Reference Documents - MCU23 0070

RATIONAL METHOD CALCULATION – SITE
Catchment Details                      EXISTING SITE PROPOSED SITE

Area (ha)                                 0.0486        0.0486
Impervious Area (ha)                      0.0277        0.044
Fraction Impervious (%)                    57%           92%
1
 I60 (mm/hr)                              75.2           75.2
C1                                        0.656          0.70
C2                                        0.70           0.75
C5                                        0.78           0.84
C10                                       0.82           0.88
C20                                       0.86           0.92
C50                                       0.94           1.00
C100                                      0.98           1.00




Time of Concentration (min)
                                         Method                                      Tc
       Catchment
      EXISTING SITE        Standard inlet time, catchment slope ~14%                 8
     PROPOSED SITE         Standard inlet time, mostly paved/impervious areas        5




Rainfall Intensities (mm/hr)
        Catchment            1yr ARI     2yr ARI   5yr ARI      10yr ARI 20yr ARI 50yr ARI 100yr ARI
      EXISTING SITE            111         139       168          196      223      257       282
     PROPOSED SITE             125         158       193          227      259      301       333




Stormwater Quantities (m3/s)
       Catchment           1yr ARI       2yr ARI   5yr ARI      10yr ARI 20yr ARI 50yr ARI 100yr ARI
      EXISTING SITE          0.010        0.013     0.018        0.022    0.026    0.033     0.037
     PROPOSED SITE           0.012        0.016     0.022        0.027    0.032    0.041     0.045




SITE BASED STORMWATER MANAGEMENT PLAN – Revision B                                             36 & 38 DUKE STREET, SUNSHINE BEACH