2022-02-14 General Committee Meeting Agenda

GENERAL COMMITTEE MEETING AGENDA   14 FEBRUARY 2022




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GENERAL COMMITTEE MEETING AGENDA                                                  14 FEBRUARY 2022

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           Small capacity (no grate and small lintel)      Damaged lintel and uneven grate
           Figure 3 — Examples of stormwater inlets within catchment (less than current standards}

           When overtand flows occur into 28 Toulambi St, the extent/width of the flowpath is not currently
           known. The frontage of 28 Toulambi St is relatively flat however and levels increase rapidly
           beyond the frontage of 28 Toulambi St. It is possible that some flow could also enter the frontage
           of the subject site from the sag point during such overtopping events, though this is considered
           unlikely and would be expected to be limited to the lowest point of the frontage (if it occurs).
           Once surface flows have entered 28 Toulambi Street, the direction of travel is highly dependent
           on localised surface features such as driveways, fencing, and raised garden beds. Based on the
           current site features it is possible that at least a portion of the surface flows from 28 Toulambi
           Street would enter the lower portions of the subject site during a major runoff event, before
           entering Pinarro Park.
           In terms of hydrogeology, no springs were observed during the site visit. The ‘waterway’ through
           Pinarro park appears to have headwaters originating at the headwall from the stormwater outlet
           from Wyandra St and no defined channel or flowpath was observed within the subject site

           Implications for Development of 30 Toulambi St
           The hydrologic constraints and risks are shown qualitatively in Figure 4. This Figure shows the
           expected preferential direction of overland flows based on the contour data and site inspection
           and are not intended to show the extent (width) of inundation.
           Overall, it is recommended that further analysis (modelling) is undertaken in order to quantify the
           extent of overland flow flooding which effects 28 and 30 Toulambi St in the 1% AEP event
           {including allowance for climate change). The identified overland flow flood extent should then be
           avoided, and sufficient (300mm) freeboard provided to any proposed building finished floor levels
           above the modelled overland flow flood level.
           It is recognised however that the subject site has over 4.5m of fall and therefore the implications
           for development do depend on the proposed built form and location within the lot.
           lf the driveway can be located on the high side of the lot frontage and the built form provided as
           elevated pole construction towards the front of the lot, then the hydrologic risks identified in the
           preceding sections would be minimised and Council may be willing to accept the residual risks
           without further analysis.

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