Development proposals in Melbourne within a Special Building Overlay (SBO) or Land Subject to Inundation Overlay (LSIO) often trigger a planning permit. Council must refer such permit applications to Melbourne Water, as the relevant floodplain management authority, for comment. Melbourne Water usually provides conditional consent and Council is required to include these conditions on any permit granted. In most cases, where the proposal includes new floor space at the ground floor level, Melbourne Water will require the floor level to be a specified height to Australian Height Datum (AHD). It is usual for this requirement to be 300mm above the 1:100 flood level for habitable parts of the dwelling and 150mm above the flood level for garages. Melbourne Water’s advice will specify the applicable flood level to AHD.
As a result of the release of the Victorian Coastal Strategy 2008, Melbourne Water now has more stringent flood protection requirements in certain locations. The Strategy considers sea level rise and the impacts of increased frequency and severity of storm events. Recent amendments to the State Planning Policy Framework of Victoria’s Planning Schemes plan for a sea level rise of not less than 0.8 metres by 2100. Melbourne Water has taken this increase into account with higher floor level requirements for new development which is located on land potentially subject to flooding or inundation.
Clause 1 has a current planning permit application lodged for the construction of a dwelling in a Heritage Overlay and within a Special Building Overlay. The property is located in Elwood and is within proximity to the Elwood Canal which connects to Port Phillip Bay. Prior to lodging the application advice was sought from Melbourne Water for the applicable flood level. The dwelling was designed on the basis that the floor levels needed to be 300mm above the 1:100 year flood level. In November 2011, after the application had been lodged with Council, Melbourne Water provided further advice on the proposal requiring the floor levels to be at least 800mm above the 1:100 year flood level. The applicable 1:100 year flood level had also increased by 50mm since the initial advice. This required a redesign of the dwelling with floor levels to be increased 550mm.
Changes to building form as a result of increased flood levels have implications for planning permit applications such as compliance with ResCode height-to-boundary and maximum-height standards. Entries to dwellings may need steps and rails. Driveways or disabled access in other buildings may need steeper gradients. Compliance with these standards will need to be balanced against Melbourne Water’s requirements if a reasonable degree of new development is to be provided for.
Where you have a project located within a SBO or LSIO that may be affected by sea level rise, we recommend that you contact Melbourne Water for floor level requirements as part of your pre-design due diligence. If you have earlier advice from Melbourne Water in areas potentially affected by sea level rise, we recommend you contact Melbourne Water again to determine whether this has changed. Melbourne Water has prepared interim guidelines titled “Planning for sea level rise” which is available from www.melbournewater.com.au.
Seek Professional Advice
Information contained in this publication should be considered as a reference only and is not a substitute for professional advice. No liability will be accepted for any loss incurred as a result of relying on the information contained in this publication. Seek professional advice in specific circumstances.
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