Noosa VMU RFI Response Lodged 23.11.23 · MCU23/0078

            •   Consider whether detention for events greater than the 63%AEP are required based on the
                analysis of the capacity of the drainage channel in Covenant J on Lot 1 and the drainage network
                further downstream.
Response:
39.     The SWMP has been revised to incorporate increased rainfall intensities (a uniform 20% increase)
        to account for future predicted storm event intensity and duration increases in the Year 2100, in
        accordance with the Noosa City Plan. These increases have been applied both to the flood
        assessment of the natural drainage channel, and when sizing the proposed stormwater detention.
        The flood study determined that under existing conditions for the 1% AEP flood event in the Year
        2100, the water level at the existing culvert system below Hofmann Drive (south-west of the site)
        is above existing roadway levels. As such, if stormwater run-off from the development site is not
        detained up to the 1% AEP flood event, water depths over Hoffmann Drive will increase for the
        1% AEP flood event due to the proposed development. This is not considered an acceptable
        outcome and thus detention up to the 1% AEP flood event is proposed to ensure no worsening of
        downstream flood levels at the Hoffmann Drive culvert crossing.


 Issue – Stormwater Quality

 The proposed use of an underground proprietary system for achieving the required pollutant load reduction
 targets does not meet the requirements of PO7 of the Water Quality and Drainage Code, which requires the use of
 natural systems and process to enhance landscape and biodiversity benefits, or PO3 of the Sustainable Building
 Design Code.

 Information Required:

 40.     Provide a revised SWMP and design drawings which achieve compliance with PO7 of the Water Quality
         and Drainage Code and PO3 of the Sustainable Building Design Code.
Response:
40.     The attached SWMP has been revised and proposes bio-retention treatment systems only to
        achieve the required water quality run-off objectives, in accordance with the Noosa City Plan.


 Issue – Water efficiency and stormwater reuse

 PO2 of the Sustainable Building Design Code requires rainwater collection and reuse for non- potable uses. This
 does not appear to have been addressed.

 Information Required:

 41.     Provide updated plans and a SWMP which incorporates rainwater/roofwater collection and reuse at
         the site, sufficient to supply external non-potable fixtures such as landscape irrigation and bin
         washdown and internal non-potable fixtures such as toilet flushing.
Response:
41.     The revised proposal provides for adequate roofwater/rainwater collection tanks to be located
        within the at grade and basement carparks for reuse of water for landscape irrigation, bin
        washdown and toilet flushing.
        Refer to the revised proposal plans for locations of rainwater tanks incorporated into the
        development.
        The SWMP and Serviceability Report have both been revised noting proposed locations for roof
        water harvesting tanks for water re-use across the development site. Following the conservative
        methodology that any roof water harvesting tanks may already be full prior to significant rainfall


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