steeper section of the Ste. Anne River. The struc-
Breakup ice retention at dam spillways
ture has dual roles. The 15-ft-deep pool behind
The Sartigan Dam at St. Georges, Quebec, (Fig.
the weir stores frazil, preventing its deposition
10) is mentioned again in this section due to its
in St. Raymond, as well as protecting the town
role as a breakup ice control structure (Michel
from breakup ice jam flooding.
1971, Perham 1983). The dam is a larger version
Information on the design approach and per-
of the Ste. Anne River weir-with-piers structure
formance of the St. Raymond structure was diffi-
at St. Raymond, with eleven 20-ft-wide overflow
cult to find. Albert Real Tremble of the Quebec
gates, separated by concrete piers. The gates are
Ministry of Environment and Forests was in-
equipped with steel grates with 2.0-ft-wide by
volved with the St. Raymond structure and simi-
3.5-ft-high openings to retain breakup ice. Resi-
lar ice control projects in Quebec. The design
dents of St. Georges interviewed in 1994 believed
process was somewhat empirical, relying on the
that the dam has solved the town's historic ice
successful experience with the ice control dam at
jam flood problem.
St. Georges.* During breakup, a floating accu-
A 7-ft-high timber crib dam, designed by the
mulation of broken ice pieces, and not sheet ice,
Corps of Engineers, was constructed on the
arches between the piers.† Jean-Phillipe Saucet
Narragaugus River in 1961 to protect the town of
of LaSalle Consulting Group Inc. is working on
Cherryfield, Maine, (roughly 1 mile downstream)
the design of a similar breakup structure for the
from breakup ice jams (Fig. 21) (Perham 1983).
Becancour River, near Trois Rivieres, Quebec.
Upstream of the dam are three rock-filled timber
The key is to design a weir that will create up-
cribs on 50-ft centers, designed to prevent large
stream hydraulic conditions that allow the for-
pieces of sheet ice from passing the dam's 140-ft-
mation of a stable floating equilibrium ice accu-
wide central spillway. The dam creates an ice
mulation, for the expected range of breakup dis-
storage reservoir and is similar to the proposed
charges.** The plans for the Becancour structure
ice control project for the Mohawk River at Cole-
show a 140-ft-wide weir with piers spaced at 20
brook, N.H. During an intense rainfall event in
ft and a gated bottom outlet.
February 1968, the sheet ice behind the dam re-
Figure 20. Proposed ice control structure for
Cazenovia Creek near Buffalo, New York.
The St. Raymond structure influenced the de-
sign of a similar breakup ice control structure for
Cazenovia Creek near Buffalo, N.Y. (Gooch and
Deck 1990). Although a promising design was
developed (Fig. 20) through a physical model
study at CRREL, lack of funding prevented con-
struction of the prototype.
* Personal communication with Albert Real Tremble, Sep-
tember 1994.
† Personal communication with Marc Delgrave of Roche Itec
Consultants, September 1994.
Figure 21. Rock-filled timber cribs upstream of the
** Personal communication with Jean-Phillipe Saucet of
dam at Cherryfield, Maine.
LaSalle Consulting Group Inc., September 1994.
17
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