Flood mapping seeking Ministerial authorisation

30 Sep 2015
Well Governed Council

Manningham Council will be writing to the Minister for Planning to seek authorisation to implement the findings of a review of flood mapping of five local catchments within Manningham.

Undertaken in conjunction with Melbourne Water, the review recommends the introduction and/or revision of Special Building Overlays (SBO) and a Land Subject to Inundation Overlay (LSIO) proposed to apply to land identified as being subject to either overland flows in the event of a storm exceeding the design capacity of the underground drainage system, or liable to inundation from an open watercourse, during a 1 in 100 year storm event.

Ministerial authorisation would allow Council to prepare and exhibit Amendment C109 to the Manningham Planning Scheme, to include additional properties (and in some instances remove properties) in the Special Building Overlay and Land Subject to Inundation Overlay and also amend the Municipal Strategic Statement.

Council’s review of local catchments has been driven by both internal and external factors:

An Auditor General’s recommendation that Councils provide a higher level of flood protection, carry out reliable flood mapping and include the results in their planning schemes.
A subsequent action for local council’s and Melbourne Water to work collaboratively to better address flood risk.
Council’s Drainage Strategy 2004-2014 which recognised the need for buildings and other vulnerable assets to be above flood levels and not to be surrounded or isolated by deep or fast flowing waters.

Manningham Mayor Cr Paul McLeish noted that accurate flood mapping is a critical foundation for the development of sound drainage and flood management activities and it will offer significant benefits to the local community.

“Determination of flood levels and identification of affected properties for the local catchments through overlays in the Manningham Planning Scheme will facilitate the following outcomes:

Greater control over new buildings and works through the planning permit process, to ensure that new habitable floor areas are developed above known flood levels.
Identification of existing affected properties to enable assessment of affected floor levels in a catchment and targeting of community education regarding flood impacts.
Understanding of the numbers of properties impacted by flooding in a catchment which will assist with prioritisation of drainage infrastructure improvement works.

Cr McLeish said that while approximately 10,300 properties across the five urban catchments are affected by the proposed changes, it should be noted that the majority (59 per cent) of properties will have minimal impacts from the proposed amendment, as they will either have:

  • Their existing flooding overlay removed completely,
  • Minor changes made to the boundary of their existing flooding overlay, or
  • Permit exemptions that will ensure that planning permit approval is not required if certain conditions are met.

“Existing houses or buildings will not retrospectively be required to obtain planning permit approval and only new development will require a planning permit where planning permit exemptions are not met.”

“The proposed flooding overlays will only affect small parts or sections of properties in most instances, and therefore new development will only need a planning permit if it is located within the overlay itself (where planning permit exemptions are not met),” he said.