Table 6 



Bayou Fontanelle Jetties 



Empire, Louisiana 



Date(s) Construction and Rehabilitation History 



1950 Two rubble-mound jetties were constructed (Figure 17, existing lay- 

 out) in conjunction with a 9- by 80-ft navigable channel (between 

 Empire, Louisiana, and the Gulf of Mexico). The jetties were 

 constructed out to the -5 ft mlg contour (original lengths unknown) 

 and spaced ^25 ft apart. The jetties were of rubble-mound construc- 

 tion placed on fascine mattresses. The design geometry (Figure 17) 

 had a +6-ft mlg crown elevation, 10-ft crown width, and 1V:1.25H side 

 slopes. 



1970 The seaward ends of the jetties were repaired, the landward end of 



the west jetty was repaired and extended 420 ft, a 475-ft-long groin 

 was constructed 300 ft west of the west jetty, and a 325-ft-long tie 

 dike was built, connecting the groin to the west jetty (Figure 17, 

 repair history prior to 1970 not known). Prior to repairs, the east 

 and west jetties were 1,800 and 1,850 ft long, respectively, and typ- 

 ical center-line elevations (1970 surveys) varied from +3 to +6 ft 

 mlg on the east jetty, and from +4 to +6 ft mlg on the west Jetty. 

 The landward end of the west jetty had been flanked and was about 

 300 ft from the existing shoreline with intervening water depths to 

 -7.5 ft mlg. The jetty sections were to be built to an elevation of 

 +6 ft mlg, a 10-ft crown width, and 1V:1.5H side slopes. Sections of 

 the seaward ends of the east and west Jetties, 960 and 190 ft long, 

 respectively, and the landward end of the west jetty, 400 ft long, 

 were repaired with 1- to 6-ton stone. The groin, dike, and west 

 Jetty extension were constructed with 300-lb to 2-ton stone and a 

 shell blanket, to be placed to -2.5 ft mlg or a minimum thickness of 

 1 ft. A shell core placed to -1 ft mlg, a top width of 20 ft, and 

 1V:4H side slopes was used on the west Jetty extension where the 

 existing grade was less than -3.5 ft mlg. The "as built" stone side 

 slopes of this section were approximately 1V:2H. The shallower side 

 slopes provided a cover layer of stone along the exposed toes of the 

 shell core. Prior to this modification, scour and undermining were 

 removing the shell material. The groin and dike design elevations 

 were +5 and +4 ft mlg, respectively, with 6-ft crown width and 

 1V:1.5H side slopes. The cost for placing an estimated 16,900 tons 

 of stone and 7,400 cu yd of shell was $196,000. 



1978 The west jetty was repaired along 75- and 1,375-ft sections at the 

 landward and seaward ends, respectively; its landward end was ex- 

 tended 325 ft; and the tie dike and groin were repaired. A graded 

 stone, with a maximum stone size of 5,000 lb, was placed on the 

 structures using the 1970 design geometries. (The jetty extension 

 had a 1-ft-thick shell bedding layer.) The preexisting center-line 

 elevations (April survey) on the west Jetty averaged +2 and 



(Continued) 



40 



