PART 11: SUMMARY OF CORPS BREAKWATER
JETTY
STRUCTURES IN SAD
3.
SAD has 3 2 projects which contain breakwater and/or jetty structures
that are located in the following five coastal districts: US Army Engineer
Charleston (SAC)
Savannah (SAS)
Districts, Wilmington (SAW)
and Mobile (SAM) ( 6 ) .
Jacksonville
Case histories for these
structures are included in Tables 1-32 which are arranged according to the
preceding districts and coastal locations. Twenty-five of the projects are
situated in an ocean environment, and the remainder are located in sounds or
bays.
All of the structures have been constructed on top of existing sedi-
ments (usually fine to coarse sand), typical of barrier islands. Overall,
there are approximately 256,000 lin ft* of breakwater (10.5 percent) and jetty
Although a variety of construction methods
(89.5 percent) structures in SAD.
and materials have been used, the structures' cross sections are predominantly
of rubble-mound (83.7 percent) or sand dike (14.8 percent) construction.
Con-
struction materials that have been used include steel sheet piles
(Panama City, Casey's Pass), concrete cap (Jacksonville, Palm Beach), concrete
grout (Bakers Haulover Inlet), asphaltic concrete (Panama City, Casey's Pass),
asphalt mats (Panama City), precast concrete panels (weir jetties) and timber
Structures constructed prior to 1900 were built up from log and
(Belhaven).
brush mattresses which were sunk by placing stone to a thickness of 1 2 to
18 in.
The remainder of the section was built up with either additional stone
or multiple layers of weighted log and brush mattresses (and then additional
stone was placed).
4. Six of the projects have a sand weir in their design, and they are
located at Masonboro Inlet, Little River Inlet, Murrells Inlet, Ponce De Leon
The weir segments of four of these (chrono-
Inlet, East Pass, and Perdido Pass.
logically the first four constructed) were built with precast concrete sec-
tions.
Shortly after construction, the concrete weir sections were supplemen-
ted with rubble-mound sections.
The modified cross sections were required be-
cause of scour problems leading to potential or actual failure of the weir
sections. The two most recently constructed sand weirs have a rubble-mound
cross section.
*
A table of factors for converting non-SI to SI (metric) units is presented
on page 3.
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