WAG objects to the impact the WestConnex project, including the New M5, on flooding impacts and hazard risks, and the failure of this EIS to properly investigate and report on these risks.

The analysis contained in the EIS fails to meet at least one of the SEARS, “Soil and Water - including but not limited to: Identification of potential impacts of the project on existing flood regimes, consistent with the Floodplain Development Manual (Department of Natural Resources, 2005), including impacts to existing receivers and infrastructure and the future development potential of affected land, demonstrating consideration of the changes to rainfall frequency and/or intensity as a result of climate change on the project. The assessment shall demonstrate due consideration of flood risks in the project design.” 

In general, the assessment of flooding and any necessary stormwater upgrades and improvements has not been addressed sufficiently within the EIS. Much of the EIS states that further detailed investigations will need to be undertaken during detailed design and construction planning. It is not acceptable that so much of this investigation has not taken place as part of the EIS itself, which would have given affected Councils and residents an opportunity to review, assess and comment on the risks identified. It is also not acceptable to leave these investigations to simply be summarised in a Submissions Report, as a condition of Planning approval, or once the project starts, when the community will have little to no ability to comment on or modify the proposed approach.

This is particularly concerning given areas of St Peters, such as the parts of Campbell St towards Unwins Bridge Rd, are already subject to flooding in heavy rains.

The key stormwater and flooding issues are as follows: 

●      The assessment of flooding and any necessary stormwater upgrades and improvements has not been addressed sufficiently within the EIS

●      There are unacceptable proposed increases in flooding to downstream properties

●      There are potential increases in stormwater volumes within the local council stormwater pit and pipe network.

In general, the assessment of flooding and any necessary stormwater upgrades and improvements has not been addressed sufficiently within the EIS. Much of the EIS states that further detailed investigations will need to be undertaken during detailed design and construction planning. 

Specific details of the location and possible upgrade/changes to stormwater structures have not been provided within the EIS. If there are to be direct connections to existing downstream stormwater system, then a detailed hydraulic assessment and understanding of the proposed performance of the system should have been provided as part of this EIS. Where the connection is likely to increase the impacts on the local stormwater system, details of how it would be upgraded to meet the increased demand from the project should also have been included.

With the substantial works being undertaken for the project, this will pose a significant impact on the existing drainage network within this area. This will also have an adverse affect on the road network and neighbouring properties.

Overland flow paths will alter and be diverted. This will also have an adverse affect on the road network and neighbouring properties.

Some existing pipe networks will no longer be functional. This will also have an adverse affect on the road network and neighbouring properties.

WAG formally and strongly objects to the potential flooding impacts that WestConnex, including the New M5, will cause if built, and to the EIS’s inadequate analysis of these risks. We ask the Minister for Planning to reject the WestConnex New M5 project.