tural width of 650 ft, the cost would come to
about 00/ft, but the project cost also includes
excavation to enlarge the pool upstream of the
structure as well as the construction of a 200-ft-
wide floodway to route flows around the struc-
ture at higher discharges.
Belore et al. (1990) described an ice control
structure on the Lower Credit River in Canada
consisting of concrete piers placed at approxi-
mately 7-ft spacings across the main river chan-
nel. The structure was designed to stop the down-
stream movement of ice at breakup and make use
of the available channel and floodplain storage.
Ice booms, the most widely used type of ice
Figure 10. Plan view of the Allegheny River ice boom.
retention structure, are essentially a series of logs,
(From Perham 1983.)
timbers or pontoons tethered together and strung
across a river to control the movement of ice (Fig.
Table 6. Summary of costs for existing ice boom in-
10). In some locations, however, the boom ele-
stallations. (After Perham 1976.)
ments are supported by fixed piers. Ice booms are
most commonly used to stabilize or retain an ice
Length
Cost
Unit cost
Body of water
(ft)
Year
($M)
($/ft)
cover in areas where flow velocities are 2.5 ft/s or
less and relatively steady.
St. Lawrence River,
16,830
1960
0.8
48
While conventional ice booms are normally
Ogdensburg, New York
Prescott, Ontario
used to promote ice cover formation during
freezeup and during midwinter in areas of mar-
Lake Erie, Niagara River,
8,800
1964
0.9
103
ginal stability, if properly designed they can have
Buffalo, New York
application in some breakup situations. The Lake
Beauharnois Canal,
17,000
1964
1.5
92
Erie ice boom located at the head of the Niagara
St. Lawrence River,
Beauharnois, Quebec
River has been employed for many years to keep
lake ice floes from passing into the river, causing
Copeland Cut,
750
1974
0.25
333
flooding and disrupting hydroelectric plant oper-
St. Lawrence River,
Massena, New York
ations. Perham (1983) recounted a description of
an experimental ice boom built on the Chaudiere
Riviere des Prairies,
2,300
1975
0.25
109
Montreal, Quebec
River in Quebec:
The boom was like a horizontal rope ladder with
Lake St. Francis,
7,200
1975
2.0
278
steel structural channel sections for rungs. The
Valleyfield, Quebec
spaces between the rungs were filled with wood-
St. Marys River, Sault
2,400
1975
0.5
212
en blocks. The two parallel 25-mm-diameter
Ste. Marie, Michigan
wire ropes were anchored to heavy concrete
structures at each shore. The arrangement was
expected to retain ice until a flow of 207 m3/s
cost approximately 0,000 to construct in 1982.
It spans a river that is 540 ft wide, for a unit cost of
(four-year flood) was reached.
Costs for ice booms can vary with river size
about 00/ft. The Montreal ice control structure,
and ice conditions. Table 6 summarizes the costs
on the St. Lawrence River, is a rigid ice boom that
for a number of flexible ice boom installations as
uses floating steel booms or stop logs set between
compiled by Perham (1976). The costs listed have
concrete piers to collect ice floes and stabilize an
not been converted to a common year but corre-
ice cover. The 1.27-mile-long structure cost ap-
spond to costs at the time of design and construc-
proximately million in 1964-65 (Perham 1983),
tion as indicated in the table; costs for structures
or about 00/ft.
in Canada are in Canadian dollars. The only
Groins, dikes or jetties can be used to constrict
Corps of Engineers structure is the St. Marys Riv-
channel width, raise water levels and reduce up-
er ice boom, which had a unit cost of about 2/
stream velocities to promote the formation of a sta-
ft of river width spanned in 1975. More recently
ble ice cover (CummingCockburn and Associates
the Pittsburgh District constructed the Allegheny
1986, Janzen and Kulik 1979). Sometimes the ice
River ice boom shown in Figure 10. This boom
retention capacity of such structures is enhanced
21
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