less desirable habitat.
2. Sheet-pile groins require pile drivers 'for construction and may require
pile removal equipment for repair.
The construction of rubble-mound groins
involves the use of a variety of heavy construction equipment. Access to
the construction site must be available if such equipment is required. In-
stallation of steel and concrete sheet-piles involves skilled labor, high
material and fabrication costs, and heavier construction equipment than that
required for timber sheet-piles.
3. P r e t r e a t m e n t , to retard deterioration, is always required for timber
and may be required for steel used in saltwater.
In addition, maintenance
is necessary to control the rotting and splintering of wood, the corrosion
of steel, and the spalling of concrete. Timber structures often can be
repaired by bolting new members over broken ones or in place of damaged
sections, but damaged components of steel and concrete structures must be
entirely replaced. Rubble-mound structures can be repaired by adding new
quarrystone to the damaged area.
REFERENCES:
U.S. ARMY, CORPS OF ENGINEERS, COASTAL ENGINEERING RESEARCH CENTER,
3d ed., Vols. I, II, and III, Stock No. 008-022-
00113-1, U.S. Government Printing Office, Washington, D.C., 1977.
U.S. ARMY CORPS OF ENGINEERS, COASTAL ENGINEERING RESEARCH CENTER, Fort
Belvoir, VA., 1981:
CETN-111-7, "Bulkheads - Their Applications and Limitations,"
C E T N - 1 1 1 - 1 1 , "Protective Beaches - Their Applications and Limitations."
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