3
DESIGN OF ICE BOOMS
2. Ice boom with a
navigation opening,
designed to prevent
wind-driven lake ice
from entering a
hydropower canal on
the St. Lawrence
Seaway.
force levels on the booms. Once a solid ice cover has formed,
most of the downstream forces on the ice cover are transferred to
the channel banks rather than to the boom, and the flow can be
increased to pre-freezeup levels.
Formation booms are also used to reduce the threat of ice jam
flooding on poolriffle river reaches by capturing and retaining
frazil at locations upstream of the problem area, thus preventing
the formation of freezeup jams farther downstream. By decreas-
ing the volume of frazil accumulations in problem reaches, the
booms may also alleviate ice jam flooding by reducing the pre-
breakup ice volume.
In addition to promoting ice formation, booms are used to
control ice accumulations made up of floes or brash. Booms have
been used successfully at channel constrictions, both to promote
arching and to prevent brash ice from blocking the narrower
downstream channels. Figure 2 is an example of a boom with a
navigation opening, designed to prevent wind-driven lake ice from
entering a hydropower canal. Booms may be designed to divert
frazil or brash ice away from lock entrances or hydropower in-
takes. In some applications a boom may have the dual purpose of
retaining frazil early in the ice season and controlling brash ice as
the ice cover begins to deteriorate.
Additional information on successful ice boom designs may be
found in EM 1110-2-1612 Ice Engineering (U.S. Army Corps of
Engineers 1982) and CRREL Report 83-30, Ice Sheet Retention
Structures (Perham 1983). CRREL Special Report 95-18, Struc-
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