STP22-0347 DA Engineering Report RFI Response Rev C

                                                                                                           STP CONSULTANTS



        RAINFALL & RUNOFF PARAMETERS

                              Parameter                             Roof/ Road/Ground Level

                     Rainfall Threshold (mm/day)                                1

                      Soil Storage Capacity (mm)                              18

                  Soil Initial Storage (% of Capacity)                        10

                         Field Capacity (mm)                                  80

                  Infiltration Capacity coefficient - a                      243

                  Infiltration Capacity exponent - b                          0.6

                          Initial Depth (mm)                                  50

                       Daily Recharge Rate (%)                                  0

                       Daily Baseflow Rate (%)                                31

                     Daily Deep Seepage Rate (%)                                0

           Table 9.4 – Water by Design MUSIC Quantity Parameters for South-East Queensland (Commercial)

        POLLUTANT GENERATION
         In MUSIC, stormwater quality is characterized by event mean concentrations (EMC) for storm flows and base
         flows. In this study, the EMC were adopted from the Water by Design MUSIC Modelling Guidelines. The
         pollutants of concern that were assessed include total suspended solids (TSS), total phosphorous (TP) and
         total nitrogen (TN). The quality of stormwater runoff is characterised by inputting event mean concentrations
         (EMC) for storm flow and base flow conditions as well as the standard deviation of each EMC.

         Pollutant concentrations are based on Commercial land use parameters.

                                                    TSS (log10 values)              TP (log10 values)       TN (log10 values)
           Flow Type       Surface Type
                                                  Mean          Std Dev.        Mean            Std Dev.   Mean         Std Dev.


          Baseflow        Roof                     0.00           0.00          0.00              0.00     0.00           0.00

                          Roads                    0.78           0.39          -0.60             0.50     0.32           0.30

                          Ground level             0.78           0.39          -0.60             0.50     0.32           0.30

          Stormflow       Roof                     1.30           0.38          -0.89             0.34     0.37           0.34

                          Roads                    2.43           0.38          -0.30             0.34     0.37           0.34

                          Ground level             2.16           0.38          -0.39             0.34     0.37           0.34

          Table 4.5 – Water by Design MUSIC Modelling Parameters - Commercial Split Catchment (SEQ)

        RESULTS
         The indicative layout of the MUSIC model and results are shown below in Figure 9.1 and Table 9.6.




Civil Engineering Report & Site Based Stormwater Management Plan | STP22-0347                                               23