Table 23 



Plymouth Harbor Breakwater 



Plymouth, Mass. 



Date(s) Construction and Rehabilitation History 



1968- A rubble-mound breakwater, with east and west legs 2,100 and 1,400 ft 

 1971 long, respectively, was constructed providing protection to rec- 

 reational and commercial vessels using Plymouth Harbor (Figure 26, 

 plan view). The design crown elevation was +15 ft mlw, but to allow 

 for foundation settlement the construction elevations were +16 and 

 +15.5 ft mlw on the east and west legs, respectively. The crown 

 width was 7 ft, and side slopes were 1V:1.5H. The breakwater cross- 

 section was made up of 2-ft-thick bedding layer of 0- to 12-in. 

 stone, followed by a core of 0- to 600-lb stone, and the 3-ft-thick 

 outer layer required stone weighing a minimum of 600 lb and 2 tons on 

 the side slopes and crown, respectively. The stone size was based on 

 Hudson's slope stability formula and a design wave height of 3.5 ft, 

 and the crown elevation was based on a design tide of +12.7 ft mlw. 

 The contract price for breakwater construction, using an estimated 

 total of 219,000 tons of stone, was $1,145,100. 



1972- Inspections during this period showed the breakwater was in excellent 

 1978 condition. 



1982- Visual inspections of the breakwater indicated it was in good 

 1984 condition. 



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