Attachment 7B - Site Based Stormwater Manamgment Plan by ADG

                                                                   RACV Noosa Resort: 94-142 Noosa Drive, Noosa Heads

                                                                             ADG Ref: 22366 C R10 Rev04 14.12.22.docx

                                                                                                       December 2022

          All erosion and sediment control measures are to be designed and installed in accordance with IECA
          Guidelines. Further details regarding the proposed erosion and sediment control measures will be
          provided during the detailed design phase of the development.

 6.2.4    Maintenance

          All erosion and sediment control devices are to be maintained through the entire phase of the
          development leading up to the operational phase. Erosion and sediment control devices will need to
          be monitored closely throughout the entire project to ensure they are operating correctly and
          efficiently. No erosion and sediment control devices are to be removed unless otherwise authorized
          by a suitably qualified engineer or the site superintendent.

 6.3      Operational Phase Treatment
          Once directed to be commissioned by the superintendent and engineers, the Stormwater Quality
          Improvement Devices (SQIDs) will provide the required level of stormwater quality treatment to runoff
          from the site. It is expected that sediment laden runoff and the erosion potential at the subject site
          during the operational phase will be minimal. This is due to impervious developed areas in the form
          of roofs, driveways and carparking. It is understood that the footprint of these impervious areas has
          been reduced as much as practicable. The proposed landscaped areas will be maintained in a
          manner that will minimise erosion.

          Existing grassed and proposed landscaped areas will be maintained in a manner that will minimise
          erosion, some of which would be subject to erosion of topsoil from garden beds, erosion of soil from
          behind retaining walls, etc.

 6.4      Stormwater Quality Improvement Devices (SQIDs)
          A stormwater treatment train has been established to treat the runoff from the proposed development
          that includes the developable works area only (impervious carparking and units). The remaining
          catchment consists of heavily vegetated landscaping. The proposed treatment train will enable a
          higher level of pollutant removal efficiency by using stormwater quality improvement devices
          (SQIDs). Maintenance of the SQIDs will be the responsibility of the owners of the development. The
          maintenance should be carried out in accordance with the Council and Noosa RACV Resort
          recommendations.

 6.4.1    First Flush Device

             First flush device/s to divert initial flows (first 12mm of rainfall or hose-down) to the vegetated
             area.

          The initial runoff from the site’s roof area will be directed to the non-disturbed vegetated areas via a
          first flush device/s. This will ensure that accumulated loose material collected in the initial roof runoff
          during a rainfall event is collected and diverted to landscape/garden areas before flows enter the
          rainwater tank. A first flush device has a set limit on its capacity to convey flows. Once the initial
          runoff from a rainfall event meets this capacity of the first flush device, the remainder of flows for the
          event are diverted to the Lawful Point of Discharge.

 6.4.2    Bioretention Basin

             A minimum 30m2 surface area bioretention basin.

          Bioretention basins remove contaminants and sedimentation from stormwater runoff via infiltration
          through layers of soil media. The basin is made of a 400mm filter media layer, a 100mm transition
          layer and a minimum 200mm drainage layer located above the silty sand sub-strata. The basin is to
          be vegetated, as per the landscape architect’s recommendations or with suitable plants listed in

BRISBANE / DARWIN / GOLD COAST / HOBART / MELBOURNE / PERTH / SUNSHINE COAST / SYDNEY / TOOWOOMBA            Page 15