(c) Currents. Tidal currents in the area are reported as negligible. 



(d) Winds. Winds from the northeast quadrant are prevaihng and predominant 

 (U.S. Congress, 1947). 



(e) Storm Surge and Tides. 



Extreme high tide, 15 feet above MLW 

 Extreme low tide, —3.0 feet below MLW 



Mean normal tidal range, 9.0 feet 



Mean spring tidal range, 10.4 feet 



(f) Littoral Transport. Predominant direction of transport along Winthrop 

 Beach is from north to south. 



(g) Water Depth at Structure. Varies from to 10 feet below MLW. 



(h) Foundation Conditions. Available information indicates the breakwater rests 

 on the base of eroded drumUns, hills of compacted clay, and sand and gravel with numerous 

 cobbles and boulders. 



(5) Structural Features (Fig. 38). 



(a) Dimensions of Basic Structure. 



1 Length. Five detached breakwater sections. One 400- and four 300-foot- 

 long sections, spaced 100 feet apart at MHW. Overall length about 2,250 feet. 



2 Side Slopes. Seaward slope, 1.75 to 1; shoreward slope, 1.5 to 1; and 

 between sections, 2.0 to 1. 



3 Crest Elevation and Width. +8.0 feet above MLW, 9.0 feet above MHW, 

 and 12.0 feet wide. 



(b) Unusual Structural Features. Gaps in structure provided to save stone, 

 permit circulation and enable small boats to pass through. Gaps not wide enough to permit 

 passage of sizeable wave. Cross-section shape in form of an ellipse to offer less resistance to 

 overtopping wave. 



(6) Design Data. 



(a) Design Conditions. Not available. 



(b) Model Study. None. 



(c) Instrumentation. None. 



(7) Structural Performance. 



(a) Effectiveness of Structure. Good. Field surveys and observations indicate 

 that breakwater has been effective in lessening wave action and in protecting the shore of 

 Winthrop Beach for a distance equal to the breakwater length. Substantial accretion has 

 taken place within this protected zone moving the shorehne seaward. Some erosion north 

 and south of the protected area has occurred. Increased beach wddth has decreased wave 

 attack on seawall protecting Winthrop, Massachusetts. 



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