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
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-lb core stone and 2- to
cover stone. The 3-ft-thick
blanket of 0.5-in. to 200-lb stone extended 1
beyond the toe of
0
ft mlt and a side
the cover layer. The section was brought up to
Water depths were -35
slope of
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
ft mlt. The stone sizes used were smaller than
surge was
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 4,000
using a total of 60,600 tons of stone.
During September 1967, storm waves from Hurricane Beulah damaged the
1967
of the 1965-1966 south jetty repairs. About
1968
landward 1,130
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
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
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-lb toe protection stone. The existing stone had moved up the
shore slope during large storm events. Approximately 550
ft of
shore protection were placed landward of the jetty. The total cost
of the repairs was 4,000 using 14,100 tons of stone.
(Continued)
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