B-3 – Area 3 - Assessment of Environmental Effects 29 The only substantive noise effects associated with the construction and operation of the Wharekirauponga Access Tunnel relate to the establishment of the portal at the Waihi SFA. The effects of this activity are addressed in the Area 5 AEE and for the reasons set out in that document are considered by Marshall Day to be acceptable. 5.7 BLASTING AND VIBRATION EFFECTS An assessment of the actual and potential effects from blasting and vibration associated with the establishment of the Wharekirauponga Access Tunnel and portal at the Waihi SFA is provided in Heilig (2022), a copy of which is provided as Part H of these application documents. Blasting to construct the tunnel and portal could potentially generate detectable vibration at some residences. Where potentially detectable, such effects would occur for short periods as development approached then moved away from a receiver. Once the tunnel is constructed, there would be no further blast-related or vibration effects. Operationally, there will be no detectable vibration from the use of the tunnel. Due to the potential for blast vibration to be detectable, control of vibration magnitude and timing during construction of the tunnels is considered appropriate by Heilig (2022). However, the currently applied vibration assessment in Waihi requiring the complex tasks of calculating, maintaining and reporting both the 95th percentile and “average” levels of vibration for each monitoring location is considered unnecessarily complex, and perhaps impractical for developing these section lengths, while not adding a meaningful level of amenity protection. In recognition of the difference between the transitory effects that may be associated with construction of these tunnels and those associated with the ongoing underground mining within Waihi, a modified and simplified set of conditions is proposed, by Heilig (2022) being: The level of vibration for all blasts events must be monitored at non-company owned residences, and the peak level of vibration at any location must comply at the 95th percentile with 5mm/s between the hours of 7am to 8pm, Monday to Saturday, excluding public holidays; The 95th-percentile with 1 mm/s will apply for all blast events at all other times; The percentile calculation is based upon all recorded vibration data that exceeds the pre-set threshold level set in the Vibration Management Plan; and The duration of the underground development blast events shall be limited to no more than 12 seconds. By meeting these limits, Heilig (2022) considers the vibration effects of the proposed activities will be acceptable.
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