5179Flood Report_REVISION_2_7Feb2021

                                                                                                           Callaghan & Toth




1.0       INTRODUCTION
This Flood Study has been prepared as part of the Reconfiguration of a Lot application to Noosa Council.

The lot contributing to the overall development and subject to this report is shown in Site Location Plan, Figure 1.1
and is described as Lot 3 on RP113733, located at 2 Pearsons Road, Cooroy.

The site is traversed by a tributary of Six Mile Creek, which flows across the north-eastern corner of the lot.

Most of the increased stormwater runoff from the proposed residential areas is proposed to be mitigated by
conventional detention volumes in the detention basin in the park and the increase in size of stormwater pipe from
600dia to 1050 dia.

The development proposal is particularly cognisant of the need to not increase local stormwater peak discharge
rates to the adjoining floodway and to not adversely affect the storage-routing capacity of the floodway.

The assessment process was therefore structured as follows:
     Abstraction of the Year2100 1%AEP flood levels from a flood model of the adjoining floodway (previously
        compiled by Brisbane Stormwater Management Pty Ltd, 2014), and arranging the stormwater detention
        facilities to not intrude into that floodway - as described in Section 2.0 of this report.
     Determination of the required detention volume so as to match the post-development peak discharges to
        the pre-development peak discharges, from 1 year ARI to 100 year ARI, and proposing a detention
        arrangement that will achieve that volume – as described in Section 3.0 of this report.




                                                                                 Site location




Figure 1.1:         Site Location




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2035 2 Pearsons Road – Flood Study – Revision 2                                                 Feburary 2021