GHD | Oceana Gold New Zealand Ltd. | 12552081 | Waihi North Project E-12 Figure 3 Calculated background uncaptured contaminant mass loads The additional load for manganese shows a weak correlation to flow however is has been assumed a constant uncaptured load of 0.8 kg/day is applicable. For sulphate, the additional load is reasonably consistent and an additional uncaptured load of 2,000 kg/day is assumed. The lack of additional load for the majority of the trace elements and observed additional loading for manganese and sulphate is likely explained via differing attenuation and/or precipitation controls. Sulphate is largely controlled by the ratio of calcium to sulphate and the formation of gypsum whereas manganese will stay in solution unless under elevated pH conditions (in excess of pH 8). The other trace elements are more likely to precipitate at a lower pH and hence any leaching of these trace elements from existing facilities is likely to be attenuated and ly to add to the additional mass loads within the Ohinemuri River. Water Balance Modelling The water balance model has elements provided to calculate a cumulative mass loading at sample location OH6 in the Ohinemuri River. The following elements have been added as direct inputs representing uncaptured contaminant mass loads:
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