Table 7 (Continued) 



Date(s) Construction and Rehabilitation History 



1978- Waterways Experiment Station (WES) (Seabergh 1976), indicated that 

 1980 the navigation channel would realign itself between the jetties in 

 (Cont) conjunction with inlet dredging. The outer portion of the jetty 

 trunk was also model tested at WES (Carver and Markle 1978) to 

 design a stable section for the breaking wave environment. From 

 these tests it was determined that the design section was adequate 

 for the +8.5-ft mlw storm surge condition but could accrue signifi- 

 cant damage for storm surges greater than +8.5 ft mlw. Wave heights 

 and periods used in the tests were 13.5 ft, 15 sec and 15.0 ft, 

 15 sec for +8.5 and +10.5 ft mlw surge levels, respectively. 



The jetty design (Figure 13) consisted of a 750-ft shore anchor sec- 

 tion, two trunk sections, 550 and 2,050 ft long, respectively, and a 

 100-ft head section. The concrete sheet-pile sections were precast 

 and prestressed with steel cable and were 3 ft wide, 12 or 16 in. 

 thick, and 25.5, 31, or 33 ft long. The main purpose of the sheet 

 pile was to provide an effective means of stopping the transport of 

 sand through the jetty. The sheet-pile top elevation varied from 

 +11 to +5 ft mlw, from the shoreward end to the seaward end (but not 

 incorporated into the head section), respectively. The shore anchor 

 section was built with sheet-pile top elevations of +11 to +9 ft mlw 

 and channel side toe protection (20 ft wide) made up of 1.5-ft-thick 

 foundation blanket of 2- to 12-in. stone and a single layer of 3,000 

 to 5,600-lb armor stone. The inner 550-ft trunk section consisted 

 of the 1.5-ft-thick foundation blanket of 2- to 12-in. stone, 1,000- 

 to 1,600-lb underlayer (core) stone, and 5- to 8-ton capstone. The 

 capstone crown width and elevation were 16 ft and +9 ft mlw, re- 

 spectively. The top elevation of the sheet pile was +7 ft mlw. Toe 

 protection overlaying the foundation blanket was three stones wide 

 (approximately 15 ft), using 5- to 8-ton stone on the channel side, 

 and 25 ft wide using a double layer of 3,000- to 5,600-lb stone on 

 the ocean side. The outer 2,050-ft trunk section consisted of a 

 1-ft-thick gabion foundation blanket of 4- to 8-in. stone, 300- to 

 5,600-lb underlayer (core) stone, and 14- to 22-ton capstone. The 

 capstone crown width and elevation were 22 ft and +7 ft mlw, respec- 

 tively. The top elevation of the sheet pile was +5 ft mlw. Toe 

 protection, overlying the gabion mat, was 3 stones wide (approxi- 

 mately 21 ft) using 14- to 22-ton stone on the ocean side; 25 ft 

 wide using a double layer of 3,000 to 5,600-lb stone for (inner) 

 1,200 ft of the channel side, and 4 stones wide (approximately 

 28 ft) using 14- to 22-ton stone for the remaining (outer) 850 ft of 

 the channel side. The head section was similar to the outer trunk 

 section except for an additional layer of 14- to 22-ton capstone. 

 It excluded the concrete sheet pile, and the 4-stone-wide channel 

 side toe protection extended around the head section to the 



(Continued) 



(Sheet 3 of 4) 



25 



