Sheet Piling. Sheet pile groins (Figure 50), an old and proven means of shore protection, can
employ timber, steel, or aluminum sheeting. Toe protection or adequate penetration is required to insure
the structure's stability. Recommendations for sheet pile bulkheads and breakwaters also apply to groins.
Timber and Rock. Many structural forms are possible for timber and rock groins. Figure 51
shows a timber crib structure that retains a stone fill. Care must be taken to insure that the rock is larger
than the gaps between the timbers. Rock has escaped from the offshore compartment of the groin in the
figure for that reason. Treated timbers should be used and securely fastened together with long wrought-
iron or coated steel rods that are threaded at the ends to accommodate washers and nuts.
Beach fills are quantities of sand placed on the shoreline by mechanical means, such as dredging
and pumping from offshore deposits, or overland hauling and dumping by trucks. The resulting beach
provides some protection to the area behind it and also serves as a valuable recreational resource.