| Dispersion Modelling Methodology | WNP Processing Plant Air Discharge Assessment | 4397169-66885702-113 | 16/06/2022 | 17 Sensitivity: General 5-1. The windrose shows a predominance of winds from the west and west-southwest directions. Similar distribution of wind flows was recorded at the Waihi Mine meteorological monitoring station. Figure 5-1. Predicted distribution of wind speed and wind direction at the Processing Plant for 2016 5.8 Terrain and Receptors Terrain can have a significant influence on the dispersion of pollutants and predicted ground level concentrations. Terrain effects were incorporated into the dispersion model using a CALMET meteorological model grid and using CALPUFF’s partial plume path adjustment method. The method reduces the effective height of the emission plume above ground level by up to 75%, as it travels over elevated terrain features. As a consequence, higher concentrations are predicted for receptors located at elevated terrain features compared to receptors located on flat terrain. In CALPUFF, receptor points were defined every 50 m in the north-south and east-west directions within a 6 km (E/W) x 5 km (N/S) area. An additional 13 discrete receptor points were defined at the location of nearby rural dwellings. The location of these discrete residential receptor points is shown in Figure 5-2. Ground level elevations used in the model were derived from the SRTM1 (Shuttle Radar Topography Mission) digital elevation database.
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