Table 24 

 Cape Cod Canal Jetties 

 Cape Cod Canal, Mass. 



Date(s) Construction and Rehabilitation History 



1908- Two rubble-mound jetties were constructed by non-Federal interests at 

 1913 Cape Cod Canal's eastern entrance (Figure 27). The north jetty was 

 3,000 ft long, with a +18 ft mlw crown elevation, a 25-ft crown 

 width, a 1V:1H channel side slope, and a composite seaside slope of 

 1V:2H and 1V:1H above and below -12 ft mlw, respectively. Stone 

 placed above and below -12 ft mlw weighed approximately 3 to 6 tons 

 and 100 lb to 2 tons, respectively. At the seaward end a concrete 

 cap was placed. The crown width was 30 ft, and the existing bottom 

 elevation was -32 ft mlw. The south jetty appears to have been 

 constructed to a length of 600 ft, a +10 ft mlw crown elevation, a 

 20-ft crown width, and 1 V: 1H side slopes. The south jetty armor 

 stone weighed approximately 3 to 5 tons. 



1927 The Cape Cod Canal, including the eastern entrance jetties, was 

 purchased by the Federal government. 



1962- The seaward 925 ft of the north jetty was rebuilt to +18 ft mlw. 

 Stone 1963 placed on the structure weighed a minimum of 6 tons, 

 except on the 125-ft-long head section, where the minimum size was 

 12 tons. The head section had a 25-ft crown width and a transition 

 in side slopes from 1V:2H to 1V:3H in the seaward direction. A 20-ft 

 crown width and 1V:2H side slopes were specified on the jetty trunk 

 section. Prior to the repairs, typical crown elevations were from 

 +14 to +18 ft mlw on the trunk section and from +7 to +18 ft mlw on 

 the head section. The contract price for placing an estimated 

 20,000 tons of stone was $260,000. 



1967- Inspection reports indicate the north jetty was in good condition, 

 1974 while the south jetty was in poor condition with numerous voids and 

 displaced slope stone along its entire length. 



1974 The south jetty was rebuilt to +13 ft mlw. The rebuilt section was 

 690 ft long and terminated at the jetty's seaward end. Side slopes 

 were 1V:1.5H. A 13-ft crown width and 5- to 7-ton stone were speci- 

 fied on the seaward 200 ft. The remaining section required a 10-ft 

 crown width and 1- to 2.5-ton stone. A 1-ft-thick layer of bedding 

 stone, to 50 lb in size, was placed along the outermost 450 ft of 

 the jetty's seaside toe. Prior to the repairs, crown elevations were 

 typically from +3 to +8 ft mlw. The contract price for placing an 

 estimated 15,500 tons of stone was $224,800. 



1977 The jetties were visually inspected. The south jetty was found to be 

 in good condition, while the north jetty needed repairs throughout 

 its entire length. 



1986 Recent yearly visual inspections indicated the jetties were in good 

 condition. 



56 



