Table 45 



Shilshole Bay 



Seattle, Washington 



Date(s) Construction and Rehabilitation History 



1954 The project was adopted for the boat basin and a 4,200-ft breakwater. 



1958 The breakwater was completed. The breakwater was constructed of 

 dredged sand-fill between mounds of Class "C" rock which form the 

 breakwater toes. Mounds were 7 ft above the ground line but not 

 higher than -10 ft mllw to avoid disturbances during low tide periods 

 during construction. A 3-ft-thick layer of gravel was placed over 

 the dredged fill and used as a filter between the rock toes and the 

 fill. Class "B" rock was placed over the Class "C" rock to a 1:1.5 

 finished slope, with a minimum thickness of 5 ft where it is exposed 

 to wave action and 3 ft where it is covered by Class "A" rock. Class 

 "A" armor rock weighing 1,500-3,000 lb was placed on the slopes to 

 -10 ft mllw elevation. The breakwater crest was at +20 ft mllw; the 

 breakwater was designed to withstand a 5-ft, 5-sec wave. 



1961 A 240-ft-long rubble-mound extension was added to the existing 

 breakwater. 



1985 The harbor and cross sections of the breakwater are illustrated in 



Figure 78. There are no reports of needed repairs or rehabilitation. 



168 



