Flood Study BSM Job2013 08 Date 15 Sep 2014 Revised

5.      Please confirm that the maximum flow through the bio retention swales in a Q100 event do not
        exceed 1.0m/s in accordance with Healthy Waterways Design Guidelines.

Refer to Callaghan & Toth response.


6.      Please confirm Q100 flood depths over the footbridge. It is unclear of the blockage factor that has
        been applied to the bridge and handrail and its impact on flood levels.

The Q100 flood depth over the footbridge, as per the design in the previous (original) edition of this
report was 0.19 metre. This revised report includes a revised design for the footbridge, including the
removal of the land-spans and a 0.13 metre raising of the deck level. The revised Q100 headwater level is
0.20 metre above the revised deck level, resulting in about 0.16 metre depth of water across the deck and
a DxV product of 0.15. With 50 % blockage of the bridge opening and 100% blockage of the handrails,
the Q100 headwater level rises to 0.28 metre above the deck level and the DxV product increases to
0.255 – which is within safe limits.

A complete listing of 100 year upstream water levels, with 50% blockage of the bridge opening and
100% blockage of the handrails, is given in Table 24 of this report.


7.      The hydrologic regime is proposed to be changed over 2 Pearson’s road in a minor event. Please
        provide owners consent from 2 Pearsons Road for this change to hydrological flows on their
        property.

        a.     No comment on the environmental impact of this (2 Pearsons Road) change to the
               hydrological flow has been provided.

Refer to Callaghan & Toth response.




     Brisbane Stormwater Management Pty Ltd Document File: ValkevSDF.Doc                            Page 7