Attachment 6 - Stormwater Management Plan

R1767: NOOSA LANDFILL: CLEAN WATER DRAIN AND HES BASIN (SW5) – DESIGN REPORT & MAINTENANCE AND INSPECTION PLAN



       +      All concentrated stormwater flows (including ‘clean’ stormwater and ‘dirty’ stormwater) should have
              concentrated flow paths, such as drainage lines, diversion drains, channels and batter chutes (where applicable)
              which have been designed, constructed, effectively armoured and maintained to convey the runoff from events
              up to and including the average recurrence interval (ARI) of 1 in 10 year critical duration ARI storm event without
              causing water contamination, sheet, rill or gully erosion, sedimentation, or damage to structures or property.

The Environmental Authority (EPPR01855314) also specifies that the design event for temporary drainage works to convey
waters to the sediment basin and around disturbance areas is a 1 in 10 year ARI event plus 150mm freeboard for > 24
months disturbance. Design has been undertaken to ensure this criteria is satisfied, with an additional assessment of the
1 % AEP (100 year ARI) undertaken as a sensitivity analysis on flow depth within the drains.

The peak flow rates for locations within the drains are detailed below in Table 3.

Table 3 – Peak Flow Rates & Velocities


                                       PEAK FLOW (M3/S) – UPSTREAM OF NODE                          MAX. VELOCITY (M/S) – UPSTREAM OF NODE

           LOCATION

                                              10% AEP                           1% AEP                       10% AEP          1% AEP


                 CH0                               -                                -                              -             -

               CH100                            1.443                            2.470                           0.766        0.906

               CH132                            1.442                            2.465                           1.245         1.464

               CH282                             1.418                            2.412                          0.762        0.885

               CH430                            1.955                             3.316                          0.831         0.976

               CH523                            1.950                            3.306                           1.394         1.635

               CH558                            3.404                            5.739                           1.187         1.394

               CH623                            3.499                            5.902                           1.797         2.101

               CH668                            3.498                            5.900                           1.435         1.687

               CH716                            3.472                            5.858                           0.796        0.940

            HES DWD                                -                                -                              -             -

            Doser Inlet                         1.530                             1.915                          0.774         0.910

              Forebay                           1.530                             1.916                          3.856        4.448




Environment. Engineering. Education.                                                                                                   PAGE 5