EGL Ref: 8983 23 June 2022 Page 8 WAI-985-000-REP-LC-0004_Rev0.docx This report shall only be read in its entirety. The annual reports (Ref. 8 and 9) and Geotechnical PRP report (Ref. 13) confirm that the management and operation of the current TSFs are performing well and providing for safe storage of tailings and minimising any environmental effects on the environment. Partial closure of Storage 2 has demonstrated effective closure of the TSFs can be achieved with over 15 years of monitoring of closure conditions (Ref. 14). Pond water on top of the tailings is now clean and can be discharged direct to the Ohinemuri River (via. a tributary stream). Both pasture and planted vegetation has been able to be established and maintained effectively on the Storage 2 slopes. Groundwater chemistry from beneath Storage 2 has stabilised with the partial closure of the facility (Refs. 15 and 16). The dam safety management systems and operational strategies successfully implemented for Storage 1A and 2 will be extended to Storage 3. 4.0 WAIHI NORTH PROJECT AND STORAGE 3 TSF 4.1. Waihi North Project (WNP) The Waihi North Project adds the Wharekirauponga Underground Mine (WUG) 10km north of Waihi and Gladstone Open Pit (GOP) Mine adjacent to the Process Plant to the existing mining operation at Waihi. This requires new tailings storage to accommodate the increased tailings production. The new tailings storage is to be provided by the proposed new TSFs Storage 3 (this report) and GOP (Ref. 2). Gladstone Open Pit provides an additional source of overburden material to MOP which can be used for the construction of downstream TSF embankments. Like MOP overburden materialverburden material from GOP will be part Non Acid Forming ( NAF) and part Potenital Acid Formation (PAF). Some of the GOP material will have shorter acid generation lag times, compared to MOP, and some of the material will have higher mercury contents. 4.2. Storage 3 - TSF Storage 3 is to be located approximately 3.5km south-east of the Waihi Township. It is to be formed using a ‘L shaped’ embankment dam which abuts the Storage 1A embankment at its west extent and rising land to the east. Storage 2 is to the west of Storage 1A. The layouts of the TSFs are shown in Figure 3. The impoundment will be created between this embankment and the hills to the north. Storage 3 will be constructed primarily from the overburden material that is excavated as part of the process of obtaining ore from the GOP and MOP. The layout of Storage 3 to RL155 is shown in Figure 4.2 below. The proposed crest height for the embankment is RL155, forming a 46m high embankment above the existing ground at the downstream toe (RL109). The proposed impoundment partially covers the existing East Stockpile area. While further additional storage is not required for the WNP project described here, the upstream toe position of the embankment is set to allow sufficient space downstream to raise the facility in the future using a downstream embankment profile to a crest level of RL177, or to store excess overburden material from future open pit
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