Subject Turf Farm at Gleneagle - Flood Impact Assessment

1 Methodology Aurecon is currently finalising the update for the Logan River Flood Study for Scenic Rim Regional Council. It should be noted that this report is currently still in Draft format. Scenic Rim Regional Council gave permission for Aurecon to use the hydraulic TUFLOW model from this study for the assessment of the Turf Farm at Gleneagle. This TUFLOW model was developed on a 20 m grid spacing which was deemed appropriate to enable assessment of the hydraulic impacts of the proposed turf farm development. Accordingly, the base-case model from the aforementioned study was deemed suitable for use in this flood impact assessment. It was determined that the 720 minute 1% AEP event is critical at the site. The model was only run for the critical event duration to assess any possible hydraulic impacts of the development. Four design scenarios have been assessed by Aurecon. For each scenario a 3D AutoCAD file was provided by Ryacon Engineers which contained the design data for the earthworks pad. This was manipulated and converted into a DEM (Digital Elevation Model) which was subsequently imported into the TUFLOW hydraulic model to generate the ‘developed conditions’ model. 2 Results The hydraulic model outputs were used to generate an afflux map – this is derived from a direct comparison of the base-case flood levels and those of the developed conditions. The resulting afflux