Selection of Site-specific Stabilization Techniques
vegetation must withstand both water-borne and air-borne agents, and to a lesser
degree, abrasion by sediment. Materials above the permanent vegetation line may
not need to be highly resistant if site conditions insure that vegetation will become
established sufficiently well to function as upper bank protection after the metallic
components deteriorate. However, practical considerations of design and
construction may make simply using a single design that will withstand the worst
case less costly than using the "zone concept."
5.1.1.6 Other Hazards
The following destructive agents are potential problems in some cases:
Vandalism;
Theft;
Animals;
Insects; and
Fire.
Selecting a technique which minimizes temptation will reduce problems with
vandalism and theft. Some materials which are obvious targets for vandals and thieves are
posts, boards, concrete blocks and stones of an attractive size and shape, small cables and
wire, and easily removable fasteners. Vandals may write graffiti on the smooth surfaces of
rigid armor revetments and retaining walls. They may snip readily accessible wires, and cut
or build fires on fabric mattress.
Making a potential thief's job difficult will greatly reduce the damage from theft.
Increasing the size of components to make their removal or destruction more tedious, peening
threaded fasteners, and thinly grouting the surface of vulnerable mattresses, may suffice to
keep the work intact. In areas of especially high risk, surveillance arrangements with local
law enforcement or security agencies may be worthwhile. The risk will often be reduced by
the passing of time, because weathering, the growth of vegetation, and the deposition of
sediments serve to make the materials less attractive and accessible to vandals and thieves.
Animals are usually considered in the context of environmental impacts of a
stabilization project. Occasionally, they can be a problem to consider in the evaluation of the
durability of a stabilization method. For example, beavers have a remarkable talent for
girdling, felling, or eating vegetation of all sizes and species. This can be disconcerting if the
success of the project depends upon quickly establishing a strong vegetative cover. Cows,
deer, rabbits, and other animals may also find tender young vegetation on new stabilization
plantings to their liking.
To evaluate the potential for problems related to animals, the designer can inspect
existing vegetation for heavy browsing, and obtain information from local biologists, resource
managers, and agriculturalists. The conclusion will depend on how conducive site conditions
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