Environmental Impact Statement (EIS) - 1994
The preferred option identified in the 1994 EIS included air intakes at the eastern and western portals of the tunnel and a single exhaust stack located in the car park of Earlwood Shopping Centre.
Impacts on air quality were predicted for motor vehicle emissions during operation and ventilation of the tunnel. A specialist report recommended measures to ameliorate these impacts which were incorporated in the RTA's commitments in relation to the EIS.
Supplement to EIS - 1996
In response to community submissions, the RTA examined alternatives to the route between Bexley Road and the Cooks River. A process of public consultation in relation to the alternative routes was undertaken. A more direct alternative route was identified and subsequently assessed in the 1996 Supplement to the EIS.
The alternative proposal included three tunnel exhaust stacks and three air intakes between Bexley Road and Marsh Street. The location of the stacks and intakes were identified through an assessment of engineering, air quality, land use, visual and community impacts.
A specialist's report found that the predicted increase in traffic associated with the modified proposal would result in slightly higher vehicle emissions on the motorway and hence higher roadside concentrations compared to those predicted in the 1994 EIS. However, for most pollutants, the overall emissions to surrounding areas would be reduced, due in part to the shorter travel distance of the alternative proposal. The air quality modelling of the exhaust stacks predicted ground level pollutant concentrations well within the goals set by the Environment Protection Authority.
Representations Report, 1997 - prepared by RTA
The Representations Report considered all submissions made in response to the 1994 EIS and the1996 Supplement to the EIS.
Air quality from the surface road and the exhaust stacks was a general concern and the most frequently raised issue in the representations made by private individuals, community and interest groups and government authorities.
The Representations Report concluded that the proposal should proceed with a number of amendments including:
- a single air exhaust stack and connecting tunnel constructed on RTA land within the Wolli Creek corridor to the north of Turella Railway Station.
- an additional air intake structure and connecting tunnel constructed within the Wolli Creek corridor, on the western side of Wolli Creek at Earlwood.
- an air intake structure located in Bardwell Valley Golf Course.
- the RTA to continue to investigate potential emission treatment systems.
Numerous alternatives were considered and the basic assumptions concerning levels of air emissions were reviewed.
As part of the Representations Report, the engineering feasibility of the construction of a single air exhaust stack was examined and the air quality impacts re-assessed. The Air Quality Impacts Report concluded that a stack height of 20 to 25 metres would ensure dispersion of air from the tunnel in accordance with the EPA's air quality goals.
Director-General's Report and Conditions of Approval - 1997
In November 1997 the Director-General of the Department of Urban Affairs and Planning, in accordance with the Environment Planning and Assessment Act, prepared a report reviewing the EIS.
The review commissioned an international assessment of tunnel ventilation and exhaust systems based on a literature review, worldwide surveys, and discussions with officials, leading practitioners and institutions in Japan, Norway and Austria.
The Director-General concluded that the potential environmental impacts associated with the project could be reduced and managed by adopting and strengthening various measures and safeguards as specified in the conditions of approval.
150 conditions of approval were issued and included requirements for the measurement and reporting of air quality, and the need to operate the tunnel and the stack to meet air quality limits (described in the conditions).
Since May 2004 the RTA has also been monitoring air quality outside the tunnel portals.
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