SECTION 4 Assessment of Effects 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 34 Figure 30 Surface Exposure of Rhyolite Rocks 4.4 Effects on Groundwater or Surface Water Quality During mining groundwater will be pumped back to the water treatment plant at Waihi and treated prior to discharge. The water quality in the veins is expected to be elevated in heavy metals and other constituents. The general mine dewatering strategy includes the off-site treatment and disposal of the pumped water and this means the effects on groundwater quality will be absent during mining. On completion of mining, the aquifer will cease being pumped and the natural groundwater system will be reinstated. Localised discharge of this water will return to natural discharge pathways once water pressures are re-established. We note that at the time of preparing this report further studies related to groundwater and surface water interaction are still being undertaken and for that reason the precise nature of all groundwater discharge locations cannot be completely determined. It can, however, be stated with some certainty that the warm spring location will return to being a discharge point for the groundwater system after rewatering has taken place. The quality of the groundwater following mining will be determined by a number of factors including the chemistry of the backfilled materials, the amount of grout placed during mining and the amount of stabilisation required to neutralise the backfill. To some degree the final chemistry of the backfilled stope, and therefore the groundwater quality after interacting with
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