20220206 48 Elm St SWMP

pipe makes a 90 degree change in direction at this pit and continues to the east in the verge.

A DRAINS model has been prepared for the existing 300mm diameter roofwater pipe through the site and
immediately downstream to make an assessment of the capacity of the existing pipe. Below in Figures 3.5 and 3.6
are the existing network modelled in DRAINS and the catchment details for the adjoining lot.




                                              Figure 3.5 – DRAINS Network – Roofwater pipe




                                                Figure 3.6 – Upstream lot catchment details

The DRAINS model was run for the 10% and 1% AEP storm events. The results indicate that the existing roofwater
pipes have adequate capacity to convey the 10% AEP storm event. The existing roofwater pipe is almost capable of
conveying the 1% AEP storm event, with only minor bypass occurring during this event. The results are shown in
Figures 3.7 and 3.8 below.




Project number 20220206                                                                                 Page 10 of 19
File 20220206 48 Elm St SWMP, 2023-02-03 Revision 1

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