B-7 – Area 7 - Assessment of Environmental Effects 33 3. PROJECT DESCRIPTION 3.1 OVERVIEW It is proposed to construct TSF3 to the east of existing TSF1A to accommodate additional tailings volume from the processing of ore from the Waihi North Project and other mining activities to be undertaken by OGNZL. Figure 22 shows the proposed layout of TSF3. Figure 22: Indicative TSF3 Layout Plan (EGL (2022c)). Detailed design plans and a detailed construction methodology for TSF3 are provided in EGL (2022c). A typical cross section is provided in Figure 23, below. TSF3 will be approximately 46 m in height and have a crest height of 155 m RL. The proposed 155 m RL crest height provides a total storage volume of approximately 7,000,000 m3. Allowing for freeboard requirements to store a Probable Maximum Precipitation (“PMP”) inflow design flood with 1.0 m freeboard, the volume available for tailings storage is estimated at approximately 5,700,000 m3. The proposed embankment and impoundment design for TSF3 is similar to the existing TSF2 and TSF1A, except it includes a synthetic geomembrane liner to provide enhanced containment of tailings seepage to the height of the starter embankment (135 m RL). It takes into consideration:
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