Stormwater Management Plan

GOOD SHEPHERD LUTHERAN COLLEGE                                                                 Odyssey Consulting Group
Lot 30 on SP170751                                                              Conceptual Stormwater Management Plan
115 Eumundi Noosa Road, Noosaville                                                                    Project No: K4277

         The permeable pavement has been modelled with the following properties:

                    Filter media                        Sandy Loam;
                                                         5 – 10% Organic Content in accordance                   with
                                                         AS1289.4.1.1;
                                                         Average D50 1 mm;
                                                         Ksat 360 mm/hr;
                    Filter media depth                  0.40 m;
                    Extended detention depth            Pavement 1: 0.0 m, Pavement 2: 0.1 m;
                    Seepage                             0 mm/hr;
                                                                         2                   2
                    Filter Area                         Pavement 1: 69m , Pavement 2: 150m ;
                                                                         2                   2
                    Surface Area                        Pavement 1: 69m , Pavement 2: 150m .

5.4.3 Post Development Modelling Results - Mitigated
         The stormwater quality improvement device (SQID) will reduce the amount of sediments and
         nutrients discharging from the proposed residential development. Table 15 illustrates the treatment
         train effectiveness of the proposed SQID’s.

         Table 15:       Treatment Train Effectiveness of Proposed SQID
                     Parameter                Post         Post Mitigated   Reduction (%)     Water Quality Objectives
                     Flow (ML/yr)             7.24              7.2              0.8                       -
                      TSS (kg/yr)             1650              231              86                      80%
                      TP (kg/yr)              3.16             0.797            74.8                     60%
                      TN (kg/yr)              15.1              8.1             46.8                     45%
               Gross Pollutants (kg/yr)        168               0              100                      90%

         The results demonstrate that the proposed SQID meet the intended water quality objectives for flow,
         suspended solids, phosphorous and nitrogen levels.



6.0 OPERATIONAL PHASE MAINTENANCE REQUIREMENTS
         The proposed stormwater management devices will require maintenance and monitoring to ensure
         that they function as designed. The following section provides an outline of the necessary
         maintenance tasks for the proposed devices.

6.1      Bio-retention Basin Maintenance
         The most intensive period of maintenance is during the plant establishment period (first two years)
         when weed removal and replanting may be required. It is also the time when large loads of
         sediments could impact on plant growth particularly in developing catchments with poor building
         controls.

         Maintenance is primarily concerned with:
               Maintenance of flow to and through the bio-retention basin;
               Maintaining vegetation;
               Preventing undesired overgrowth vegetation from taking over the bio-retention basin;
               Removal of accumulated sediments; and
               Litter and debris removal.




K4277-0002-C                                         05 November 2018                                     Page 14 of 16