Appendix E - Stormwater Management Plan

6        CONCLUSION
This Stormwater Management Plan has been prepared to support the Operational Works Application for Stage 2 and
subsequent Stages of the Palm Lakes Cooroy Retirement Community. The outcomes of the stormwater investigations
are listed below:

•   Stormwater Quantity – Hydrological analysis demonstrates that no actionable nuisance to adjoining properties can be
    provided as peak flows at each discharge location from the site have been reduced below existing conditions for all
    storm events up to and including the 1% AEP storm. The proposed peak flow mitigation strategy (involving the
    Northern and Central Detention Basins, integrated with stormwater quality devices) is therefore adequate. Updated
    modelling to incorporate the recent modifications to the Central basin since the Issue A report achieve the same
    outcome and results.
•   Stormwater Quality – MUSIC modelling demonstrates that water quality objectives required by Noosa and the SPP
    (2014) can be met for the proposed development. The proposed Stormwater Quality Management Strategy involving
    Gross Pollutant Trap devices (GPT’s), Bioretention Basins and a Water Quality Control Pond (WQCP, not modelled
    in MUSIC) is therefore adequate. Construction and operational management and maintenance of the GPT’s,
    Bioretention Basins and WQCP is provided in the SMCMP Report. The updated stormwater quality management
    strategy was developed alongside Council and has already been approved. The details provided in this section is in
    accordance with the approved strategy.
•   Waterway Stability Management - Results determined in the hydrological analysis demonstrate the waterway stability
    management requirements will be achieved, as there is a reduction in peak flows during the 63% AEP storm event.

Following MCU approval from Council, this report also addresses the Approval Conditions relating to stormwater
management. This has been summarised in Section 1.3 of this report.




7        RECOMMENDATIONS
It is recommended that this Operational Works design for Stage 2 (including Central Basin and Southern Basin) be
approved on the basis that acceptable outcomes will be provided for stormwater management.

With this submission we seek overall strategy approval for the balance stormwater management works (including the
Central Basin and Southern Basins). We also seek the approval for the Northern Bioretention Basin design however
inflow pipes are subject to future Civil Drainage Operational Works approval. Bio-Pod D2, D3 and the treatment system
for the Age Care Facility are subject to future Civil Drainage Operational Works approvals.




16-001014-01B | STORMWATER MANAGEMENT PLAN                     COOROY RETIREMENT COMMUNITY, TRADING POST
(SWMP) | PALM LAKE RESORTS                                                                 ROAD, COOROY             | 23