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3.3 The Illawarra region

3.3.1 Description of the region

Figure 15: The Illawarra Region Current monitoring stations are indicated by . The circle encloses the area of the three Port Kembla stations. Shading shows height above sea level (metres).

The Illawarra is the fourth major population centre of NSW. It is located on a thin coastal strip with a steep escarpment to the west. The width of the coastal strip increases from north to south until it terminates in a ridge of hills running from the escarpment to the sea, Figure 15. As the significant topographic feature, the escarpment is a major influence on meteorology and hence on air quality in the region. It can steer or deflect winds, changing the apparent direction at the surface. It can also lead to the decoupling of winds above and below the escarpment. As a result an inversion can form at the top of the escarpment, limiting the dispersion of pollutants in the Illawarra region (Hyde et al, 1997).

The region is also strongly influenced by sea breezes. In the north of the region these tend to be steered by the topography to become north-north-easterly to north-easterly in direction. In the south of the region sea breezes tend to be more north-easterly to easterly. Return-flow has been observed above the sea breeze in the Illawarra region (Hyde and Prescott, 1984). Westerly drainage flows have been observed to develop on the region overnight (Hyde and Prescott, 1984), and will also have some influence on air quality.

The Illawarra region is only 80 km to the south of the Sydney region. On occasion pollutants will be transported between the two, particularly from Sydney to the Illawarra. It could be argued that the two form one single airshed. However, each has been dealt with separately here since doing so has no impact on the analysis presented or the number of monitoring stations that would result.

The Illawarra region has a population of 220,000. The population criterion in clause 14 of the NEPM suggests at least one monitoring station in the region. Major sources in the Illawarra, apart from motor vehicle traffic, are iron and steel production and associated coke making, and primary metallurgical works.

The EPA has maintained a monitoring station at Albion Park since the early 1980s and now oper-ates a network of four comprehensive stations and an additional three locations where total suspended particulates and lead are determined. The distribution of instruments is shown in Table 19, locations being shown in Figure 15.

Table 19: Monitoring in the Illawarra airshed (2000)

1. Port Kembla Fire Station (old site)
2. Electricity Substation
3. St Patrick's Convent

3.3.2 Overall air quality

Carbon monoxide

Carbon monoxide is currently measured at one station in the Illawarra, Wollongong. Concentrtions in the region are expected to follow the pattern established in Sydney and reflect local vehicle usage densities. Table 20 summarises the data collected from the Wollongong station in the period 1993-98.

Table 20: Carbon monoxide in the Illawarra, 1993-98

As expected based on data from the Sydney and Lower Hunter regions, concentrations of carbon monoxide in the region are low. The maximum concentration in the six years 1993-98 is 55% of the goal, less than the criterion (60%) of Screening Procedure B, Table 1 of PRC (2000d). However, to provide ongoing information on concentrations of this pollutant, monitoring at the Wollongong station will continue. These data may be used to provide screening arguments in other regions with lesser emissions.

Ozone

Ozone in the Illawarra region can occur as a result of photochemical smog produced from local emissions or from smog or precursors transported down the coast from the Sydney region. It appears that most ozone events in the Illawarra occur as a result of the combined effect of these two factors. The sea breeze, generally north-easterly in direction, is the dominant meteorological influence on elevated concentrations of ozone in the region.

Emissions of NO_x may reduce ozone concentrations on a local scale close to the source by titration. However, at some distance downwind this NO_x can produce more ozone. On many event days this potential is realised by the time the plume arrives at the Albion Park station.

Based on data from 1993 to 1998 in Table 21, Albion Park records the greatest number of exceedences of the NEPM standard for both four-hour and one-hour ozone concentration. Kembla Grange is the next most significant for number of events. Both of these stations record unique events, and between them they record nearly all events in the region. Albion Park is the station furthest downwind of sources and thus provides additional information about the development of photochemical pollution from emissions in the region. It also has a valuable long-term record of ozone levels in the Illawarra.

Table 21: Ozone concentrations in the Illawarra 1993-98

To capture the range of ozone events in the Illawarra, at least Albion Park and Kembla Grange are required. Monitoring will also occur at Wollongong as a trend station.

Nitrogen dioxide

Nitrogen dioxide is currently monitored at Wollongong, Warrawong, Albion Park and Kembla Grange. Summary data are presented in Table 22.

Concentrations of nitrogen dioxide in the Illawarra can reach 50-60% of the NEPM standard. These concentrations have been recorded at all four stations, but are associated with different conditions. As in Sydney, a detailed understanding of the mechanisms leading to the occurrence of nitrogen dioxide in the Illawarra has not yet been developed. Episodes can occur throughout the year, with those in the warmer months generally associated with photochemical smog production and those in the cooler months related to more localised poor dispersion conditions. Both local NO_x sources and transport down the coast from Sydney can contribute to nitrogen dioxide in the Illawarra.

Note that the observations presented in Table 22 satisfy the criteria of Screening Procedure B, Table 1 of PRC (2000d). Thus these data would justify reducing monitoring of nitrogen dioxide in the region below the population-based minimum of one site and also in other regions with lesser emissions.

Table 22: Nitrogen dioxide concentrations in the Illawarra 1996-98

* installed 1994

While there is little difference in the maximum concentrations of nitrogen dioxide observed, the Albion Park station would appear to have the potential for the highest maximum being furthest downwind on episode days. Monitoring will also occur at Wollongong as a trend station.

Particles as PM₁₀

As in the Sydney region, the highest observed concentrations of PM₁₀ have been associated with wildfires, hazard reduction burning and dust events. Similarly there is considerable variation in the spatial distribution of PM₁₀ from event to event. This is due to the variation in the location of the sources (fires) and in the meteorological factors affecting the dispersion and transport of the particles.

TEOM data show that for the period 1996 to 1998, the highest concentrations of PM₁₀ were observed at the Wollongong station, Table 23.

Table 23: PM₁₀ in the Illawarra, 1996-1998 (by TEOM)

As there are no TEOM data from the Kembla Grange station, reference was also made to PM₁₀ data by high volume sampler operated on a one-day-in-six cycle. These data show that the highest concentrations of PM₁₀ occur at Kembla Grange. No exceedences of the goal are reported from the TEOM data in the Illawarra. However, the high-volume sampler data suggest that monitoring at Kembla Grange is needed as it may experience the highest concentrations in the region. Monitoring will be undertaken at Albion Park. Kembla Grange is nominated as an upper bound station and Wollongong is nominated as the trend station.

Sulfur dioxide

There are a number of potentially large emitters of sulfur dioxide in the Illawarra, concentrated in the Port Kembla area. The EPA measures sulfur dioxide at three locations in the Illawarra: Albion Park, Wollongong, and Warrawong. Warrawong, being close to Port Kembla, measures the highest concentrations in the network, Table 24.

Industry monitoring for sulfur dioxide is also undertaken at 10 sites in this region.

Table 24: Sulfur dioxide in the Illawarra 1996-98

1. Some stations were not operational until some number of months into 1996
2. Monitoring did not commence until January 1998

While the data for 1996-98 shows low concentrations, an increase in emissions since that time is expected to increase ambient concentrations. Monitoring will be undertaken at Warrawong to provide information on upper bound concentrations for this pollutant.

Lead

The EPA currently operates three sites in the Illawarra where lead and total suspended particulate matter alone are measured. These have been established for many years as an independent check on emissions from the operation of a particular point source. One of these sites is located close to the premise's boundary, and the other two sites are located about 1 kilometre and 2.5 kilometres from the point source respectively.

Data from these stations from 1994 (when the point source was operational) are presented in Table 25. As would be expected, the highest values observed have been at the boundary site. It is considered that all these sites are peak sites according to the Australian Standard and are hence not representative of community exposure for the purposes of the NEPM.

As none of these sites is suitable, campaign monitoring of lead will be undertaken at Warrawong. This is expected to provide an estimate of the upper-bound concentration to which the population of the region is exposed.

Table 25: Lead in the Illawarra 1994

3.3.3 Proposed AAQ NEPM assessment scheme

Figure 16: AAQ NEPM monitoring in the Illawarra Region

The presence of industrial sources in the region, the occurrence of transport from Sydney, and the complexity of the region together result in a need for a greater monitoring effort than that indicated purely on the basis of population. Accordingly, the general air quality to which the urban population is exposed will be characterised by monitoring all pollutants of interest at the trend station at Wollongong and the performance station at Albion Park. These stations will also pick up the majority of pollution events. Two additional stations are nominated to represent the local conditions at Kembla Grange and Warrawong.

The AAQ NEPM monitoring network for the Illawarra region is shown in Figure 16 and summarised in Table 26 which lists the parameters at each station.

1 P denotes performance; T denotes trend; C denotes campaign.