Stormwater management plan 20220156 9 Kauri St SWMP

                                             Figure 4.2 - Rainfall run-off parameters for SEQ

The source nodes have been created using a split catchment approach, with the roof, driveway and other ground
areas separated with stochastic pollutant generation for each of the surface types as per Table 4.2 - Urban
Residential Split Node Pollutant Generation Parameters. The area and impervious fractions for each catchment are
actual values based on the design plans as shown in Table 4.3 – Catchment Nodes.

Table 4.2 - Urban Residential Split Node Pollutant Generation Parameters

  Flow Type         Surface        TSS LOG¹º                       TP LOG¹º VALUES               TN LOG¹º VALUES
                    Type           Mean      St. Dev               Mean       St. Dev            Mean      St. Dev
  Baseflow          Roof             N/A         N/A                  N/A         N/A              N/A         N/A
                    Driveway         1.00       0.34                 -0.97       0.31              0.20       0.20
                    Ground           1.00       0.34                 -0.97       0.31              0.20       0.20
  Stormflow         Roof             1.30       0.39                 -0.89       0.31              0.26       0.23
                    Driveway         2.43       0.39                 -0.30       0.31              0.26       0.23
                    Ground           2.18       0.39                 -0.47       0.31              0.26       0.23

Table 4.3 – Catchment Nodes

  Node                    Surface Type             Surface Area               Fraction
                                                   (m²)                       impervious (%)
  Driveways                    Driveway                  640                        87.4
  Townhouse                      Roof                    799                         100
  Roofs
  Pod A&B                       Ground                     412                     33.5
  Ground
  Pod C Ground                  Ground                     289                     11.2


The proposed treatment train has been modelled as shown in Figure 4.3 - MUSIC Stormwater Treatment Train. The
proposed attenuation tank required to achieve water quantity targets has not been modelled in the treatment train
as it is not considered a water quality improvement device. As the modelling therefore wont account for the
reduced flow rates entering the bioretention area it is likely to represent a conservative assessment of the
treatment performance able to be achieved. The details of the treatments are described in the following sections.




Project number 20220156
File RECOR Stormwater Management Report - 20220156.docx, 2022-08-08 Revision 0                                       Page 13 of 26

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