Appendix E - Integrated Water Management Plan

In summary, the modelling has suggested a minimum 100 year detention volume of 118 cubic metres,
or maybe as much as 140 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 137
cubic metres at the bottom of page 4 of this report. A nominal volume of 130 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 130 cubic metre volume was then simply apportioned between the three 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 131 cubic metres, using the ecoAID
underground cellular system. Details of this system are shown in the brochure in Appendix A hereto.


                                                                         RW
      NORTH

                                                            VILLA 5                 VILLA 6
                                                                               ecoAID SYSTEM
                                                                               7 ROWS x 12 UNITS
                                                                               SPLIT INTO 2 CELLS
                                                                                   DET VOL 61 m3


                                                                               RW     B5


  0                SCALE                  50 m
                                                                     VILLA 4
                                    ecoAID SYSTEM
                                 3 ROWS x 9 UNITS
                                    DET VOL 21 m3
                                                       RW



    ecoAID SYSTEM
5 ROWS x 14 UNITS
  DET VOL 49 m3
                                                      VILLA 3

                                                                TOTAL DETENTION VOLUME 131 m3
                                                 B4
                      ENTRY
                                     RW                         B3




              B1
                                                 VILLA 2
                           VILLA 1
                                                                 B2


   COOROY - NOOSA ROAD


Figure 4:      Conceptual Arrangement Of Detention Volume


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