17 Tonkin & Taylor Ltd Wharekirauponga Underground Mine – unplanned detonation air quality assessment Oceana Gold (New Zealand) Limited June 2022 Job No: 1015212.2000 vRev0 7 Conclusion This air quality assessment has been prepared on behalf of OGNZL to inform an assessment of the impact of proposed underground storage of Class 1 explosives. The key discharges to air from the proposed vents are carbon monoxide (CO) and nitrogen dioxide (NO2), with some ammonia (NH3) also anticipated. The main conclusions of the assessment are as follows: Predicted cumulative ambient air concentrations of CO and NH3 in the vicinity of the proposed vents are very low when compared against human health assessment criteria. In terms of the impact on air quality in terms of the IAQM guidance, the impact from CO is ‘negligible’ and ‘slight’ for NH3. Predicted cumulative concentrations of NO2 in the vicinity of the vent raises will be, at a maximum, half the assessment criteria for the protection of human health. The locations that these peaks are predicted at are in DOC reserve forest, relatively remote from any public walking tracks. The likelihood of a detonation in the underground store occurring, simultaneous with worst-case meteorological conditions and a member of the public being present at the most impacted locations is very low.
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