7 Tonkin & Taylor Ltd Assessment of mine vent air quality impacts to inform an assessment of ecological effects on Archey’s frog Oceana Gold (NZ) Limited June 2022 Job No: 1017908 Figure 5.1: Reproduced Figure 4.9 from Bluet et al 2017, showing PM10 concentrations on the untreated roadway: north 5m and north 30m sites, 19 February to 16 April 2015. Weekend dates highlighted with blue circles. 6 Conclusion This air quality assessment has been prepared on behalf of OGNZL to inform an ecological assessment of the impact of proposed mine vent discharges on Archey’s frog habitat. The key discharges to air from the proposed vents are fine particulate matter less than ten microns (PM10) and nitrogen dioxide (NO2). The main conclusions of the assessment are as follows: • Predicted cumulative ambient air concentrations of PM10 and NO2 in the vicinity of the proposed vents are very low when compared against human health assessment criteria. • Predicted cumulative concentrations of PM10 in the vicinity of the vent raises will be lower than measured concentrations adjacent to an unpaved road in Northland (based on weekend traffic volumes). • Based on similarity in traffic levels, PM10 concentrations are likely to be similar in areas adjacent to an unpaved public road in the Coromandel (north of the WUG) where baseline ecological assessments of Archey’s frog habitat have been undertaken. Therefore, it can be inferred that Archey’s frogs at this Coromandel location are exposed to greater levels of PM10 than anticipated in the vicinity of the proposed vents. • Predicted NO2 concentrations in the vicinity of the proposed vent raises are very low and well within human health assessment criteria. T+T considers the predicted NO2 concentrations in the vicinity of the vent raises are likely to represent background concentrations for many rural locations.
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