Duluth-Superior Harbor Structures
Duluth-Superior, Minnesota and Wisconsin
Date ( s )
Construction and Rehabilitation History
1898-
The construction of two 1,720-ft-long entrance piers at Duluth Ship
1900
Canal (Figure
occurred during this period. These were timber
crib structures filled with stone and timber (oak and pine) with a
concrete superstructure (monolith blocks). The el of the super-
to +18 ft lwd with widths of 24 ft to 36 ft
structure ranged from
at the structure heads (Figure 1 )
2.
1904-
Construction of a 2,096-ft-long north pier and a 1,581-ft-long south
1907
pier progressed at Superior Entry (Figure
These structures were
built with concrete. Crest widths ranged from 8 to 11 ft with els
to +16 ft
ranging from
(Figure 1 )
2.
1908-
During this time, a 4,137-ft-long north breakwater and a 1,866-ft-
1913
long south breakwater were constructed (Figure 11) at Superior Entry.
The pierheads and breakwater heads were timber cribs filled with
ft lwd, and widths were 40 and
stone and timber. Crest els were
31 ft, respectively, for the pierheads and breakwater heads (Fig-
ure 1 )
2 . The breakwater trunks were rubble-mound structures in-
stalled at el
ft
(Figure 12) with
side slopes.
Ten-ton armor stone was used. The shoreward ends consisted of con-
crete structures installed on rubble (Figure 1 )
2 . Crest widths were
ft lwd.
12 ft, and crest els were
1933
A 530-ft-long rubble-mound shore connection was installed on the
inner end of the north breakwater at Superior Entry. It consisted of
an 8-ft crest width at an el of
ft
with
side slopes.
Thirty feet of the outer south pierhead at Duluth Ship Canal was re-
1949
built, and 406 ft of the south pier at Superior Entry was rebuilt.
These consisted of steel sheet-pile walls and concrete (Figure 1 )
2.
The pierhead at Duluth Ship Canal was built with a crest width of
14 ft at an el of +13 ft lwd. The pier at Superior Entry was 8 ft
wide with an el of
ft lwd.
Longitudinal cracks on the pierhead in the middle of the super-
1956
structures were repaired at Duluth Ship Canal. The repair consisted
of horizontal tie bolts through each monolith and reinforcing bars
drilled and grouted through the tunnel. After the bars were in
place, the tunnel was filled with concrete. No separation of the
monolith has occurred since then.
Twenty-six feet at the inner end of the south pierhead and 1,019 ft
1957-
at the south pier at Superior Entry were rebuilt using steel sheet-
1958
pile walls and concrete (Figure 1 )
2.
(Continued)
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