As reported in our March newsletter, the principles and methodology for construction of the new detached breakwater have been finalised and can now be viewed on the new CHC website at: cowesharbourcommission.co.uk/breakwater.
During May, a dredger and barge will be working almost continuously within the ‘Exclusion Zone’ in order to lay down the first 1.5 metres of the breakwater’s gravel core.
A conventional trailer suction hopper dredger, which emits no greater noise during its operation than a normal ship of similar size, will deliver approximately three loads a day and will be on location, discharging for approximately 1.5 hours per load before disconnecting from the pipeline and sailing away from the area. There will be little noise audible from the material being pumped along the floating pipeline, or from the spreader pontoon which will use hydraulic winches to move on the anchor wires during the spraying operation. See diagram (Fig 1) in Local Notice to Mariners No. 08(T) of 2014.
Artist’s impression of the breakwater at Sept 2014 – High Water – by Boskalis Westminster
During the course of the consolidation period (winter 2014-15), the gravel being used for the second pre-load level will be somewhat influenced by the wave action; this is expected to consist of gravel moving down the slopes of the breakwater. The whole breakwater will be surveyed regularly and where it is assessed that the gravel has moved, to the extent that it is either going to affect the pre-load characteristics, or is being moved out of the footprint, then measures will be taken to replace the gravel back up the slopes.
Artist’s impression of the breakwater at Sept 2015 – High Water – by Boskalis Westminster
Please read our May and June newsletters for further updates on the breakwater construction, including specific safety and navigational information in advance of the J.P. Morgan Asset Management Round the Island Race.
Go to cowesharbourcommission.co.uk/breakwater for further information on the construction of the Cowes breakwater.
Top photo: Boskalis dredger off Cowes.