Cover Letter, DA Form 1, Plans, Owners Consent, Coastal Environment Assessment · OPW21/0049

Noosa Spit Coastal Protection Environmental Assessment                                                          2
Introduction




         • Dredging of up to approximately 85,000m3 of sand material from the area identified in Figure 1-2,
           by Cutter Suction Dredge

         • The sand extraction zone spans approximately 187,000m2

         • The estimated volume required to fill the sand plugs is 14,000m 3 and 17,000m3 for the northern
           and southern plugs respectively

         • The depth of dredge extraction is to approximately -3m AHD

         • Delivery of the sand to Dog Beach for nourishment purposes will be via a slurry pipeline.

1.2      Existing Environment
         The lower Noosa River and river entrance are highly modified and dynamic environments influenced
         by the prevailing fluvial and coastal processes. The observed trend of shoreline recession at the
         north-facing beach of Noosa Spit, known locally as Dog or ‘Doggie’ Beach, is impacting the social
         and recreational values attributed to the area. Importantly, this beach also forms part of an artificially
         constructed river training/coastal defence strategy that protects property in Noosa Sound and the
         back of Hastings Street.

         Recently, erosion and shoreline recession has resulted in a narrowing of Noosa Spit. Consequently,
         there is concern that the river may eventually break through Noosa Spit at Dog Beach resulting direct
         impact to the adjacent urban areas.

         The area from which sand is to be sourced, sits at the mouth of the Noosa River estuary, and consists
         of ever moving alluvium sand shoals, adjacent to the trained river entrance. Historical images (refer
         to Figure 1-1), shows the dynamic nature of the river mouth. Geotechnical surveys undertaken to
         support previous dredge campaigns (Coffey Geotechnics, 2011) indicate that soils are predominantly
         clean, sands with limited presence of fine materials or ASS. Alluvial sediments are underlain by
         residual soils (consisting of sands, clayey sands and clays) at a depth of approximately 15m below
         the bed level. Based on this previous geotechnical data, Coffey have concluded that ‘dredging of the
         material from the Noosa River can be expected to have relatively quick settlement times’.




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