Table 32
Perdido Pass Jetties
Perdido Pass, Alabama, SAM
Date
Construction and Rehabilitation History
spaced 600 ft apart at their
converging jetties (Figure
1969
seaward ends, were constructed as part of a weir-jetty system to
help stabilize the natural inlet at Perdido Pass. The west jetty,
was of rubble-mound construction and extended from
the south end of a vertical seawall constructed by the Alabama High-
way Department. The east jetty, also 1,800 ft long, consisted of
1,290 f t of steel-reinforced concrete sheet pile and 560 ft of rub-
ble mound (50 f t of overlap between the two sections). The west
jetty trunk section (Figure 57) was built to a crown width of 10 ft
side slopes. One layer of 2- to 3-ton
ft
with
at
cover stone and 400- to
core stone were placed on a 1.5-ft-
thick bed of 5- to
blanket material. (A 2.5-ft-thick bed was
used on all other rubble-mound sections.) The west jetty head sec-
tion (Figure 57) was built to a crown width of 15 ft at
ft
cover stone, 1
side slopes. Two layers of 12- to
with
layer of 1- to 1.5-ton underlayer stone, and 400- to
core
stone were placed. The east jetty head section was similar except
side slopes. The
ft
crown elevation and
for a
transition section on the west jetty consisted of 1 to 2 layers of
core stone. The
3- to 12-ton cover stone and 1,000- to
east jetty trunk section was similar to the west jetty section
except for the use of 3- to 5-ton cover stone placed in one or two
layers. The east jetty transition section consisted of two layers
core stone. The
of 5- to 12-ton cover stone and 1,000- to
east jetty sheet-pile weir section was 1,000 ft long with a top ele-
The shoreward 100 ft of the sheet pile was
vation of -0.5 ft
followed by a 140-ft transition section to the weir
set to
ft
section. The concrete sheet-pile sections were 13 ft long (18 ft
long at the landward end), 2.5 ft wide, and 8 in. thick and were
reinforced with prestressed steel cable. The sheet pile was secured
via tongue-and-groove joints and mechanically fastened through their
support ends with 12- by 12-in. timber wales (on both sides of the
sheet pile) and steel connectors. The sheet pile was secured to the
existing dune line at its landward end with dredged material built
The water depths at the sea-
up to a crest elevation of
ft
ward ends were 13 and 11 ft for the east and west jetties, respec-
tively. The jetty design used Hudson's equation with design wave
heights of 15 and 14 ft for the east and west jetties, respectively.
wave heights were determined assuming depth-limiting conditions
10-year frequency tide elevation of
ft
Design of the
jetties was based partly on the recently completed project at
Inlet, North Carolina, and discussion with personnel from
CERC. Placement of the weir on the east jetty was based on the
(Continued)
(Sheet 1 of 3
)
100
Previous Page
