30. Subjection of Plan R4S2 to the abbreviated storm-surge hydrograph 

 resulted in minor damage. Two primary armor stones were displaced and several 

 others shifted slightly in place. The stability response of this plan was 

 considered acceptable. Photos 21 and 22 show the after-testing condition. 



31. Following completion of the abbreviated hydrograph tests, the 

 structure was subjected to the 13-hr hurricane storm-surge hydrograph. Again, 

 an acceptable stability response was exhibited. Although several armor stones 

 shifted positions slightly, none were displaced, and the functional and struc- 

 tural integrity of the revetment was maintained. Photos 23 and 24 show the 

 structure after completion of step U, and Photos 25 and 26 show the condition 

 at the conclusion of testing. Comparison of these photographs with Photos 21 

 and 22 indicates that very little change occurred during exposure to the 13-hr 

 storm-surge hydrograph. 



Plan R4S3 



32. After the determination that Plan R4S2 was an acceptable design in 

 terms of revetment stability, there was some concern about the amount of over- 

 topping observed with certain wave conditions. Discussions with SAW resulted 

 in a proposed modification to the recurved seawall. For aesthetic reasons, it 

 was felt that the crown elevation of the seawall should not be increased; 

 therefore, the overhang at the top of the seawall was extended seaward by 2 ft 

 as shown in Figure 7. 



33. Plan R4S3 (Photos 27 and 28) was tested to determine whether the 

 structural alteration would affect revetment stability and to compare the 

 overtopping by visual observation. The revetment of this plan was the design 

 which had proven adequate in Plan R4S2. 



34. Exposure of Plan R4S3 to the abbreviated hydrograph resulted in no 

 damage. There was some minor in-place rocking and shifting of several armor 

 stones, but no stones were displaced. Further subjection of the structure to 

 the 13-hr storm-surge hydrograph yielded similar results, and it was evident 

 that Plan R4S3 was acceptable in terms of revetment stability. The after- 

 testing condition is shown in Photos 29 and 30. 



35. During the previous testing of Plan R4S2, significant overtopping 

 was noticeable at the +8.6 ft swl with 12-sec and particularly l4-sec waves. 

 Although no quantitative measurements of the amount of overtopping were per- 

 formed, visual observations indicated that Plan R4S3 significantly reduced the 

 overtopping. 



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