| Proposed Mitigation Measures | Waihi North Project Air Discharge Assessment - Waihi Surface Facilities | 4396626-1331619777-99 | 16/06/2022 | 66 8 Proposed Mitigation Measures 8.1 Current Mitigation Measures The mitigation measures currently used to control dust at the mine will continue to be used. These methods are described in the AQMP prepared by OGNZL and are summarised in Section 3.2.3. Similarly, it is recommended that the conditions included in the current consents for the mine are included in any new consent that is granted. 8.2 Additional Mitigation Measures It is expected that the risk of dust generated by WNP creating adverse effects on the majority of properties located in the vicinity of the WNP works is low. For properties located within approximately 200 m of proposed works, there is a moderate to high risk that short term adverse dust nuisance effects may result especially in dry windy conditions. Two dwellings are located approximately 100 m from the NRS stockpiles (i.e. dwellings R21 and R22 in Figure 2-1). To mitigate the risk of dust nuisance effects at these receptors, it is recommended that continuous instrumental monitoring of TSP concentrations, wind speed and wind direction is undertaken at boundary of the site and close to these dwellings when the NRS stockpile is being worked. The outputs from the instruments should be able to be monitored remotely and should be able to produce an alarm when TSP concentrations or wind speeds approach trigger values. It is also recommended that the following wind speed and TSP concentration trigger levels for reviewing and temporarily ceasing work are included as additional mitigation measures in the AQMP. The trigger levels are based on levels recommended in the GPG Dust and are summarised in Table 8-1. Table 8-1 Trigger values for wind speeds and TSP concentrations for works taking place within 200 m of sensitive receptors Item Trigger Actions TSP Alert TSP concentration (1-hour average) exceeds 170 µg/m3, Dust sources and dust control measures within 200 m of downwind sensitive receptors will be reviewed and additional dust control methods shall be implemented if necessary, as detailed in the site AQMP. TSP Alarm TSP concentration (1-hour average) exceeds 200 µg/m3 Or TSP concentration (24-hour average) exceeds 60 µg/m3 Contributing dust generating activities will cease within 200 m of downwind sensitive receptors except for dust control activities as detailed in the AQMP. Wind Speed Alert Hourly average wind speeds exceed 5 m/s and winds are blowing towards sensitive receptors Dust sources and dust control measures within 200 m of downwind sensitive receptors will be reviewed and additional dust control methods shall be implemented if necessary, as detailed in the site AQMP.
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