Selection of Site-specific Stabilization Techniques
methods which are obviously infeasible, for that project. For example, if the proposed project
is on a shallow or ephemeral stream, then an irrelevant factor would be "Use In Deep
Water." Similarly, a method can be immediately eliminated from further consideration if a
severe deficiency in even one relevant factor precludes that method from being effective or
environmentally acceptable. For example, if the work is to be constructed in deep water, then
some types of retards would be infeasible to construct. The number of factors and the
number of alternative methods which will be eliminated in this initial iteration will vary,
depending upon the complexity of project circumstances and the experience of the evaluator.
An evaluator with sufficient experience may be able to make a competent selection simply by
objectively and qualitatively evaluating the basic factors that are pertinent to the project,
without further iterations.
The second iteration can consist of assigning qualitative ratings to each remaining
protection method for each remaining factor. The form of these ratings can be "+" for a
favorable rating, "-" for an unfavorable rating, "0" for a neutral rating or for a factor that is
not relevant to a particular technique, and "?" if the rating cannot be determined at this point
in the analysis. A qualitative rating of the importance of each factor will be inherent in this
iteration. For example, a deficiency in resistance to fire is not usually as serious as a
deficiency in ability to adjust to scour. The end result of this iteration will be the identification
of seriously deficient techniques, which can then be eliminated from further consideration.
If the optimum technique has not been identified by this point in the process, the final
iteration can consist of assigning numerical ratings to the remaining techniques, with each
technique being given a rating for each factor of effectiveness, environmental suitability, and
economics. The numeric scale for these ratings is a matter of choice, but as a practical matter
one is not likely to be able to distinguish more than five levels; for example, the ratings could
range from "1" for "poor" or "least favorable," to "5" for "excellent" or "most favorable."
In addition, it will usually be appropriate at this time to numerically weight each factor
according to its importance to the success of the project, with the weight being based on site
conditions and the project sponsor's needs and capabilities. Also, an approximate estimate
of costs for each remaining method will probably be appropriate at this point.
The preferred method can perhaps now be identified by summing the scores, and
considering the total score for each method along with estimates of cost. If the choice is still
not clearcut, more detailed estimates of cost can be prepared in order to make the final
determination. If uncertainty still exists at that point, the evaluator can select the protection