Table 8. Estimated Maintenance 



Type of 

 Maintenance 



Area 



Remaining 



(%) 



Equivalent 



Diameter 



(in) 



Estimated % 



Smaller 

 Sample 



Larger 

 Sample 



Pier 14 



None 



Wrap the Pile 



Concrete Jacket 



Replacement 



>95 

 75-95 

 50-75 



<50 



>11.0 



9.8-11.0 



8.0-9.8 



<8.0 



79.4 



18.2 



2.2 



0.0 



78.2 



18.6 



3.1 



0.0 



Pier 13 



None 



Wrap the Pile 



Concrete Jacket 



Replacement 



>95 

 75-95 

 50-75 



<50 



>11.0 



9.8-11.0 



8.0-9.8 



<8.0 



71.6 



19.0 



8.5 



0.7 



72.6 



19.2 



7.5 



0.5 



Pier 12 



None 



Wrap the Pile- 

 Concrete Jacket 

 Replacement 



>95 

 75-95 

 50-75 



<50 



>1 1 .0 



9.8-11.0 



8.0-9.8 



<8.0 



77.8 



14.6 



6.7 



0.7 



79.8 



15.0 



4.7 



0.2 



Pier 11 



None 



Wrap the Pile 



Concrete Jacket 



Replacement 



>95 

 75-95 

 50-75 



<50 



>11.0 



9.8-11.0 



8.0-9.8 



<8.0 



86.3 



12.9 



0.7 



0.0 



81.4 



16.6 



1.9 



0.0 



Smaller sample size - 30 for all piers. Larger sample sizes 

 for piers 14, 13, 12, and 11 are 205, 183, 147, and 117, 

 respectively. 



Table 8 compares the estimates of the percentages of piles in each 

 of four area-remaining categories. The four maintenance criteria inter- 

 vals were based upon an assumption that an 8-inch-diam pile was the 

 minimum acceptable diameter. The sample sizes used in the measurements 

 are in parentheses beneath the last column heading. The areas were 

 calculated from the diameter measurements. The differences between the 

 estimates for the respective sample sizes are very small. As more 

 samples are taken, the confidence intervals about the mean values (see 

 Table 8) are reduced. However, as an example, the reduction of the 

 confidence interval by 35 percent requires three times the number of 

 samples. For a pier in good condition, it is probably not worth the 

 additional expense of gathering additional samples. 



37 



