Stormwater Management Plan 12_05_26

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TABLE 3: MODEL LOSS PARAMATERS

    Surface Type        ARR Data Hub       ARR Data Hub       Adopted IL(mm)             Adopted CL
                          IL (mm)           CL (mm/h)                                      (mm/h)
 Impervious                    -                  -                   1                           0
 Pervious                      32                2.6                 25                          2.6
The DRAINS model layout is for the existing, developed, and mitigated case is shown in Figure 3




FIGURE 3: DRAINS MODEL LAYOUT

4.5.4 Existing & Developed Case Summary
DRAINS modelling was undertaken, peak flow summary of the existing case and developed case for
the site are shown in the following Table 4. The peak discharges were estimated using all storm
ensembles across 5-minute to 360-minute durations.
TABLE 4: DRAINS PEAK FLOWS

    Storm Event        Existing Case     Developed Case         Difference                Difference
       (AEP)               (m3/s)            (m3/s)               (m3/s)                      (%)
        63%                 0.041              0.073               0.032                      78.0%
        39%                 0.063              0.091               0.028                      44.4%
        18%                 0.092              0.119               0.027                      29.3%
        10%                 0.110              0.139               0.029                      26.4%
         5%                 0.134              0.171               0.037                      27.6%
         2%                 0.154              0.199               0.045                      29.2%
         1%                 0.174              0.227               0.053                      30.5%
      1% (CC)               0.218              0.283               0.065                      29.8%




12 May 2026