Water Sensitive Urban Design
Water Sensitive Urban Design (WSUD) considers stormwater management at the planning stage for new developments, to improve stormwater quality, and water reuse.
Our Planning Clause 22.03 outlines the requirements of local planning permit applications for new developments.
WSUD requirements are required when you are developing:
- new buildings and works
- extensions to existing buildings which are 50m2 in floor area or greater
- subdivision in a commercial zone
What do you include in your application to Council?
All applications must include the following four elements:
1. Drawings including a Site Layout Plan and other relevant drawings such as a roof plan, showing the location of all WSUD treatment measures and associated information including:
- location and type of all paved and sealed areas (notated as to porous/permeable or not)
- rainwater tank size/capacity, roof catchment area discharging into rainwater tank, and number of toilets rainwater tank is connected to
- cross-sections and specifications of raingarden/s and buffer strips. Note that because of Moonee Valley’s highly reactive clay soils, all raingardens and buffer strips need to be fully lined with an impervious liner and have their overflow pipe and aggie drain (agricultural pipe) connected to the stormwater system/Legal Point of Discharge. WSUD treatment measures such as infiltration sand, infiltration sandy loam, swales, unlined buffer strips and unlined raingardens are not suitable for the clay soils in the Moonee Valley area
- details of any other integrated WSUD features
2. A comprehensive WSUD report that includes:
3. A WSUD Site Management Plan (WSUD SMP) detailing how you will manage the site through construction stating how you will prevent litter, sediments and pollution from entering the stormwater system. This can be integrated into your broader SMP statement. Take a look at our Sample SMP in the Keeping Our Stormwater Clean: A Builder’s Guide (pdf, 881KB) by Melbourne Water and the EPA Victoria.
4. A WSUD Management Program with methods of operational and maintenance management of your proposed WSUD features, ie inspections and cleaning regimes.
Which WSUD features can you incorporate into your development?
Rainwater tanks
Rainwater tanks collect run-off from roof areas and can provide a supplementary source of non-potable water in urban areas.
By storing rainfall, tanks can reduce peak flow rates to the stormwater system. Tanks also provide some treatment through settlement of suspended soils.
They can be used where drinking water quality is not needed, like watering gardens and flushing toilets, and a relatively small tank can be used for this purpose domestically.
A rainwater tank is one of the most appropriate WSUD elements for residential developments to meet the stormwater management requirements.
If you are considering installing a rainwater tank as part of your planning application, see the materials and installation guide.
Buffer stips
Buffer strips are vegetated areas (typically grass or reeds/sedges) through which stormwater can evenly flow.
They take water from impervious surfaces in an evenly distributed manner (i.e not a single stream, which could cause erosion) and filter sediments and coarse pollutants contained from the runoff.
The low hydraulic loading over the vegetation allows flows to filter through the vegetation and pollutants to settle out. They also provide a detention role to slow flows down, as well as a free source of ‘passive irrigation’.
They can also be used to filter runoff from other areas, but require flows to be distributed at the entry.
Maintenance is required on buffer strips to ensure that vegetation is healthy and has good coverage over the site.
Note that because of Moonee Valley’s highly reactive clay soils, all buffer strips need to be fully lined with an impervious liner and have their aggie drain (agricultural pipe) connected to the stormwater system/Legal Point of Discharge.
If you are considering installing a buffer strip as part of your planning application, a cross section of a generic buffer strip is available here as a guide.
Porous paving
In urban environments, paved surfaces such as roads, driveways and courtyards cover a significant area.
These ‘impervious’ surfaces do not allow rainfall to soak through them to the underlying soil and as a result contribute to larger amounts of stormwater entering into our streams than would otherwise naturally occur. These stormwater flows carry with them pollution that has been washed off from roads, pavements and roofs.
The rapid pace that stormwater is delivered to the stream contributes to bank erosion and habitat scouring.
To protect our streams from this occurring, we need to reduce the amount of ‘impervious’ surfaces in our urban areas so that less water and pollutants are washed off and delivered quickly to the stream.
One way to do this is to install porous pavements instead of traditional concrete pavements in our backyards and driveways. Porous pavements reduce the amount of runoff by allowing water to soak through the surface and into the underlying soil.
If you are considering installing a porous/permeable paving as part of your planning application, see the materials and installation guide.
Raingardens
Raingardens, also called bioretention systems, are vegetated filters that slow down stormwater and filter it as it flows downward through the soil profile.
They provide high levels of stormwater treatment in a relatively small footprint and, as they resemble a normal garden bed, also offer landscaping benefits.
They provide efficient treatment of stormwater through fine filtration, extended detention, and biological uptake. They effectively remove nitrogen and other soluble or fine particulate contaminants and also provide flow retardation.
Bioretention systems can be designed in almost any shape or size.
Note that because of Moonee Valley’s highly reactive clay soils, all raingardens need to be fully lined with an impervious liner and have their overflow pipe and aggie drain (agricultural pipe) connected to the stormwater system/Legal Point of Discharge.
Raingardens must be located a minimum of 300mm away from neighbouring buildings.
If you are considering installing a raingarden as part of your planning application, materials and installation guides can be found here for in-ground, and planter box styles.
Useful tools and links
See our environmentally sustainable design toolkit for tools, resources and case studies.