MCU10/2083 Development Application part 2 - Attachment 7 - Stormwater Management Plan





3.5      RAINFALLINTENSITIES

TherainfallintensitiesforthePreandPostDevelopmentScenariosweredeterminedfromtheIFDchartforthe
NoosaRegioncalculatedfromAR&R,1987.

                                            Table4RainfallIntensities
           TimeofConcentration   1yearARI       2yearARI     5yearARI       10yearARI    20yearARI      50yearARI    100yearARI
                   (mins)           (mm/hr)          (mm/hr)        (mm/hr)          (mm/hr)        (mm/hr)          (mm/hr)         (mm/hr)


                      5.33         126.20           159.47          196.90           217.61           246.74         285.14          314.27
                      5.42         125.46           158.55          195.78           216.39           245.36         283.56          312.53


3.6      FLOWS(UNMITIGATED)

TheflowcalculatedforthePreandPostDevelopmentScenariosforarangeofstormeventsistabulatedbelow.

                                          Table5Flows(Unmitigated)
                                                      Q1            Q2             Q5          Q10           Q20            Q50          Q100
         Scenario                                     3              3               3            3              3               3             3
                                                     (m /s)        (m /s)         (m /s)      (m /s)        (m /s)         (m /s)       (m /s)
         PreDevelopment                           0.095          0.128      0.177           0.205        0.243          0.306        0.337
         PostDevelopment                          0.094          0.128      0.176           0.204        0.242          0.304        0.335


3.7      COMPARISONOFFLOWS

Thereisnonetincreaseinflowduetotheproposeddevelopmentastabulatedbelow.

                                           Table6ComparisonofFlows

                                                   Q1          Q2            Q5             Q10           Q20            Q50                3
          Scenario                                 3            3              3               3              3               3          Q100(m /s)
                                                  (m /s)      (m /s)        (m /s)         (m /s)        (m /s)         (m /s)


          PreDevelopment                    0.095           0.128         0.177          0.205         0.243         0.306          0.337

          PostDevelopment                   0.094           0.128         0.176          0.204         0.242         0.304          0.335

          ToBeDetained                     0.001          0.000         0.001         0.001       0.001         0.002        0.002

A rational method analysis of pre and post development scenarios concludes that no net increase in peak
stormwater flows will occur as a result of the proposed development. On site detention storage will not be
requiredtoensurenonetincreaseinpostdevelopmentdischargetothestreetdrainagenetworkwithinGibson
RoadandSkipperPlace.




    SITEBASEDSTORMWATERMANAGEMENTPLAN–RevisionD                37GibsonRoad,Noosaville                                                          Page 7



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URBANCONSULTANTS

3.5 RAINFALL INTENSITIES

The rainfall intensities for the Pre and Post Development Scenarios were determined from the IFD chart for the
Noosa Region calculated from AR&R, 1987.

 

 

 

 

 

 

Table 4 - Rainfall Intensities
Time of Concentration 1 year ARI 2 year ARI 5 year ARI 10 year ARI 20 year ARI 50 year ARI 100 year ARI
(mins) (mm/hr) (mm/hr) (mm/hr) (mm/hr) (mm/hr) (mm/hr) (mm/hr)
5.33 126.20 159.47 196.90 217.61 246.74 285.14 314.27
5.42 125.46 158.55 195.78 216.39 245.36 283.56 312.53

 

 

 

 

 

 

 

3.6 FLOWS (UNMITIGATED)

The flow calculated for the Pre and Post Development Scenarios for a range of storm events is tabulated below.

 

 

 

 

Table 5 - Flows (Unmitigated)
a Qi Q2 Qs aio Q20 Q50 Q100
(m*/s) (m*/s) (m*/s) (m*/s) (m*/s) (m*/s) (m*/s)
Pre Development 0.095 0.128 0.177 0.205 0.243 0.306 0.337
Post Development 0.094 0.128

 

 

 

 

0.176 0.204 0.242 0.304 0.335

 

 

 

 

 

3.7. COMPARISON OF FLOWS
There is no net increase in flow due to the proposed development as tabulated below.

Table 6 - Comparison of Flows

 

Scenario oe or oF

 

 

 

 

cfs) | (ms) | mls) | tls) | (mls) | (mifay | 200078)
Pre Development 0.095 0.128 0.177 0.205 0.243 0.306 0.337
Post Development 0.094 0.128 0.176 0.204 0.242 0.304 0.335
To Be Detained -0.001 0.000

 

 

 

 

 

-0.001 | -0.001 | -0.001 | -0.002 -0.002

 

 

 

 

A rational method analysis of pre and post development scenarios concludes that no net increase in peak
stormwater flows will occur as a result of the proposed development. On site detention storage will not be

required to ensure no net increase in post development discharge to the street drainage network within Gibson
Road and Skipper Place.

SITE BASED STORMWATER MANAGEMENT PLAN — Revision D 37 Gibson Road, Noosaville