The drainage system is designed to ensure the Melbourne Water’s downstream stormwater infrastructure’s capacity to take water is not exceeded.
In consultation with Melbourne Water, the proposal includes careful design of retarding basins and wetlands aimed at increasing the on-site storage capacity thereby reducing the likelihood of downstream flooding experienced by parts of Dingley Village over many years.
Currently, major storm events discharge 5.43m3 of water per second downstream from the site; and Melbourne Water flood mapping shows this affects approximately 70 proprieties downstream of the former golf course site. The proposal will reduce this discharge rate to less than 3.3m3 per second, which will provide improved protection to properties downstream of the site. Flood storage of approximately 62,000m3 will be provided, which is significantly more than the 11,800m3 required to address the increase in impervious area as part of the redevelopment.
To ensure this is done the development will include retarding basins and wetlands that will be landscaped to also serve as additional amenity for the community. The retention, expansion and creation of new wetlands on the site will support local biodiversity, creating new and enlarged habitats for waterbirds and other wildlife.
The Flood Management Strategy can be accessed from the Department of Environment, Land, Water and Planning website here. The report highlights that the Site meets the requirements of Melbourne Water for flood behaviours and limits outflows from the site. The Flood Management works are estimated to cost $18.7 million; $15.1 million or 80% of the works can be attributed to fixing the downstream flooding issues experienced by the entire catchment.