SECTION 2 Environmental Setting C:\D Data\GWS C Drive\GWS\Client Files\1344 OGL - WKP\4 Deliverables\WKP Final Draft Report\June Report\WAI-985-000-REP-LC-0030. Final_Rev_0.docx 5 The general site location is interpreted to be within a groundwater discharge zone within the headwaters of the Wharekirauponga Stream that flows to the north east and ultimately joins the Otahu River. Within the site locality there are a number of tributaries that come together to form the Stream. Surface water flow rates in the vicinity of the site have been gauged on a number of occasions as discussed later in this report. Based on measurements made at WKP1 (shown on Figure 23) at the catchment discharge point, the minimum low flow rate measured in June 2020 of 68 L/s (5,875 m3/d) equates to approximately 7% of the catchment water balance. Figure 3 Wharekirauponga Surface Water Catchment Area (facing Southwest) Much of the rainfall within the Wharekirauponga catchment is absorbed by the soil regolith that has formed on the rock surface, and it is drainage of this water over time that sustains the surface water flow. When these soils are saturated rainfall run-off occurs increasing flows in the streams. Under dry conditions little shallow soil drainage occurs and baseflow to the streams is supported by groundwater discharge. 2.4 Regional Geology The Coromandel Volcanic Zone (CVZ) is an extinct volcanic arc that is within the Coromandel Peninsula of the North Island, New Zealand. The associated volcanic and volcaniclastic sedimentary units record a history of andesitic and rhyolitic eruptions, which persisted throughout the Miocene to Pliocene (18 to 4 Ma; Skinner, 1986). Subsequent epithermal goldsilver deposits developed within the region between 16 to 2 Ma forming the Hauraki goldfield (Mauk et al.,2011). The region is underlain by basement rocks comprising Mesozoic sedimentary units (Greywacke) belonging to the Manaia Hill Group (Skinner, 1986). The
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