Construction and Rehabilitation History
1962-
(Figure
The outer 200
on each jetty was built as a head
1966
section with stone placed over the entire cross section. The design
(cont.) geometry was positioned ft
of the existing jetty center
line with a top elevation of
a 3-stone-wide crown, and
and
on trunk and head sections,
side slopes of
respectively. The sections were built upon a 2- to 3-ft-thick
blanket of 0.5-in. to 200-lb stone. The blanket extended beyond the
and 50
for trunk and head
cover layer toe distances of
sections, respectively. Core stone, typically 200 to 2,000
in
size, then were placed providing the necessary side slope. One layer
of cover stone was placed, except on the head sections, which used a
double layer. Cover stone varied from a maximum of 1 to 1 tons at
6
8
the heads to minimums of 2 and 6 tons at the north and south jetty
landward ends, respectively. To decrease jetty permeability, 0.5- to
filler stone was placed in the crown area beneath the cover
layer. Prior to the repairs, the jetties were in a general state of
In many cases core stone was
north jetty at or below
exposed, or cover layer stone was not tightly interlocked. Due to
these conditions and use of large core stone during original con-
struction, the jetties were considered too pervious to wave, tide,
and sediment motions. Scour on the channel side of the north jetty
was evident from sta
to
where the authorized 30-ft-
deep channel made its closest approach to either jetty. Along this
section water depths were typically 40
or greater within 1 0 ft of
0
the jetty center line, while on the gulf side the typical water depth
was 10 ft. This was a major reason for repairing the gulf side of
the north jetty, since the quantity of stone required would be much
smaller. The total costs for rehabilitation of the north and south
jetties were ,440,000and ,564,500, respectively. Although data
on complete stone quantities were not found, partial quantities and
several similar construction or repair projects (with known stone
quantities) built during this time frame yield an estimate of from
600,0 0 to 1 ,200,000 tons of stone placed.
0
The jetties have received no maintenance or repairs since rehabili-
1986
in the 1960's and are considered to be in good condition. The
present channel is authorized at 40- and 42-ft depths between inner
and outer jetty sections, respectively.
Previous Page
