Plans Tested and Results 



18. Revetment stability tests were begun with the vertical seawall in 

 place and a total of four plans were subjected to the abbreviated storm-surge 

 hydrograph before a stable design was obtained. Throughout this series of 

 tests, it was found that of the 6-, 8-, 10-, and 12-sec waves, those with a 

 period of 12 sec were the most severe in terms of revetment stability. 



19. Common characteristics of all plans were the use of a toe elevation 

 of -10 ft msl, 5-ton stapods, and filter and underlayer stone weights of 2 to 

 60 lb, and 150 lb, respectively. Also, armor materials seaward of the stapods 

 were considered sacrificial and their movement was not considered in evaluat- 

 ing the stability response of the various plans. Observations of this mate- 

 rial during testing showed that this material was usually dragged downslope 

 and did not physically impact the stapods. Details of the plans tested and 

 general results are discussed in the following paragraphs. 



Plan R1S1 



20. Plan R1S1 (Plate 3, and Photos 1 and 2) was constructed to a crown 

 elevation of +4,5 ft msl, with the stapods resting on the 2- to 60-lb filter 

 stone (Wc). Weights of the primary armor stone (Wp) and toe-protection armor 

 stone (Wo) were 2,5 tons and 1.0 ton, respectively. 



21. Exposure of Plan R1S1 to the abbreviated storm-surge hydrograph 

 resulted in extensive damage with a large amount of armor stone displacement 

 distributed over the structure; however, the stapods proved to be stable. 

 Photos 3 and 4 show the condition of the structure after testing. 



Plan R2S1 



22. Plan R2S1 (Plate 4, and Photos 5 and 6) was similar to Plan R1S1 ; 

 however, the weights of the primary armor stone (W2) and toe-protection armor 

 stone (Wo) were increased to 3.8 tons and 2.5 tons, respectively. In order to 

 maintain the -0,8 ft elevation at the top of the 1V:1,25H toe slope, it was 

 necessary to decrease the thickness of the filter stone (Wc) from 2.5 to 



0.9 ft. The slope of the primary armor stone was increased to 1V:1,8H, The 

 crown elevation of +4.5 ft was maintained, 



23. The stability response of Plan R2S1 to the abbreviated storm-surge 

 hydrograph was significantly better than that of Plan R1S1. However, this 

 revetment design was still unacceptable due to excessive displacement of the 

 3.8-ton armor stone. The after-testing condition of this plan is shown in 



Photos 7 and 8, 



16 



