Table 13 



Keweenaw Waterway Structures 



Keweenaw Waterway, Michigan 



Date(s) Construction and Rehabilitation History 



North (Upper) Entry 



1898- A 2,385-f t-long east breakwater and a 2,645-f t-long west breakwater 

 1902 were constructed at the north entrance during this time (Figure 31, 

 Sections C and D) . These structures were stone-filled timber crib 

 breakwaters. The shore wings were 20 ft wide, and the main break- 

 waters were 30 ft wide. 



1917- The main breakwaters (Figures 31 and 32, Section C) were capped with 

 1931 5-ton stone. Fifteen-ton stone was placed on the channel side of the 

 structure for stability of the cap. The el of the structure was 

 +8 ft Iwd. Rubble was placed on the lakeward side of the structure 

 on a 1-V:1.5-H slope and capped with 10-ton stone. 



1933 The Inner wings of the breakwaters (Figures 31 and 32, Section D) 



were capped with a stone fill and concrete. The el of the structures 

 ranged from +5 to +7 ft Iwd. Rubble toe protection also was 

 Installed. 



1948- Construction of the breakwater pierheads (Figures 31 and 32, Sec- 

 1949 tions A and B) progressed during this period. The 50-f t-long east 

 pierhead was built with steel sheet piles and sand, and the outer 

 cover of the entire structure was built with concrete. The crest el 

 of the structure was +18 ft Iwd. The west pierhead was 50 ft long 

 and constructed of concrete and steel sheet piles with a sand fill. 

 The el of the structure was +10 ft Iwd. 



1986 The breakwaters at the Upper Entry have undergone routine maintenance 

 and presently are in fair condition. Figure 33 is an aerial view of 

 the upper entrance to Keweenaw Waterway. 



South (Lower) Entry 



1860 Construction on the inner 950 ft of the breakwater was completed by 

 private interests (Figure 34, Section I-L) . This structure was a 

 stone-filled timber crib breakwater. The width of the shoreward 

 325 ft of breakwater was 13 ft, and the remaining structure was 30 ft 

 wide to a point 912 ft from its origin. At this point, the structure 

 width changed to 24 ft. 



1897- The outer 2,764 ft of the breakwater was built by the United States 

 1900 during this period (Figure 34, Sections L-N) . The breakwater was a 



stone-filled timber crib structure with a 24-ft width, except for the 



lakeward 100 ft which was 30 ft wide. 



(Continued) 

 60 



