Table 23 (Continued) 



Date(s) Construction and Rehabilitation History 



1930 A monolith concrete block was placed at the outer end of the north 

 Jetty. 



1938- Maintenance work on the north Jetty required 236,342 tons of stone. 

 1940 At least 45 percent of the stone above the core was class "A" stone 



weighing between 6 and 25 tons and averaging 10 tons. The stone was 



placed by dumping from cars on a tramway. 



1941- The south Jetty was restored, and monolith concrete cap was placed on 

 1942 the outer 650 ft. 



1948 A small-boat mooring basin at Charleston was authorized. 



1956- The small-boat mooring basin at Charleston was constructed, including 



1957 a 2,100-ft breakwater and a silt barrier bulkhead. The breakwater 

 had a crest elevation of +14 ft mllw, a crest width of 18 ft, and 

 required an estimated 67,000 tons of stone, of which at least 35 per- 

 cent was class "A" stone weighing 3,000 to 8,000 lb and averaging 

 5,000 lb. No more than 30 percent was class "C" weighing between 25 

 and 500 lb, and the rest was class "B" weighing 500 to 3,000 lb and 

 averaging 1,000 lb. The stone was placed by dumping from the hauling 

 vehicle. 



1957- The outer 2,879 ft of the north Jetty was repaired to crest elevation 



1958 +25 ft mllw and a 30-ft crest width using 246,529 tons of stone. The 

 design specified a minimum of 45 percent class "A" stone weighing at 

 least 6 tons and averaging 10 tons, no more than 20 percent class "C" 

 stone weighing less than 1 ton, and the remaining class "B" stone 

 weighing between 1 ton and 6 tons and averaging 3 tons. 



1962- The south Jetty was repaired between stations 47+57 and 81+80, re- 

 1963 quiring 235,000 tons of stone. The armor layer over the outer 



1,880 ft consisted of a 10-ft layer of Class "A" stone above mllw, 

 underlain by a 5-ft layer of Class "B" stone in the outer 330 ft. 

 Below mllw, the armor layer consisted of a 5-ft layer of Class "A" 

 stone. Based on a unit weight of 165 to 170 pcf, select class "A" 

 stone weighed a minimum of 16.5 tons, class "A" stone weighed between 

 9 tons and 16.5 tons and averaged 11 tons, and class "B" stone 

 weighed between 2 tons and 9 tons and averaged 4.5 tons. The rock 

 was placed and keyed by crane. 



1969 The north Jetty was deteriorating at an average rate of 60 ft annu- 

 ally since the 1957-58 repairs. 



1970 The outer 700 ft of the north breakwater was repaired. 



Erosion began on the spit adjacent to and north of the breakwater at 

 the small-boat basin. 



(Continued) 



117 



