Noosa VMU RFI Response Lodged 23.11.23 · MCU23/0078

       •   Complies with PO11:
           Garden beds in the south-eastern carpark provide the minimum area required, however garden
           beds within the north-eastern carpark do not. In this instance, it is proposed that stratacells are
           utilised to provide the remaining area required under the carpark surface. (Refer LC-01 1.1 Plans).
           This allows for a long run of landscaping through the centre of the carpark, softening the
           hardscape and providing shade in the parking area.

37. Elevations and sections are provided for Main Street, the Civic Spine (Village Green) and the eastern
       car park in the revised Landscape Concept Plan. These elevations and sections reflect the
       requirements under PO2, PO3, PO5, PO6 and PO11 of the Landscaping Code, and depict tree growth
       at 5 years


 Issue – Issue – Flooding, stormwater quality, water efficiency and reuse Issue – Flooding

 The natural drainage channel within Covenant J on Lot 1 provides conveyance for most of the “Noosa Civic” site.
 Peak flood levels within this channel need to be established in order to demonstrate that the development will
 achieve adequate freeboard and flood impacts will not result from the works.

 Information Required:

 38. Provide calculations/modelling for flow within the natural drainage channel within Covenant J on Lot 1 in
     order to establish the peak flood levels in the DFE (1%AEP including allowance for climate change at 2100).
     Provide sections which show the DFE level relative to the minimum opening elevations in the basement car
     park and demonstrate that a minimum freeboard of 300mm is provided.


Response:
38.        A flood assessment of the natural drainage channel within Covenant J on Lot 1 has been
           undertaken to determine peak flood levels in the 1% AEP flood event (with allowance for climate
           change at 2100) under both existing and developed (with stormwater quantity mitigation)
           scenarios. Details of this flood assessment, with peak flood water levels, velocities and water
           depths can be found in the attached revised SWMP.
           The 1% AEP flood event water levels within the natural drainage channel can also be found in the
           revised earthworks sections found in the revised SWMP and Serviceability Report. It is noted that
           these levels are slightly above the minimum basement level, however the minimum opening
           elevation between the basement and Covenant J are a minimum of 1.5m higher than the
           basement floor level based on the architectural drawings. As such, 300mm freeboard between
           the openings of the basement wall and the 1% AEP flood levels is achieved.


 Issue – Stormwater Quantity

 The analysis of stormwater quantity impacts is required to include allowance for climate change, and it is not
 clear whether this has occurred. Detention to mitigate the 63%AEP in order to achieve the Waterway stability
 design objectives is supported. Consideration should be given to whether detention for events beyond the
 63%AEP is required based on analysis of the drainage channel in Covenant J and further downstream system.

 Information Required:

 39.        Provide an updated SWMP and stormwater detention analysis which addresses the following:
            •   Clarify whether rainfall intensities have been increased to account for the effects of climate
                change at year 2100, and if not provide a revised analysis for the 1%AEP which includes allowance
                for climate change.

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