waterfront facilities, assess their physical condition, and report these 

 assessments to NAVFAC (Code 100) , the Engineering Field Divisions 

 (EFDs), the activities Public Works Offices (PWOs) , and the Public Works 

 Centers (PWCs) . 



To establish uniformity of cost and inspection performance, a survey 

 was conducted in which inspection contractors were consulted to determine 

 the inspection costs by pile material (Ref 1) . This analysis led to a 

 projection for the total cost of inspecting the 1,200 plus waterfront 

 facilities identified for inclusion in this program. However, these 

 projections did not include a standardized procedure for determining the 

 number of piles or elements to be inspected within a facility. 



Based on a review of over 100 inspection reports of waterfront facil- 

 ities (Ref 2) , it was found that the selection of the number of elements 

 to be inspected within a facility does not currently follow any consistent 

 approach. Most of the underwater surveys included a 100-percent Level I 

 (visual swim-by) inspection. The remainder of the inspection then usually 

 focused on areas of suspected damaged through the execution of additional 

 Level II or Level III inspections. The function of each of these levels 

 of inspection is described in Reference 3. Whenever there was a "random" 

 selection process introduced into the inspection, the specifications set 

 for the number of samples to be taken did not follow any statistical 

 basis. 



None of the inspection and assessment reports reviewed identified 

 any standard statistical inference methods to assess the results of the 

 observations. No attempt was made to guarantee that random sample 

 selection was used in the selection of the elements for inspection. 



The concept of using statistical sampling techniques to aid in the 

 planning of underwater inspections was first presented in Reference 3. 

 This report includes a discussion of inspection strategy and is broken 

 into three distinct areas: 



(1) Calibration of equipment (i.e., measurement errors related 

 to the measurement tools) . 



(2) Number of measurements per pile (i.e., the number of 

 measurements needed to provide the required accuracy of 

 estimating the average cross section, thickness, or other 

 measurement parameter) . 



(3) Number of piles to measure (i.e., a determination of the 

 number of piles that would make up a sample needed to provide 

 a required accuracy and confidence level for the assessment 

 of the overall condition and maintenance requirements for 

 the entire structure) . 



Prior to undertaking the formal development of statistical sampling 

 criteria, a survey was conducted to determine what procedures, if any, 

 commercial port authorities used as criteria for scheduling and conduct- 

 ing underwater waterfront facility inspections. This report (Ref 4) was 

 to determine what criteria were used for sampling and how they deter- 

 mined the inspection frequency. It was found that there have not been 



