Approved Plans - MCU18-0097 · MCU18/0097

                 GOOD SHEPHERD LUTHERAN COLLEGE                                                                     ODYSSEY CONSULTING GROUP
                 Lot 30 on SP170751                                                                      Conceptual Stormwater Management Plan
                 115 Eumundi Noosa Road, Noosaville                                                                            Project No: K4277

                          Table 2:       Pre Development Coefficients of Runoff

                            Catchment             2                 5                     10                      20                100

                                 A               0.60             0.67                   0.70                    0.74               0.84


                          Time of Concentration
                          To calculate the time of concentration for the internal catchment the Friends Equation (tc =
                          (107nL0.333)/S0.2) from QUDM has been applied for overland sheet flow with the remaining distance
                          calculated as concentrated flow. Please refer to Table 3 for the calculated time of concentration.

                          Table 3:       Pre Development Time of Concentration

                                                                                                     Time of concentration

                                            Catchment        Catchment                                   Concentrated
                            Catchment                                              Overland flow             flow
                                             Area (m2)       Properties                                                           Total tc
                                                                                 Friend’s Equation       QUDM Figure
                                                                                                            4.09

                                                                Open               Horton’s (n) =
                                                            Space/parks –               0.045
                                 A             5,014         Light cover              L = 90 m                  n/a              12.50 min
                                                           bushland / poor         Slope = 4.38%
                                                             grass cover            t = 12.5 min


                          Design Flow Rates
                          Design storm flow rates have been calculated for standard storms with an ARI of 2, 5, 10, 20, 50 and
                          100 years for the pre development case using design rainfall intensities from the Bureau of
                          Meteorology Rainfall IFD Data System. The Rational Method (Q = 2.78 x 10-3 CIA) has been used to
                          calculate the required design flow rates for the subject site. The calculated pre development peak
                          flows for the subject site are presented in Table 4.

                          Table 4:       Catchment A - Pre Development Internal Catchment Peak Flow Rates
                            Average Recurrence
                                                            ARI              2              5              10            20             100
                            Interval
                            Coefficient of Runoff             C            0.60            0.67           0.70           0.74           0.84
                            Average Rainfall Intensity
                                                              I           114.91         142.10          157.53         178.98        228.29
                            (mm/h)
                            Area of Catchment (ha)           A            0.501           0.501           0.501         0.501          0.501
                            Peak Flow Rate (m3/s)            Q            0.095           0.132           0.154         0.183          0.267


                 3.3      Post Development

                          Catchment Definition and Lawful Point of Discharge
                          The post development scenario consists of three internal catchments that convey the stormwater to
                          the south and west of the site. Catchment A & Catchment B will discharge into existing Council
                          stormwater infrastructure on Walter Hay Drive on the southern corner of the site. Catchment C will
                          remain mostly unchanged due to the existing vegetation and will continue to discharge to Council
                          stormwater infrastructure on Walter Hay Drive. These discharge points represent the Lawful Points of
                          Discharge (LPOD) for the site.

                          The post development catchment areas and lawful points of discharge are shown on the Odyssey
                          Consulting Group, Post Development Catchment Plan (Ref: K4277/P006/E) included as Appendix D.




                 K4277-0002-E                                            18 June 2019                                                Page 4 of 14
Document Set ID: 20894174
Version: 1, Version Date: 03/07/2019