RFI - D - Civil Engineering Response

The upstream catchment is assumed to be worst case from the rear yards only. A quick
check of Streetview confirms that the two upstream properties discharge their roofwater
to the kerb and channel in Orealla Crescent and the property surfaces have been built up
so that any gutter runoff would flow to the street as well.

         Roof Catchment       = 105m2
         Ground Catchment = 497m2
         Ground Fraction Imp = 0.61
         Time of Concentration= 5 minutes

         Q100 (includes >Q20 from roof catchment) = 48L/s

This flow would probably be split each way around the proposed building and would easily
be managed by “scupper” pipes through the terraced wall, down to the driveway area
below. Alternatively, a 250x250 floor grate with 100mm of water above the grate surface
can capture 24L/s at 50% capacity. One of these on each side as “relief” would be
sufficient to convey any major storm surface water to Margit Crescent. Again, design of
the building surrounds and site stormwater management would be addressed as part of
a hydraulic design in accordance with AS3500.2 to be incorporated in a Building
Application.




                                    Indicative Ground Level Drainage




2008 – Margit Cres, Sunrise Beach                                                      5
CL/cl