PART II: SUMMARY OF CORPS BREAKWATER 

 AND JETTY PROJECTS IN NED 



3. NED is presently responsible for 37 jetties and 46 breakwaters which 

 are principal or partial features of 52 projects. All of the projects are 

 located on or near the Atlantic coastline from northern Maine to western 

 Connecticut (Figure 1). There is a total of 154,185 lin ft* of breakwater 

 (62.4 percent) and jetty (37.6 percent) structures which are almost entirely 

 (99.7 percent) of stone construction. With the exception of a few projects 

 which were originally constructed using regularly shaped stone blocks, the 

 rubble-mound structures have been built using various sizes of stone. Use of 

 concrete as a building material has been limited to 2 or 3 projects and has 

 not been used in the past 35 years. Steel sheet piles were used in construc- 

 tion of one breakwater (Eastport Harbor). 



4. The cross sections of many structures are constructed with steeper 

 channel or harbor-side slopes than sea-side slopes. The largest cover stones 

 are typically placed in a single row on the crown, and the core is usually 

 made up of smaller "quarry run" stone. Most of the structures have been built 

 without blanket or apron stone. Typical crown elevations are from +5 to 



+26 ft mean low water (mlw). The large variation in crown elevations is 

 mainly due to local tide levels, which vary in the mean from 2 to 18 ft. 

 Relative to mean high water (mhw) , crown elevations are typically +2 to 

 +8 ft. Crown widths on structures with one stone crown width are typically 4 

 to 8 ft, while the variation in crown width for all structures is usually from 

 2 to 20 ft. Side slopes are typically 1V:1H on the channel or harbor side and 

 1V:1.5H on the sea or ocean side. Side slopes on the newer structures are 

 typically 1V:1.5H on both sides. Repaired side slopes are usually from 

 1V:1.5H to 1V:2H. Cover stone, usually placed to a relative thickness of 1 or 

 2 layers, varies from a minimum of 0.25 ton in low wave climate environments 

 to a maximum of 15+ tons (Point Judith). The newest projects (Plymouth and 

 Provincetown Harbors breakwaters and Andrews River west jetty) were all 

 completed in the early 1970' s. 



5. Sufficient quantitative information on long- or short-term struc- 

 tural deterioration due to various wave climates was not found. Periodic 



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

 units is presented on page 3. 



