Appendix F - SBSMP

 5.2     Proposed Design

5.2.1    External Catchment
Runoff from the External Catchment area currently flows through the Development Area.
It is proposed to capture the flows (including up to 1%AEP design flows) from the External Catchment area and
pipe it through the Development Area and discharge to the existing infrastructure.
Refer to Appendix C for the concept stormwater layout.

5.2.2    Development Area
A new internal stormwater pit and pipe drainage system with a detention basin is proposed for the Development
Area. The proposed system will discharge to the existing stormwater infrastructure within the Development Area
and the existing Bunnings Site.

The piped flows from the External Catchment area will bypass the detention basin.

Refer to Appendix C for the concept stormwater layout sketch for the development.

5.2.3    Detention System
The following table summarises the proposed detention system characteristics:
Table 3 – Detention Basin Details

                                        Detention Basin Parameters

           Minimum surface area of the base of the basin (m2)                           150


                       Lowest Invert Level (m AHD)                                      9.100


                     1% AEP Storage Level (m AHD)                                       9.980


        Minimum detention volume at 1% AEP storage level (m3)                           132


                        Low Level Orifice Control                           1 x 225mm dia @ IL 9.100 mAHD


                         High Level Weir Control                             3.6mm wide @ IL 9.900 mAHD


Further refinement of the detention system location, layout, sizing and outlet configuration will need to be
undertaken as part of detailed design and after revised detailed survey has been received.




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