preclude damage by floe ice and debris, and the critical seaward barrels should be capped with concrete.
Also, partial burial of the barrels increases stability.
Concrete Slabs
Wave Height Range: Below five feet.
Photographs of a typical structure were shown on Figure 20. The structure failed for a number of
reasons, including improper filtering, inadequate toe protection, and lack of flank protection. Placed on a
flatter slope, and with due regard for proper design considerations, this type of structure can provide low
cost protection when large slabs are available.
Fabric and Ballast
Revetments using a fabric filter cloth as the slope's armor layer, held in place by some form of
ballast, have not been successful And are not recommended.
BREAKWATERS
Breakwaters are either floating or fixed. Floating breakwaters function at or near the water's
surface and must be firmly anchored to prevent displacement. Fixed breakwaters are constructed on the
bottom and may or may not pierce the water's surface. When they do not, they are called sills. Their
height and porosity determines how effectively they dissipate wave energy.
By trapping sand on their landward side, breakwaters protect the shore while simultaneously
enhancing recreational uses. Unlike groins, they are able to trap sand moving both parallel and
perpendicular to shore. Unfortunately, this sand-trapping (accreting) ability can also cause erosion of
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