RFI - Attachment B - Stormwater management Report · MCU20/0026

Table 3 below compares the peak flow rates and total runoff volume for the existing and developed
model.

Table 3 - XP Storm Results

          Duration                          Peak Flow Rate (L/s)              Total Volume (m3)
 AEP                  Median Storm
           (min)        Pattern            Existing       Developed        Existing      Developed

 10%           10            8                21             16 (-5)         8.41        4.48 (-3.94)

               25            5                16             12 (-4)         14.94       9.70 (-5.24)

               60            6                13             10 (-3)         23.10       16.54 (-6.57)

  1%           10            8                32             30 (-2)         15.35       11.36 (-3.99)

               25            10               28             25 (-3)         27.44       21.67 (-5.77)

               60            6                24             23 (-1)         43.42       35.91 (-7.51)

As shown in Table 3, the peak flow rate of stormwater runoff and the total runoff volume off site has not
increased as a result of the development. The proposed infiltration/detention tank is therefore
considered to be adequate. Results for the 10 minute duration for the 1% AEP event are outlined in
Figure 4 & 5 below.



     Total runoff volume across NE
     boundary (Node A inflow) = 15.35m3




                                                   Peak flow rate across
                                                   NE boundary = 32L/s


       Figure 4 – XP Storm Results; Pre-Developed Model (1% AEP, 10 minute duration)




11 June 2020                           Stormwater Management Report                                      6
S20-023                              40 Park Crescent, Sunrise Beach