of the Freeport jetties which have received only minor repairs since the 
1940's. The possibility of project modifications at Freeport has delayed 
jetty rehabilitation. 
11. Design of the structures during the past 25 years is based on 
various engineering memorandums and Coastal Engineering Researcen Center 
(CERC) publications, in addition to the experience gained from construction 
and maintenance of the existing structures. Selection of armor stone size 
and slope is based on Hudson's slope stability formula. For the gulf coast 
wave climate, stability coefficients used in designs typically are above zero 
damage levels, resulting in a nonconservative design at the structures' sea- 
ward ends but considered adequate in light of past experience and additional 
costs required for a fully stable design. Design wave heights and maximum 
surge levels are typically determined from historical hurricane events, 
observed wind and tide data, and an expected 50- to 100-year storm recurrence 
interval. Design wave heights are depth-limited in regions where they exceed 
0.78 times the water depth. Actual wave data were not used in any design, and 
it is not known whether any useful data exist. Although no model studies have 
been conducted on stability of structure cross sections, prototype data were 
collected and analyzed for Port Mansfield (Kieslich 1977), and functional 
hydraulic model studies were conducted for Galveston (Simmons and Boland 1969) 
and Matagorda (Rhodes and Simmons 1966). 
12. Case histories of the structures for each project are included in 
Tables 1-12. Pertinent summary information on each project is presented in 
the following listing. 
