GHD | Oceana Gold New Zealand Ltd. | 12552081 | Waihi North Project 38 Area Gladstone Pit Sump WUG RS Seepage5 NRS Leachate (Development)3 Data Source AECOM 2022 LD06, LD07, LD08, LD09, LD10, LD11, LD12, LD13, LD14, LM02, LM05 AECOM 2022 Parameter Min Med 95th %ile Max n (last 3 years) Min Mean / Med 95th %ile Max n (last 3 years) Min Med 95th %ile Max n (last 3 years) pH 2.5 4.0 - 4.4 na 4.6 6.3 7.1 8.6 2243 4.54 4.61 - 7.9 na TSS - - - - na <3 3 37 13000 1557 - - - - na Ni 0.02 0.13 - 0.43 na 0.0005 0.004 0.3 4.33 1498 0.0027 0.777 - 1.36 na Cd 0.0001 0.0006 - 0.0018 na <0.0001 0.0001 0.001 0.006 1374 0.00005 0.007 - 0.012 na Se 0.0003 0.0012 - 0.0035 na <0.005 0.001 0.005 0.14 1724 <0.001 0.002 - 0.005 na Cu 0.03 0.16 - 0.51 na <0.003 0.001 0.003 2.700 1720 0.0005 0.027 - 0.36 na As 0.042 0.23 - 1.2 na <0.005 0.001 0.003 0.013 1368 <0.001 0.002 - 0.068 na Pb 0.0001 0.0004 - 0.0011 na <0.0005 0.0001 0.0004 0.060 1450 <0.0001 0.0002 - 0.0007 na Sb 0.0001 0.0001 - 0.0002 na 0.00 0.0002 0.01 0.28 1384 0.0002 0.0021 - 0.003 na Al 13 77 - 234 na <0.015 0.006 0.33 31.9 1023 0.003 11.8 - 25 na Hg 0.00003 0.00003 - 0.00004 na 0.000 0.0001 0.001 0.002 1261 <0.00008 0.00008 - 0.0005 na CN_Tot - - - - na 0.0 0.001 0.5 3.2 1964 - - - - na Zn 0.04 0.22 - 0.71 na 0.00 0.02 0.19 4.96 1498 0.0025 1.24 - 2.81 na SO4 180 785 - 2470 na 3 194 2400 4230 2122 198 1,440 - 2,400 na Fe 2.5 45 - 150 na <0.1 0.04 19.2 38.8 1556 0.02 300 - 470 na Mn 0.06 0.33 - 1.1 na 0.0005 0.6 48 312 1721 0.3 15.55 - 61 na Na - - - - na 5 23 126 560 1972 11.7 101 - 159 na Mg 1.4 2.3 - 2.3 na 1 15.15 250 459 1990 15.4 115 - 280 na K - - - - na 1.1 8.1 18.4 73 1972 3.7 13.7 - 22 na Co 0.055 0.3 - 1 na 0.00 0.02 0.14 0.71 1382 0.0002 1.86 - 3 na Ca 32 46 - 85 na 1.1 34 560 644 2023 31 480 - 590 na NH3-N6 0.01 0.025 0.054 0.058 11 <0.01 0.01 2.6 21.2 2011 <0.01 0.01 2.6 21.2 387 Notes: 0.00615 Greyed out cells signify data is utilised within WBM 95th %ile Conservative estimates for Wharekirauponga Component of WBM 1 Based on site monitoring data 2 Conservative estimate based on Waihi dewatering data 3 Median numbers modelled reflective of the NRS, maximum numbers are conservatively assumed for RS1 and RS2 at Willows Farm 4 Median numbers modelled reflective of the NRS, Waihi TSF embankments, 95%ile numbers are conservatively assumed for RS1 and RS2 at Willows Farm 5 Median numbers modelled reflective of the Waihi TSF embankments, 95%ile numbers are conservatively assumed for RS1 and RS2 at Willows Farm 6 Ammoniacal N numbers not provided in the AECOM assessment. Numbers used based on monitoring data from TSF1A
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