16-001014-01A (Swmp)

    runoff below the 63% AEP storm event (<0.29m3/s) to the Central Bioretention Basin and a secondary drainage link
    to direct high-flows to the towards the proposed WQCP (not modelled in MUSIC).

A layout of the primary and secondary drainage links modelled is indicated on the MUSIC configuration layout provided in
Appendix F. Drawing No. B14158.W-SK102 also provides further details of the site’s internal drainage strategy.

No routing was adopted for drainage links within MUSIC model in accordance with Section 4.17 of the MUSIC Modelling
Guidelines (2010). This assumes flows and associated pollutants from all parts of the catchment arrive at the treatment
nodes at the same time. This is conservative as it means that MUSIC may overestimate the overflow volumes.

4.4.4     TREATMENT NODES

4.4.4.1 BIORETENTION TREATMENT NODE

Bioretention treatment nodes were used to model the proposed bioretention filter in the northern and southern basin and
bio-pod. Default K and C* values were adopted for these treatment nodes. These treatment nodes were set up generally
in accordance with the MUSIC Modelling Guidelines (2010) and Interim MUSIC Bioretention Treatment Node (2013).
Refer to Table 4-2 for the bioretention treatment node configuration. All other parameters have been adopted from
MUSIC Modelling Guidelines (2010).

                                 Table 4-2:       Bioretention Basin Modelled Parameters

            Parameter               Northern Basin        Central Basin    Southern Basin        Pod D2        Pod D3
                     2
 Filter Media Area (m )                   525                  200              305               25            50
 Surface Area (m2)                        525                  220              340               25            50
 Extended Detention Depth (m)             0.3                  0.3              0.3               0.2           0.2
 Filter Depth (m)                         0.4                  0.4              0.4               0.4           0.4
                                                                                                 Sandy         Sandy
 Filter Media Type                    Sandy Loam          Sandy Loam        Sandy Loam
                                                                                                 Loam          Loam
 Saturated Hydraulic
 Conductivity of Filter Media             200                  200              200               200           200
 (mm/hr)
 TN Content of Filter Media
                                          400                  400              400               400           400
 (mg/kg)
 Orthophosphate Content of
                                           30                  30                30                30            30
 Filter Media (mg/kg)
 Overflow Weir Width Modelled
                                              4                 5                6                2.4           2.4
 (m)1
                            1The width of the major overflow weir was conservatively modelled.

            Refer to Drawing No. B14158.W-SK102 and SK113 in Appendix G for further treatment train details.

4.4.4.2 POND NODE

A separate MUSIC model was configured, including the WCQP to determine Hydraulic Residence Time (HRT), which is
an important feature of the pond required for avoiding outbreaks of algae (as discussed below). Table 4-3 indicates the
pond node configuration adopted in MUSIC. Further details of the WQCP are indicated on the Drawing No. 16-001014-
402 in Appendix G.




16-001014-01 | STORMWATER MANAGEMENT PLAN (SWMP)                    COOROY RETIREMENT COMMUNITY, TRADING POST
| PALM LAKE RESORTS                                                                             ROAD, COOROY            | 19