Date(s) 
1967 
1968 
Table 12 (Continued) 
Construction and Rehabilitation History 
breaking up the concrete cap at sections where underlying cavities 
had formed. The released cover stone was left in place and overlaid 
with new cover stone bringing the sections up to the +6 ft mlw design 
elevation. The north jetty repair, located approximately 3,500 ft 
from the seaward end, brought the channel side up to grade by placing 
blanket stone, resetting existing cover stone, and adding new 200- to 
1,000-1b core stone and 2- to 4-ton cover stone. The 3-ft-thick 
blanket of 0.5-in. to 200-lb stone extended 10 ft beyond the toe of 
the cover layer. The section was brought up to +6 ft mlt and a side 
slope of 1V:2.5H. Water depths were -35 ft mlt along the seaward end 
of the north jetty toe and from -20 to -40 ft mlt along the seaward 
end of the south jetty toe. The authorized 38- by 300-ft channel has 
been maintained since 1957. Hudson's slope stability formula was 
used in the design with 10- to 35-ft wave heights. The design storm 
surge was +13 ft mlt. The stone sizes used were smaller than 
required to satisfy a no-damage criterion, with slope stability 
coefficients varying from 2.5 to 12.5 but being used for practical 
and economic reasons. The total cost of the repairs was $584,000 
using a total of 60,600 tons of stone. 
During September 1967, storm waves from Hurricane Beulah damaged the 
landward 1,130 ft of the 1965-1966 south jetty repairs. About 
90 percent of this section of gulf side slope repairs had varying de- 
grees of displaced stone. The damage appeared to be due to the 
placement of the stone against the concrete cap (a smooth impermeable 
section allowing very little natural interlocking of the cover layer 
combined with possible adverse changes in the magnitude and direction 
of wave forces). In 1968 this section and a portion of the jetty's 
channel side slope were repaired. On the gulf side, the concrete cap 
edge was broken off providing a buttress for the cover layer which 
was rebuilt by resetting existing cover stone and adding new filler, 
core, and cover stone. Also repaired were sections where undermining 
and cavities had formed beneath the concrete cap. In these areas the 
cap was broken up and overlaid with core and cover stone as was done 
for the 1965-1966 repairs. A 700-ft section of the south jetty 
(located approximately 3,700 ft from its seaward end) was repaired 
along its channel side by rearranging the existing cover stone and 
adding new filler, core, and cover stone. The south jetty repairs 
employed 0.5-to 4-in. filler stone, 200- to 1,000-lb core stone, and 
6- to 8-ton cover stone. The north jetty shore protection was 
repaired by placing a 2-ft-thick bedding layer of 0.5-in. to 200-lb 
stone, 15-ft-wide cover layer of 6- to 8-ton stone, and 200- to 
2,000-1b toe protection stone. The existing stone had moved up the 
shore slope during large storm events. Approximately 550 lin ft of 
shore protection were placed landward of the jetty. The total cost 
of the repairs was $274,000 using 14,100 tons of stone. 
(Continued) 
50 
