Table 22
Columbia River At The Mouth
Oregon
Date(
Construction and Rehabilitation History
A study was authorized for improvement of navigation at the mouth of
1882
the Columbia River. The study, submitted in 1882, recommended con-
struction of a south jetty approximately 4 . 5 miles long.
1884
Construction of the south jetty was authorized.
1885
Construction of the south jetty was initiated.
The Board of Engineers recommended increasing crest elevation of the
1893
jetty to +12 ft mlw at the shore, sloping to
mlw at a distance
of 1.125 miles from shore, then sloping to
mlw at the outer
end. Also recommended was the construction of groins on the north
side of the jetty.
The south jetty was completed, including the recommendations made in
1895
1893. Jetty length was 22,440 ft and required 945,923 tons of stone.
The channel depth decreased as the channel shifted to the north. A
new study was authorized for stabilization of the channel at - 40 ft
mllw.
The report authorized in 1899 was submitted for study. The report
1903
recommended extending the south jetty 2.5 miles westerly and con-
structing a north jetty to extend westerly from Cape Disappointment.
The extension to the south jetty was constructed. The extension was
12,514 ft long and required 4,837,311 tons of stone.
1913
The north jetty was constructed to a crest elevation of +28 to
ft
mllw, a crest width of 25 ft, side slopes of
and length of
1917
approximately 2 . 5 miles.
The inner 3 . 3 miles of south jetty were rehabilitated with
2,207,613 tons of stone.
1937
portion of the south jetty was repaired during
The outer
1937
with 10,636 tons of stone. The outer 500 ft were impregnated
with 12,737 tons of asphaltic mix with 18 percent asphalt and 82 per-
cent beach sand.
The north jetty was rehabilitated except for the outer 1,700 ft.
A concrete terminus was placed at the end of the rehabilitated
1939
section.
(Continued)
113
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