Table 4 (Concluded)
Construction and Rehabilitation History
A hydraulic model investigation (Wilson 1963) was conducted at
Superior Entry to improve wave conditions in the navigation channel
and at the ore docks located opposite the entry. Proposed plans in-
volved detached breakwaters lakeward of the existing entrance. Im-
provements were never constructed at the site.
The concrete superstructures of the north and south piers and the
substructures at Duluth Ship Canal were inspected. The timber cribs,
riprap, and armor protection were determined to be, generally, in
good condition. Small gaps were noted along the joints of the cribs,
but the timbers were still firm, and no warping was noted. Some
cracks were noted in the monolith blocks, but there was no misalign-
ment or settlement; and the joints were all tight.
An inspection of the piers at Duluth Ship Canal was conducted. The
north pier was in need of work both above and below the surface, and
the south pier was reported in very good condition. An inspection of
the Superior Entry inner piers indicated that the structures were in
fair condition. In general, the structures needed maintenance, and
repairs were done.
In general, very little maintenance has been needed since
of the project. Minor patching of spalling concrete has been
attempted with generally poor results. The structures overall are
presently in fair condition.