Stormwater management plan 20220156 9 Kauri St SWMP

     2.3. Proposed Development Drainage Pattern

          2.3.1 Stormwater Concept
An internal stormwater drainage network within the driveway will be used to capture run-off from the internal
impervious areas and provide house drainage connections for roof run-off from the units.

Litter basket pit inserts will be provided to the inlet pits to provide primary treatment to run-off through filtration of
gross pollutants, coarse sediment as well as capturing particulate nutrients.

An inline below ground attenuation system will be provided for stormwater quantity management. All run-off from
the site is attenuated to restrict developed state flows to ensure they are no greater than existing run-off prior to
discharge from the development to achieve no worsening to the existing conditions.

At the south eastern boundary, a bioretention garden will provide tertiary treatment through biological uptake of
nutrients, absorption and infiltration. The bioretention garden will dispose of runoff primarily through infiltration into
the site soils, with excess run-off from the garden spilling over the boundary as sheet flows

The roof and allotment drainage system for the proposed site shall be designed to comply with:

     1. Noosa Shire Council Planning Scheme Policy (PSP) - Engineering Design Standards – Roads, drainage and
        earthworks;

     2. The Queensland Urban Drainage Manual (QUDM); and

     3. AS/NZS 3500.3:2015 - Plumbing and Drainage Part 3: Stormwater Drainage.

Refer to Appendix A Proposed Development Concept Plan for the proposed stormwater drainage layout plan
illustrating the concept described above.



          2.3.2 Lawful Point of Discharge
The site typically drains southeast towards an existing watercourse in the undeveloped bushland adjoining the
subject site, which continues downstream to the north. The lawful point of discharge test, as described in Section
3.9.1 of QUDM, requires:

      •    The development does not change the flow characteristics leaving the site; or
      •    The proposed development will not alter the sites stormwater discharge in a way that may substantially
           damage a third-party property; or
      •    The location of the discharge from the site is under lawful control of the government or other statutory
           authority from whom permission to discharge has been received; or
      •    An authority to discharge has been obtained.

The site will make use of stormwater attenuation to ensure that peak flow rates arising from the proposed
developed will not exceed the existing site’s peak flow rates. Run-off will be discharged via soil infiltration and
sheet flows to minimise flow concentrations and localised flow volumes.

The proposed discharge from the site will therefore not alter run-off conditions in a way that may substantially
damage third party property and remains consistent with the existing drainage characteristics. The proposed
discharge will also improve conditions in the allotment to the south by capturing surface run-off that would
previously drain across this boundary and discharging it to the undeveloped allotments rear of the site. The
proposed point of discharge is therefore able to achieve a lawful point of discharge for the development.




Project number 20220156
File RECOR Stormwater Management Report - 20220156.docx, 2022-08-08 Revision 0                                Page 6 of 26

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