Flooding is a possibility that flooding of the tunnels and stations could occur during construction if a significant flood or rainfall event occurs. Such flooding would have potentially serious implications for the health and safety of construction workers. This risk be reduced substantially by the adoption of the approach to flood immunity outlined in Section in the design of tunnel portals, station entrances and other critical infrastructure to provide appropriate protection for construction works and workers from the impacts of floodwaters and overland stormwater flows. This would be informed by a flood immunity risk assessment that considers a range of flood events, and to the requirements and satisfaction of the responsible authority and owner of the rail network. Areas identified as being potentially susceptible to major flood events are: Precinct 1 - Tunnels where the tunnels are prone to flooding from the Yarra – River entering the City Loop tunnel portal east of Flinders Street Station and then flowing into the Melbourne Metro tunnels through the cross-connection between the two at CBD North station Precinct 2 - Western portal where areas around the existing rail – embankment are in the Maribyrnong River floodplain Precinct 3 - Arden station where land around the station box would be – located in the Moonee Ponds Creek floodplain Precinct 6 - CBD South station where areas along Swanston and Flinders – Streets are prone to flooding from local stormwater runoff Precinct 7 - Domain station where the station box is proposed to extend – across an overland flow path Precinct 8 - Eastern portal where the areas around the proposed portal are – subject to flooding from the Yarra River. These potential impacts are discussed in greater detail under each precinct. Where required, design mitigation measures (such as flood gates) and emergency measures (such as flood warning systems and emergency evacuation procedures) would be developed and implemented to manage the impacts of large flood events. Disruption of Riverine and Drainage Temporary or permanent works undertaken for Melbourne Metro could obstruct riverine flood or overland drainage flows or result in a loss of flood storage. This could potentially increase flood levels or velocities, heightening the flood risk to infrastructure and property. However, these impacts can generally be avoided or mitigated.
Flooding is a possibility that flooding of the tunnels and stations could occur during construction if a significant flood or rainfall event occurs. Such flooding would have potentially serious implications for the health and safety of construction workers. This risk be reduced substantially by the adoption of the approach to flood immunity outlined in Section in the design of tunnel portals, station entrances and other critical infrastructure to provide appropriate protection for construction works and workers from the impacts of floodwaters and overland stormwater flows. This would be informed by a flood immunity risk assessment that considers a range of flood events, and to the requirements and satisfaction of the responsible authority and owner of the rail network. Areas identified as being potentially susceptible to major flood events are: Precinct 1 - Tunnels – where the tunnels are prone to flooding from the Yarra River entering the City Loop tunnel portal east of Flinders Street Station and then flowing into the Melbourne Metro tunnels through the cross-connection between the two at CBD North station Precinct 2 - Western portal – where areas around the existing rail embankment are in the Maribyrnong River floodplain Precinct 3 - Arden station – where land around the station box would be located in the Moonee Ponds Creek floodplain Precinct 6 - CBD South station – where areas along Swanston and Flinders Streets are prone to flooding from local stormwater runoff Precinct 7 - Domain station – where the station box is proposed to extend across an overland flow path Precinct 8 - Eastern portal – where the areas around the proposed portal are subject to flooding from the Yarra River. These potential impacts are discussed in greater detail under each precinct. Where required, design mitigation measures (such as flood gates) and emergency measures (such as flood warning systems and emergency evacuation procedures) would be developed and implemented to manage the impacts of large flood events. Disruption of Riverine and Drainage Temporary or permanent works undertaken for Melbourne Metro could obstruct riverine flood or overland drainage flows or result in a loss of flood storage. This could potentially increase flood levels or velocities, heightening the flood risk to infrastructure and property. However, these impacts can generally be avoided or mitigated.
MMRP_Chapter-17_Surface-Water.docx