GHD | Oceana Gold (New Zealand) Ltd | 12552081 | Waihi North 143 Parameter WRS (maximum height) Mg 1.9 Mn 0.4 Na 1.0 NH3-N 0.02 Ni 0.002 Pb 0.000003 Se 0.00004 Sb 0.00004 SO4 18 Zn 0.001 6.5.3 Monitoring recommendations Environmental monitoring is likely to be a required condition of consent as per the other mine elements. This section provides only a high-level overview of monitoring recommendations. Specific requirements should be provided in a detailed monitoring plan, which should include baseline monitoring (for future effects to be assessed against), trigger levels, and mitigation/contingency measures to manage any potential exceedances. – Groundwater quality and water levels: It is anticipated that selected groundwater monitoring wells from the established well network near the proposed WRS can be utilised to provide baseline data and long-term monitoring. The wells should include both shallow and deeper aquifer wells. Water samples are expected to be analysed for a suite of key indicator parameters indicated by the leachate testing of the WKP rock (currently underway). – Surface water quality: Surface water quality monitoring has periodically occurred at location ID Mataura Stream 1, with one sample collected to date in the lower WRS gully tributary. It is recommended that these locations and possibly an additional site on the Mataura stream (immediately after the Tributary 2 confluence) be considered for the monitoring schedule. The parameters to be analysed should be considered in conjunction with the key leachate parameters. – Surface water flow: Continuous monitoring of the Mataura Stream is undertaken at location M1. Periodic flow gauging of the stream and the lower WRS tributary have also been undertaken. It is expected that the M1 monitoring will continue to occur. A formal gauging programme should also be considered for the lower WRS gully tributary, including assessment of the Tributary 2 baseflow. This would allow for assessment of WRS mass flux seepage through the shallow groundwater system to surface water.
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