| Existing Effects of Waihi Operations on the Environment | WNP Wharekirauponga Underground Mine - Assessment of Effects of Discharges to Air | 4397169-66885702-23 | | 36 The results of long-term monitoring at the Waihi mine are summarised in Section 6-2 of the Waihi North Project Air Discharge Assessment-Waihi Facilities Report (Beca, 2022). From this summary, it is concluded that: ● Dust deposition rates at all sites surrounding the mine are relatively low and generally comparable to local background levels (MfE and consent trigger levels only exceeded infrequently during previous 20 years of monitoring19). Deposition rates are relatively low when compared to the MfE guideline of 4 g/m²/30-days. ● TSP concentrations are only elevated close to the mine pit (beyond 150 – 250m concentrations are similar to those recorded in other parts of Waihi) ● OGNZL has not carried out any monitoring of ambient PM2.5 concentrations in the Waihi area. However, dust from mining sources consists predominantly of larger particles that are greater than PM10 in size. The major sources of anthropogenic PM2.5 in Waihi is expected to be domestic heating sources and vehicle emissions and will include a minor contribution from OGNZL ● PM10 and silica concentrations (24-hour average) based on OGNZL monitoring until the end of 2014 and continuous monitoring by Waikato Regional Council (WRC) between 2008 and 2011 were well within health-based guidelines20. Monitoring was discontinued by agreement with the WRC as ambient air quality within the Waihi Airshed did not pose any significant potential health risks for these contaminants. Blast contaminant emissions from the Favona Mine Vent shaft were measured in August 2007 by Watercare Services Ltd21 and can be compared approximately to the 1-hour average ambient NESAQ and AAQG values for CO and NO2. While short term peak concentrations of both CO and NO2 were elevated above averages, the average concentrations were all less than the AAQG and NEASQ values. 6.4 Complaints 6.4.1 Dust related OGNZL records all complaints it receives regarding mining operations at its Waihi operations. Figure 6.2 shows the number of complaints received by OGNZL each year since 2002 which related to dust and other discharges to air. All complaints that are received are included in the data record even if the cause of the complaint could not be determined or attributed to the mine. However, two complaints attributed to pollen have been excluded. The historical complaints data demonstrates that in most years, the number of dust related complaints received is less than 10 which is considered to be a moderate to low level for a mining activity the size of the Waihi Mine and which is located within a sensitive receiving environment. During 2004 and 2011, the number of complaints was on average higher, with 18 complaints being received in 2004 and 28 in 2011. The complaints were attributed to a very dry windy November, combined with a water cart breakdown for 36 hours and no sprinklers being used on a temporary portable crusher. To prevent a recurrence of the problems, a back-up water cart was contracted and a requirement for using sprinkler systems on any new crushing equipment was implemented. 19 Note: not all these exceedances were due to mining; e.g eruptions of Mt Ruapehu have had significant effects on dust deposition at monitoring sites 20 From Waihi Gold Annual Monitoring Report 2014 21 Watercare Services Ltd (2007) “Newmont Waihi Gold; Particulate, Carbon Monoxide and Oxides of Nitrogen Emission Testing” August 2007
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