4 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 A two-year meteorological dataset was developed using the CALMET meteorological model for the years 2016 and 2017. We note that 2016 and 2017 are expected to provide a suitable range of meteorological conditions due to those years experiencing a mix of La Niña and El Niño climatic conditions. The model domain covered an area of 12.75 km (east to west) by 15km (north to south) at a 150 m grid resolution. Input data for the CALMET model were derived from the meteorological component of the TAPM model, as well as terrain and land use information sourced for Land Information New Zealand (LINZ). Appendix A provides figures that illustrates the CALMET model domain and terrain inputs along with details of the configuration of both the CALMET and CALPUFF models. 3.3 Background air quality Indicative background concentrations, to enable an estimate of cumulative contaminant concentrations, have been sourced from the Waka Kotahi interactive background map (Figure 3.1).4 The corresponding background concentrations for PM10 and NO2 are summarised in Table 3.1. In practice, background concentrations in the forest area will better than expected of a rural area. Accordingly, we consider that these default background concentrations are likely to significantly overstate existing air quality in a pristine forested location. Table 3.1: Background air contaminant concentrations (CAU number 534200) Contaminant and averaging time Concentration PM10 24-hour average 19 µg/m³ NO2 1-hour average 37 µg/m³ NO2 24-hour average 23 µg/m³ Figure 3.1: Waka Kotahi interactive map for background air quality concentrations. 4 https://www.nzta.govt.nz/roads-and-rail/highways-information-portal/tools/air-quality-map/
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