Overland Storm Water Flows and
Proposed Banyule Special Building Overlay
Frequently Asked Questions
Who is responsible for stormwater drainage and management of severe storm impacts in Banyule?
Melbourne Water is the Catchment Management Authority for Greater Melbourne. Melbourne Water has
responsibility for the parts of the drainage system which have large catchment areas (Greater than 60
hectares.). The remaining catchments including the majority of the drains, pits and pipes within Banyule are
managed by Council.
All drainage systems, including Melbourne Water’s, are designed to carry normal stormwater flows. They
are not designed to manage the flows resulting from extreme or severe storm events. However, Council and
Melbourne Water are required to assess and manage stormwater overland flows that may result from such
events.
Is there already a Special Building Overlay in the Banyule Planning Scheme?
Yes, this Special Building Overlay was introduced into the planning scheme by Melbourne Water and
covers overland stormwater flow paths associated with Melbourne Water Drains.
Why is Council proposing its own stormwater management Special Building Overlay?
The Special Building Overlay relates to stormwater management in areas of the drainage network that
Council is responsible for. The Melbourne Water Special Building Overlay does not extend into Council
managed parts of the system.
Why is this happening now?
Council recently completed a detailed analysis of its stormwater network. This analysis included an
assessment of the overland stormwater flows associated with extreme rainfall. In response to this new
information, Council will amend the Banyule Planning Scheme to include a stormwater management
Special Building Overlay which identifies areas that may be affected by overland stormwater flows during
extreme rainfall events.
How did Council identify overland stormwater flow paths?
A detailed stormwater catchment analysis was commissioned to show the effect of 1 in 100-year rainfall on
Council’s drainage network. An outcome of this study was the identification of the overland stormwater flow
paths associated with such an event.
What is a 1 in 100-year storm event?
Storms are classified using historical rainfall data and statistical probability; a 1 in 100 year storm event is a
storm with characteristics that are only expected to occur on average once every 100 years. For more
information visit the Bureau of Meteorology:
http://www.bom.gov.au/water/designRainfalls/rainfallEvents/why100years.shtml
My property is included in the proposed Special Building Overlay. What does this mean?
The proposed Special Building Overlay identifies overland stormwater flows that may exceed 200mm in
depth and/or may result in hazardous flow velocities. If you have received a letter from Council regarding
the Special Building Overlay it is because your property is either fully or partially within the defined Special
Building Overlay areas.
Within the Special Building Overlay areas, any building or development will require a Planning Permit. The
planning permit conditions will likely require that living and sleeping areas are protected from a 1 in 100
year storm event and that works do not increase the overland flow risk to neighbouring properties.
How will this proposal affect the value of my land?
There are many factors that influence land value. These include location, amenity, recent sales results and
property improvements. It is important to note that the potential overland stormwater flow paths identified in
the Special Building Overlay are due to the topography of your land and the surrounding neighbourhood.
This has not changed. The Special Building Overlay identifies and quantifies the risk that was always
present. Amending the Planning Scheme to include the Special Building Overlay will help Council and
property owners better manage risk through appropriate development.
Can I see how the proposed Special Building Overlay affects my property?
Council has prepared a plan showing the overland stormwater flow paths identified by the Stormwater
Catchment Analysis. Copies of this plan are available for viewing at Council’s offices and on Council’s
website.
In this plan, different coloured shading has been used to represent the following:

Blue shaded areas show the proposed Special Building Overlay;

Green shaded areas show lesser overland stormwater flow paths which will not be included in the
Special Building Overlay. Buildings or works within these areas will be managed under Building
Regulation provisions;

The purple shading shows areas which are currently identified by Melbourne Water as overland
stormwater flow paths and included in the Planning Scheme as a Special Building Overlay or Land
Subject to Inundation.
What should I do if the proposed Special Building Overlay affects my property?
Examine the plan of overland stormwater flow paths prepared by Council and identify the parts of your
property that are shaded in blue. Once the Special Building Overlay has been enacted you will be required
to obtain a Planning Permit for any buildings or works within the blue shaded areas. (The proposed Special
Building Overlay does trigger the need for a Planning Permit if the proposed buildings or works are outside
of the blue shaded areas.)
Regardless of whether your building or works require a Planning Permit, you will also need to submit a flood
level application to Council if any part of your property is shaded blue or green and a flood level application
to Melbourne Water is required if any part of your property is shaded purple.
If you are not planning any new buildings or works, you should take note of the overland stormwater flow
paths that have been identified through your property and do what you can to maintain a clear path for
overland stormwater flows. You should also avoid placing items that may be damaged by stormwater within
these flow paths.
I have never experienced overland stormwater flows on my property. Why then is my property in
the Special Building Overlay?
The Special Building Overlay maps are based on the forecasted overland stormwater flows associated with
a 1 in 100-year storm event. It may be that you never experience such an event in your lifetime but there is
a 1% chance that such an event can occur in any year.
When will the proposed Special Building Overlay come into effect?
The process to amend the planning scheme to include the Special Building Overlay will commence in early
2015. All property owners who are affected by the amendment will be contacted directly again during this
process and will have the opportunity to make comment. Council will consider all submissions and make a
decision on how to progress the amendment.
What is the Banyule Planning Scheme?
It is the ‘rule book’ that sets out the way land can be used and developed in the City. The planning scheme
is important because it informs the development potential of land through zoning of land for different uses
and other requirements. These other requirements include overlays that are for important planning issues
– such as where overland stormwater flows may affect land.
What is a Planning Scheme Amendment?
The planning scheme needs to be amended to introduce a new ‘rule’ like a Special Building Overlay. A
formal planning scheme amendment process will occur in 2015.
I’m thinking of doing some development on my property, what should I do?
Council’s Development Planning team assesses planning applications for residential developments. If you
are thinking of making a planning application and would like to discuss your proposal with Council, please
contact the Duty Planner on 9457 9808 or drop in to the Planning Counter at our Rosanna office between
8.30am – 5pm Mon, Tues, Thurs, Fri or Wednesday 8.30am – 7pm.
Where can I get more information?
More information on the amendment is available on Council’s website: www.banyule.vic.gov.au; email
enquiries to: enquiries@banyule.vic.gov.au or telephone 03 9490 4222
Overland Flow Mapping and SBO FAQ1 13.11.2014