PART II: SUMMARY OF CORPS BREAKWATER AND JETTY 

 STRUCTURES IN SAD 



3. SAD has 32 projects which contain breakwater and/or jetty structures 

 that are located in the following five coastal districts: US Army Engineer 

 Districts, Wilmington (SAW) (7), Charleston (SAC) (4), Savannah (SAS) (1), 

 Jacksonville (SAJ) (14), and Mobile (SAM) (6). 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 

 (89.5 percent) structures in SAD. Although a variety of construction methods 

 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 

 (Belhaven) . Structures constructed prior to 1900 were built up from log and 

 brush mattresses which were sunk by placing stone to a thickness of 12 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 

 Inlet, East Pass, and Perdldo Pass. The weir segments of four of these (chrono- 

 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. 



