Table 3
Knife River Harbor Breakwater
Knife River, Minnesota
Date
Construction and Rehabilitation History
1957-
Construction of a 245-ft-long breakwater occurred at the site (Fig-
1958
ure 9 during this time frame. The shoreward 215 ft of the structure
)
was of rubble-mound construction, and the lakeward 30 ft was a stone-
filled timber crib breakwater (Figure 1 )
of the breakwater had a crest width of 8 ft and an el of
ft lwd.
were constructed, and armor stone ranging from
Side slopes of
3 to 5 tons was used. The timber crib structure was 30 ft wide with
a crest el of
ft lwd. It was constructed on a stone mattress and
had a timber deck. Rock was placed around the toe of the structure
comprised of cover stone ranging from to 5 tons. After construc-
tion it was noted that a design deficiency existed in that the break-
water did not effectively protect the harbor entrance from adverse
wave conditions from northeasterly storms.
1974
A modification to the project authorized the construction of a
451-ft-long rubble-mound breakwater with four 62.8-ft
steel
sheet-pile cells (250 ft) at its head (Figure 9 ) . Construction of
the breakwater has not been initiated.
1986
Since the original breakwater was completed, it has sustained some
localized damage which was repaired during routine maintenance. The
structure is presently in good condition.
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