2014-11-17 General Committee Agenda

GENERAL COMMITTEE MEETING AGENDA   17 NOVEMBER 2014




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GENERAL COMMITTEE MEETING AGENDA                                                                 17 NOVEMBER 2014

                   on the concept of setting minimum floor levels as the greater of:
                 (i) the flood level generated by the nominated design storm with ‘design’ blockage conditions,
                     plus the nominated freeboard (in this case the nominated design storm does not refer to
                     the 10% AEP design storm used in the design of the roadway, but the 1% AEP [1 in 100
                     year] storm nominated by the state government)
                (ii) the flood level generated by the 1% AEP design storm with ‘severe’ blockage included, but
                     with no freeboard added to the flood level.
                e  Time restrictions have not allowed me to conduct a detailed assessment of the site based
                   on the AR&R Project 11 Stage 2 report ‘Blockage of Hydraulic Structures’, but with my
                    knowledge of the ‘intent’ behind the Project 11 report | have summarised in Table 1 my
                    recommendations for the use of blockage factors as applicable to the Garnet Street
                    upgrade.
                Table 1 —- Recommended design blockage conditions
                                                       Recommended blockage conditions
                Design of Garnet         Q100 (1% AEP) ‘design’ storm conditions:
                Street upgrade and       20% blockage of culvert inlet for unscreened culverts
                assessing of ‘no             % block      f        aiptet
                worsening’ condition     100% blockage of screened   inlets
                                         100% blockage of solid steel traffic barriers
                                         100% blockage of cable zone {i.e flow passes underneath wires)
                                         of a wire cable traffic barrier system
                                         No increase in flood levels compared to existing conditions if Q100
                                         freeboard to habitable floor levels is less than 300 mm
                                         Otherwise, a minimum Q100 freeboard to habitable floor levels of
                                         300 mm
                Design ‘check’ of        Q100 (1% AEP) ‘design’ storm conditions:
                Garnet Street upgrade | 599% blockage of culvert inlet for unscreened culverts
                and assessing of ‘no         °            f          int
                worsening’ condition      100% blockage of screened inlets
                                          100% blockage of solid steel traffic barriers
                                          100% blockage of cable zone (i.e flow passes underneath wires)
                                          of a wire cable traffic barrier system
                                          No increase in flood levels compared to existing conditions if
                                         floodwaters overtop habitable floor levels
                                          Otherwise, zero freeboard to habitable floor levels
                The setting of minimum | Q100 (1% AEP) ‘design’ storm conditions:
                pares      of ‘new        100% blockage of culvert inlet for unscreened culverts
                                          100% blockage of screened inlets
                                          100% blockage of solid steel traffic barriers
                                          100% blockage of cable zone {i.e flow passes underneath wires)
                                          of a wire cable traffic barrier system
                                          Minimum 300 mm freeboard to habitable floor levels

                 Recommendations with regard to debris management along Cooroy Creek
                 | refer to the recommendaiions contained with the ‘Hydrology & Water’ report of 29 July 2014,
                 page 13. The recommendations presented here with respect to Noosa Council conducting ‘on-
                 going inspections of this culvert’ and the removal of loose debris from the creek, needs to be
                taken in context. In this case | would suggest that these recommendations represent only the

                 Printed: 06 November 2014        CREEKS: CORRIDORS OF OPPORTUNITY                  Page 3.

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