Construction and Rehabilitation History
1978-
Waterways Experiment Station (WES) (Seabergh
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
mlw storm surge condition but could accrue signifi-
for the
cant damage for storm surges greater than
ft mlw. Wave heights
and 15.0 ft,
and periods used in the tests were 13.5 ft, 15
for
and
ft mlw surge levels, respectively.
15
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
ft mlw, from the shoreward end to the seaward end (but not
to
incorporated into the head section), respectively. The shore anchor
section was built with sheet-pile top elevations of +11 to
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,
to 1,600-lb underlayer (core) stone, and 5- to 8-ton capstone. The
capstone crown width and elevation were 16 ft and
ft mlw, re-
spectively. The top elevation of the sheet pile was
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
gabion foundation blanket of 4- to 8-in. stone, 300- to
5,600-lb underlayer (core) stone, and 14- to 22-ton capstone. The
ft mlw, respec-
capstone crown width and elevation were 22 ft and
tively. The top elevation of the sheet pile was
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
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