Construction of the new detached breakwater for Cowes is set to commence in early May. The initial construction phase will be completed this autumn, at which point the gravel core will be visible approximately 5 metres clear of Low Water spring tides.
Following a settlement period, Boskalis Westminster will return in spring 2015 to level up the core and complete the project.
The first stage this year involves the installation of an initial 1.5m layer of sand and gravel using a small trailer dredger, discharging via a floating pipeline to a sprayer barge anchored west/east along the line of the breakwater.
Once the initial layer is sufficiently progressed, the second stage will see the installation of a series of wick drains using a stitcher sited on a large barge. Once the drain installation has been finalised, a geotextile membrane will be laid on top of the sand and gravel layer.
The next stage involves the installation of the gravel pre-load up to approximately 5.0m above chart datum. When the crest levels reach around Mean High Water, gravel will be sprayed against the slopes of the breakwater. Excavators will be utilised to shape the breakwater and retrieve gravel outside of the intended profile.
A nine month consolidation process will then follow over the autumn and winter of 2014-2015, to allow for settlement of the gravel core.
It must be emphasised that the breakwater will resemble a gravel spit during the winter of 2014/15 and will only begin to take its final finished appearance during the 2015 works.
Related:
Boskalis Westminster Wins Cowes Breakwater Contract
[mappress]
Press Release, April 1, 2014