B-7 – Area 7 - Assessment of Environmental Effects 24 2.13 HYDROGEOLOGY The hydrogeology attributed to Area 7 is described at a regional level and at a local level in section 5.2 of GHD (2022b), which is provided in Part H of these application documents. GHD (2022b) describe groundwater at Area 7 as recharging in the ridge to the north/northeast (in SNA166), then flowing south/southwest to the Ruahorehore Stream. Shallow groundwater emerges near the rhyolite foothills to produce springs, but the Ruahorehore Stream has a limited groundwater catchment at TSF3 (see Figure 15 below). The deeper groundwater system also recharges from infiltration in the SNA166 ridges to the north, but is assessed by GHD (2022b) as ultimately discharging to the Ohinemuri River. Figure 15: TSF3 groundwater system (GHD 2022b) 2.14 HYDROLOGY The hydrology of Area 7 is described in EGL (2022c) and GHD (2022b), which are provided in Part H of these application documents. Area 7 is contained within the Ruahorehore Stream catchment which is a sub catchment of the Ohinemuri River. Ruahorehore Stream has a catchment of approximately 20 km2, with flow ranging from 1,850 – 1,500,000 m3/day, and a median flow of 27,900 m3/day as measured at the Ruddock flow gauge (see Figure 16). The Ruahorehore Stream catchment at the toe of TSF3 (see Figure 16) is 5.8 km² and contains flows of between 540 m³/day to 3,600 m³/day with a median flow of 1,349
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