Construction of Stabilization Works
and clauses concerning "acts of God" may enter the fray, with final resolution often resting
on legal rather than engineering determinations.
10.2.3 PRECONSTRUCTION VERIFICATION OF DESIGN
If site conditions are likely to change between design and construction to such a
degree that details of the work will require modification, provision should be made for this
in the contract. An effective procedure is to advertise for bids based on general site
conditions, showing sufficient design detail to allow confident bidding, and to state in the
specifications that details of the work will be provided prior to notice to proceed with the
work. The site can then be surveyed and inspected at the last moment that allows detailed
plans for the work to be finalized and furnished to construction personnel on schedule. The
possibility of a claim for changed site conditions still exists, but this procedure reduces that
risk. It also provides for the most effective and efficient final design, and is especially useful
in emergency situations or to meet a compressed schedule for project completion.
10.2.4 STONE GRADATION AND QUALITY
Appendix A contains detailed guidance for designing the gradation for stone armor
for a specific site. However, it is not usually essential that precisely that gradation be
specified. Stone of a similar and equally effective gradation may be commonly used in the
area; if so, it can usually be obtained at a lower cost, and with a high probability of meeting
the specification without intensive inspection. Even if the commonly used gradation requires
a slightly greater blanket thickness total cost may still be less than if a slightly thinner blanket
of a "new" gradation is specified, and the safety factor will be greater.
If standard specifications for stone gradation and quality do not exist within one's own
organization, it is advisable to obtain guidance from large construction organizations in the
region. Such guidance should include specification of stone quality, testing and inspection
procedures, and a list of quarries known to be capable of producing acceptable stone, as well
as standard gradations.
Verifying that the gradation and quality of stone produced for the project meets
specifications can be difficult, because determining the precise gradation of quarried stone
requires tedious and expensive handling of large quantities. Determining stone quality also
requires sophisticated and expensive testing. These difficulties can be reduced by:
Specifying a standard gradation, as discussed above;
Minimizing the number of different gradations used in a contract;