Hydraulic Assessment_compressed

Table 1 – Peak Discharge at Culvert Crossing

         Location                1% AEP (m³/s)             10% AEP (m³/s)              50% AEP (m³/s)

 3 x 600 RCP
                                        60.0                    32.1                          16.3
 (Existing Driveway)
 3 x 900x600 RCBC                       51.9                    32.7                          17.3

 1500 x 900 RCBC                        8.2                      2.6                          0.2



Table 2 –Culvert Crossing Capacity

                        Pipe Capacity
     Location                                  1% AEP (m³/s)        10% AEP (m³/s)          50% AEP (m³/s)
                           (m³/s)
 3 x 600 RCP
 (Existing
                            4.119                  60.0                  32.1                    16.3
 Driveway)
 at 5% grade
 3 x 900x600 RCBC
                            6.882                  51.9                  32.7                    17.3
 at 3% grade
 1500 x 900 RCBC
                            9.967                   8.2                   2.6                       0.2
 at 5% grade


As demonstrated in Table 2, the existing driveway location to the dwelling (3 x 600 RCP) and the crossing to
the proposed units would be inaccessible during the design storm events. However, the existing culvert (1500
x 900 RCBC) linking the existing dwelling/managers residence to the cabin locations is immune to flooding for
each of the design events. Considering the flooding which would be occurring external to the site - along the
Eastern Branch Road - and would restrict access to the property during rain events, the only consideration
should be for clients who are already at the accommodation and are obliged to seek refuge.
It could therefore be considered the location of the existing dwelling/managers residence at a much higher
elevation would provide suitable protection during such times until water levels resided.

            Flood Extents

The flood extents for each storm event have been modelled and shown in Appendix D. The locations of each
of the proposed cabins are immune from flooding for all the design events. Though, it is noted that the most
eastern cabin would likely become isolated – albeit intermittently - during the designed storm events.




                                              Page 13 of 17
   2261 david low way, peregian beach, qld 4573      acn: 626 671 092           [email protected]