25 June 2012 URBAN AIRSHED MODEL AND METEOROLOGICAL DATA SETS Airshed Modelling of Exposure to Particulates in the Hawke's Bay Region Prepared for Hawke's Bay Regional Council June 2012 Submitted to: Hawke's Bay Regional Council 159 Dalton Street EMT 12/08 Napier 4110 HBRC Plan No 4359 New Zealand Report Number. 1178104049_001_R_Rev0 Distribution: REPORT HAWKE'S BAY AIRSHED MODELLING Executive Summary This report addresses several air quality management issues of importance to the Hawke’s Bay Regional Council (HBRC), using meteorological and airshed dispersion modelling techniques. The report focuses on current and future levels of airborne fine particulate matter (PM10 – particles less than 10 micrometres in diameter) in the region, identification of peaks in PM10, effects of emissions reduction scenarios, cross- boundary dispersion, and compliance with the National Environmental Standard (NES) for 24-hour-average PM10 and World Health Organization (WHO) guideline for 24-hour-average PM2.5. It also gives a qualitative comparison of source apportionment and emissions inventory studies carried out in the region, and provides a suite of modelled meteorological data sets for use in dispersion modelling as part of industrial resource consent applications. Source-apportionment data were used to give an indication of naturally-occurring levels of PM10. These have been combined with airshed modelling results for the dispersion of PM10 from sources such as domestic heating, motor vehicles and industry. This work thus gives estimates of total PM10, from both anthropogenic and natural sources. The airshed model, TAPM, performed well in simulating peak PM10 concentrations measured at the HBRC air quality monitoring sites at Marewa Park and St John’s College. It identified other ‘hot spots’ of PM10 due to domestic heating during winter. These were at Pirimai in Napier, and in an area encircling central Hastings (including the St John’s College site but not including Hastings Central itself). The modelling 3 indicates levels of PM10 higher than 90 μg/m are possible in locations in both Napier and Hastings other than the monitoring sites (this the 24-hour average PM10 based on 2010 emissions data), although the spatial extent of higher concentrations is larger in Hastings. Reductions in emissions from domestic heating by 47% in Napier and 50% in Hastings (relative to current emission levels) were indicated by the model for compliance with the NES for PM10. These percentages may be converted to numbers of wood burner removals or replacements, although the calculation is not done in this report. It is unclear whether emission reductions measures need to be taken in Havelock North, as the model indicates that this urban area is currently compliant with the NES by a small margin. Dispersion between the urban areas was indicated by the model to be small in worst-case conditions, so that reduction measures applied to one area would have very little effect on air quality in the other. Significant dispersion between Census Area Units (CAUs) within the urban areas was found by the model in worst-case conditions, meaning that the results of CAU-specific reduction measures would be complex and difficult to predict. The model indicated that all airsheds would be compliant with the NES for PM10 by 2020, based on projected emissions. However, there are some uncertainties in the emissions projections supplied to Golder, and these results should be treated with care. Estimates of peak PM2.5 (particles less than 2.5 micrometres in diameter) have been provided, based on a re-scaling of PM10 emissions, for comparison with the WHO 24-hour guideline PM2.5 concentration. The domestic heating component of PM2.5 was assumed to be 85% of PM10, such that resulting peak modelled concentrations of PM2.5 were close to those of PM10. As the WHO PM2.5 guideline concentration is one-half of the NES for PM10, emissions reductions required for compliance with the PM2.5 guideline would be more stringent than those required for compliance with the NES. The modelling indicated a required reduction in domestic heating emissions of 72%, in both Napier and Hastings. High-resolution meteorological data sets have been produced, covering Napier, Hastings, Awatoto, Whirinaki and Wairoa, based on modelled meteorology and local climate-site data. These have been created using the meteorological model CALMET, and are intended for used by consultants running the pollution- dispersion model CALPUFF for industrial assessments. Additional meteorological files have been extracted from the CALMET data sets for use with the AUSPLUME dispersion model. The report makes several suggestions for improvements in the modelling and associated data sets, and for further applications of the models to the management of air quality in the Hawke’s Bay region. 25 June 2012 Report No. 1178104049_001_R_Rev0 HAWKE'S BAY AIRSHED MODELLING Table of Contents 1.0 INTRODUCTION ................................................................................................................................................. 1 2.0 REVIEW OF EMISSIONS INVENTORIES AND SOURC APPORTIONMENT STUDIES IN THE HAWKE’S BAY REGION ...................................................................................................................................................... 4 2.1 Introduction ............................................................................................................................................. 4 2.2 Hawke’s Bay Emissions Inventory ........................................................................................................... 4 2.3 Source Apportionment Studies ................................................................................................................ 5 2.3.1 Introduction ....................................................................................................................................... 5 2.3.2 Napier source apportionment ............................................................................................................. 5 2.3.3 Hastings source apportionment .......................................................................................................... 5 2.4 Comparison between Source Types Identified by the Emissions Inventory and Source Apportionment Studies ............................................................................................................................ 6 2.5 Combining Natural Sources with Airshed Modelling Results ...................................................................... 7 2.6 Summary ................................................................................................................................................ 9 3.0 TAPM CONFIGURATION AND EVALUATION ..................................................................................................... 9 3.1 Background – Use of TAPM in the Hawke’s Bay region ............................................................................ 9 3.2 Meteorological Modelling with TAPM...................................................................................................... 10 3.3 Inventory Emissions Data and TAPM Airshed Modelling ......................................................................... 13 3.4 Airshed Model Optimization for PM10 Dispersion .................................................................................... 14 4.0 AIRSHED MODEL RESULTS FOR PRESENT-DAY PM10 .................................................................................. 15 4.1 Introduction ........................................................................................................................................... 15 4.2 Peak PM10 at Air Quality Monitoring Sites .............................................................................................. 15 4.3 Peak Modelled PM10 Concentrations over the Heretaunga Plains ........................................................... 16 4.4 Hour-by-hour Dispersion of PM10 ........................................................................................................... 18 4.5 Cross-Boundary Dispersion of PM10....................................................................................................... 19 4.5.1 Introduction ..................................................................................................................................... 19 4.5.2 Dispersion of PM10 between Airzone 1 areas .................................................................................... 19 4.5.3 Dispersion of PM10 between CAUs ................................................................................................... 23 4.5.4 Implications of cross-boundary dispersion for emission reduction measures ...................................... 25 5.0 AIRSHED MODEL RESULTS FOR FUTURE PM10............................................................................................. 25 5.1 Introduction ........................................................................................................................................... 25 5.2 Reductions Relative to Present-Day Emissions ...................................................................................... 26 25 June 2012 Report No. 1178104049_001_R_Rev0 i HAWKE'S BAY AIRSHED MODELLING 5.3 Modelled PM10 with Emissions Projected to 2020 ................................................................................... 27 6.0 COMPLIANCE WITH PM2.5 GUIDELINES