Attachment E - Stormwater Management Report · MCU24/0112

2. 2       Law fu l P oint of D is ch ar ge

There is currently no stormwater infrastructure within the proposed development site. Roof water from
the existing dwellings is assumed to discharge to the Hilton Tce kerb and channel via kerb adapters
and the remainder of the site assumed to discharge toward Hilton Tce and the northern boundary as
overland sheet flow

Stormwater drainage for the proposed development shall ensure no adverse impact on upstream,
downstream or adjoining properties. The proposed lawful point of discharge for the development shall
be the existing stormwater infrastructure on Hilton Tce, with the stormwater infrastructure to be
extended along Hilton Tce and a connection into the existing manhole proposed (Asset ID 189981).
Minor amounts of stormwater will continue to discharge to Hilton Tce as per existing site conditions.
New on-site stormwater infrastructure shall be constructed to direct stormwater to the lawful point of
discharge to ensure no adverse impacts on adjacent properties.

Refer to Appendix B for further information regarding the proposed stormwater works.

2. 3       Ups tr e am D r ain ag e C onne ct ion

The development site does not have any upslope properties unable to gravity drain to a lawful point of
discharge.

2. 4       Flood ing

A Noosa Council Flood Information Certificate has indicated that the proposed development site is
within the flooding and inundation overlay mapping, with the defined flood event the 1% AEP Under
2100 Climate Change Conditions. The certificate identifies a defined flood event level (DFL) of 2.40m
AHD. To ensure immunity to flooding throughout the site, the building floor levels are set at 2.70m AHD
as a minimum to ensure 300mm freeboard is achieved and is in line with the requirements. Refer to the
flood information certificate in Appendix D.

3      STO R M WAT E R Q UA N TIT Y M AN AG E ME NT


A detailed stormwater quantity analysis of the existing and developed site conditions has not been
undertaken as the proposed development's final impervious area is considered in line with existing
conditions. It is considered that as a result of the proposed development, it is unlikely to increase the
run-off to such an extent that the downstream drainage cannot cater for the site as it is already
developed to its full potential. It is also noted that stormwater detention on the proposed development
site would not be of benefit in reducing adverse impacts on downstream roads and adjoining
properties.

4      W AT ER Q U AL IT Y M A NAG E M EN T


4. 1       O pe r at io na l Ph a se

The proposed development must address the State Planning Policy (SPP 2017) as the development
site area exceeds 2500m2. The development shall ensure that environmental values of receiving waters
downstream of the development are maintained or enhanced during the construction and operation of
the development in accordance with State Legislation and Local Government requirements. The
stormwater quality management proposed for the development are required to achieve the following
pollutant load reduction objectives in accordance with SPP requirements for South-East Queensland
(south):

       •    ≥ 80 % reduction in total suspended solids load (TSS)


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