Appendix D - Engineering Assessment · OPW26/0090

                                                                                        RATIONAL METHOD CALCS




PROJECT NUMBER                26022 ADDRESS 28 OVERLANDER AVENUE, COOROY
                                                                                                                                                                          Rainfall
                                                                                                                   Frequency                Catchment                                       Peak Discharge
                                                         Inputs                                                                                                          Intensity
                                                                                                                   Factors [-]            Coefficients [-]                                      [m3/s]
                                                                                                                                                                          [mm/hr]
                    Area      Tc                           Climate Change                                                                                           Tc
 Catchment ID                          fi          C10                    Notes                                 F39% (0.5EY) F1%          C39% (0.5EY) C1%           i39% (0.5EY) Tci1%     Q39% (0.5EY) Q1%
                    [ha]     [min]                            Factor [-]
Site Predev         0.1710     5.00         0.29    0.76              1.15 FOR 1 DEGREE OF WARMING (1DW)               0.85        1.20          0.65        0.91           173       363         0.053   0.157

LOT 1 (Vacant)      0.0540     5.00         0.00    0.70              1.15 FOR 1 DEGREE OF WARMING (1DW)               0.85        1.20          0.60        0.84           173       363         0.015   0.046
LOT 1 (Developed)   0.0540     5.00         0.75    0.85              1.15 FOR 1 DEGREE OF WARMING (1DW)               0.85        1.20          0.72        1.00           173       363         0.019   0.054
LOT 2               0.1170     5.00         0.42    0.88              1.15 FOR 1 DEGREE OF WARMING (1DW)               0.85        1.20          0.75        1.00           173       363         0.042   0.118