Figure 31 . View of a CORE-LOC with multiple targets 



analysis, horizontal displacements for the nontargeted armor units were similar 

 to those obtained for the targeted units. 



Evaluation of the vertical motions of the additional dolosse revealed that 

 some units moved upward and some subsided. Comparisons of the vertical data 

 for the nontargeted units indicated average displacement of 0.064 m (0.21 ft) and 

 0.067 m (0.22 ft), respectively, for the north and south jetties. The maximum 

 vertical displacement for any point on a dolos was 0.27 m (0.9 ft) on both the 

 north and south jetties. Considering all values obtained for the nontargeted 

 units, 50 percent of the elevation changes were 0.03 m (0.1 ft) or less on both 

 structures. 



Examination of the dolosse armor unit positions for the 1994-1998 period 

 revealed significantly less movement than obtained during previous survey per- 

 iods. However, the more significant movement in previous surveys occurred 

 around the heads of the jetties. During the 1997 rehabilitation, CORE-LOCs 

 were placed around the jetty heads. Dolosse were covered and/or repositioned 

 during this process. Therefore, no correlation in movement could be made for 

 armor units in areas where the more significant movement occurred previously. 

 In addition, the dolosse have been subjected to their environment for about 

 15 years and experienced several storm wave events. This has resulted in the 

 armor units being shaken down. They have settled into the structure, which 

 increases their stability. During the 1994-1998 monitoring period, several storm 

 events occurred. These were generally northeasters that occurred in December 



54 



Chapter 3 Current Monitoring Plan and Data Comparison 



