REPS - Updated SWMP

5. CONCLUSION
Engeny have completed this SMP for Devtex Nominees Pty Ltd to represent the proposed townhouse development to be incorporated into
a portion (located on approved lots 1, 2, 3, 48, 49 and 50) of a previously approved reconfiguration of Lot (Planning and Environment Court
(Appeal No: 118 of 2006) and Operational Works application (Ref: OPW15/0133 dated 6 March 2017)). The approved roads, lots and
detention / bioretention basins have been constructed as part of the Operational Works approval. This assessment has been completed to
determine if the approved / constructed detention and bioretention basin can manage the new townhouse site within the approved
developed.

The following summarises the findings from the Stormwater Management Plan for the proposed development at 73 Eumundi Noosa Road,
Noosaville.

Stormwater Quality

The existing bioretention basin (403m2 filter surface) is suitable to achieve the Water Quality Objectives outlined in the NSC Planning Scheme.
Details of the water quality modelling and sizing of the treatment train are summarised in Section 3.

Stormwater Quantity

The existing detention basin (1,019 m3 storage volume) is suitable to provide mitigation for the stormwater quantity flows, with only minor
increases noted in peak flows in the smaller events (<10% AEP) and the 1% AEP, with reductions in the 5% and 2% AEP events. As the
catchment details have not significantly changed between the approved SMP and this assessment, it is considered the minor increases are a
result of the change in the hydrologic method from ARR1987 to ARR2019 and the updated catchment losses. As such it is considered that
these minor increases would not result in actionable nuisance, and the outcome remains consistent with the approved SMP.

In addition, a new 50m3 detention tank is proposed within the townhouse site to manage flows to ensure design outcomes within the existing
downstream stormwater is maintained, with flows in the 10% AEP mitigated back to align with the original design (refer Section 4.2)

Details of the water quantity modelling is summarised in Section 4.

Preliminary Engineering Plans

Preliminary engineering plans detailing the stormwater management arrangement is provided in Appendix B.




73 EUMUNDI - NOOSA ROAD, NOOSAVILLE I BBNE00529_0002_0001-REP-001-2                                                                         19