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Attachment C further issues response table 2 stormwater
Proposed Bunnings trade centre, Gateway Drive, Noosaville
Response to further issues email of 17 April 2023 (stormwater)
Council request Applicant’s response
Issue A preliminary section of the basin has now been provided within the SWMP as part of the preliminary
The proposed bioretention/detention basin is deep stormwater layout sketch. This shows that the maintenance access will be via a ladder located outside the
compared to the surrounding pavement levels and it bioretention area. However, due to the limited space batters cannot be achieved and the basin will require
has not been demonstrated how adequate walls. Accordingly, safety fencing will be provided around the basin.
maintenance access and landscape integration will
be achieved. It is should be acknowledged that fencing would be provided around the basin in any case, to ensure
Outstanding Information Request customers do enter the basin. This is consistent with the existing basin (that serves the existing retail
Provide additional preliminary design plans, including warehouse). This existing basing also has fencing, as shown below.
design sections, which demonstrate how
maintenance access, safety (without the need for
fencing) and landscape amenity integration will be
achieved for the bio-detention system based on the
depth proposed for the device
The landscape concept design allows for a substantial landscaped zone between the street frontage and the
bio-detention basin. This will contain three tiered planting. The basin will also be landscaped in accordance
with Council guidelines. In combination this will ensure the attractive appearance of the building setback
zone (including the basin) from the street.
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An extract from the landscape concept design is included below.
Issue
Stormwater management details and detention basin
sizing
Outstanding Information Request
Provide an updated SWMP and architectural/design
plans which address the following:
• Off-set the northern retaining wall from the The retaining wall will be offset to allow for a swale to be installed and direct the flows to the stormwater pits
property boundary a sufficient distance such that proposed to diver the external flows through the site. Final sizing of the swale and pits to be confirmed during
the 1%AEP (2100) flows from the external detailed design.
catchment can be collected within the
development site without causing ponding on the This is shown on the catchment plan at Appendix D of the SWMP. (see extract below)
upslope property
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As this is clearly shown in the SWMP it is not necessary to update architectural plans which are conceptual
only. This will be incorporated into the design at detail design phase.
• Updated the figure in Appendix C of the SWMP Appendix C has been amended to correctly reflect the bio basin parameters outlined within the report.
to refer to the correct (updated) filter area and
correctly label the different elements of the bio-
detention basin profile/section
• Explain the reduction in detention volume from
the original submission and provide further
details in relation to the detention modelling:
o Clarify what initial and continuing loss ILSAX has been utilized in drains and the hydrological model parameters have now been added to the report
values have been adopted for pervious and in section 5.1 Table 1
impervious surfaces in the models,
consistent with ARR2019 recommendations
and DataHUB
o Provide a comparison of existing and Rational method peak flow comparison has now been included within the report in section 5.3 Table 3.
developed (unmitigated) flows estimated
from the Rational Method and DRAINS in
order to confirm acceptable results are
achieved
o It appears that rational method results for Results have been amended to correctly show the drains results.
the existing site have been compared to
DRAINS results for the developed site. The
same hydrologic method should be used
when comparing results/impacts
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