September 13, 2011 at 11:50 AM

Recent localised flooding events in Melbourne, together with the major natural disaster in Queensland in early 2011, serve as a reminder of the combined impact of climate change and urban consolidation on increased runoff volumes and flood risk in existing urban areas.

Melbourne Water works closely with local councils to carry out extensive flood mapping which is then incorporated into Planning Schemes in the form of overlays to show the location and extent of land subject to flooding.  The two most common flooding overlays are:

• Special Building Overlays (SBO) – areas prone to overland flooding.
• Land Subject to Inundation Overlays (LSIO) – areas affected by flooding associated with waterways and open drainage systems (floodplains).

These overlays play a crucial role in ensuring that proposals in affected areas are appropriately designed to be protected from flooding and to minimise potential impacts on existing development.

If you are the owner / developer of a site affected by a flooding overlay, you should consider whether it is necessary to incorporate some specific design measures as part of your proposal to maximise your chances of gaining a planning permit.  These may include the following.

• Raising the finished floor levels so that they are above the identified flood level for the subject site. 
• Avoiding boundary-to-boundary development to provide overland flow paths across the site.
• Stormwater collection / retention measures to reduce overland flow, such as stormwater detention pits, rainwater tanks, rain gardens and maximising the amount of porous surfaces.

 Through the incorporation of good planning principles and our relationships with experienced Architects / Designers, Keen Planning can help you to successfully design your proposed development to include these flood prevention measures, whilst at the same time still achieving your overall development goals.

To discuss your development options, please contact us today on 9596 9000 or email enquiries@keenplanning.com.au.