Appendix C - Stormwater Management Plan

TfA Project Group Pty Ltd                                                                                 Stormwater Management Plan
                                                                                                               Development Application




   Table 6: Fy factors for the nominated ARI’s

                1 year ARI       2 year ARI           5 year ARI         10 year ARI      20 year ARI     50 year ARI         100 year ARI
                 (mm/hr)            (mm/hr)              (mm/hr)          (mm/hr)          (mm/hr)           (mm/hr)               (mm/hr)
      Fy           0.80                0.85               0.95              1.00             1.05               1.15                1.20


   The coefficient of discharge for both pre and post-development catchments is calculated based on equation 4.05
   of QUDM and the results shown in Table 7.


   Table 7: Coefficients of discharge for pre and post-development scenarios

           Coefficient of Discharge              1 year      2 year          5 year       10 year        20 year         50 year     100 year
                                                  ARI            ARI          ARI           ARI           ARI             ARI          ARI
      Pre-development Catchment                   0.56           0.60        0.67          0.70           0.74            0.81         0.84
     Post-development Catchment                   0.67           0.71        0.80          0.84           0.88            0.97         1.01


   6.2.5        Rainfall Intensities
   The rainfall intensities for the site were read from an IFD table obtained from the BOM website for the project site
   on 25 September 2015. The rainfall intensities for a given time of concentration for the pre and post-development
   cases for the nominated ARI’s are shown in Tables 8 and 9.


   Table 8: Rainfall intensities for the nominated ARI’s for the pre-development scenario

           tc      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)
        10             99.3               126               156               173              196                 227                250


   Table 9: Rainfall intensities for the nominated ARI’s for the post-development scenario

           tc      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)
       6.0             121                154               189               210              238                 275                302


   6.2.6        Stormwater Design Flows
   Table 10 shows the stormwater runoff flows for the pre-development case calculated using the rational method.


   Table 10: Stormwater flows generated by the pre-development catchment

      Catchment             Q1 (l/s)          Q2 (l/s)       Q5 (l/s)         Q10 (l/s)      Q20 (l/s)        Q50 (l/s)            Q100 (l/s)
      A (QoutPC)            37.78             50.94              70.48          82.28          97.88             124.16              142.68


   Table 11 shows the stormwater runoff flows for the post-development case calculated using the rational method.




                            123 Eumundi Road (Cnr Walter Hay Drive), Noosaville QLD 4566                                               Page 6