PART II: SUMMARY OF CORPS BREAKWATER AND JETTY STRUCTURES IN NCD • 



3. NCD has a total of 107 projects located in the Great Lakes region 

 which include breakwater and/or jetty structures. NCD refers to many struc- 

 tures as piers which actually function as jetties. Therefore, the term "pier" 

 used in this report will carry the same meaning as the term "jetty." Seventy 

 of the projects are within US Army Engineer District, Detroit's (NCE's), area 

 of responsibility; six are located within US Army Engineer District, Chicago's 

 (NCC's) boundaries; and thirty-one are under the jurisdiction of US Army 

 Engineer District, Buffalo (NCB) . Figures 1-3 show the locations of these 

 projects along the Great Lakes. Overall, there is a total of about 



481,570 lin ft* of breakwater and/or jetty structures in NCD. Breakwaters ac- 

 count for approximately 69 percent of this total, and jetty structures account 

 for the remaining 31 percent. Construction materials used for these struc- 

 tures include stone, concrete, steel sheetpiling, woodpiling, timber, and con- 

 crete armor units (dolosse used at Cleveland Harbor, Ohio) . 



4. Twenty-one projects are located on the United States shoreline of 

 Lake Superior, thirty-eight on the Lake Michigan shoreline, fifteen on the 

 Lake Huron shoreline, one on the Lake St. Clair shoreline (small lake between 

 Lake Huron and Lake Michigan), twenty-two on the southern shore of Lake Erie, 

 and ten on the Lake Ontario shoreline. Structures within NCD have experienced 

 problems in all four major REMR problem areas (runup and overtopping, local- 

 ized damage, toe stability, and use of dissimilar armor). Many of NCD's proj- 

 ects have deteriorated and have been repaired or modified since construction. 



5. Breakwaters and jetties in NCD have been constructed on top of exist- 

 ing sediments (usually fine to coarse sand) in water depths ranging from 8 to 

 70 ft. These structures have crest elevations (el) ranging from 4 to 18 ft 

 and crest widths ranging from 1 to about 60 ft. Side slopes of stone struc- 

 tures range from 1V:1.25H to 1V:2H. Design guidance for breakwater cross- 

 sections (stone sizes, crest height, width, etc.) is provided by the Shore 

 Protection Manual (SPM) (1984) or other appropriate Corps engineering manuals. 

 Several of NCD's projects have been model tested at the US Army Engineer 

 Waterways Experiment Station. 



* A table of factors for converting non-SI units of measurement to SI 

 (metric) units is presented on page 3. 



