Your Planning Permit and Endorsed Plans may require you to:
- install an On-Site Detention system (OSD), and/or
- have Water Sensitive Urban Design (WSUD) in the drainage design.
These designs must be to our satisfaction, which are assessed in line with our guidelines.
- Stormwater design computations (OSD4W or equal) including:
- Storage requirement
- Orifice size calculation
- Available storage
- Pump calculation as per AS/NZS3500, if applicable
- Design plans showing:
- Levels, dimensions and relevant notes for pipe inverts, top of pits, pavements etc.
- Pits, storage pits, pump well, storage tanks, backfill etc.
We aim to respond within 15 business days for simple and complete applications.
Incomplete and complex applications will extend processing time. Make sure you have all the information on hand when you apply.
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Drainage Design Parameters
DDP are engineering requirements we provide you to design your property's drainage system. They typically include:
- allowable discharge rates
- detention requirements
- rainfall data
- the legal point of discharge.
On-site Detention
An OSD system temporarily stores stormwater on your property. It releases it at a controlled rate to prevent overloading the public drainage network during heavy rainfall.
Water Sensitive Urban Design
WSUD are provisions in the Planning Scheme to improve stormwater quality before it enters waterways.
Example methods:
- Rain gardens
- Rainwater tanks
- Permeable paving
- Bio-retention systems.
When to apply
Apply for DDP or WSUD after your Planning Permit’s plans have been endorsed, and before your engineer begins designing the drainage system.
You can apply for OSD assessment after a qualified practitioner has designed your plans in line with our Drainage Design Parameters.
FAQ
What’s the difference between DDP, OSD and WSUD?
What’s the difference between DDP, OSD and WSUD?
Drainage Design Parameters are engineering specifications you must use to design your OSD.
On-Site Detention manages the quantity of stormwater by slowing its release.
Water Sensitive Urban Design improves the quality of stormwater by removing pollutants before discharge.
Some developments require both.
Can I determine my own DDP?
Can I determine my own DDP?
No. Parameters need to be determined by Council or a qualified drainage engineer.
How will I know if I need an OSD system?
How will I know if I need an OSD system?
Your Planning Permit will have a condition like this example:
“An on-site stormwater drainage retention/detention system must be installed on the subject land to the satisfaction of the Responsible Authority".
This requirement is applied to developments only when necessary.
Where a Planning Permit is not required or issued by Department of Transport and Planning, our Legal Point of Discharge advice may request an on-site detention system be included to the drainage system.
Can I design my own OSD system?
Can I design my own OSD system?
We recommend engaging a qualified civil or hydraulic engineer to prepare the design and supporting calculations.
Does Council build or inspect the OSD system?
Does Council build or inspect the OSD system?
No. We only assess applications to ensure they meet our guidelines.
Construction is carried out by your builder or contractor.
Do I need DDP for every development?
Do I need DDP for every development?
No. They are only required if your Planning Permit has a condition requiring our approval of a drainage system with on-site detention measures.
What types of development trigger WSUD?
What types of development trigger WSUD?
A WSUD is normally for developments such as:
- large residential, commercial, or industrial developments; and
- developments that may generate or manage pollutants, such as service stations, recycling facilities, or vehicle repair businesses.
When is a WSUD assessment required?
When is a WSUD assessment required?
If required, it is a condition in the Planning Permit under the Engineering section.
The condition may require the WSUD be prepared and certified by a qualified engineer and submitted to Council for assessment and approval.
If you are unsure whether your development requires a WSUD assessment, check your Planning Permit or contact our Engineering Department for advice.
Can we use BlueFactor for WSUD assessment?
Can we use BlueFactor for WSUD assessment?
Maybe. BlueFactor may be used where the development does not include a treatment train. And is only applicable to sites up to 10,000 m² in area.
If a treatment train is proposed, a MUSIC model must be submitted to demonstrate compliance with the required WSUD targets.
