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                                                                                                    CALIBRE CONSULTING




3         CONCEPT BASIN DESIGN
Brown Consulting previously provided a Concept Stormwater Management Report in 2008 (Report No. B07056-02A
dated June 2008) which analysed catchment hydrology, flood investigation, culvert capacities, detention basin modelling,
stormwater quality modelling and water balance modelling. This report (Report No. B14158.W-01A) however only
considers stormwater quality. The previous report proposed three detention basins with stormwater quality measures.
Locations and general sizing of basins will remain consistent in the updated strategy.

Incorporated into each of the basins are stormwater quality measures that will form part of the water quality treatment
train for the site. Flows leaving the basins will discharge offsite to the downstream drainage system.

Concept basin designs in this report has also adopted preliminary detention areas and detention storage provided from
the previous report (No. B07056-02A) and incorporated in the concept designs of the stormwater quality systems. Refer
to Table 3-1 below.

                                   Table 3-1: Stormwater Detention Basin Concept Details


                                                                Previous Report:       Current Report:
                                                                B07056-02A             B14158.W-01A
                Basin                       Basin Details       (June 2008)            (December 2012)
               Northern Basin           Detention Storage m3                 1330m3                   1360m3
                                        Min. Detention Level              RL98.40m                  RL 99.4m
                                        Embankment Level                 RL100.30m              RL101.30m
                                                         2                         2
                                        Detention Area m                     1290m                    1390m2


               Central Basin            Detention Storage m3                 1940m3                   1980m3
                                        Min. Detention Level             RL 99.60m                   RL 99.6
                                        Embankment Level                 RL101.00m              RL101.00m
                                                         2                         2
                                        Detention Area m                     2200m                    2810m2


               Southern Basin           Detention Storage m3                2135 m3                  2240 m3
                                        Min. Detention Level             RL101.50m                  RL101.5m
                                        Embankment Level                 RL103.00m              RL103.00m
                                                         2                         2
                                        Detention Area m                      2630m                   2470m2
                           1
                               – Basins have been preliminary sized for 1 to 100 year ARI events.




B14158.W-01A | COOROY RETIREMENT COMMUNITY| PALM LAKE RESORTS                                                             |4