Stormwater Reporting · RAL22/0021

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Discharge to Noosa Drive pre-development site parameters:

Area: 1447m2
Fraction impervious: 39%
Average slope: 33%

Discharge to Noosa Drive post-development site parameters:

Area: 934m2
Fraction impervious: 4%
Average Slope: 33%

Using the above parameters, the stormwater discharge in the pre-development and post-
development scenarios to Noosa Drive were calculated as shown in Appendix B and
summarised in Table 2. It is noted that the post-development flows have decreased compared
to the pre-development case due to the future roof areas discharging to the south towards
Picture Point Crescent instead of discharge over the northern boundary towards Noosa Drive.
Therefore, the proposed development will have a non-worsening effect on the peak stormwater
discharge towards Noosa Drive and the surrounding properties.

                      Table 2 – Site peak flow discharging to Noosa Drive


                                             Peak Flow (l/s)
        AEP
                   Pre-development        Post-Development             Difference

        39%                40                      30                       -10
         1%                110                     70                       -40


Conclusion

This Stormwater Management Plan (SMP) has shown compliance with the stormwater
drainage requirements outlined in the Noosa Plan (2020). This site based SMP has
demonstrated that efficient management of stormwater runoff for the proposed development
is possible by adopting the stormwater strategies set out in this report.

Trusting the above is to your satisfaction. Should further information be required please contact
this office.

Yours faithfully
COVEY ASSOCIATES PTY LTD



ALLISTER GAFFNEY
Civil Engineer
BEng(Civil), MEng, RPEQ 24345