Appendix D - Engineering Assessment · OPW26/0090

An aerial image of the site is shown in Figure 1. For further detail of the existing site, refer to the detailed
survey plan prepared by Surveyors Co dated 08 May 2025.




Figure 1 Subject Site Aerial (Source: Noosa Intramaps)

Flooding
The subject site is not flagged by Council’s Flood Hazard Overlay Map. No recommendations are provided.

Stormwater Quantity
A Rational Method hydrologic model in accordance with the Queensland Urban Drainage Manual (QUDM)
was developed to quantify the stormwater discharge for the major and minor storm event. The following
parameters were used for the model:
    - Storm event recurrence intervals were selected in accordance with QUDM Tables 7.3.1 and 7.3.2:
            o Minor event: 0.5 EY
            o Major event: 1% AEP
    - Intensity, Frequency, and Duration rainfall data was sourced from the Bureau of Meteorology’s
        2016 dataset. Intensities were multiplied by 1.15* to estimate present-day intensities due to
        Climate Change.
    - Catchment coefficients and areas were obtained by comparing the detailed survey against QUDM
        Table 4.5.3
    - Time of Concentration was taken as the standard inlet time of 5 minutes (QUDM Section 4.6.4)
    - In the ultimate post-development scenario, it is assumed that Lot 1 will be developed to
        approximately 75% impervious, and Lot 2 will remain as-is.



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