Reference Document - Stormwater Management Plan - RAL26/0001 (As Published)

                                                Pre-Development       Post-Development

                       Catchment                    Pre-01                Post-01

                        Area (Ha)                    0.153                 0.153

                    Fraction Imp (%)                  20                     57


              Time of Concentration (mins)           10.13                 10.13




TABLE 3 MODELLING PARAMETERS

Pre and post discharge rates have been calculated using DRAINS software to evaluate the effect of
the development. Attenuation of post-development flows have achieved by modelling a single 9kL
underground detention tank servicing all catchments.

                     Underground tank 9kL
                     Orifice (@0mm of Storage Depth)         Or_100 mm
                     Orifice overflow (@0.75 of Storage      Or_225 mm
                     Depth)
                     Max depth                               0.84 m
TABLE 4 DETENTION TANK CONFIGURATION




FIGURE 4 POST-DEVELOPMENT DRAINS MODEL LAYOUT