PA3660-Coastal Hazard Assessment - 4 arakoon

                                                Project related




Figure 6-7 Dune height iterative methodology


6.2.4           Summary of the Erosion Prone Area Reassessment
The erosion prone area reassessment for this site has been undertaken in accordance with the
Department of Environment and Heritage Protection (2013) requirements with a planning period of 100
years to accommodate the asset lifespan of the proposed house. We have considered the effect of beach
erosion associated with a 100-year ARI storm event.

The site-specific erosion prone area calculated for the site is 80 metres, measured from the seaward toe
of the frontal dune (2.25 meters AHD). It's worth mentioning that there is a 40% safety factor (19m) built
into this EPA width of 80mThe components of the erosion prone area for 4-6 Arakoon Crescent, Sunshine
Beach are presented in Table 6-6 and the spatial extents are shown in Figure 6-8.

The assessment presented above indicates that the proposed build seaward of the coastal building line
will not be directly impacted by erosion up to 2100. However, if erosion does extend back to the zone
indicated the building may be located on a zone of reduced foundation stability. The building will therefore
be designed with footings extending to a level below the zone of reduced foundation stability.

The possible erosion cut, from the EPA assessment is provided in Figure 6-9. The advice of a
Geotechnical Engineer will be required to inform the design of the house to accommodate future site
conditions and implement the management measures in the Landslide Risk Management Manual
(Australian Geomechanics, 2007) where suitable.


Table 6-5 Reassessed Erosion Prone Area for 4-6 Arakoon Crescent, Sunshine Beach
 Erosion Prone Area Component                          100- year ARI Event

 Long-term Erosion (m)                                         10

 Short-term Erosion (m)                                        19

 Recession due to 0.8m SLR (m)                                 18

 Safety Factor                                                 1.4

 Dune scarp slumping (m)                                       14

 Erosion prone area Width (m)                                  80



11 April 2024        4-6 ARAKOON CRESCENT, SUNSHINE BEACH                    PA3660-RHD-XX-ZZ-RP-Z-0001   32