Table 4 



Hllo Breakwater 



Hilo Harbor, Hawaii, Hawaii 



POD, POH 



Date(s) Construction and Rehabilitation History 



1930 Corps completed 10,070-f t-long rubble-mound breakwater. 



1946 Tsunami of April 1946 severely damaged 6,000 ft of the break- 

 water; primary armor stone and core material displaced both 

 seaward and toward the harbor down to an average elevation of 

 -3.0 ft mllw; 1 , 100-f t-long breech occurred. 



1946-1948 Tsunami damage repaired using original design criteria. 



1949-1952 Storm waves of December 1951 caused damage to 13 areas. By 

 October 1952 structure repaired to original cross section. 



1954-1957 Storm waves of March 1954 caused damage to several areas. By 



August 1957 structure repaired to original cross section. 



Structure exposed to tsunami of 9 March 1957 but sustained no 

 apparent damage. 



1960-1967 Tsunami of I960 produced significant damage; however, no work 

 done between 1960 and 1967 due to possibility of totally 

 rebuilding breakwater as one leg of a proposed tsunami barrier 

 for Hilo Harbor. 



1968 Repair work completed in August 1968; 11 areas repaired. Due to 

 severity of wave overtopping and the recurrence of damage in 

 many years, armor stone weight used for repair of crown in- 

 creased from a minimum of 8 tons to a minimum of 10 tons. 

 Remainder of repair work followed original cross-section 

 design. 



1971-1973 An inspection of 7 April 1971 revealed deterioration of structure 

 at various points along entire length; immediate repair of 

 1,700 ft of the shoreward end of structure needed to protect 

 the berthing area. Emergency repair work completed in 1973; 

 original cross section design used for repair. 



(Continued) 



NOTE: Design Storm Conditions. 1981 tribar repair not model tested but used 

 13.5-ft breaking waves in water depth of 15.5 ft and stability coeffi- 

 cient of 7.5; design conditions for remainder of structure unknown. 



Maximum Storm Condition Exposure. Wave height unknown, but old stone 

 structure exposed to large wave conditions on a regular basis. 



