Engineering Hydrology Plans (IWMP)

4 Conclusions

It can be seen from the results, presented in Table 10 and Table 11 that the
treatment train proposed for the development site achieves the performance
criteria set by the Sunshine Coast Regional Council. Annual Load Reductions of Total
Suspended Solids (TSS), Total Phosphorus (TP), Total Nitrogen (TN) and Gross
Pollutants (GP) between the Mitigated and Unmitigated Scenarios have been met.
It is proposed for the site to implement two detention systems within the catchment
in order to achieve Council’s non-worsening criteria. Table 19 provides a
comparison of the peak existing, developed and mitigated flows. It can be seen that
whilst peaks flows increase at Outlets 2 and 3, the modeled mitigation solutions
ensure non-worsening is achieved. Mitigation to Outlet 1 is not required due to a
reduction in overall catchment area in the developed scenario.
This plan demonstrates that effective treatment of stormwater at the proposed
development can be achieved through the integration of Water Sensitive Urban
Design (WSUD) principles. Through the incorporation of swales, GPT’s and
stormwater reuse tanks, the plan successfully demonstrates:
•    Compliance with the requirements of Sunshine Coast Regional Council’s Load
     Based Objectives;
•    Ecological sustainability in terms of the development’s impact upon receiving
     waters and the viability of the proposed site development; and
•    Compliance with SCRC non-worsening of peak flows in the 2, 10 and 100 year
     ARI storm event.




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