GHD | Oceana Gold New Zealand Ltd. | 12552081 | Waihi North Project 72 To decrease the risk of surplus of Priority One waters during peak mine development and low summer flow periods, the WTP operation will need to maximise the treatment and discharge of non-Priority One waters when the WTP capacity and river flows allow (to ensure the tailings ponds have capacity to receive Priority One water during periods of restricted discharge). There will be a number of years where two TSF decant ponds require treatment and the rate of MUG dewatering drops as target depths have been met. However, the large volume of water sourced from the WUG mine means that the proportion of cyanide water remains low and the discharge will be able to be operated at Regime E most of the time. The RO plant provides contingency that has not been included in the analysis presented in this report. The RO plant can be used to change Regimes (and increase the allowable discharge) and remove additional contaminant flux if required.
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