Table 2 



Hilo Breakwater 



Hilo Harbor, Hawaii, Hawaii 



Date(s) Construction and Rehabilitation History 



1930 The Corps completed the 10,080-ft-long rubble-mound breakwater 

 (Section A-A, Figure 3). 



1 93 1 — Only minor repairs were required to restore the original construc- 

 1945 tion at an average annual cost of $10,000 based on 1967 money. 



19^6 The tsunami of 1 April severely damaged 6,000 ft of the break- 

 water. Primary armor stone and core material were displaced both 

 seaward and toward the harbor down to an average elevation of 

 -3.0 ft mllw. A 1 , 100-ft-long breach occurred adjacent to the 

 piers. 



1946- Tsunami damage was repaired using original design criteria at a 

 1948 total cost of $1,500,000. 



1949- Storm waves of December 1951 caused damage to 13 areas (Figure 4). 

 1952 By October 1952 the structure had been repaired to the original 

 cross section at a cost of $76,000. 



1954- Storm waves of March 1954 caused damage to several areas (Fig- 

 1957 ure 4). By August 1957 the structure had been repaired to its 

 original cross section at a cost of $80,000. The structure was 

 exposed to the tsunami of 9 March 1957 but sustained no damage. 



1960 The tsunami of 1960 caused breakwater damage (Figure 4), but it 

 was not as severe as that sustained by the 1946 tsunami. Less 

 severe damage was attributed to the direction of wave attack. The 

 1960 approach was less direct than that of 1946; therefore, wave 

 energy reaching the structure was less than what had occurred in 

 1946. Between 1946 and I960 average annual maintenance costs were 

 $25,000. It was thought that the 1946-1948 repair work did not 

 key the replacement armor into the existing structure, thus 

 resulting in weaker cross sections in these repair areas. 



1965 Storm waves of February 1965 caused additional damage at 

 sta 15+00, 36+30, 73+40, 83+00, and 90+00. 



1967 Between the 1960 and the 1967 tsunami, no repair work was done due 

 to the possibility of total rebuilding of the breakwater as one 

 leg of a proposed tsunami barrier for Hilo Harbor. The average 

 annual cost of structure maintenance had been $43,900 for the 

 first 37 years of the project. 



(Continued) 



(Sheet 1 of 3) 



