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What is On-Site Detention (OSD)?

On-Site Detention (OSD) systems used to temporarily store stormwater runoff on-site. They release the stored water into the local drainage system at a controlled rate, reducing the risk of flooding and minimizing environmental impacts. OSD tanks are vital in managing stormwater in urban areas with limited space and increased density.

When is On-Site Detention (OSD) required?

An on-site detention (OSD) system, designed in accordance with Council’s Specification for On-Site Stormwater Detention System should be provided for the following types of development:

  • Subdivision
  • Single dwellings where required by covenant
  • Two or more dwellings, or
  • Non-residential developments with external alterations.

When is OSD Design Approval by Council required?

If your development includes on-site stormwater detention (OSD) and your Certifier requires Council approval of the OSD Design, you will need to lodge an application with Council.

Documents required for submission:

  • Certification of design by a chartered civil engineer, verifying that it has been designed to meet the calculated specifications.
  • Detailed stormwater plan and elevation of the OSD system and a detailed design of the orifice, including all dimensions
  • The location of OSD storage in relation to overall development and site drainage
  • The permissible site discharge (PSD l/sec) and the site storage requirement (SSR m3) values for the subject site
  • Construction plans and details of the OSD system
  • Maintenance schedule for the OSD system
  • Plan of the OSD identification plaque.

Apply online

Click below to apply for Council approval of an On-Site Detention (OSD) Design.

Apply for Council approval of On Site Detention (OSD) Design