1714 IWMP_Report_Carramar_Version2 Oct 2018

In summary, the modelling has suggested a minimum 100 year detention volume of 92 cubic metres, or
maybe as much as 124 cubic metres if like-for-like storm durations are considered to be a vital
requirement. Both of these volumes are reasonably consistent with the broad-brush estimate of 117
cubic metres at the bottom of page 4 of this report. A nominal volume of 110 cubic metres was
therefore adopted, on the basis that the use of the latest infiltration allowances and temporal patterns at
the detailed design stage will most likely result in a slight reduction in the required detention volume,
albeit at the expense of substantially greater design complexity..

The 110 cubic metre volume was then simply apportioned between the two groups of roof areas, on the
basis of contributing roof area as a proportion of total roof area, resulting in the conceptual arrangement
shown in Figure 4 below. This provides a total of 110 cubic metres, using the ecoAID underground
cellular system. Details of this system are shown in the brochure in Appendix A hereto.


   NORTH                                                           RW




                                                       VILLA 4          VILLA 3



   0            SCALE             50 m                                 ecoAID SYSTEM
                                                                    5 ROWS x 12 UNITS
                                                                       DET VOL 48 m3


                                                      B4




                    ecoAID SYSTEM
                 7 ROWS x 11 UNITS    B4
                    DET VOL 62 m3




                                       RW
                         ENTRY      LANDSCAPED
                                     PODIUM




                          VILLA 1           VILLA 2



                        COOROY - NOOSA ROAD


Figure 4:    Conceptual Arrangement Of Detention Volume




                                                                                                    Page 8
   Brisbane Stormwater Management Pty Ltd Document File: Carramar.Doc