Table 5
Tiger Pass Jetties
Mississippi River Outlets, Venice, Louisiana
Construction and Rehabilitation History
1978-
Two parallel rubble-mound jetties were built at the entrance to
dredging required for safe navigation. These jetties were part of
navigation improvements which included similar jetties at the en-
trance to Baptiste Collette Bayou (Figure
also built during this
time. These waterways provide a shorter navigational route between
east and west gulf waters and are used primarily by smaller vessels.
The north and south jetties were 4,700 and 2,700 ft long,
respectively, and spaced 540
apart with a 17- by 250-ft channel
between them. The north jetty extended 2,000
past the seaward end
elevation of
mlg, a crest width of 26 ft, and
side
slopes. Shell material was used as core and bedding material
minimum thickness). A
layer of graded
stone (500-lb
maximum) was placed on the core side slopes followed by a 2-ft-thick
layer of graded stone (1,200-lb maximum) placed on the side slopes
and crown. Plastic filter fabric was placed at four test sections
(two per jetty) prior to placing the shell and stone. Two 500-ft
sections were at the seaward ends of the jetties and the remaining
two (500 and 1,000 ft long on the north and south jetties,
respectively) begin 1,000 from the landward ends and extend sea-
ward. Test sections were subdivided into 250-ft reaches, in which
different tensile strength fabric was placed or the design section
was modified
stone omitted on two reaches). Settlement plates
were placed at 80- to
intervals within the test sections and
intervals elsewhere. These were placed to monitor settlement
and effectiveness of the test sections. The jetties were built on
top of mostly soft clays and were expected to settle 2 ft. For this
reason, the south jetty, which eventually was to be built up to
ft
mlg with graded stone (5,000-lb maximum) was to be constructed in two
ft mlg t o be built at a later date.
phases, with the portion above
to -6
Prior to jetty construction, existing elevations were from
ft mlg. The total construction cost was ,085,000 using 31,500 sq
yd of plastic filter fabric, 76,400 cu yd of shell material, and
tons of graded stone. A late 1979 inspection indicated that
the jetties had what appeared to be large amounts of differential
settlement and already constituted a maintenance problem,
Repairs were made to both jetties. The south jetty was raised with
1984-
graded stone
maximum) to an elevation of
ft NGVD, a 4-ft
1985
side slopes. The north jetty was repaired
crown width, and
with graded stone (1,500-lb maximum) to an elevation of
ft NGVD, a
14-ft crown width, and
side slopes (NGVD datum approximately
datum). Raising the south jetty was the second
0.5 ft above
(Continued)
37
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