Table 12 



Ontonagon Harbor Piers 



Ontonagon, Michigan 



Date (s) Construction and Rehabilitation History 



1868- Construction of the inner 1,069 ft of the west pier (Figures 28 

 1872 and 29, Section E) occurred during this time. This structure con- 

 sisted of woodpiling filled with stone. The pier width ranged from 

 8.5 to 11 ft. 



1868- The outer 1,515 ft of the east pier (Figures 28 and 29, Section A) 

 1879 was built during this period. This was a rock-filled timber crib 



structure. The pier was 20 ft wide and had stone toe protection at 



its base. 



1875- Construction of 1,398 ft of the west pier (Figures 28 and 29, Sec- 

 1890 tion A) progressed. The pier had the same cross section as the pier 

 built during 1868-79. 



1881- Construction of an additional 255 ft of the east pier (Figures 28 

 1882 and 29, Section B) was completed. This was a 20-ft-wide stone-filled 



timber crib structure with stone toe protection. 



1882- The inner 545 ft of the east pier (Figures 28 and 29, Section C) was 

 1888 built. This pier also was a stone-filled timber crib structure with 



a 20-ft crest width. 



1920- A stone superstructure was built on 1,515 and 1,398 ft of the east 



1935 and west piers, respectively (Figure 29, Section A). The el of these 

 piers was +5 ft Iwd. 



1933 A concrete cap (superstructure) was constructed on the inner 1,069 ft 

 of the west pier (Figure 29, Section E) . The el of the channel side 

 of the pier was +4 ft Iwd. 



1935- A stone and concrete cap (superstructure) was installed on 800 ft of 



1936 the east pier (Figure 29, Sections B and C). The shoreward 545 ft of 

 structure had a crest el of +5 ft Iwd (Section C) , while the remain- 

 ing pier had an el of +6 ft Iwd (Section B) . 



1947 The 96-ft-long west pierhead was rebuilt with steel sheetpiling that 

 was stone filled. It was capped with 5-ton minimum cover stone. The 

 pierhead was 22 ft wide with a crest el of +6 ft Iwd. Riprap was in- 

 stalled to provide toe protection. It is not clear when the pierhead 

 was originally constructed. 



1983 A structural inspection of the piers was made. A void up to 20 ft 

 wide was observed on the west pier, and sand was being lost through 

 the cribbing under the superstructure. Additional stone was required 



(Continued) 



55 



