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Missed opportunity to do a proper study : Bay dredging


The Beagle Editor, The Clyde River bar is to be dredge using money Andrew Constance has found and announced yesterday. The Batemans Bay Boaters Association has advocated for the last 15 years to the Member for Bega and others to undertake a scientific study to determine the real sand movement within the Bay and not rely on hearsay when advocating matters relating to the bar or the bridge.

Too frequently (like yesterday) absurd claims have been made regarding the Batemans Bay bar and the impact it’s depth will have on businesses and the boating public. The depth of the bar has varied form .86 to 2.6 m from datum over time irrespective of dredging or other methods that have been employed. Infill rates depend on a number of variables and where the sand comes from and where it goes to has never been tracked.

Sea bars are dangerous and any master of a vessel who crosses them using the best information available (charts, channel leads or local knowledge) does so with great caution. It is just simplistic to think that by deepening the current bar it will become safer and attract more vessels. Any commercial vessel traversing the bar that comes to grief deserves investigation.

The current bar was created because of the rock training wall was constructed and subsequently extended and raised. If the river had been left to meander as it was in the early days it would have turned north at Spinnaker Reach towards the isolated danger mark – where the ships dropped their ballast and then swept past Square Head where the early Pilot Books record the bar to be.

The sand movement in the Bay has never been studied using radio active isotopes. Studies of the sand from the last dredging taken by the Batemans Bay Boaters Association clearly indicated that it was not river sand being removed.

So where does the sand come from to create the bar? Nobody really knows and we the taxpayers will continue to pour more and more money into dredging the current bar without knowing why we are doing it. Other than for a political and Shire agenda.

The current GHD study paid for by RMS is looking at the impact of the old and proposed new bridge on sand movement particularly along Wharf Road and the north shore. This study’s terms of reference could easily be extended to include the sand movement in the wider bay and track the sand at the bar. We would then have conclusive evidence as to what happens in the bay rather than looking backwards as to what may have occurred as a result of a particular event – 1973 super storm or the current bar infill.

So delay the proposed dredging program and hasten the GHD study. Make the results freely available to all. Then start a discussion as to what is best for the Bay.

This would also provide a basis for a comprehensive benefit cost analysis for a cruise ship facility and a deep water marina. It may even support the proposition that we could have floating pontoons in the CBD. Batemans Bay Boaters Association


Image: an excellent example by MARINE DOCK SYSTEMS

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