Information your Civil Engineer requires before designing residential stormwater drainage

If you’re building a new proposed house or multi-units, chances are you will need a stormwater drainage design. Civil engineers need to account for multiple factors such as environmental factors, the location of the site, and the natural ground level using the Australian Height Datum (AHD). The designs are produced in conjunction with your local council and are approved by them for construction.

Prior to commencing any design works, drainage engineers will obtain all relevant documents from either the client or the local authorities. The documents include but are not limited to:

  • Town Planning Permit
  • Legal Point of Discharge
  • Stormwater Design Assessment Report (SDA)
  • Feature and Level Survey Plan
  • Endorsed Architectural Drawings
  • All underground Assets locations
  • Sewer Depth & Offset
  • Onsite detention volume

Engineers review the Town Planning Permit conditions before commencing any designs and acknowledge all council requirements. Once the engineers have a grasp of the scope of work outlined by the council, the engineers will obtain a Legal Point of Discharge (LPOD). The LPOD document will nominate the stormwater point of discharge and the connection type (See example in Figure 1). Once the abovementioned documents are obtained, it is sufficient to calculate the required on-site detention volume.

Figure 1: Example snapshot of Legal Point of Discharge (LPOD) nominated by the local council.

The engineer will follow all the SDA report requirements to achieve the Water Sensitive Urban Design regulations. This helps reduce the negative impacts on the environment, especially in heavy storm events. WSUD regulates stormwater for different reuse purposes and discharges in a sustainable manner. Engineers may use an orifice pit or control pit for a permissible site discharge (PSD) rate.

Figure 2: Example job illustrating the WSUD achievement and the water catchment areas to be treated.

Strength Engineering offers a variety of engineering services to achieve environmentally sustainable designs for projects varying from residential, and commercial to institutional. To find out more information about the drainage designs and requirements, be sure to contact our friendly team at Strength Engineering.

For more information about Water Sensitive Urban Designs, click on the link here.

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