Attachment 7 - Flood Impact Assessment - Covey · 132005.638.06

                                           Table 3-3 - Developed Hydraulic Structures
                                  Type                Upstream      Downstream
                                C=circular           Invert Level   Invert Level         Size    No. of
                     ID
                               R=box culvert           (m AHD)        (m AHD)           (mm)     Pipes

                   DEV01              R                 12.310        12.200       2100 x 1500     6


         3.14    Developed Case Scenario

         The changes to the developed case scenario included:
             •      A design TIN to represent finished elevation levels for the proposed development site at each
                    stage of the development. Refer to Figure 2-3 for the developed case topography adopted
                    for each development stage in the model;
             •      Added a set of culverts for the road crossing at the existing clean water drain;
             •      Update the impervious area to represent the proposed development site; and
             •      Updated Manning’s n roughness coefficients and soil infiltration rates based on values shown
                    in the developed model Manning’s maps in Appendix B.




Flood Impact Assessment                                                                                   Page 14 of 25
Project No 244035 | Ref No M25-0479Rpt – Issue A – January 2026