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 Selection of Site-specific Stabilization Techniques
5.1.1.5 Corrosion and Abrasion
These mechanisms can greatly reduce the durability of structures which rely on
metallic components for long-term structural integrity. The critical factors are water
chemistry, air quality, and the concentration and velocity of coarse sediment impinging on the
metallic components. A corrosive or abrasive environment does not necessarily rule out the
use of vulnerable techniques, but it does dictate that they be approached cautiously and that
they be carefully designed.
If metallic components are used the most vulnerable structures are the following:
Flexible mattresses of:
Concrete blocks
Gabions
Used tires
Wood;
Dikes; and
Retards.
Three ways of avoiding failure in a corrosive/abrasive environment are:
Select a technique that has a high resistance to corrosion and abrasion, such as:
Stone or other self-adjusting armor;
Rigid armor;
Gabions grouted with asphalt or mastic;
Flexible mattress without metallic components; and
Stone dikes;
Use special components which are highly resistant to the worst-case agent at the
site, such as heavily galvanized or pvc-coated metal and wire, and stainless steel or
synthetic fasteners and strand. Even this may not assure success if highly corrosive
or abrasive conditions exist, particularly if high concentrations of coarse sediment,
high velocities, and highly corrosive water are all present. Even galvanized or
coated components are susceptible to "nicking" of the protective layer during
construction, which may affect their integrity.
Use a "zone" selection concept, the zones being:
Below low water;
Between low water and the permanent vegetation line; and
Above the permanent vegetation line.
Materials in the zone below low water must resist only water-borne corrosive
agents and abrasive sediments. Materials between low water and permanent
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