24-01-2020 - Appeal No. 245 of 2019 - Final Order of Judge Rackemann · 51987.2951.01

                  hoc basis local variations in approach and that the BMT WBM (2018) report was endorsed
                  by both the State and the Council.
      RECESSION DUE TO SEA LEVEL RISE

160   a.   Points of agreement
           i)     The Bruun Rule is the agreed methodology for calculation of the estimated shoreline
                  recession due to sea level rise.
           ii)    The Bruun Rule assumes uniform physical characteristics of the sand across and through
                  the beach profile
165        iii)   The predicted sea level rise by 2050 is 0.3 metres, 2070 is 0.5 metres and 2100 is 0.8
                  metres.
           iv)    The depth of closure for assessment of this component of the erosion prone area is ‐
                  12m AHD
      b.   Points of disagreement
170        i)     PP opinion is that the height of the dune that should be adopted for this assessment
                  should be 17m AHD based on site survey and not 4.5m AHD as adopted by BMT WBM
                  (2018). This gives an active beach width of 550 metres and therefore a recession of 5.7
                  metres by 2050 and 15.2 metres by 2100.
           ii)    NC says that until the State Government and Council carry out more details assessments
175               of coastal erosion for regional planning, it would not be appropriate to adopt on an ad‐
                  hoc basis local variations in approach and that the BMT WBM (2018) report was
                  endorsed by both the State and the Council.
      DUNE SCARP RECESSION

      a.   Points of agreement
180        i)     The Dune Scarp component is based on the angle of repose for dry sand (i.e. 34o) and
                  does not consider the actual geotechnical stability of the slope.
      EROSION PRONE AREA CALCULATION

      a.   Points of agreement
           i)     The erosion prone area is a conservative estimation of erosion vulnerability and does not
185               consider the durability of underlying soil/rock layers in the profile.
      COASTAL BUILDING LINE

      b.   Points of agreement
           i)     The Coastal Building Line is an arbitrary line originally created by the former Beach
                  Protection Authority to allow for beach erosion and accretion associated with storm
190               events to occur without impacting on infrastructure.
           ii)    Both BMT WBM (2018) and Omtrek Pty Ltd assessments have shown that the subject
                  property is outside of the short‐term erosion component of the erosion prone area.




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