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

Noosa Spit Coastal Protection Environmental Assessment                                                     1
Introduction




1        Introduction
         The Noosa Spit at Dog Beach is narrowing and is at risk of a breakthrough, primarily driven by
         channel migration processes. Works completed in 2013 have only stabilised the western extent of
         Dog Beach. The rate of shoreline recession through the middle section has increased and the
         channel adjacent to Dog Beach is now commonly used by recreational and commercial vessels.

         The importance of maintaining The Spit and avoiding a breakthrough is primarily related to protecting
         existing development within Noosa Sound and the back of Hastings Street. The consequence of a
         breakthrough includes:

         • Reduced attenuation of the ocean tide and increases to peak high tide water levels in the lower
           Noosa River. This reduces the freeboard for waterfront development and therefore increases the
            likelihood of flooding driven by coastal and/or fluvial processes.

         • Rapid and unpredictable morphological change following a breakthrough and further loss of
           coastal land and open space that shelters existing development.

         A Shoreline Erosion Management Plan (SEMP) was developed to quantify the combined dynamics
         of the river entrance and Noosa Main Beach investigate impacts of various river mouth alignments,
         simulate the impacts of a breakthrough event, and propose erosion mitigation options for Dog Beach
         (BMT, 2019).

         A number of design options were investigated as part of the SEMP; however it was determined that
         the preferred design involved placing sand plugs at either end of Dog Beach. This involves using a
         small cutter suction dredge and slurry pipeline to relocate sand from the adjacent Noosa River
         estuary to the two locations. Approximately 85,000m3 of sand would be needed to form the two plugs
         and nourish the shoreline.

         Over time the plugs will be gradually modified by the flood tide currents with sediment eroded from
         the crest and likely deposited in the adjacent channel area. This could be described as a gradual
         ‘smoothing’ of the constructed sand plugs.

         This will relieve erosion pressure at the Dog Beach shoreline and will promote the development of a
         central channel. The project will restore and maintain the existing recreational beach and redirect
         boat traffic away from the Dog Beach Channel, providing a safer environment for swimmers.

         This document supports a development approval application for owners consent and subsequent
         operational works (also encompassing a number of other approvals) and examines the Matters of
         State Environmental Significance (MSES) that may potentially be impacted by the project, the
         significance of that impact, the controls and/or mitigation framework to be applied and finally, the
         residual effects relevant to the Environmental Offsets Act 2014.

         A pre-lodgement meeting was held with state agencies in September, 2020; a formal pre-lodgement
         response is attached in Appendix A.

1.1      Project Description
         The project will involve the following activities:



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