MCU14/0056 Response to SARA - Consulting Report

                                                                                                                 ENG
                                                    Engineering Report & Stormwater Management Plan
                                            Date:          27/01/2015      Document No.:     14012-ENG-04.Docx

                                             By:               AvT          Revision No.:             F


                      f. Stormwater Quantity Management

 Noosa Regional Council Policy requires that a development ensure Non Worsening of
 stormwater flows up to and including Q100 stormwater events. The proposed development
 includes detention basin storage in the South East corner of the site. With this detention
 basin, it is considered that the proposed development will not cause any worsening of flows
 from the site.

 The new proposed multi-use development will have a larger impervious area than the existing
 undeveloped site and will require a stormwater detention system to mitigate the effects of
 the additional runoff. Detailed calculations of the detention required are included in Appendix
 H of this report and are summarised in the table below:


            Runoff Coefficient (C10) - Undeveloped:        0.65          tc =      6 min.
            Runoff Coefficient (C10) - Developed:          0.85          tc =      6 min.

                                            PARAMETERS
      ARI                                                2yr   5yr  10yr 20yr 50yr                    100yr
Rainfall Intensity                          mm/hr       150.0 184.0 204.0 232.0 268.0                 296.0
Frequency Factor              fy=                       0.85      0.95     1.00     1.05    1.15      1.20
 Undeveloped C                Cu=                       0.60      0.67     0.70     0.74    0.81      0.84
  Developed C                 Cd=                       0.70      0.78     0.82     0.86    0.94      0.98

                                                   FLOWS
Undeveloped Flow              Qu=   C*I*A     l/s       1248      1711    1997      2385    3018      3478
 Developed Flow          Qd=Qi=     C*I*A     l/s       1462      2005    2340      2794    3535      4074
   Difference                              l/s          214        293     342       409     517      596
   Outlet Flow           Qo =              l/s          1248      1711    1997      2385    3018      3478
      Table 5.12:         Quantity Summary




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