OceanaGold Waihi North Project Vibration Performance Assessment Page 16 of 41 Project Number: HP2006-2 Heilig & Partners Save Date: 21/06/2022 5:55:00 PM ABN 56 082 976 714 File Name: WAI-985-000-REP-LC-0018_Rev 0 proposed to use roving monitors. With the plant access tunnel expected to be developed from each end, two locations would be monitored throughout its construction. Conversely, monitoring of vibration for the Willows access tunnel would only be required at one site at any time, although that site may need to move as development progresses from the portal towards the west before swinging towards the north and the junction with the dual tunnels. The roving monitors would be removed on completion of the development. 8.3. Dual Access Tunnels No vibration monitoring is proposed for this section of development. The dual access tunnels are remote from any dwelling. Potentially, the alignment may pass under Archey’s frog habitat, but any vibration effects from the development blasting would be low amplitude and transient. 8.4. WUG The WUG mine is remote from residences, meaning that blast vibration magnitude at surface would be irrelevant in terms of effects on amenity. For the same reason, limits on numbers of blast events or timing for the protection of amenity would be meaningless. Accordingly, no limits are considered necessary or are proposed for the protection of amenity. There is however some concern relating to the potential sensitivity of Archey’s frog to vibration. In the interests of caution to avoid any negative effects, an assessment was undertaken of the levels of vibration to which known populations of Hochstetter’s frogs were exposed during blasting at the nearby Golden Cross mine. Coupled with the ecological work undertaken by RMA Ecology , a condition limiting vibration magnitudes is as follows; The level of vibration for all blasts events must be monitored, and the peak level of vibration at any location must comply with 95% of blast events to be below 15mm/s. Section 15 describes how this is monitored. 8.5. Summary A summary of the proposed conditions is given in the following Table 2. Project Departures from Existing Conditions Limits Times Gladstone Open Pit Daytime limits extended to permitted activity time durations. Low level blasting provided for. 5mm/s at 95 percentile 1mm/s at 95 percentile 120dBL Monday to Saturday blasting between 7am and 6pm, excluding public holidays. All other times At all times Plant access tunnel and Willows access tunnel Allowance for night time blasting with stringent vibration limits 5mm/s at 95 percentile 1mm/s at 95 percentile Monday to Saturday, 7am to 8pm All other times including public holidays Dual access tunnels N/A None No time conditions WUG Increased compliance vibration limit. No limit on number of blasts or blast duration. 15mm/s at 95 percentile No time conditions Table 2 - Summary of proposed blasting conditions
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