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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; 
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