RFI - SWMP Elands

                             PRE & POST DEVELOPMENT STORMWATER DISCHARGE CALCULATION
Spreadsheet based on QUDM 5.02, "The Rational Method"

      Project Number                                WCD-22936
      Project Address                   65-67 Elanda Street, Sunshine Beach
        Description                                    SWMP

         Designer                                           JP
           Date                                          11-Jan-21



                                 EXISTING USE                                                                                                                     PROPOSED USE
                         Co-efficent of Run-Off Calculation                                                                                                 Co-efficent of Run-Off Calculation
      Catchment Name                  Area (m2)                             Co-efficent                                               Catchment Name                    Area (m2)                      Co-efficent
        Impervious                         121                                0.900                                                     Impervious                         695                           0.900
         Pervious                          899                                0.700                                                      Pervious                          325                           0.700




                Total Area             1020                                                                                                    Total Area               1020
                                    Adopted C10 :                              0.724                  ; Co-efficent of Run-Off                                       Adopted C10 :                        0.836          ; Co-efficent of Run-Off

Tc (min.) :                                8                                                          ; QUDM Table 5.05.1        Tc (min.) :                                6                                            ; QUDM Table 5.05.1
Area (ha) :                              0.102                          (10,000m2 = 1 ha)             ; QUDM Table 5.05.5        Area (Ha) :                              0.102                     (10,000m2 = 1 ha)    ; QUDM Table 5.05.5




        Flood Event                    Existing                        Post Development                                 RAINFALL INTENSITY                      Peak Outflow Capacity               Peak Inflow Rate              Difference
            ARI                       Cy = Fy x C10                       Cy = Fy x C10                         Existing             Post Development               Qo (Existing)                Qi (Post Development)         Qi-Q0 (Post - Pre)
              1                          0.579                                 0.669                         133.44 mm / hr            144.48 mm / hr                     0.022                           0.027                      0.005
              2                          0.615                                 0.711                         150.48 mm / hr            162.96 mm / hr                     0.026                           0.033                      0.007
              5                          0.688                                 0.794                         203.04 mm / hr            221.28 mm / hr                     0.040                           0.050                      0.010
             10                          0.724                                 0.836                          237.6 mm / hr             259.2 mm / hr                     0.049                           0.061                      0.013
             20                          0.760                                 0.878                         270.24 mm / hr            295.68 mm / hr                     0.058                           0.074                      0.015
             50                          0.832                                 0.962                           312 mm / hr              343.2 mm / hr                     0.074                           0.094                      0.020
            100                          0.868                                 1.000                         342.72 mm / hr            378.24 mm / hr                     0.084                           0.107                      0.023

                                                                                                                                                                      Rational Method                 Rational Method
                             Where Coefficients of Runoff calculated from the above equation exceed
                                                                                                                                                                       Q = CIA / 360                   Q = CIA / 360
                                 1.00, they should be arbitarily set to 1.00. QUDM Table 4.05.2