Table 30 



Lagoon Pond Jetty 



Martha's Vineyard, Mass, 



Date(s) Construction and Rehabilitation History 



1935 The State of Massachusetts constructed approximately 450 ft of 



rubble-mound jetty on the east side of the entrance to Lagoon Pond 

 (Figure 33). It appears that the crown elevation and width were 

 +8 ft mlw and 4 ft, respectively. The crown consisted of 4- by 7- by 

 2-ft granite blocks, and 1- to 5-ton riprap was used on the side 

 slopes. 



1973 As part of navigation improvements, to increase harboring areas for 

 the recreational fleet, the jetty was extended 200 ft seaward, 

 terminating at about the -8 ft mlw contour. The landward side of the 

 existing jetty had accreted sediment and created a fillet out to its 

 seaward end. The plan of improvement called for an 8-ft-deep channel 

 into Lagoon Pond and an extension of the jetty to reduce future 

 channel shoaling. The design section called for a 6-ft crown width 

 at +8 ft mlw and 1V:1.5H side slopes. The seaward end had a 1V:2H 

 side slope. The jetty was built with a 2-ft-thick bedding layer of 

 1- to 50-lb stone, a sand tight core of 1- to 300-lb core stone, and 

 a 4-ft-thick cover layer of 5- to 6-ton armor stone. The design was 

 based on an 8-ft breaking wave height. The contract cost for placing 

 an estimated 5,700 tons of stone was $98,200. 



1974 The jetty and extension were considered to be in excellent condition 

 during a visual inspection. 



1982- Yearly visual inspections of the jetty revealed that it was in good 

 1986 condition. 



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