Supporting Technical Assessments

Overview: GHD provided Oceana Gold Ltd (OGL) several recommendations1 associated with tributary and mainstream flow monitoring in the Wharekirauponga Stream catchment (WKP). Several new continuous flow monitoring locations were proposed. The existing and GHD proposed monitoring locations were visited by GHD (T Mulliner) and Riley Consultants (L Palmer) on the 2 May 2022. Access to and suitability of the proposed new tributary monitoring locations were assessed. Further GHD recommendations provided in Section 2.1 of their memo, such as site telemetry and other methods of Stream measurement, were also discussed. The following briefly summarises this site visit and discusses the GHD proposed new continuous monitoring locations and other GHD memo recommendations. Site visit: Table 1 of the GHD memo lists the five existing WKP continuous monitoring flow locations and the additional seven proposed locations. All the existing monitoring locations in the catchment were visited, along with the proposed GHD tributary locations that had reasonable access. Discussion with OGL staff indicated that access is difficult to two of the proposed sites, namely, the upper Edmonds Stream (GHD site #C) and upper Thompsom Stream (#G) locations. It was decided that these sites would not be visited due to the difficult access and as they were unlikely to be initially considered for continuous monitoring (and time constraints that day). Figure 1, Figure A-1 and Table A-1 provide the approximate locations for the existing continuous monitoring locations, proposed locations, and other “gauged” locations. Table 1 summarises access and site aspects for each of the GHD proposed monitoring location. Table A-2 provides photographs of these locations. The weather was mild and settled, however, flows were up because of rain the previous day. The flow at T-Stream East was approximately 200L/s. Figure 1 – WKP mid and upper catchment logger and tributary locations 1 “Proposed Surface Water Monitoring Conditions – Wharekirauponga catchment”. GHD memo to OGL dated 13 April 2022.

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