GHD | Oceana Gold (New Zealand) Ltd | 12552081 | Waihi North 85 Figure I.2 TSF3 Cross-section 1 SEEP/W model set-up with close up of undercut and key monitoring locations Table I.1 TSF3 base model set-up Boundary type Adopted boundary conditions Justification Rainfall recharge Water flux - potential seepage face review: – Upper catchment: 2 x 10-3 m/d (35% average annual rainfall) – Lower catchment: 3 x 10-5 m/d (0.5% average annual rainfall) – Lower catchment, artesian conditions: 0 m/d Values adjusted to achieve sufficient flow through the aquifer and artesian conditions in the lower TSF3 valley, where adopted rainfall = 2,110 mm/year6 These values are considered appropriate where recharge is inferred to occur across the upper catchment (rhyolite ridge) where downward gradients occur, versus the lower valley where very low permeability surface cover is present and surface ponding occurs. Upgradient groundwater boundary (north) Constant Head – 1,117 mRL Values were derived by calibration in conjunction with rainfall, to achieve measured groundwater levels and gradients (Appendix C) and low stream flow. Downgradient groundwater boundary (southeast) Constant Head – 1,104 mRL Ruahorehore Stream Water rate – potential seepage face review set to 1,108 m RL Set to the elevation measured during the January 2019 stream survey (Appendix F). 6 NIWA, 2019. Climate data obtained from Waihi, Station Agent No. 1550.
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