SCG 31131(SWM).RevB - REceived 3.3.22

catchment B of the proposed development prior to discharging to the lawful point of discharge as
discussed in section 4.2.



Catchment A will result in an increase to stormwater runoff rates to existing flow conditions. Refer to
section 6.4 for the downstream infrastructure considerations.



6.3      Hydraulic Modelling (PC Drains)


Hydraulic modelling has been undertaken using the software package PC DRAINS. We have modelled
the site to establish existing and proposed stormwater drainage characterisitics.



6.3.1    Rainfall Data



Rainfall data accompanied with Initial Loss (IL) and Continuing Loss (CL) was sourced from the
Australian Rainfall and Runoff (ARR) data hub and were imported into the model.



6.3.2    Initial Loss (IL) and Continuing Loss (CL)



Initial Losses (IL) and Continuing Loss (CL) were approximated based on the storm losses from the
ARR Data Hub, Table 6.4 below states the adopted values: -



                                  Table 6.4: Adopted (IL) and (CL) Values

                                     AREAS              (IL)        (CL)
                                                        (mm)      (mm/hr)

                                   Impervious             0           0

                                     Pervious            27          2.6




SCG Consulting Engineers                  Page 19                             SCG Ref: 31131(SWMP).RevB