B-1 - Area 1, Coromandel Forest Park – Assessment of Environmental Effects 78 To ensure appropriate geochemical management of potentially acid forming (“PAF”) spoil to reduce potential effects on water quality, the implementation of an appropriate spoil management strategy will therefore be required. OGNZL has utilised a combination of methods to effectively manage spoil at its Waihi operations to date, and it is proposed that management of rock sourced from the Dual Tunnels and WUG will employ similar methods. They include: Oxidation control – Control of oxygen flux to reactive sulphides, such as by deposition under water or through the application of low permeability layers; Geochemical control - Blending rock types or addition of neutralising materials to control pH and oxidation rates; and Hydrological control - Placement of low permeability layers, evapotranspiration layers and spoil management structures to control the potential leaching rate from the disposal facility. During the development and operation of the WUG and Dual Tunnels, groundwater will be diverted around active workings (using grouting or similar techniques). However, some will be drained into the mine workings. This water will either be recycled for drilling purposes or diverted out of the CFP via the Dual Tunnels and Willows Access Tunnel to collection ponds at the Willow Road SFA and ultimately the WTP at the Waihi SFA for treatment prior to discharge. This will ensure it is contained and does not have an adverse effect on the environment. 5.8 NOISE EFFECTS An assessment of the actual and potential noise effects as a result of the WNP is provided in Marshall Day (2022), a copy of which is provided in Part H of these application documents. For the ventilation raise sites, Marshall Day (2022) assesses that noise levels from the construction of the vent raises, both on ground and from helicopter operations, would have potentially some small effects on recreational users of the DOC land but would be of no appreciable significance due to the relatively short duration and the infrequent use by recreational users. During operation, noise emissions from the vent raises are predicted to be generally only above ambient noise levels (of around 40 – 45 dB LAeq) within 100 – 200 m of the ventilation raise located at the orebody. Noise levels at the other sites are predicted to be barely audible against the background noise activity, and likely only if receivers are directly at the raise site itself. It is unlikely that noise from the raises would be audible on the Wharekirauponga walking track. Therefore, Marshall Day predict that these operational noise levels will not be significant.
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