MCU14/0056 Stormwater Quantity Management Plan Att D Information response

•   design flood peak discharges for the site and surrounding area after the development
    has occurred for all flood and stormwater events up to a 1% Annual Exeedance
    Probability (AEP) (equivalent to 1/100 year Average Recurrence Interval (ARI)). This
    should include at least the following flood and stormwater events: 50, 20, 10%, 5%, 2%
    and 1% AEP (equivalent to 2, 5, 10, 20, 50 and 100 year ARI events).

SWC Response
Design flood peak discharges for the 50%, 20%, 10%, 5%, 2% and 1% AEP storm events
have been calculated for the existing and developed site. Detailed URBS calculations and
results have been provided in this report.


RFI Item
All relevant legal points of discharge for the development site are identified. No new
discharge points for stormwater will be permitted on state controlled roads;

SWC Response
The legal point of discharge is to the existing waterway which extends through the site. No
new discharge points are required.


RFI Item
The impact of existing or proposed noise barriers on overland flow paths is taken into
account

SWC Response
Noise Barriers will not be located through the 100y ARI flood extent.


RFI Item
Overland flow paths are identified and hydraulic conveyance is maintained on the site as
part of the proposed development

SWC Response
The hydraulic conveyance of the waterway is maintained. Hydraulic modelling in Section
5.0 of this report shows no impact due to the development.


RFI Item
Flood storage capacity is maintained on the site as part of the proposed development

SWC Response
Flood Storage is reduced by approximately 140m3 due to the development. This equates to
1.5% of the total volume of flood storage on the site. This does not result in an increase in
flood levels or peak discharges and is therefore considered to be negligible.




                                J4279 Report 1.0.doc
                                  14 January 2015                                        Page 4