float with the required uniform freeboard and had to be ballasted with Styro- 

 foam billets. Presumably, a form slipped during casting, resulting in a heav- 

 ier and nonuniform unit. 



The 2- by 4-inch tie piece on the bull rail is too light for its purpose 

 and has broken in a few places. This member should be at least 4 by 4 inch- 

 es. The installation of the anchors required extra, expensive site prepara- 

 tion which might have been avoided with more informative foundation surveys 

 and better matching of anchor type to bottom conditions. No special mainten- 

 ance problems have developed. 



d. Discussion. The breakwater type is very appropriate for the site and 

 has met the users' expectations. 



7. Blaine, Washington. 



a. Location. Semiahmoo Spit Marina is located in Drayton Harbor (see 

 Fig. 23) at Blaine, Washington. 



b. Site Conditions . Drayton Harbor (Fig. 23) is quite shallow; the 

 marina site had to be dredged to -10 feet MLLW. The site is exposed only to 

 the southerly quadrant, with a high tide fetch of 1.5 nautical miles to the 

 south and 2 nautical miles to the southeast. 



Tide data include a mean range of 5.9 feet and a diurnal range of 9.5 

 feet. No data are available on tidal currents. 



Data on wind waves used for design are not available. The exposure to the 

 south and southeast is likely to experience winds in the more than 40-knot 

 range every winter, with 50-knot speeds on occasion. 



c. Breakwater Description . 



(1) Design and Installation. The breakwater is of the concrete cais- 

 son type cast in 4.5- by 15- by 15-foot units using polystyrene foam blocks as 

 interior formwork and for positive flotation, with a 3-foot draft. The total 

 length of the breakwater, arranged in a U-shape (Fig. 24), will be 3,500 

 feet. The marina will have 840 slips for pleasure craft and fishing boats. 



The units are truck-hauled to the site where four of the units are post- 

 tensioned together to form 60-foot modules, which are then coupled by a chain- 

 rubber fender connector as illustrated in Figure 24. 



The anchor system makes use of clump weights on anchor lines consisting of 

 successive length of nylon rope and chain to stake piles, as shown in Figure 

 25, with a set of lines at each module connection. Figure 26 illustrates the 

 units and connections. Those responsible for the breakwater design, construc- 

 tion, and operation are as follows: 



Owner-Operator: Port of Bellingham 

 P.O. Box 728 

 Bellingham, Washington 



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