(USACE 1982). The screen created sufficient hori-
nificantly reduces the problem of ice accumula-
zontal water velocity in the upstream direction
tion on lock walls. The air screen system demon-
to keep the downbound ice from being pushed
strated during the program largely solves the float-
ahead by a ship. This system has also been used
ing ice problem by diverting ice from the lock
more recently to keep debris out of the lock ap-
and its approach. This not only limits the quan-
proach during open water periods.
tity of ice that can hinder gate operation and block
A compressor with an output of 1150 cfm at
the entry of ships into the lock, but it also reduces
110 psi was available at the Soo Locks for use in
the supply of ice that can be crushed and smeared
the air screen trials. The optimum air flow condi-
onto the lock wall.
tions were obtained using a 2-in.-diameter mani-
fold and supply line system, with 0.40-in.-diam-
eter nozzles spaced 10 ft apart. The manifold line
LITERATURE CITED
was 2-in. galvanized pipe with 2- 2- 1-in. tee
joints for each 10 ft of pipe. A 1-in. stainless steel
Acres American, Inc. (1975) Ice model study of
plug was mounted at each tee, and each plug had
the Little Rapids Cut area of the St. Marys River,
a 0.4-in. hole drilled in it that acted as the nozzle.
Michigan. Draft contract report to the Detroit Dis-
The air screen was installed at the upper ap-
trict, U.S. Army Corps of Engineers, Contract No.
proach to the Poe Lock on the downstream, ver-
DACW35-75-C-0014.
tical face of an emergency stop-log gate sill. The
Acres, Ltd. (1972) Study of Lake Erie ice boom.
sill is located about 200 ft above the lock gates.
Prepared by Water Supply Canada by H.G. Acres,
The riser line was installed in a stop-log recess in
Limited.
the wall. The width of the lock at this point is 110
Alger, G.R. (1977a) A study of ice related sedi-
ft, and the height from the top of the sill to the
ment transport and shoreline erosion, St. Marys
top of the lock wall is 39 ft.
RiverSault Ste. Marie, Michigan, Vol. 1: Main
The air screen has demonstrated that it can hold
Report. Contract Report to the USA Cold Regions
back ice pushed ahead of downbound traffic. With
Research and Engineering Laboratory, Contract
ships in the 70-ft-beam class, the ice was held back
No. DACA89-76-C-0013.
until the bow entered the air stream. The screen
Alger, G.R. (1977b) A study of ice related sedi-
was not as effective with 105-ft-beam ships. Once
ment transport and shoreline erosion, St. Marys
the bows of these wider ships pass the nose pier
RiverSault Ste. Marie, Michigan, Vol. 2: Appen-
about 130 ft upstream of the screen, the approach
dices. Contract Report to the USA Cold Regions
is just a little over 110 ft wide, so most of the ice
Research and Engineering Laboratory, Contract
remaining ahead of the ship is pushed into the
No. DACA89-76-C-0013.
lock. This problem might be remedied by relo-
Alger, G.R. (1978) A study of ice related sediment
cating the air screen upstream of the nose pier
transport and shoreline erosion, St. Marys River,
area and providing an area for ice to be pushed
St. Clair River, Detroit River, Michigan, Vol. 3.
out of the vessel track.
Contract Report to the USA Cold Regions Re-
search and Engineering Laboratory, Contract No.
DACA 89-76-C-0013.
Summary
One of the major obstacles to be overcome in
Alger, G.R. (1979a) A study of ice related sedi-
extending the navigation season on the St. Marys
ment transport and shoreline erosion; St. Marys
River was to develop methods to mitigate ice prob-
River, St. Clair River, Detroit River, Michigan, Vol.
lems in and around the Soo Locks. The two ma-
4, with Appendix. Contract Report to the USA
jor ice problems encountered were ice accumula-
Cold Regions Research and Engineering Labora-
tions on lock walls, which reduced the usable
tory, Contract No. DACA89-76-C-0013.
width of the lock, and large quantities of brash
Alger, G.R. (1979b) Ship-induced waves: Ice and
ice entering the lock from upstream, which could
physical measurements on the St. Marys River.
hinder the operation of the miter gates and inter-
Report to the Great Lakes Basin Commission in
fere with ships entering the locks.
support of the Winter Navigation Board-Environ-
During the program a variety of concepts were
mental Evaluation Work Group.
examined, including changing lock-operating pro-
Alger, G.R. (1980) A study of ice related sediment
cedures, minimizing ice adhesion, removing the
transport and shoreline erosion, St. Marys River
mechanically and controlling floating ice. A chemi-
Sault Ste. Marie, Michigan, Vol. 5. Contract Re-
cal, ice-release coating was developed that sig-
port to the USA Cold Regions Research and En-
47
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