property Consented groundwater take (year granted) Depth (m) Approximate distance from Gladstone Pit (m) 72_959 (1999) Mullan D - 72 430 72_960 (2000) - 85 430 72_961 (2000) - 126 440 72_9336 (1965) Black Hill Orchard - 183 810 72_9798 (2018) AUTH139311 (2018) 350 820
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