Table 16 



Ponce de Leon Inlet Jetties 



Ponce de Leon Inlet, Florida, SAJ 



Date(s) Construction and Rehabilitation History 



1968- Rubble-mound jetties (Figure 29) were constructed to provide safe 

 1972 passage via a 15-ft-deep by 200-ft-wide dredged channel. The north 

 jetty, as originally constructed, consisted of a landward concrete 

 sheet-pile section 500 ft long, a 1,800-ft weir section consisting 

 of horizontal precast concrete beams placed between king piles, and 

 a 1 ,800-ft-long seaward rubble-mound section. The top elevation of 

 the sheet-pile section consisted of 235 ft at +10 ft mlw, and 265 ft 

 from +10 to +4 ft, mlw. The weir section consisted of 300 ft at 

 +4 ft mlw and 1,500 ft at mlw. If needed, the elevation of the weir 

 section could be changed by addition or removal of the horizontal 

 beams. The rubble-mound section (Figure 29) was built to +7 ft mlw 

 with a 10-ft crest width and 1V:1.5H side slopes for 650 ft and 

 IV: 3H side slopes on the seaward 1,150 ft. The cross section con- 

 sisted of a 2-ft foundation blanket (1- to 12-in. stone), 500- to 

 2,500-lb core stone, and one layer of 8- to 12-ton capstone (with 

 12-ton minimum on the outermost 50 ft of the structure). The south 

 jetty was a curved rubble-mound structure 4,080 ft long. The crest 

 elevation and width were +7 ft mlw and 10 ft, respectively, with 

 1V:1.5H side slopes on the inner 3,500 ft and IV: 3H on the outer 

 580 ft. A 2-ft-thick foundation blanket of 1- to 12-in. stone was 

 placed along the length of the south jetty with similar size stone 

 used as a core on the inner 2,215 ft (Figure 28) and covered with 

 1,000- to 2,000-lb capstone. An Intermediate section, 235 ft long, 

 consisted of 500 to 2,500 core stone and 1,000- to 2,000-lb cap- 

 stone. The seaward section of the jetty consisted of 500- to 

 2,500-lb core stone and 8- to 12-ton capstone (with 12-ton minimum 

 on the outermost 50 ft of the structure) . The landward side of the 

 south jetty (inner 3,200 ft) had a filter layer placed in the cap- 

 stone voids prior to backfilling of dredged material. In selecting 

 the capstone, design wave heights of 16 and 11 ft were used on sea- 

 ward and landward sections, respectively, in conjunction with 

 Hudson's equation. In 1972 the weir section was supplemented with a 

 rubble-mound section which was added because of concern for the wave 

 climate that the weir could receive over its design lifetime. The 

 design section consisted of a 2-ft-thick foundation blanket (1- to 

 12-in. stone) with 500- to 2,500-lb core and capstone placed to 

 +1 ft mlw, a 10-ft crest width, and 1V:2H side slopes. Total cost 

 of the jetties was $2,145,000. 



1978 A blanket of armor stone was placed at the base of the north jetty 

 along the seaward 2,550 ft. A total of 23,100 tons of up to 700-lb 

 riprap stone and 9,100 tons of 500-lb to 3-ton stone (75 percent 

 greater than 1 ton) was placed. The cost of the repair was 

 $1,453,000. 



(Continued) 

 52 



