8 Tonkin & Taylor Ltd Waihi North Project - Technical Review of Air Quality Assessments Oceana Gold (New Zealand) Limited 22 June 2022 Job No: 1017908.0000 Section 5.27 notes the use of water as a means for dust suppression, which is typical for mines, quarries and large-scale earthworks. It notes MfE guidance suggests a ‘rule of thumb’ of applying 1 L/m²/hr may be needed for this purpose. It is T+T’s experience that this application rate is highly conservative overstatement of water application rates, even for much dryer parts of the country such as Canterbury and Central Otago, and in practice much lower water application rates are typically needed. Section 5.3 covers the discharge of combustion products from surface vehicles. As with the Waihi Facilities report, we do not consider vehicle combustion emissions will cause an air quality issue given the number of vehicles/machines and location of the site. We also note that Oceana Gold proposes to use electric powered equipment where practicable, although details of this are not set out in the WUG report. Section 5.4 discusses air discharges from underground tunnelling and mining. In practice these emissions are not canvased directly by the WUG report and are provided more for information purposes. Section 5.5 discusses the potential for odour associated with proposed wastewater treatment and effluent disposal area associated with treating wastewater from toilets, staff washing and lunchroom facilities. We agree with Beca that this is not expected to cause any adverse odour nuisance issues. 3.4 Section 6: Existing effects of Waihi Operation on the Environment Section 6 of the WUG report is essentially the same as Section 6 of Waihi Facility report and therefore our commentary in Section 2.4 of this report is applicable here. 3.5 Section 7: Potential effects of project on environment Section 7 of the WUG report primarily focuses on the potential for dust nuisance effects impacting on surrounding sensitive receptors (i.e., rural dwellings). The general approach is the same as that described in Section 7 of the Waihi Facilities report. Consequently, our review comments set out in Section 2.5 of this report are applicable here. The assessment identifies there being a ‘high’ and ‘moderate to high’ risk of dust nuisance effects impacting on the dwellings at 111 and 122 Willows Road respectively from the development of stockpiles of topsoil. Figure 7-1 of the WUG report (reproduced as Figure 1 below) shows the location of various surface features associated with the project, overlays the windrose for Waihi, and notes the location of various residences. This figure would benefit from showing the boundary of land owned by Ocean Gold and labelling the residences associated with 111 and 122 Willows Road. For clarity, the reproduced figure below identifies what we understand to be the residences associated with these two addresses. Overall, we agree with Beca that the residences at these two addresses have the potential to be impacted by dust from the topsoil stockpile given their proximity and that they are downwind under prevailing wind conditions.
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