Selection of Site-specific Stabilization Techniques
to remain effective, and that expense should be accounted for in the life-cycle
Contingencies are normally expressed as a percentage of the estimated cost,
but if unpredictable changes in site conditions or materials and fuel costs
would impact some methods more than others, good practice would be to
weight the estimate of contingencies accordingly.
If precise cost estimates to compare techniques cannot be made, and the work is to
be contracted, alternative bid items can be used to allow final selection of techniques after bid
opening. However, the extra effort required for detailed design of more than one method may
not be worthwhile.
5.3.2 AVAILABLE RESOURCES
Resources that will be available for the construction of a bank protection project are
in the form of funds, labor, materials, and equipment. One of these will be the critical
constraint for a specific project.
Funds are usually the greatest constraint on selection of the preferred technique. The
sponsor of the proposed work may have a limited amount of funding, and any project that
costs more than that simply cannot be built. A requirement that the calculated benefits exceed
the project cost may be a similar constraint. Unfortunately, the laws of physics cannot be
repealed to fit these constraints. Selection of an inadequate technique simply because it could
be built within available funds will obviously be a mistake. Funds spent to construct such a
project are wasted, the remnants of the work may create problems, unfavorable publicity may
prejudice or preclude future efforts, and the engineer's reputation and credibility suffer.
It is the designer's duty to insist on adequate design, although works built for research
or demonstration purposes, or works for which project authority allows speedy reinforcement
if necessary, may be designed on the thin edge of adequacy. In this situation, the increased
likelihood of failure, and the probable need for rehabilitation work if the project is to remain
functional, should be recognized and provided for in the initial stages of project planning.