No 'silver bullet' solution to Red River ice jams
There is "no 'right' way" to deal with river ice, "no silver bullet" to prevent jams before a flood, one of the nation's leading authorities on ice jams said Monday.
Kate White, a hydraulic engineer with the Cold Regions Research and Engineering Laboratory in Hanover, N.H., arrived in Fargo on Monday, part of a team assembled by the Army Corps of Engineers to track the formation and movement of ice in the Red River flood.
Dealing with ice jams, such as the 4-mile-long slab threatening bridges at Oslo, Minn., depends on such variables as ice thickness, water flow, what's happening upstream and downstream, and potential risks.
"The key is whether the ice jam is amenable to being broken up ahead of time," White said. "Or are you just moving the jam downstream, or breaking the ice up too early only to have it freeze again?"
Explosives "are not always the first choice," she said, with safety and environmental concerns and risks to levees.
"But explosives can be effective if used in a right way," and she cited last week's assault on Missouri River ice jams near Bismarck. A solid ice cover allowed charges to be set into the ice, and that broke open a channel "so the flow could carry the ice away."
The first demolition used 160 pounds of C-4 plastic explosive supplied by the North Dakota National Guard. The C-4 was packed into 80 holes drilled into ice 3 feet thick. Later, helicopters dropped road salt onto other parts of the river ice to weaken it.
Many places have tried drilling holes in the ice to hurry breakup, White said, "but there's no firm way to quantify benefits."
A more expensive response: the strategic placement of ice control structures, such as dams and booms, which could control where jams form.
Nebraska set up a statewide ice reporting system after damaging 1993 ice jams on the Platte and Missouri rivers. "It's an excellent system," she said.
White was in Grand Forks and Crookston 20 years ago to study ice jams during the 1989 floods. Early this year, she watched the prairie winter from afar, noting icy similarities to 1997.
"You're dealing with pretty thick ice, like in 1997, yet you've also had a record snowpack," she said. "I remember looking at numbers back in February and saying, 'Well, we're setting ourselves up.' "
Jamming in Oslo
In Oslo on Sunday, flood fighters tried lowering a 4,200-pound weight from a Minnesota National Guard Chinook helicopter onto ice to the north, to little effect.
Excavators were to be used this week to grab at the southside ice from atop the railroad bridge. Workers with Gowan Construction of Oslo and personnel from the railroad and the Corps of Engineers were helping, City Council member Scott Kosmatka said.
The aerial effort to the north Sunday "broke the ice a little but not enough to make a difference," he said. "And the helicopters had to use so much fuel."
Ice jams are nothing new on the Red River. At public meetings after the 1997 flood, the International Joint Commission and its task force on the Red River Basin heard many suggestions on how to deal with them.
In a 2000 report prepared for the commission (www.ijc.org/rel/pdf/
icereport.pdf), researchers found that certain river features, such as sharp bends, "are highly conducive to jamming."
That's the Red River of the North, with its hairpin curves and slight gradient. Also, tributaries with "relatively significant channel gradients and confined channels are prone to ice jams," including the Red Lake River at Crookston -- where an ice jam early last week caused a sharp and sudden rise in river level and prompted some temporary evacuations.
River ice can erode stream banks as well as make flood forecasting difficult, the report states. "Small bridges can be swept away," and approaches may erode.
Kevin Dean, Grand Forks information officer, said City Engineer Al Grasser and other officials are familiar with the IJC report and recommendations.
"The problem is that with ice jams, although there are many different ways to deal with them -- sand to hurry melting, dynamite, backhoes -- there really aren't any absolutely foolproof methods," Dean said. "It's mostly Mother Nature you have to rely on to break them up."
Dean said the margin between the expected crest and the city's defenses could withstand some fluctuations caused by a local ice jam.
Manitoba employs some high-tech equipment to deal with jams threatening Winnipeg and its environs.
After warnings earlier this month of potential major flooding on the Red River, Manitoba paid $1.2 million for an Amphibex ice-breaking machine, a sort of floating backhoe that claws through river ice with an articulated arm.
Think of it as a Zamboni with attitude.
The new machine complements one already operated by two municipalities and the city of Selkirk. They were pressed into service north of Winnipeg last week on an ice jam that had backed up the Red River and caused flash flooding, forcing more than 30 families from homes in the municipality of St. Andrews.
Mayor Steve Strang of nearby St. Clements said the ice jams, ice-clogged culverts and the rising river threaten the "worst two weeks" in the community's history.
According to a company Web site, the Amphibex was designed in Quebec and can be used to clean contaminated waterways, install pipelines and underwater cables and do dredging work, as well as control river vegetation.
It is "highly effective" for breaking up and preventing ice jams and making it "unnecessary to use dynamite, which can harm the environment," according to the company site (www.normrock.ca/1/
The IJC, the Army Corps of Engineers and other agencies have identified several other means of mitigating ice jams. Structural measures -- such as the smoothing out of some river curves, part of the Grand Forks-East Grand Forks project after 1997 -- are more expensive but generally more effective than trying to break up or weaken winter ice by drilling or using icebreakers, chemicals or explosives.
In some locations, flood planners have tried to hurry ice breakup by dusting the ice surface with certain materials to enhance solar radiation. But this must be done about a month before the anticipated breakup, and the application could be rendered useless by new snowfall. The IJC report says a dusting on the Red River years ago failed because the sand was too light in color.
Still, the report's authors recommend an ice management approach in the Red River basin that relies primarily on channel modifications, dusting with "chemically benign substances," and ice cutting and drilling -- not so much on things that go "boom!" or monster ice-eating machines.
They also note that "very little work has been done on the more complex question of how climate change may influence the frequency and severity of ice jams."
Reach Haga at (701) 780-1102; (800) 477-6572, ext. 102; or send e-mail to email@example.com.