4 Tonkin & Taylor Ltd Waihi North Project - Technical Review of Air Quality Assessments Oceana Gold (New Zealand) Limited 22 June 2022 Job No: 1017908.0000 Modelling’3. The use of this relationship in this instance is not appropriate in our view given the very large difference in averaging period between annual and 24-hour periods. Instead, we consider a more valid approach is to simply compare the long-term average of measured RCS concentrations against the OEHHA annual average guideline of 3 µg/m³. In this regard, we note that the long-term average of the 24-hour average results are below the OEHHA guideline of 3 µg/m³. Section 6.3 discusses estimates of background PM2.5 in the Waihi Airshed. Overall, we agree with the commentary that background PM2.5 concentrations are likely to be derived largely from domestic home heating and vehicle emission sources. We also agree that the dust from mining sources consists predominantly of large particles that are greater than PM2.5 in size and that discharges of PM2.5 from the WNP are expected to have a minimal effect on concentrations of PM2.5 in airshed. Section 6.4 provides a useful and comprehensive discussion of historic dust related complaints relating to existing mining activities in and around Waihi. Of note is the significantly reduced number of complaints that have occurred since 2016, although we note that this may reflect the reduced production capacity over this period (as indicated in Figure 6-4 of the Beca Report). Section 6.5 provides a summary of current and past effects and concludes that the “results of the long-term monitoring programme indicates that any such events [i.e., short term events] do not occur sufficiently frequently, or are of sufficient magnitude, to increase the longer-term average concentrations above the relevant guidelines and standards.” We consider there is insufficient information to reasonably make this conclusion. However, going forward the lack of information can be addressed using continuous dust monitoring as part of the WNP to provide real time notification of dust events as they occur, enabling a proactive response. 2.5 Section 7: Potential Effects on the Environment of WNP Section 7.1 of the Waihi Facilities Report describes the use of a qualitative approach for assessing potential effects of the proposed development and refers to guidance published by the UK Institute of Air Quality Management (IAQM). The IAQM approach used is broadly analogous to the FIDOL (frequency, intensity, duration, offensiveness, and location) approach described in the MfE ‘Good Practice Guide for Assessment and Managing Dust’4. We therefore agree that the assessment approach is appropriate in in this instance. Section 7.2 discussed the effect of separation distances from dust source on measured dust concentrations. It notes that the results of monitoring programmes suggest there is a low risk of dust nuisance effects for locations “more than 150-210 m from the mine” where appropriate mitigation procedures are implemented. While this statement is difficult to reconcile with the historic monitoring results presented in the report5, the overall conclusion is not inconsistent with T+T’s experience evaluating dust nuisance effects associated with similar extractive industries. Notwithstanding the above, the Beca report notes the IAQM separation distance of 400 m for hard rock extractive industries. This is broadly consistent with the Victorian EPA guidance, which is widely referred to in NZ, which recommends 500 m for hard rock extractive industries. Section 7.2 describes the sensitivity of different locations/activities surrounding the WNP. We agree with the evaluation of the sensitivity of the receiving environment described in this context. In particular, the classification of residential areas and rural residences as having a high sensitivity to nuisance dust effects. 3 MfE 2002. Good Practice Guide for Atmospheric Dispersion Modelling. Ministry for the Environment. Air Quality Technical Report 27. 4 MfE 2016. Good Practice Guide for Assessment and Managing Dust. Ministry for the Environment. Publication number: ME 1277 5 Due to an absence of detail regarding the separation distance of the monitoring sites to mine activities.
RkJQdWJsaXNoZXIy MjE2NDg3