Table 7 (Continued) 



Date(s) Construction and Rehabilitation History 



1965- Cost of the jetty construction was $955,400, and dredging of the 



1966 deposition basin was $169,300. 



(Cont) 



1969- Because of the migration of the navigation channel toward the north 

 1970 jetty with its potential for scour and undermining, a stone apron 



was placed to provide toe protection along the rubble-mound section 

 of the jetty (Figure 12). A survey of the structure taken during 

 the first half of the year showed several sections, along the sea- 

 ward 900 ft of the structure, with centerline elevations up to 5 ft 

 below the design grade. The centerline elevations over the remain- 

 der of the rubble-mound section were within 1 ft of the design ele- 

 vation. The sheet-pile weir section was usually within 0.2 ft of 

 the design elevation of +2 ft mlw. The survey also showed that 

 approximately 50 ft of rubble mound at the seaward end had either 

 been displaced or had not been placed originally. The toe apron was 

 placed along the entire channel side of the rubble mound and ex- 

 tended around the head section, covering an additional 50 ft on the 

 ocean side. The width of the apron varied from 30 ft at the inner 

 end to 50 ft at the seaward end of the repair. The apron consisted 

 of a 1-ft-thick stone foundation blanket covered with a 2-ft-thick 

 section of 25- to 250-lb riprap. In addition, the apron section en- 

 compassing the head had a third layer, 3 ft thick, of 500 to 

 2,000-lb riprap. Capstone totaling 510 tons was to be placed to 

 bring the structure up to grade. On 1-2 November 1969, during the 

 repairs, a moderate northeasterly storm, with estimated wave heights 

 close to those of the design wave, displaced an additional 

 3,400 tons of stone from the structure. Costs of the original re- 

 pair and subsequent repairs to bring the structure up to grade were 

 $479,400. 



1973- Toe protection (Figure 12) was placed along the channel side of the 

 1974 1,100-ft weir section because of continued movement of the naviga- 

 tion channel and the costs Involved should a catastrophic failure 

 occur (loss of sheet-pile sections resulting from scour and under- 

 mining) . The toe apron was to be 50 ft wide with a 1-f t-thlck 

 foundation blanket of 2- to 6-in. stone overlain with a 2.5-ft layer 

 of 25- to 250-lb riprap. Total cost of the repair was $248,800. 



1978- Construction of the south jetty, built of quarry stone and concrete 

 1980 sheet pile to a length of 3,450 ft, began in July 1978 and was 



completed in August 1980. A bathjnnetric survey taken in 1978 showed 

 the channel to be extremely close to the north jetty with water 

 depths up to -25 ft mlw along the rubble-mound section and 

 -12 ft mlw along the weir jetty section. Model tests of the south 

 jetty alignment and geometry, conducted at the US Army Engineer 



(Continued) 



(Sheet 2 of 4) 



23 



