9.6 Assessment of potential construction impacts
This section deals with the potential impacts of the construction phase of the project. The construction activities for the project are described in section 9.3.
- Identifies the project footprint and construction scenarios
- Identifies the risk associated with the various construction activities
- Discusses the significance of the identified risks.
9.6.2 Construction surface works and scenarios
The impacts associated with surface works and construction sites are described below. The above ground construction activities would take place at several separate locations (see Table 9-13). The concept design considers two possible combinations for construction ancillary facilities around Haberfield and Ashfield. These are described and assessed in this EIS (Option A and Option B). The construction ancillary facilities that comprise these options have been grouped together and are denoted by the suffix a (for Option A) or b (for Option B) eg C1a is Wattle Street civil and tunnel site. The preferred combination of construction ancillary facilities would be determined during detailed
design and would meet the environmental performance outcomes stated in the EIS and the Submissions and Preferred Infrastructure Report, satisfy criteria that would be identified in any relevant conditions of approval and manage environmental risks.
Table 9-13 M4-M5 Link construction ancillary facilities
The construction activities in several of the construction ancillary facilities are expected to take place concurrently and in close proximity to one another. Therefore, for the assessment the construction ancillary facilities were combined according to the seven ‘worst case’ scenarios listed in Table 9-14.
Table 9-14 M4-M5 Link construction scenarios
The number of receptors in each distance band from construction sites was estimated from land use zoning of the site. The exact number of ‘human receptors’ is not required by the IAQM guidance, which recommends that judgement is used to determine the approximate number of receptors within each distance band. For receptors that are not dwellings, judgement was used to determine the number of human receptors. The results of the screening assessment of receptors in proximity to the
various construction sites are shown in Figure 9-14.
In the case of the M4-M5 Link, the following numbers of receptors per building were assumed:
– B1 – Neighbourhood Centre = five
– B2 – Local Centre = five
- Mixed use:
– B4 – Mixed Use = three
– B6 – Enterprise Corridor = five
– B7 – Business Park = 20
– Community centre = 20
– Childcare = 30
– School = 500
– IN1 – General Industrial = 10
– IN2 – Light Industrial = 10
– R1 – General Residential = three
– R2 – Low Density Residential = three
– R3 – Medium Density Residential = five
– R4 – High Density Residential = 50.
Table 9-15 shows the results of the risk categorisation for the construction activities that would be carried out in each construction scenario.
Table 9-15 Criteria for assessing the potential scale of emissions
Sensitivity of area to dust soiling effects on people and property
The criteria for determining the sensitivity of an area to dust soiling impacts are shown in Table 9-17. The sensitivity of people to the health effects of PM10 is based on exposure to elevated concentrations over a 24 hour period. High-sensitivity receptors relate to locations where members of the public are exposed over a time period that is relevant to the air quality criterion for PM10 (in the case of the 24 hour criterion a relevant location would be one where individuals may be exposed for eight hours or more in a day). The main example of this would be a residential property. All non-residential sensitive receptor locations were considered as having equal sensitivity to residential locations for the purposes of this assessment. In view of the types of receptor shown in Figure 9-14, being predominantly residences in addition to community centres, and in consideration of the IAQM guidance, the receptor sensitivity was assumed to be ‘high’.
Table 9-17 Criteria for sensitivity of area to dust soiling impacts
Sensitivity of area to human health impacts
The criteria for determining the sensitivity of an area to human health impacts caused by construction dust are shown in Table 9-19. Air quality monitoring data from Rozelle were used to establish an annual average PM10 concentration of between 16 µg/m3
and 18 µg/m3 for 2010 to 2016 (refer to Annexure F of Appendix I (Technical working paper: Air quality)). Based on the IAQM guidance the receptor sensitivity was assumed to be ‘high’. The numbers of receptors for each scenario and activity, and the resulting outcomes, are shown in Table 9-20. The sensitivity for all areas and all activities was determined to be ‘medium’.
Table 9-19 Criteria for sensitivity of area to health impacts
Table 9-20 Results for sensitivity of area to health impacts Scenario Activity Receptor
Sensitivity of area to ecological impacts
The criteria for determining the sensitivity of an area to ecological impacts of construction dust are shown in Table 9-21. Based on the IAQM guidance, the receptor sensitivity was assumed to be ‘medium’ for ecologically sensitive areas such as threatened flora and fauna, and ‘low’ for areas that were classed as ‘forest reserve’. Scenarios 3, 4, 5 and 7 all contained areas within 50 metres that had the potential for ecological significance. The results for the respective scenarios are shown in Table 9-22. All activities in Scenarios 4 and 5 were determined to have a ‘medium’ sensitivity to ecological impacts. All activities in Scenario 7 were determined to have a low sensitivity.
Table 9-21 Criteria for sensitivity of area to ecological impacts
The results for the risk assessment are provided in Table 9-23, combining the scale of the activity and the sensitivity of the area. As the level of risk varies in accordance with scenario and activity, those activities that were determined to be of high risk have been identified as follows:
- Scenario 1 (C1a–C3a): Track-out for dust soiling
- Scenario 2 (C1b–C3b): Track-out for dust soiling
- Scenario 3 (C4): Demolition and track-out for dust soiling
- Scenario 4 (C5, C6, C7): All activities for dust soiling, and demolition for human health and ecologically sensitive receptors
- Scenario 5 (C8): Earthworks and construction for dust soiling
- Scenario 6 (C9): All activities for dust soiling, and demolition for human health
- Scenario 7 (C10): Earthworks, construction and track-out for dust soiling.
Mitigation measures were determined for each of the four potential activities in Table 9-16. This was based on the risk of dust impacts identified. For each activity, the highest risk category was used. The suggested mitigation measures are discussed in section 9.10.1.
Table 9-23 Summary of risk assessment for the construction of the project
9.6.4 Significance of risks
Once the risk of dust impacts was determined, and the appropriate dust mitigation measures identified, the final step is to determine whether there are significant residual effects arising from the construction phase of a proposed development. For almost all construction activity, the aim should be to prevent significant effects on receptors through the use of effective mitigation. Experience shows that this is normally possible. Hence the residual effect would normally be ‘not significant’ (IAQM 2014).
However, even with a rigorous Dust Management Plan in place, it is not possible to guarantee that the dust mitigation measures would be effective all the time. There is the risk that nearby residences, commercial buildings, hotel, cafés and schools in the immediate vicinity of the construction zone, might experience some occasional dust soiling impacts. This does not mean that impacts are likely, or that if they did occur, that they would be frequent or persistent. Overall construction dust is unlikely to represent a serious ongoing problem. Any effects would be temporary and relatively short-lived, and
would only arise during dry weather with the wind blowing towards a receptor, at a time when dust is being generated and mitigation measures are not being fully effective. The likely scale of this would not normally be considered sufficient to change the conclusion that with mitigation the effects would be ‘not significant’.
The construction of the proposed future Western Harbour Tunnel and Beaches Link project at the Rozelle Rail Yards has been included in this assessment. The CBD and South East Light Rail Rozelle maintenance depot works would be completed prior to commencement of the project.
9.7 Assessment of potential operational impacts
9.7.1 In-tunnel air quality
The three pollutants assessed for in-tunnel air quality were NO2, CO and visibility, which is expressed as a coefficient of extinction (of light). The coefficient of extinction is proportional to the PM2.5 concentration (refer to section 9.2.3) as light is scattered or ‘extinguished’ by particulate matter in the tunnel air. It is not a direct measure of particulate matter from vehicle exhausts.
The information presented in Annexure L of Appendix I (Technical working paper: Air quality) has confirmed that the tunnel ventilation system would be able to maintain in-tunnel air quality well within operational limits for all scenarios assessed, including congestion and incidents within the tunnel. The project is proposed to be delivered in two stages:
- Stage 1 – construction of the mainline tunnels and stub tunnels to the Rozelle interchange at the Inner West subsurface interchange
- Stage 2 – construction of the Rozelle interchange and Iron Cove Link including:
– Connections to the stub tunnels for the mainline tunnels (built during Stage –
– Connections to the surface road network
- Civil construction of tunnels, entry and exit ramps and infrastructure (a ventilation outlet and ancillary facilities) to provide connections to the proposed future Western Harbour Tunnel and Beaches Link project.
The ventilation system analysis for the project has been undertaken with both stages noted as completed. For interim operation, with only the mainline tunnel between M4 East and New M5 in operation, restricting all tunnel sections within the project to a maximum of two traffic lanes would not require any increase in the installed ventilation capacity over and above that required for the completed project.
The levels of NO2 and visibility throughout a 24 hour period for the expected traffic scenarios with the project in 2023-DS and 2033-DS are shown in Figure 9-15 to Figure 9-21 and the cumulative impacts in 2033-DSC are shown in Figure 9-22 to Figure 9-25. The plots, which show the change in the peak in-tunnel value across 24 hours, throughout the project tunnel and the adjoining WestConnex tunnels, confirm that the tunnel ventilation system would maintain in-tunnel air quality well within operational limits, including the fifteen minute route-averaged NO2 criterion. Each plot represents multiple journeys
through the WestConnex tunnels, including the project, for each hour of the day.
2033 cumulative scenarios
These scenarios include traffic coming into the WestConnex tunnels from other proposed projects, ie the proposed future Sydney Gateway, Western Harbour Tunnel and Beaches Link and the F6 Extension projects.
Figure 9-25 Maximum In-tunnel visibility for M5 Motorway to M4 Motorway direction 2033-DSC Maximum in-tunnel concentrations across all time periods for the expected traffic scenarios, and the regulatory demand traffic, or maximum traffic flow, are presented in Appendix I (Technical working paper – Air quality). The maximum concentrations for all traffic scenarios were within the concentrations predicted in the regulatory worst case.
Worst case operations
For the worst case operations, the ventilation system in each simulation was adjusted such that the system met, or was marginally better than, the in-tunnel air quality criteria. Generally speaking, the project ventilation system is expected to be operating in the range of 50 – 75 per cent of its required capacity to meet worst case traffic conditions for expected traffic volumes. The traffic cases assessed are considered to be the theoretical worst case for the purpose of design because in practice, achieving for example, an average speed of 20 kilometres per hour along 22 kilometres of tunnel
would be very difficult, if not impossible. Data from the four kilometre long M5 East tunnel in congested conditions, shows that traffic does not travel at or less than 20 kilometres per hour for the length of the tunnel, even though the traffic may be stop/start for short sections near start and end of the tunnel.
Figure 9-25 shows that for almost all cases, 20 kilometres per hour results in the highest pollutant levels in the tunnel. This case determines the number of jet fans required in the tunnel for pollutionmanagement because there is less air moving along the tunnel due to the lack of piston with an average traffic speed of 20 kilometres per hour. This compares to 80 kilometres per hour traffic speed where very few (if any) jet fans are needed to generate the required air flows within the tunnels.
For the higher speed cases, the pollutant levels along the tunnel are lower because of greater airflow and fewer vehicles in the tunnel because at higher speeds the vehicles are a greater distance apart compared with lower speeds. It is the high-speed case which determines the volumetric capacity of the ventilation outlets as all air travelling along the tunnel plus air drawn in from the portals must be exhausted at the outlets.
Based on real time travel speed data from the M5 East tunnel, the likelihood of average traffic throughout the tunnel being less than 20 kilometres per hour is of the order of 0.5 per cent of the sampled period from January 2016 to September 2016 (Annexure L of Appendix I (Technical working paper: Air quality)). Traffic Management Plans will be developed during the detailed design phase, to provide the capability to further reduce the likelihood of slow moving traffic within the M4-M5 Link. Traffic Management Plans may include active and/or passive control measures to influence driving behaviour to maintain the speed of traffic through the tunnel.
Traffic management measures to prevent average speeds falling below 20 kilometres per hour will include:
- Providing warnings via the tunnel message signs and variable message signs to motorists both inside the tunnel and outside of the tunnel that there is congestion. This would normally result in some motorists in the tunnel exiting via the nearest exit and motorists approaching the tunnel choosing to take an alternative route
- Reducing speed limits on the variable speed limit signs at the tunnel approaches to regulate traffic inflow into the tunnel
- Closing tunnel lanes within ramps and the mainline tunnel to reduce the total volume of traffic within the tunnel to the point where the ventilation system will be able to control air quality to within required limits regardless of average traffic speed. Lane closure is achieved with the use of Lane Use Signals (LUS) located over each lane in the tunnel at 120 metre intervals and tunnel message signs (variable signs) also at 120 metre intervals throughout the tunnels
- Closing ramps and/or the mainline tunnel, generally in response to an incident within the tunnels or downstream of the motorway.
Managing traffic speed above 20 kilometres per hour in any section of the tunnel is also required for safety to minimise the chance of a fire at the rear of a queue of stopped traffic allowing vehicles in front of any fire to drive out of the tunnel without being overrun by smoke. Therefore, it is appropriate to adopt 20 kilometres per hour as the appropriate minimum average traffic speed when designing the ventilation system and assessing pollution.
Further detailed results from the analysis of the worst case operations scenarios are given in Annexure L of Appendix I (Technical working paper: Air quality).
9.7.2 Ambient air quality
For surface roads the emission and dispersion modelling was undertaken for the main roads in the study area, as defined in the WRTM (v2.3). The WRTM output included surface roads, tunnels, and tunnel access ramps. The road links in the study area are shown for each scenario in Appendix I (Technical working paper: Air quality).
It should be noted that some minor changes to the project design were made after the air quality assessment had been completed. These changes were as follows:
- Construction and operation of an additional right-hand turn lane on The Crescent at the intersection with Johnston Street. This would require widening of The Crescent to the north east by around three metres
- The enabling a triple right turn to occur from Wattle Street into Parramatta Road
- Changes to the lane configuration to and from the M4-M5 Link mainline tunnels at St Peters interchange, with a small portion of the ramps being increased by one additional lane.
None of these changes would affect the traffic data from WRTM, and the small changes in road width would have negligible effect on the predictions from the dispersion model.
Percentage changes in emissions between scenarios are shown in Table 9-24. Comparing the Do
something scenarios with the Do Minimum scenarios, emissions of CO, NOX, PM10 and PM2.5
increased by 1.6–2.9 per cent in 2023, and by 2.9–3.2-5 per cent in 2033, depending on the pollutant. For the Do Something Cumulative scenarios, emissions of these pollutants increased by 3.2–5.1 per cent in 2023 and by 7.2–8.2 per cent in 2033, depending on the pollutant. The changes in total hydrocarbons (THC) emissions were relatively small (less than or equal to 1.6 per cent).
The overall changes in emissions associated with the project in a given future scenario year (2023 or 2033) would be smaller than the underlying reductions in emissions from the traffic on the network between 2015 and the scenario year as a result of improvements in emission-control technology. Although there are some differences between the definitions of the Base Year and Do Minimum scenarios, it can be seen from Table 9-24 that between 2015 and 2023 the total emissions of CO, NOX and THC from the traffic on the road network are predicted to decrease by about 40 per cent. Between 2015 and 2033 the reductions are between around 50 per cent and 60 per cent. For PM10
and PM2.5, the underlying reductions are smaller: around six to nine per cent for PM10 and 17 to 19 per cent for PM2.5. This is because there is currently no anticipated regulation of non-exhaust particles, which form a substantial fraction of the total. In the case of PM10, the underlying reductions in emissions are similar to the increases associated with the project, whereas for PM2.5 the underlying reductions are larger than the increases due to the project.
The changes in the total emissions resulting from the project can be viewed as a proxy for its regional air quality impacts. These are discussed further in section 9.10.
Table 9-24 Percentage changes in total traffic emissions in the GRAL domain
9.7.3 Results for expected traffic scenarios (ground-level concentrations)
The predicted ground-level concentrations for the expected traffic scenarios are presented, by pollutant, in the following sections of the report. All results, including tabulated concentrations and contour plots, are provided in Annexure K of Appendix I (Technical working paper: Air quality).
The pollutants and metrics are treated in turn, and in each case the following have been determined for the 40 community and 86,375 RWR receptors:
- The total ground-level concentration for comparison against the NSW impact assessment criteria and international air quality standards
- The change in the total ground-level concentration. This was calculated as the difference in concentration between the ‘Do Something’ and ‘Do Minimum’ scenarios, ie the difference in ground-level concentrations as a result of the project
- The contributions of the background, surface road and ventilation outlet sources to the total ground-level concentration.
The results are presented in the following ways:
- As pollutant concentrations at discrete receptors, using:
– Bar charts for absolute concentration, and changes in concentration, at the community
– Ranked bar charts for absolute concentration, and changes in concentration, at the RWR receptors
- As spatially mapped pollutant concentrations (ie contour plots) across the GRAL modelling domain, and also changes in concentration across the domain. These have only been provided for the most important pollutants: NO2, PM10 and PM2.5
- As spatially-mapped pollutant concentrations, and changes in concentration, for the areas around project tunnel ventilation facilities. Again, these are only provided for NOX, PM10 and PM2.5.
Carbon monoxide (maximum rolling eight hour mean)
Results for community receptors
No model predictions were available for the period with the highest background concentration, so the maximum background value was combined with the maximum model prediction at each receptor. The background was therefore taken to be the same at all locations. As with the one-hour mean, at all the receptors the concentration was well below the NSW impact assessment criterion, which in this case is 10 mg/m3 . No lower criteria appear to be in force internationally.
The changes in the maximum rolling eight hour CO concentration at all the community receptors were mostly less than 0.4 mg/m3 . The largest increase with the project was around 0.6 mg/m3 (equating to six per cent of the criterion).
The maximum surface road contribution in any with-project scenario was 28 per cent, whereas the tunnel ventilation outlet contribution was zero in all cases. Appendix I (Technical working paper-air quality) shows the detailed results for the carbon monoxide predictions.
Nitrogen dioxide (annual mean)
Results for community receptors
Figure 9-27 shows the annual mean NO2 concentrations for the with-project scenarios at the community receptors. At all these locations, the concentration was below 32 µg/m3, and therefore well below the NSW impact assessment criterion of 62 µg/m3. The concentrations at receptors were also below the lower air quality standards that have been adopted elsewhere (eg 40 µg/m3 in the EU).
Concentrations at the vast majority (more than 98 per cent) of receptors were between around 20 µg/m3 and 30 µg/m3. The annual mean NO2 criterion for NSW of 62 µg/m3
was not exceeded at any of the receptors in any scenario.
At all but 11 receptors in the 2023-DS scenario, NO2 concentrations were also below the EU limit value of 40 µg/m3. However, the 11 receptors with an exceedance in the 2023DS scenario (with the project) was lower than the 17 receptors with an exceedance in the 2023-DM scenario (without the project), so that the project provides a benefit in these locations. The highest concentrations with the project in 2023 D-S scenarios were predicted to be around 43 µg/m3. The highest concentrations withthe project in 2033 DS were predicted to be around 39 µg/m3.
The maximum contribution of tunnel ventilation outlets for any scenario and receptor was 0.6 µg/m3, whereas the maximum surface road contribution was 21.6 µg/m3. Given that NO2 concentrations at the majority of receptors were well below the NSW criterion, the contribution of the ventilation outlets was not a material concern.
There was predicted to be an increase in the annual mean NO2 concentration at between 15 per cent and 20 per cent of receptors, depending on the scenario. Only around 0.1 per cent of receptors were predicted to have an increase of greater than two µg/m3. Conversely, there was a reduction in annual mean NO2 at between around 80 per cent and 85 per cent of receptors.
Contour plots – all sources
Contour plots were developed to illustrate the spatial distribution of pollutant concentrations (from all sources) across the GRAL domain. Only the contour plots showing the change in pollutants as a result of the project in 2023 and 2033 are shown in this chapter (see Figure 9-31 and Figure 9-32). The contour plots for all other scenarios are given in Annexure K of Appendix I (Technical working paper: Air quality). The green shading show decreases in concentration and the purple shading shows an increase in concentration. The scale on the plots indicates the concentrations represented by the
depth of the colour.
The plots are based on 1.8 million grid points, spaced at 10-metre intervals across the domain. Many of the points fall along the axes of roads, and are therefore not necessarily representative of population exposure. The plots illustrate the strong links between the spatial distribution of air pollution and the traffic on the road network. The figures also show main surface roads and the locations of tunnel ventilation outlets.
It should be noted that some of the roads in the model are presented as being on the surface, whereas in reality, they are (minor) tunnels. The main examples of this are the relatively short tunnel on General Holmes Drive that passes under the airport runway, and the Cooks River Tunnel. It was not considered necessary to represent these roads as tunnels given that they were some distance from sensitive receptor locations (moreover, decreases in concentration were predicted along these roads).
The highest absolute concentrations are found along the most heavily trafficked roads in the GRAL domain, such as the Western Distributor, Anzac Bridge and General Holmes Drive to the south of the airport. It should be noted that the Do Minimum scenarios also include the M4 East and New M5 projects, and therefore some roads which are currently heavily trafficked are not as prominent as might be expected. A good example of this is Parramatta Road, which would have reduced traffic as a result of the M4 East project. It is noticeable that the tunnel ventilation outlets have little impact on total annual mean NO2 concentrations.
The purple shading to the north of Sydney Airport is the estimated change from the proposed future Sydney Gateway which would be a new surface road, hence there would be a re-distribution of traffic and therefore emissions from other parts of the road network to this new road.
There are predicted to be marked reductions in concentration along some major roads, and increases on others, in proportion to the changes in traffic in WRTM. Table 9-25 summarises the average weekday two-way traffic on some affected roads in all scenarios from WRTM, and Table 9-26 gives the changes between scenarios.
In Figure 9-31 there are noticeable decreases in NO2 along Dobroyd Parade/City West Link and Parramatta Road to the southeast of the Parramatta Road ventilation station. In the 2023-DM scenario, the traffic to and from the M4 East tunnel would access the tunnel using these roads. In the with-project scenarios, the M4-M5 Link tunnel connects to the M4 East tunnel, thus relieving these roads. There are reductions in traffic on City West Link and Parramatta Road of between 19 and 27 per cent.
A substantial reduction in surface traffic and consequent reduction in NO2 concentration is predicted along the Victoria Road corridor south of Iron Cove at Rozelle. This is due to traffic being diverted through the Iron Cove Link tunnels. For example, the average traffic volume on Victoria Road would decrease from around 76,000 vehicles per day without the project in 2033 to around 29,000 vehicles per day with the project in 2033 which is a reduction of around 60 per cent. On the other hand, there would be around a six percent increase in traffic to the north of the Iron Cove Link in 2023 with the project and seven per cent in 2033 with the project. An increase of around 13 per cent is expected in both the 2023 and 2033 cumulative scenarios.
There would also be reductions in concentrations along General Holmes Drive, the Princes Highway and the M5 East Motorway. NO2 concentrations are predicted to increase along Canal Road, which would be used to access St Peters interchange, and other roads associated with the proposed future Sydney Gateway project.
Results for RWR receptors
The maximum one hour mean NO2 concentrations at the RWR receptors in the with-project contributions and cumulative scenarios are shown, with a ranking by total concentration, in Figure 9-36. There were some predicted exceedances of the NSW one hour NO2 criterion (246 µg/m3), both with and without the project.
In the 2023-DM (without the project) scenario the maximum concentration exceeded the NSW criterion at around 5,700 receptors (6.6 per cent of all receptors), but with the introduction of the project in the 2023-DS scenario, this decreased to around 3,700 receptors (4.4 per cent). In the 2023-DSC scenario, the number decreased further (3,200 receptors, 3.8 per cent). In the 2033-DM scenario, there were exceedances at around 1,100 receptors (1.3 per cent), decreasing to 880 receptors (one per cent) in the 2033-DS scenario. In the 2033-DSC scenario, the number decreased to around 660 receptors (less than one per cent).
Although the ventilation outlet contributions to NO2 could not be separated from surface contributions, the maximum contribution of tunnel outlets to NOX at any receptor in the with-project scenarios was 57 µg/m3 in 2023-DSC. This would equate to a very small NO2 contribution relative to the air quality assessment criterion.
No exceedances of the NSW NO2 criterion have been measured at ambient air quality monitoring stations in Sydney in recent years, and to some extent the predicted exceedances may be a result of the conservatism in some of the modelling assumptions, and the tendency of the modelling process to overestimate maximum NO2 concentrations (see Figure J-6 in Annexure J of Appendix I (Technical working paper: Air quality)). The extent of the overestimation may also be high in 2023 and 2033 given the assumption of a higher NO2/NOX ratio in future years.
The changes in the maximum one hour mean NO2 concentration at the RWR receptors in the withproject scenarios are shown and ranked by change in concentration as a result of the project, in Figure 9-36. Increases in the maximum one hour NO2 concentration of between 26 per cent and 33 per cent of receptors were predicted, depending on the scenario. Conversely, there was a reduction in the maximum concentration between around 67 per cent and 74 per cent of receptors.
At the majority of receptors the change was relatively small. At around 93 per cent of receptors in 2023, the change in concentration (either an increase or a decrease) was less than 20 µg/m3. Some of the changes at receptors were much larger and unrealistically high (up to 234 µg/m3). An explanation of these high concentrations is provided in section 9.7.4.
Contour plots – all sources (background, surface roads and ventilation outlets)
Contour plots of change in maximum one hour NO2 concentrations in the 2023-DS and 2033-DS scenarios are provided in Figure 9-37 and Figure 9-38.
It is important to note that these plots do not represent a particular time period; each point in the plot is a maximum value for any hour of the year. The locations with the highest concentrations and largest changes in concentration are similar to this for annual mean NO2 (refer to Appendix I Technical working – Air Quality).
Results for community receptors
The annual mean PM10 concentrations community receptors are shown in Figure 9-39. These were all below the NSW impact assessment criterion of 25 µg/m3. At all but one of the receptors the concentration was below 20 µg/m3; receptor CR10 (University of Notre Dame, Broadway) had concentrations that were slightly above 20 µg/m3. PM10 concentrations at these receptors – several of which are near busy roads in Sydney – were only slightly above the lowest PM10 standards in force in other countries (18 µg/m3
in Scotland). Figure 9-39 Annual mean PM10 concentration at community receptors (with-project (DS) and cumulative (DSC) scenarios) Figure 9-40 shows the changes in PM10 concentration. The largest increase was around 0.8 µg/m3 (three per cent of the criterion) at receptor CR38 (Active Kids, Mascot), and the largest decrease slightly more than 1.0 µg/m3. Concentrations decreased at most of the receptors. There is a high
background and surface road contribution at receptor CR38.
Results for RWR receptors
The ranked annual mean PM10 concentrations at the RWR receptors are shown in Figure 9-42. The concentration at the majority of receptors was below 20 µg/m3, with only a very small proportion of receptors having a concentration just above the NSW assessment criterion of 25 µg/m3. The highest predicted concentration at any receptor in a with-project scenario was 26.5 µg/m3. The surface road contribution was between 0.05 µg/m3 and 9.8 µg/m3, with an average of 1.1–1.2 µg/m3. The largest contribution from tunnel ventilation outlets was 0.37 µg/m3 in the 2023-DSC scenario.
The changes in the annual mean PM10 concentration at the RWR receptors are shown, ranked by change in concentration, in Figure 9-42. There was an increase in concentration at 32 to 36 per cent of the receptors, depending on the scenario. At the majority of receptors the change was relatively small, and where there was an increase, this was greater than 2.5 µg/m3 at only a single receptor in the 2023-DSC and 2033-DSC scenarios.
Results for community receptors
Figure 9-45 presents the maximum 24 hour mean PM10 concentrations at the community receptors. At all locations, and in all scenarios, the concentration was close to the NSW impact assessment criterion of 50 µg/m3, which is also the most stringent standard internationally. The number of community receptors with an exceedance of the criterion decreased from 16 in the 2023-DM scenario to 11 in the 2023-DS scenario and 12 in the 2023-DSC scenario. In 2033, the number of receptors exceeding the criterion decreased from 14 in the 2033-DM scenario to 12 in the 2033-DS scenario, but increased to 17 in the 2033-DSC scenario. However, it should be noted that the community receptors only formed a very small subset of all the receptors, in the GRAL domain.
Figure 9-46 shows the changes in concentration in the Do Something and Cumulative scenarios relative to the Do Minimum scenarios for the community receptors. At most receptors, the change was less than two µg/m3, and at all receptors it was less than four µg/m3. There was no pattern in thechanges by year or by scenario.
Figure 9-47 demonstrates that the surface road contribution to the maximum 24 hour PM10 concentration at each receptor was small (generally less than around five µg/m3). The exception to this was receptor CR10, which had a road contribution of 15.1 to 21 µg/m3. This receptor (University of Notre Dame at Broadway) is a unique case as a result of a particularly low background combined with a large traffic contribution on the date that the synthetic background profiles were developed as discussed in Appendix I (Technical working paper: Air quality). At all community receptors except CR10, the maximum total 24 hour concentration occurred on one day of the year (1 July), and
coincided with the highest 24 hour background concentration in the synthetic PM10 profile (46.2 µg/m3).
The tunnel ventilation outlet contribution at the community receptors was negligible, being less than 0.4 µg/m3 in all cases.
Results for RWR receptors
The results for the RWR receptors were highly dependent on the assumption for the background concentration. Because this was assumed to be the maximum concentration in the synthetic background profile (ie 46.2 µg/m3), the total concentration at the majority of receptors in the withproject scenarios (77 to 80 per cent) was above the NSW impact assessment criterion of 50 µg/m3.
The proportion of receptors with a concentration above the criterion decreased slightly as a result of the project, such as from 82 per cent in the 2023-DM scenario to 78 per cent in the 2023-DS scenario. The contributions of surface roads and ventilation outlets were not additive. The maximum contribution of tunnel ventilation outlets at any receptor in a scenario was between 1.2 µg/m3 to 1.9 µg/m3 , depending on the scenario.
The changes in the maximum 24 hour mean PM10 concentration with the project are ranked by change in concentration in Figure 9-48. There was an increase in concentration at between 37 and 39 per cent of the receptors, depending on the scenario. The largest predicted increase in concentration at any receptor as a result of the project was 13.3 µg/m3, and the largest predicted decrease was 11.8 µg/m3. Where there was an increase, this was greater than five µg/m3 (10 per cent of the criterion) at just 0.1 per cent of receptors.
Contour plots – all sources
The contour plots for maximum 24 hour average PM10 in the 2033-DM and 2033-DSC scenarios are given in Figure 9-49 and Figure 9-50. The changes in maximum 24 hour PM10 are shown in Figure 9-51.
Results for community receptors
Figure 9-51 presents the annual mean PM2.5 concentrations at the community receptors. The results are based on an assumed background concentration of eight µg/m3
(the AAQNEPM standard), and therefore the Figure shows exceedances at all receptors. Clearly, there would also be exceedances of the NSW target of seven µg/m3. Internationally, there are no standards lower than eight µg/m3 for annual mean PM2.5. The next lowest is 12 µg/m3 (California and Scotland). Any increases with the
project were generally less than 0.2 µg/m3; the largest increase (0.56 µg/m3t receptor CR38, in the 2033-DS scenario) equated to seven per cent of the air quality criterion.
Figure 9-52 shows that concentrations were again dominated by the background contribution. The surface road contribution was between 0.5 µg/m3
and 2.7 µg/m3. The largest contribution from tunnel ventilation outlets at any receptor was just 0.14 µg/m3
Results for RWR receptors
The ranked annual mean PM2.5 concentrations at the RWR receptors in the with-project scenarios, are shown in Figure 9-52, including the contributions of surface roads and ventilation outlets. As the background concentration was taken to be the same as the NSW criterion of eight µg/m3, the total concentration at all receptors was above this value. The highest concentration at any receptor was 14.2 µg/m3 but, as with other pollutants and metrics, high values were only predicted for a small proportion of receptors and are unlikely to reflect real-world exposure situations. In the with-project
scenarios, the largest surface road contribution at any receptor was 5.4 µg/m3. The largest contribution from tunnel ventilation outlets in these scenarios was 0.17 µg/m3.
The change in the annual mean PM2.5 concentration at the RWR receptors in the with-project scenarios, are ranked in Figure 9-53. There was an increase in concentration at between 29 per cent and 37 per cent of the receptors, depending on the scenario. The largest predicted increase in concentration at any receptor as a result of the project was 2.3 µg/m3, and the largest predicted decrease was also 2.3 µg/m3. Where there was an increase, this was greater than 0.1 µg/m3 at around 2–3 per cent of receptors.
The increase in annual mean PM2.5 at sensitive receptors with the project (∆PM2.5) is a key metric for assessing the risk to human health. For the M4-M5 Link project, the acceptable value of ∆PM2.5 was determined to be 1.8µg/m3. Only one receptor (RWR-46456) had a predicted change in PM2.5 above this value. However, this receptor is a commercial/industrial building that is very close to the indicative alignment of the proposed future Sydney Gateway, and would not represent a real-world exposure
situation in the future. Given the proximity of these areas to Sydney Airport (runways and flight paths) it is considered unlikely that they would be rezoned for residential use and the increases in PM2.5 are principally related to the Sydney Gateway project. Emissions to air related to the Sydney Gateway project have been estimated on the basis of provisional information in relation to roadway layout only. The maximum impacts predicted are on roadways/locations that may be within the future roadway
alignments. The Sydney Gateway project would be subject to separate environmental assessment and approval, in which more detailed assessment of impacts in this area would be undertaken.
Contour plots – all sources
The contour plots for absolute annual mean PM2.5 are given in Figure 9-54 (2033-DM) and Figure 9-55 (2033-DSC). The contour plot for the change in concentration associated with the project is shown in Figure 9-55.
Results for community receptors
The maximum 24 hour mean PM2.5 concentrations at the community receptors with the project are presented in Figure 9-56. At all receptor locations, the maximum concentration was above the NSW impact assessment criterion of 25 µg/m3, although exceedances were already predicted without the project. Internationally, there are no standards lower than 25 µg/m3 for 24 hour PM2.5, however, the AAQNEPM includes a long-term goal of 20 µg/m3
Figure 9-57 presents the changes in maximum 24 hour PM2.5 with the project at the community receptors. At the majority of receptors, there was a decrease in annual mean PM2.5. Most of the increases with the project were less than 0.2 µg/m3
. The largest increase (2.9 µg/m3 at receptor CR40, in the 2033-DSC scenario) equated to 11 per cent of the air quality criterion.
Figure 9-57 Change in maximum 24 hour PM2.5 concentration at community receptors (DS and DSC scenarios), relative to corresponding DM scenarios
The combined road and ventilation outlet contributions to the maximum 24 hour PM2.5 concentration at the community receptors were relatively small, as shown in The tunnel ventilation outlet contributions alone were negligible in all cases (<0.15 µg/m3).
Figure 9-58 shows that the concentrations were again dominated by the background contribution. The surface road contribution was between 0.5 µg/m3 and 2.7 µg/m3. The largest contribution from tunnel ventilation outlets at any receptor was 0.14 µg/m3.
Results for RWR receptors
The ranked maximum 24 hour mean PM2.5 concentrations at the RWR receptors in the with-project scenarios are shown in Figure 9-59. The concentration at all receptors was above the NSW impact assessment criterion of 25 µg/m3. As with PM10, the contributions of surface roads and ventilation outlets are not shown separately as these were not additive. The maximum contribution of tunnel outlets at any receptor with the project was 1.2 µg/m3
The changes in the maximum 24 hour mean PM2.5 concentration at the RWR receptors in the withproject scenarios are ranked in Figure 9-59. There was an increase in concentration at between 36 per cent and 39 per cent of the receptors, depending on the scenario. The largest predicted increase in concentration at any receptor as a result of the project was 8.7 µg/m3 2023-DSC scenario), and the largest predicted decrease was 8.2 µg/m3. or most of the receptors the change in concentration was small; where there was an increase in concentration, this was greater than 2.5 µg/m3 at only 0.2 to 0.3 per cent of receptors.
Contour plots – all sources
The contour plots for maximum 24 hour PM2.5 in the 2023-DS and 2033-DS scenarios are given in Figure 9-60 and Figure 9-61 respectively.
Four air toxics – benzene, PAHs (as BaP), formaldehyde and 1,3-butadiene – were assessed. These compounds were taken to be representative of the much wider range of air toxics associated with motor vehicles, and they have commonly been used for assessment of road projects.
The changes in the maximum one hour benzene concentration at the community receptors as a result of the project are shown in Figure 9-62, where they are compared with the NSW impact assessment criterion from the NSW EPA Approved Methods. These changes took into account emissions from both surface roads and tunnel ventilation outlets. It can be seen from the Figure that there where there was an increase in the concentration, this was well below the assessment criterion. The changes in the maximum one hour BaP, formaldehyde and 1,3-butadiene concentration are
presented in Figure 9-63, Figure 9-64 and Figure 9-65 respectively. For each compound, where there was an increase in the concentration, this was well below the NSW impact assessment criterion. The largest increases for the community receptors were also representative of the largest increases for the RWR receptors.
9.7.4 Reasons for unrealistically high ground level concentrations at some RWR receptor locations
The predicted maximum one-hour NO2 concentrations were very high at a small number of RWR locations. These elevated levels are not considered to be representative of exposure concentrations that would occur within the study area. This is due to the combined effect of the approach adopted for converting NOx to NO2 (that overestimates short-term one-hour average concentrations), and the use of a contemporaneous assessment of background and project impacts. The contemporaneous approach assumes that the highest background concentrations may occur during the same hour as the maximum incremental change from the project. This results in a very high estimate of total NO2 concentrations that is not expected to occur (refer to Appendix I (Technical working paper: Air quality) for more detailed discussion).
9.7.5 Results for expected traffic scenarios (elevated receptors)
Annual mean PM2.5
Figure 9-66 and Figure 9-67 present contour plots for the changes in annual mean PM2.5
concentration in the 2033-DSC scenario, and for receptor heights of 10 metres and 30 metres respectively. These plots can be compared with the changes in ground level annual mean concentration for the same scenario. It should be noted that, for the 10 metre and 30 metre outputs, it was not necessarily the case that there were existing buildings at these heights at the receptor locations.
The reduced influence of surface roads at a receptor height of 10 metres compared with ground level can be seen in Figure 9-66. However, because the influence of surface roads in the Do Minimum case at 10 metres was also reduced, the distributions of changes in annual average PM2.5 concentration at 10 metres and ground level were quite similar. For example, where there was an increase in annual mean PM2.5 at the height of 10 metres, this was greater than 0.1 µg/m3 for 2.9 per cent of receptors (compared with 3.2 per cent at ground level). However, the largest changes in concentration at 10 metres were smaller than those at ground level. The largest increase at the height of 10 metres for the RWR locations was 0.79 µg/m3, which can be compared with the maximum
increase for any ground level receptor in the 2033-DSC scenario of 2.3 µg/m3
Figure 9-67 show that the situation was quite different at a height of 30 metres. At this height the changes in annual mean PM2.5 associated with surface roads are negligible at all locations, with the small increases closer to the ventilation outlets. The increase in PM2.5 was greater than 1.8 µg/m3 at a height of 30 metres at just one industrial location. However, the height of the existing building is 8.3 metres. The largest increases for residential locations at a height of 30 metres is between 1.41 and 1.43 µg/m3
for a small group of locations close to the location of the M4-M5 Link ventilation facility
at Campbell Road, St Peters. However, the height of the existing buildings at these locations is less than five metres. The results show that there would not be any significant impact on existing buildings however consideration would need to be given to detailed assessment of any future high rise buildings planned for these locations.
Maximum 24 hour PM2.5 Figure 9-68 and Figure 9-69 present the contour plots showing the changes in maximum 24 hour PM2.5 concentration in the 2033-DSC scenario at receptor heights of 10 metres and 30 metres respectively. There are no existing buildings greater than 10 metres in height at the RWR receptor locations.
At a height of 10 metres, the maximum changes in concentration were slightly lower than at ground level but, as with the annual mean, the distributions of changes were quite similar. The largest increase in 24 hour PM2.5 at the height of 10 metres for the RWR receptors was 6 µg/m3 , which can be compared with the maximum increase for any ground-level RWR receptor in the 2033-DSC scenario of 7.7 µg/m3. Where there was an increase in PM2.5 at the height of 10 metres, this was greater than 2.5 µg/m3 (10 per cent of the assessment criterion) for 0.1 per cent of receptors locations (compared
with 0.2 per cent at ground level).
At the height of 30 metres the largest increases in the maximum 24 hour PM2.5 concentrations were again in the vicinity of the ventilation outlets, and these largest increases were greater than those at 10 metres and ground level. Again, there was a large increase of 36.6 μg/m3 at one industrial location. There was predicted to be an increase in maximum 24 hour PM2.5 of more than 2.5 μg/m3 (10 per cent\ of the assessment criterion) at 86 (0.1 per cent) receptors. Of these, 67 were at residential locations, and of these 67, the ones with the largest increases were close to the location of the M4-M5 Link ventilation facility at St Peters. Again, the actual height of buildings at these locations was less than 10 metres so no actual exposures would occur at a height of 30 metres.
The implications of the results for elevated receptors can be summarised as follows:
- For all receptor locations, the changes in PM2.5 concentration at 10 metres are acceptable
- Future developments to the height of 10 metres should be possible at all locations in the study area. This assumes that the changes in PM2.5 concentration for heights between ground level and 10 metres are also acceptable. This is a reasonable assumption because the influence of surface roads diminishes by 10 metres, so that the largest changes at 10 metres were smaller than the changes at ground level
- The predictions do not indicate the need for any restrictions on future developments to 30 metres height, except in the immediate vicinity of ventilation outlets, in particular at St Peters:
– The ventilation outlets were predicted not to result in adverse air quality impacts at any existing receptors as there are no existing buildings 30 metres or higher located close to the proposed ventilation facilities at St Peters
- Planning controls should be developed in the vicinity of St Peters to ensure future
developments at heights 30 metres or higher are not adversely impacted by the ventilation outlets. Development of planning controls would need to be supported by detailed modelling addressing all relevant pollutants and averaging periods.
9.7.6 Results for regulatory worst case scenarios
The following sections highlight the results of these scenarios for the receptors with the largest impacts. As noted in the methodology, a more detailed approach was required for NO2 than for the other pollutants. The objective of these scenarios was to demonstrate that compliance with the concentration limits for the tunnel ventilation outlets would deliver acceptable ambient air quality. The scenarios assessed emissions from the ventilation outlets only, with concentrations fixed at the limits. This represented the theoretical maximum changes in air quality for all potential traffic operations in
the tunnel, including unconstrained and worst case traffic conditions from an emissions perspective, as well as vehicle breakdown situations.
Further detail of the regulatory worst case scenarios is in Appendix I (Technical working paper- Air Quality). The analysis was undertaken to assist regulatory authorities in assessing and determining potential ventilation outlet concentration limits that could be applied to the ventilation outlets through conditions of approval. Assuming that concentration limits are applied to the ventilation outlets, the results of the analysis would demonstrate the air quality performance of the project if it operates continuously at the limits. In reality, ventilation outlet concentrations would only occasionally approach the concentration limits under heavy traffic or incident conditions. Ventilation and traffic management would be used to avoid reaching concentration limits to avoid exceeding the limits. Experience in operating tunnels in Sydney shows that normal tunnel operations including congested traffic cases, are well below outlet limits.
CO and PM
The results for CO, PM10 and PM2.5 in the regulatory worst case scenario (RWC-2033-DSC only) are given in Table 9-27. The table shows the maximum contribution of tunnel ventilation outlets at any of the RWR receptors in this scenario, as well as the maximum contribution at any residential receptor. For most of the pollutant metrics, the results were the same in both cases.
Table 9-27 Results of regulatory worst case assessment (RWR receptors) – CO and PM
The concentrations in the regulatory worst case scenario were higher than those for the expectedtraffic scenarios in all cases, and the following points are noted for the former:
- The maximum one hour CO concentration was negligible, especially taking into account the fact that CO concentrations are well below the NSW impact assessment criterion. For example, the maximum one hour outlet contribution in the regulatory worst case scenario (0.50 mg/m3) was a very small fraction of the criterion (30 mg/m3). The maximum background one hour CO concentration (3.27 mg/m3) was also well below the criterion. Exceedances of the criterion are therefore highly unlikely
- For PM10 the maximum contributions of the ventilation outlets are predicted to be small. For both the annual mean and maximum 24 hour metrics the outlet contributions were less than 10 per cent of the respective criteria
- The ventilation outlet contribution would be most important for PM2.5, with the maximum contributions equating to 13 per cent and 18 per cent of the annual mean and 24 hour criteria respectively. Again, any exceedances of the criteria would be dominated by background mconcentrations.
NOX and NO2
The results of the more detailed assessment for NO2 at the M4-M5 Link ventilation facilities are shown in Appendix I (Technical working paper: Air quality). The criterion was not exceeded in any of the project scenarios.
Total hydrocarbons and air toxics
The maximum outlet concentrations for the four specific air toxics considered in the regulatory worstcase assessment (scenario RWC-2033-DSC only) were determined using the THC predictions in conjunction with the speciation profiles stated in Appendix I (Technical working paper: Air quality). The results are given in Table 9-28. The Table shows the maximum contribution of tunnel ventilation outlets at any of the RWR receptors in this scenario (for most of the pollutant metrics these were residential receptors). The outlet contributions to the specific air toxics are well below the impact
assessment criteria in the NSW EPA Approved Methods.
Table 9-28 Results of regulatory worst case assessment (RWR receptors) – air toxics (ventilation outlets only)
Table 9-29 shows that, even if the maximum outlet contribution is added to the maximum increase in concentration with the project (which implies some double counting), the results are still well below the impact assessment criteria.
9.7.7 Sensitivity tests
In the EISs for the M4 East and New M5 projects, several sensitivity tests were conducted for variousmodel inputs (Pacific Environment 2015). These included:
- The influence of ventilation outlet temperature
- The influence of ventilation outlet height
- The inclusion of buildings near tunnel ventilation outlets.
These tests were based upon a sub-area of the M4 East and New M5 GRAL domains of about two to three kilometres around the project ventilation outlets. Only the ventilation outlet contribution, and annual mean PM2.5 and maximum 24 hour PM2.5, were included in the tests. A sub-set of sensitive receptors was evaluated. The predicted concentrations were indicative, as the aim of the sensitivity tests was to assess the proportional sensitivity of the model to specific input parameters.
As the parameters for the tests from both the M4 East and New M5 projects were very similar to that for M4-M5 Link, the outcomes from those projects would also apply to the M4-M5 Link project.
The following sections present a summary of the tests.
Ventilation outlet temperature
The ventilation outlet temperatures for the M4 East and New M5 projects were around 25ºC. For this test, the effects of using outlet temperatures 10˚C below, and above, this value were modelled.
The results of the tests showed that the predicted concentrations for the ventilation outlets were higher for the lower temperature (by a factor of, on average, around 1.5). The predicted concentrations for both projects remained well below the standards for PM2.5, and made up a very small proportion of the total combined results (for surface roads and ventilation outlets). Even with a significant change in ventilation outlet temperature, the total predicted concentration (roads and ventilation outlets) is unlikely to be significantly affected.
Ventilation outlet height
The height of the ventilation outlets for the M4 East and New M5 projects was around 30 metres. For this test, the effects of using outlet heights 10 metres below and above this value were modelled. The nresults for both projects were similar to those for the temperature sensitivity tests, with the lower outlet resulting in concentrations that were around 1.3 times greater, on average, than the higher outlet. Again, ventilation outlet height is unlikely to represent a large source of uncertainty in the overallpredictions.
The sensitivity of the inclusion of buildings to predicted concentrations was assessed in both the M4 East and New M5 projects. Modelling of the ventilation outlet was undertaken using inclusion and exclusion scenarios of the closest buildings.
The results showed that, when buildings were included, there was an average increase in
concentrations associated with the ventilation outlet by a factor of about 1.3 to 1.5. Whilst these tests were not comprehensive, they indicated that the inclusion or exclusion of buildings is unlikely to represent a large source of uncertainty in the overall predictions. The total predicted concentrations, and the conclusions of the assessment, would not change significantly with the inclusion of buildings.
9.8 Regional air quality
The changes in the total emissions resulting from the project are shown in Figure 9-70, Table 9-30 and Table 9-31.
These changes can be viewed as a proxy for the project’s regional air quality impacts which, on the basis of the results, are likely to be negligible. For example:
- The increases in NOX emissions for the assessed road network in a given year ranged from 71 to 174 tonnes per year. These values equate to a very small proportion (around 0.3 per cent) of anthropogenic NOX emissions in the Sydney airshed in 2016 (around 53,700 tonnes)
- The increases in NOx in a given year are much smaller than the projected reductions in emissions between 2015 and 2033 (around 2,340 tonnes per year).
The regional air quality impacts of a project can also be described in terms of its capacity to influence ozone production. NSW EPA has developed a Tiered Procedure for Estimating Ground Level Ozone Impacts from Stationary Sources (ENVIRON 2011). Although this procedure does not relate specifically to road projects, it was applied here to give an indication of the likely significance of the project’s effect on ozone concentrations in the broader Sydney region.
The first step in the procedure involved the classification of the region within which the project is to be located as either an ozone ‘attainment’ or ‘non-attainment’ area, based on measurements from OEH monitoring stations over the past five years and criteria specified in the procedure. Following this approach, the project was identified as being in an ozone non-attainment area.
The second step involved the evaluation of the change in emissions due to the project against thresholds for NOX and VOCs. For both attainment and non-attainment areas the procedure gives an emission threshold for NOX and VOCs (separately) of 90 tonnes per year for new sources, above which a detailed modelling assessment for ozone may be required. Some lower thresholds are also specified for modified sources and for the scale of ozone non-attainment.The results in Table 9-32 show that for the 2023-DSC and 2033-DSC scenarios, the increases in
NOX emissions with the project (127 and 174 tonnes per year respectively) were above the 90 tonnes per year threshold. In such cases, the procedure specifies that a ‘Level 1’ assessment is to be undertaken using a screening tool provided by the NSW EPA9. The tool estimates the increases in one hour and four hour ground level ozone concentrations, based on an input of emissions of CO, NOx and VOC (THC) in tonnes per day. For sources located within ozone non-attainment areas, the incremental increases in ozone concentration predicted by the tool are compared against a screening
impact level (SIL) of 0.5 ppb, and against a maximum allowable increment of one ppb. In cases where the maximum ozone increment is below the SIL and/or below the relevant maximum allowable increment, further ozone impact assessment is not required, but a best management practice (BMP) determination should be undertaken for the source. The results from the tool, shown in Appendix I (Technical working paper: Air quality) show that the project increment is below the SIL.
Overall, it is concluded that the regional impacts of the project would be negligible, and undetectable in ambient air quality measurements at background locations.
For each of the RWR receptors, the change in the maximum one hour THC concentration as a result of the project was calculated. The largest change in the maximum one hour THC concentration across all receptors was then determined, and this was converted into an equivalent change for three of the odorous pollutants identified in the NSW EPA Approved Methods (toluene, xylenes, and acetaldehyde). These pollutants were taken to be representative of other odorous pollutants from motor vehicles.
The changes in the levels of three odorous pollutants as a result of the project, and the corresponding odour assessment criteria from the NSW EPA Approved Methods, are given in Table 9-33.
Table 9-33 Comparison of changes in odorous pollutant concentrations with criteria in NSW EPA Approved Methods (RWR receptors)
The change in the maximum one hour concentration of each pollutant was well below the corresponding odour assessment criterion in the NSW EPA Approved Methods.
The SEARs for the project require details of, and justification for, the air quality management measures that have been considered. This section of the report firstly reviews the measures that are available for improving tunnel-related air quality, and then describes their potential application in the context of the project. The measures have been categorised as follows:
- Tunnel design
- Ventilation design and control
- Air treatment systems
- Emission controls and other measures.
9.10 Environmental management measures
9.10.1 Construction impacts
Mitigation and management measures for potential ambient air quality impacts during construction are shown in Table 9-34. Most of these measures are routinely employed as ‘standard practice’ on construction sites.
It is acknowledged there is potential for crystalline silica emissions to occur during tunnel excavation due to the high temperatures caused at the excavation face. The potential for crystalline silica to be released is primarily relevant to occupational exposure, and would be managed in accordance with relevant NSW and Australian guidelines. The controls would effectively eliminate its discharge into the atmosphere. Safe work method statements would be developed as part of the project safety
management system. In relation to non-occupational exposures the World Health Organization (WHO 2000a) states ‘there are no known adverse health effects associated with the non-occupational exposures to quartz’ (where quartz is crystalline silica).
A Construction Air Quality Management Plan (CAQMP) will be produced (as a sub-plan to the Construction Environmental Management Plan) to address the construction impacts of the M4-M5 Link project. The CAQMP will contain details of the site-specific mitigation measures to be applied. Additional guidance on the control of dust at construction sites in NSW is provided as part of the NSW EPA Local Government Air Quality Toolkit10. Detailed guidance is also available from the United Kingdom (GLA 2006) and the United States of America (Countess Environmental 2006). Dust control procedures will be included as part of the CAQMP.
Table 9-34 Mitigation for all sites: communication
Mitigation measure All scenarios 1 – 7
1 Communication, notification and complaints handling requirements regarding air quality matters will be managed through the Community Communication Strategy (CCS).
Table 9-35 Mitigation for all sites: dust management
2 A Construction Air Quality Management Plan will be developed and implemented to monitor and manage potential air quality impacts associated with the construction for the project. The Plan will be mimplemented for the duration of construction.
3 Regular communication to be carried out with sites in close proximity to ensure that measures are in place to manage cumulative dust impacts.
4 Regular site inspections will be conducted to monitor for potential dust issues. The site inspection, and issues arising, will be recorded.
Preparing and maintaining the site
5 Construction activities with the potential to generate dust will be modified or ceased during unfavourable weather conditions to reduce the potential for dust generation.
6 Measures to reduce potential dust generation, such as the use of water carts, sprinklers, dust screens and surface treatments, will be implemented within project sites as required.
7 Unsealed access roads within project sites will be maintained and managed to reduce dust generation.
8 Where reasonable and feasible, appropriate control methods will be implemented to minimise dust emissions from the project site.
9 Storage of materials that have the potential to result in dust generation will be minimised within project sites at all times.
Operating vehicle/machinery and sustainable travel
10 All construction vehicles and plant will be inspected regularly and maintained to ensure that they comply with relevant emission standards.
11 Engine idling will be minimised when plant is stationary, and plant will be switched off when not in use to reduce emissions.
12 The use of mains electricity will be favoured over diesel or petrolpowered generators where practicable to reduce site emissions.
13 Haul roads will be treated with water carts and monitored during earthworks operations, ceasing works if necessary during high winds where dust controls are not effective.
14 Suitable dust suppression and/or collection techniques will be used during cutting, grinding or sawing activities likely to generate dust in close proximity to sensitive receivers.
15 The potential for dust generation will be considered during the handling of loose materials. Equipment will be selected and handling protocols developed to minimise the potential for dust generation.
16 All vehicles loads will be covered to prevent escape of loose materials during transport.
Table 9-36 Mitigation specific to demolition
Mitigation measure Scenario
17 Demolition activities will be planned and carried out to minimise the potential for dust generation.
18 Adequate dust suppression will be applied during all demolition works required to facilitate the project.
Desirable Highly recommended
19 All potentially hazardous material will be identified and removed from buildings in an appropriate manner prior to the commencement of demolition.
Desirable Highly recommended
Table 9-37 Mitigation specific to earthworks
Mitigation measure Scenario
20 Areas of soil exposed during construction will be minimised at all times to reduce the potential for dust generation.
Desirable Highly recommended
21 Exposed soils will be temporarily stabilised during weather conditions conducive to
dust generation and prior to extended periods of inactivity to prevent dust generation.
Desirable Highly recommended
22 Exposed soils will be permanently stabilised as soon as practicable following disturbance to minimise the potential for ongoing dust generation.
Desirable Highly recommended
Table 9-38 Mitigation specific to construction
Mitigation measure Scenario 1- 7
23 Ensure sand and other aggregates are stored in bunded areas and are not allowed to dry out, nunless this is required for a particular process, in which case ensure that appropriate additional control measures are in place.
24 Ensure fine materials are stored and handled to minimise dust.
Desirable Highly recommended
Table 9-39 Mitigation specific to track-out of loose material onto roads
Mitigation measure All scenarios 1 – 7
25 Deposits of loose materials will be regularly removed from sealed
surfaces within and adjacent to project sites to reduce dust generation.
26 During establishment of project ancillary facilities, controls such as wheel washing systems and rumble grids will be installed at site exits to prevent deposition of loose material on sealed surfaces outside project sites to reduce potential dust generation.
9.10.2 Operational impacts
The SEARs for the project require details of, and justification for, the air quality management measures that were considered for the project. This section reviews the environmental management measures that are available for improving tunnel-related air quality, and then describes their potential application in the context of the project. The measures are categorised as follows:
- Tunnel design
- Ventilation design and control
- Air treatment systems
- Emission controls and other measures.
Tunnel infrastructure is designed in such a way that the generation of pollutant emissions by the traffic using the tunnel is minimised. The main considerations are minimising gradients and ensuring that lane capacity remains constant or increases from entry to exit point. Traffic management can also be used to improve traffic flows, which results in reduced overall emissions.
Ventilation design and control
There are several reasons why a tunnel needs to be ventilated. The main reasons are:
- Control of the internal environment. It must be safe and comfortable to drive through the tunnel. Vehicle emissions must be sufficiently diluted so as not to be hazardous during normal operation, or when traffic is moving slowly or stationary
- Protection of the external environment. Ventilation, and the dispersion of pollutants, is the most widely used method for minimising the impacts of tunnels on ambient air quality. Collecting emissions and venting them via elevated ventilation outlets is a very efficient way of dispersing pollutants. Studies show that the process of removing surface traffic from heavily trafficked roads and releasing the same amount of pollution from an elevated location results in substantially lower concentrations at sensitive receptors (PIARC 2008)
- Emergency situations. When a fire occurs in a tunnel, the ventilation system is able to control the heat and smoke in the tunnel so as to permit safe evacuation of occupants, and to provide the emergency services with a safe route to deal with the fire and to rescue any trapped or injured persons.
The ventilation system design options that were considered for the project are discussed in Chapter 4 (Project development and alternatives) and the system adopted for the project is described in Chapter 5 (Project description).
Air treatment systems
There are several air treatment options for mitigating the effects of tunnel operation on both in-tunnel and ambient air quality. Where in-tunnel treatment technologies have been applied to road tunnels, these technologies have focused on the management and treatment of PM. The most common of these is the electrostatic precipitator (ESP), and this is discussed in detail in Appendix I (Technical working paper: Air quality). Information is provided on the method of operation, the international
experience with ESPs in tunnels, and the effectiveness of systems. Other techniques include filtering, mdenitrification and biofiltration, agglomeration and scrubbing. These are described in Appendix I (Technical working paper: Air quality).
Emission controls and other measures
Various operational measures are available to manage in-tunnel emissions and ambient air quality.
These include the following:
- Traffic management. Traffic management will be employed by tunnel operators to control exposure to vehicle-derived air pollution. Measures can include (PIARC 2008):
– Allowing only certain types of vehicle
– Regulating time of use
– Tolling (including differential tolling by vehicle type, emission standard, time of day,
– Reducing traffic throughput
– Lowering the allowed traffic speed
- Incident detection. Early detection of incidents and queues is essential to enable tunnel operators and the highway authority to put effective traffic management in place. Monitoring via CCTV cameras is normally a vital part of the procedure for minimising congestion within tunnels and allowing timely operator response to changes in traffic flow
- Public information and advice. Traffic lights, barriers, variable message signs, radio broadcasts, public address systems (used in emergencies) and other measures can help to provide driver information and hence influence driver behaviour in tunnels
- Cleaning the tunnel regularly assists in reducing concentrations of small particles (PIARC 2008), as is common practice in Sydney tunnels.
Detailed design of the In-tunnel monitoring system will be undertaken during future project development phases and will include the following:
- NOx, NO2, CO and visibility. Monitoring of each pollutant will be undertaken throughout the tunnel. The locations of monitoring equipment will generally be at the beginning and end of each ventilation section. This would include, for example, monitors at each entry ramp, exit ramp, merge point and ventilation exhaust and supply point. The location of monitors will be governed by the need to meet the in-tunnel air quality criteria for all possible journeys through the tunnel system, especially for NO2. This will require sufficient, appropriately placed monitors to calculate a journey average
- Velocity monitors will be placed in each tunnel ventilation section and at portal entry and exit points. The velocity monitors in combination with the air quality monitors will be used to modulate the ventilation within the tunnel to manage air quality and to ensure net air inflow at all tunnel portals.