075-028 SWMP Report

                        DESIGN REQUIREMENTS – HYDROLOGY

To demonstrate that no increase in peak flows is occurring to the east (LPD1), the predevelopment catchment
was compared against the pre-development for flow contribution.

                                 Peak Flows

         Flows from each catchment for the pre and post development were calculated using the Rational
         Method and compared against the XPSWMM estimates for the 63 % to 1 % Annual Exceedance
         Probability (AEP) storm event for standard duration storm events.
         The Rational Method calculation parameters are provided in Table A and Table B for the pre and post
         conditions respectively.
         Calculations of the storm events using the Rational Method are provided in Table C and Table D.



Table A -Rational method calculation parameters (Pre Development)

    Catchment             C01

      Area (ha)          0.074

   Fraction Imp. (%)       53

         1
          I10              75

       Time of
                          11.1
 Concentration (mins)




Table B -Rational method calculation parameters (Post Development)

    Catchment            P01

      Area (ha)          0.074

   Fraction Imp. (%)      71

         1
          I10             75

       Time of
                         11.1
 Concentration (mins)




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