| Potential Effects of Project on Environment | WNP Wharekirauponga Underground Mine - Assessment of Effects of Discharges to Air | 4397169-66885702-23 | | 42 TSP concentrations measured at monitoring Site 6.78 (Slevin St) and Site 6.61 (Grey Street) are only slightly higher than background TSP concentrations. Site 6.78 (Slevin St) and Site 6.61 (Grey Street) are both located in the prevailing wind direction and would therefore be frequently downwind of the mine and potentially exposed to site emissions. Only one exceedance of the consented TSP trigger limit was recorded at Site 6.78 (Slevin St) over the monitoring period. The monitoring results suggest that emissions from mine operations have only a small impact on the air quality at these locations Higher average TSP concentrations and dust deposition rates are measured at Site 6.63 (Met Station) which is located approximately 140 m from the mine operations. However, only 6 exceedances of the TSP consent trigger limit have occurred since 2005, and one exceedance of the dust deposition rate consent limit since 2000. No exceedances have been recorded since the site office carpark (50m upwind of monitor) was sealed in 2010. Although it not possible to assess the occurrence of any short-term dust nuisance effects, the monitoring results suggest there is a relatively low risk that receptors located more than 150 – 210m from the mine would experience dust nuisance effects when appropriate mitigation procedures are implemented. The Institute of Air Quality Management (IAQM) provides guidance for the assessment of impact of dust emitted from mineral extraction and processing operations and consider receptors located more than 400 m from open dust generation activities processing hard rock, or more than 250 m from dust generation activities processing soft rock (e.g. sand, gravel, and soil), are unlikely to experience adverse nuisance or health effects. 7.5 Consideration of FIDOL Factors The dust generated from the project during construction and operation is likely to be of reasonably low intensity under lighter wind conditions (ie <5m/s) and unlikely to be discernible beyond the site boundary. However, under the reasonably frequent higher wind conditions (>5m/s) from the southwest to west also experienced at the site (~20% of the time) there is the potential during construction for higher intensity dust generation to occur from exposed excavations and topsoil storages. The separation distances are relatively small to the nearest sensitive receptor (privately owned dwelling at 111 Willows Road), which may not be sufficient (in the absence of appropriate management) to effectively mitigate infrequent, short duration dust nuisance under strong wind conditions. Dust emissions will not be continuous and will vary with wind speed and areas of exposed land or unconsolidated topsoil material. While the rural area, in which the neighbouring dwellings are located, may occasionally also receive dust from other sources, nuisance dust from the Willows Road site could be considered offensive if it occurs more frequently, or in greater quantities than is typically experienced. Based on an assessment of the proposal against the FIDOL factors, the risks from infrequent, short duration adverse effects (nuisance dust), arising from the proposed construction activity (in the absence of appropriate mitigation and management) is considered to be moderate to high at the privately owned dwelling located on 111 Willows Road and moderate at the privately owned dwelling at 122 Willows Road. The dwelling at 111 Willows Road is located within approximately 145m from the topsoil storage at its closest point. The topsoil area will be a relatively large source of dust (ie up to 3ha) during construction (and then later when recovered). The distances from the nearest noise bund and the topsoil storage area to the dwelling at 122 Willows Road are 109m and 234m respectively. The noise bund is a relatively small and temporary source of dust. The risk from dust during construction is considered low at all other dwellings at a greater distance from the site.
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