21-0288-FS001-V2_GlenridgeDr_FS-reduced

      4.3.2.7. Severe Storm Assessment

      A severe storm assessment was completed for the 1% (2100) AEP event assuming all of the
      stormwater culverts are 100% blocked to ensure the future dwellings within the development
      site do not become inundated and no new flow paths are formed that may impact
      adjoining properties.
      The assessment found that the building envelopes are not impacted by the 100% blocked
      scenario with a flood level increase of up to 0.08m noted, which is less than the minimum
      0.3m freeboard required. It is also noted that no new flow paths form as a result of the 100%
      blocked scenario and adjoining properties are not impacts.
      Whilst it is not a design requirement for the 100% blocked scenario to achieve QUDM design
      requirements, a comparison against the QUDM road drainage criteria has been made for
      some context. In the 100% blocked scenario, the depth of flow exceeds the 0.2m QUDM
      depth criteria in the upstream lane (with depths up to 0.25m noted), however, is less than
      0.2m on the downstream lane. Flow velocity is up to 1.75m/s. Approximately 80m of the
      road has a hazard greater than the 0.3m2/s QUDM hazard criteria (with hazard up to 0.5m2/s
      noted).
      A flood depth map for this scenario is provided in Appendix H.



      4.3.3. Flood Hazard Overlay Code Response

      Code responses to Flood Hazard Overlay Code is presented in Appendix I.




21-0288-FS001-V2 | Flood Investigation | 60 Glenridge Drive, Cooroibah                                | 16