Table 7 



Breakwater 



Nawiliwili Harbor, Kauai, Hawaii 



Date(s) Construction and Rehabilitation History 



1926 The original Corps-constructed (Figure 15) 2, 150-ft-long rubble- 

 mound breakwater was completed (construction started in 1922). It 

 consisted of one-layer 8-ton keyed and fitted armor stone over 

 core stone (500 lb and less) with 1 -V : 1 -H slopes and a 15-ft-wide 

 crown at +11.0 ft mllw. Except for severe wave action, it was 

 considered to be a satisfactory empirical design cross section. 



1927- Minor repair work was done at various times during this period. 



1953 In 1931 114 stones were reset, and 3,153 tons of stone and 



concrete blocks were placed (no details available) at a cost of 

 $46,040. In 1930, 1932-37, 1945, 1951, and 1952, 1,998 tons of 

 stone were used in repair work at a total cost of $78,285. 

 Details of the repair work were not found. 



195l|_ The breakwater was severely damaged as the result of a storm in 

 1957 1954 (hindcasted depth-limited breaking wave height of 24 ft at 

 structure) which destroyed the head, washed 100 ft of core stone 

 shoreward, and settled capstone to an elevation of a few feet 

 below mllw with little lateral movement. Storm waves displaced 

 armor stone and exposed and removed core material between 

 sta 17+50 and sta 20+45 in 1956. Observed wave heights of 16 ft 

 at the breakwater in September 1957 caused additional armor stones 

 and core displacement between sta 16+00 and 20+45 and displacement 

 of a few armor stone and core exposure between sta 14+00 and 

 sta 16+00. Hydrographic and topographic surveys of January 1958 

 revealed that Hurricane Nina (depth-limited breaking waves at 

 structure on 1 and 2 December 1957) displaced a few armor stones 

 and exposed core material on the sea-side slope between sta 14+00 

 and sta 15+00. It also caused settling and raveling of all armor 

 stone on the crown and sea-side slope between sta 15+00 and 

 sta 20+20, resulting in an exposed core and large voids between 

 armor stones and all armor stone and core above mllw (sta 19+25 to 

 sta 19+50 and sta 20+20 to sta 20+45) which was displaced 

 shoreward . 



1958- The head was rebuilt 100 ft landward of the original head (new 

 1959 head at sta 20+45), and 500 ft of the adjacent trunk were repaired 

 (Figure 16) at a cost of approximately $1,000,000 (model tested by 

 Jackson, Hudson, and Housley 1960). Additionally, 17.8-ton tri- 

 bars were randomly placed in two layers on the sea-side slope of 

 the head and uniformly placed in one layer on the sea-side slope 



(Continued) 



(Sheet 1 of 3) 



29 



