Why is Amendment C221 required?

Melbourne Water and the City of Stonnington are proposing changes to Stonnington’s Planning Scheme, under Amendment C221, to minimise the effects of overland flows and flooding on new buildings, and ensure new developments don’t adversely affect existing properties.

What is an overlay? What is an LSIO and a SBO?

An overlay is a planning control in an area where proposed buildings or developments may require special consideration because of particular features, such as heritage protection, or in areas prone to flooding or bushfires.

Flooding overlays are based on the extent of flooding resulting from a 1 in 100 year storm – an event of such intensity (based on historical rainfall data), that it has a one per cent chance of occurring in any given year.

There are two types of overlays affected by this proposal:

1.  Special Building Overlay (SBO) is a planning control that identifies areas prone to stormwater overflow from either Melbourne Water or Council drains.

2.  Land Subject to Inundation Overlays (LSIO) is a Melbourne Water specific control that applies to land affected by flooding associated with waterways and open drainage systems.

Properties included in the overlay can still be developed, built on or subdivided, but they may require a planning permit. That will ensure any drainage and flooding issues are addressed at the start of the development process and minimise the potential for flood damage.

These overlays ensure public health and safety are considered when new buildings or extensions are proposed in areas subject to flooding. Most commonly this is achieved by requiring raised floor levels within a new building or extension.

Why are we updating the overlays now?

Since the present overlays were introduced in the planning scheme, there have been a number of revisions to the flood mapping. These revisions resulted from:

·  Council and Melbourne Water flood mitigation works

·  additional areas that are prone to flooding being identified, and

·  more detailed localised flood models following assessment of drainage upgrades.

While most of the existing overlays remain unchanged, the revision includes a number of minor boundary changes and the addition or removal of some properties to the overlay.

We have also distinguished between which drainage systems are managed by Council and which are managed by Melbourne Water by introducing different overlay schedules. So, a new schedule may be applied to the properties already covered by an existing overlay.

·  SBO 1 – flooding associated with main drainage infrastructure (managed by Melbourne Water)

·  SBO 2 – flooding associated with local drainage infrastructure (managed by Council)

·  LSIO 1 – flooding associated with waterways

Does the LSIO/SBO affect owners and/or occupiers?

You can find out the exact boundaries of the LSIO and SBO that may affect your properties by viewing our interactive map
Owners: The overlay/s generally only affects future developments and may require a planning permit for buildings and works. Owners/Occupiers: While not a result of this amendment (the SBO and LSIO does not cause or change the likelihood of flooding from a 1 in 100-year storm), overland flow paths may impact on property and possessions, which are located at ground floor/basement levels of existing developments. 

Is a planning permit required?

For properties in the LSIO and SBO, a planning permit may be required to construct a building or carry out works and to subdivide land. This enables drainage and flooding issues to be addressed early in the development process. This includes setting building floor levels to address flood risk and ensure flood waters are not obstructed or diverted by development.

Do all buildings and works need a planning permit?

No, there are a number of exemptions for minor works and where certain conditions are met. These may be set out in the schedule to the overlay or in the clause itself. Refer to the amendment documents. 

My property is just touching the overlay, why am I in?

The property is included in the overlay because it has been identified as being within a 1 in 100-year storm overland flow path. Flow paths do not stop at property boundaries even if they only cover a small area. 

Any future development on the property will be considered against where the extent of the overlay is on the property.  

How has the flood mapping been determined?

The flood mapping has been determined by expert water and drainage engineers using detailed localised flood models and newer technology. The mapping work is consistent with methods used by Melbourne Water and Council, and is considered to be industry best practice. 

If I am in a flood overlay, will my insurance premiums increase?

Insurance premiums are based on the most up-to-date available flood studies, rather than the Planning Scheme controls. The insurance industry has its own National Flood database where this information is kept. Flood information can help ensure properties are not under-insured. For more information, go to the Insurance Council of Australia website at ica.com.au, or check with your insurance provider.

Will it impact on the value of my property?

The value of any property is determined by the complex interplay of many different factors such as location, streetscape and amenity, and it is difficult to assign what effect, if any, the identification of land liable to flooding may have on the value of a property. In previous instances where an independent planning panel has been asked to consider and report on submissions opposing the application of a flooding overlay, the issue of property devaluation has been considered and rejected by the panel. The SBO and LSIO does not cause or change the likelihood of flooding, but recognises the existing condition of land. The SBO and LSIO will not be described on title, but will be included in information available to the public through property information statements issued by the retail water companies, such as South East Water under Section 158 of the Water Act 1989. Information will also be included in planning certificates contained within Vendor’s Statements issued under Section 32 of the Sale of Land Act 1962.

Is new development causing the flooding problems with existing drainage infrastructure?

The risk of flooding from major storm events is not attributable to new development in Stonnington. 

I am already affected by one of these flooding overlays on my property, what will the difference be with this amendment?

The current LSIO and SBO already require a planning permit for some buildings, works and subdivision. The proposed schedules include the following changes:

·  LSIO Schedule 1 updates the Clause number in the title

·  SBO Schedule 1 introduces new exemptions for some types of development, and

·  SBO Schedule 2 identifies Council as the authority responsible for local drains.