Historic Snowmelt Causes Flooding, Problems for Utilities

Historic Snowmelt Causes Flooding, Problems for Utilities

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Though flooding isn’t a new challenge for heartland utilities, the unpredictable nature of snowmelt is a cause for anxiety.

“There’s a lot of pre-planning that’s going on right now, at this point just getting everyone aware and making sure we’re doing the things that we need to do to prepare,” says Hugh Kirkpatrick, general manager of the Caribou (Maine) Utilities District.

Caribou leadership met with regional agencies and municipalities in mid-March to discuss preparedness. At one meeting, a National Weather Service representative said that there was a foot of water content on the ground, meaning that if it were all to melt in a short span, it would be the equivalent of 12 inches of rain.

“Every spring, it’s really the rate of how everything melts,” Kirkpatrick says. “At what rate does all this snow turn into water? If we get a slow gradual melt, there might not be any problem. Anything more than that, or if you get a pile of rain . . .”

Kirkpatrick made that comment just before a warm rain swept across the Midwest, causing disaster and emergency proclamations throughout the region. Dozens of counties and cities declared emergencies and evacuations through Nebraska, Iowa, Kansas, South Dakota, Minnesota and Wisconsin.

A severe winter storm that hit Nebraska and Iowa was described by many as a “bomb cyclone” due to an extreme drop in atmospheric temperature that created hurricane-like conditions.

The greatest challenge of snowmelt is that it is impossible to predict how and where it might affect a system.

“The flooding doesn’t necessarily occur because we have too much water coming down the river, the flooding occurs because of ice jams. Interestingly enough, there’s no way to predict that,” Kirkpatrick says. “When you’ve got a winter’s worth of ice that goes downriver and jams up against a bridge, there’s really no way to predict how bad that’s going to be.”

Because of that, one of the most significant preparations a utility can make is simply having their equipment tested, prepped and read to go at a moment’s notice in case they do need to respond.

Catch basin issues

A compounding issue for utilities is that the freeze-thaw cycle of late winter can result in ice accumulation in catch basins — doubly so with the record-breaking snowfall that many areas saw in February.

“We had 16 inches of snow one day, and then a few days later we had some rain, then a significant freeze-up that night,” says Adam Cate, deputy director of operations for South Burlington (Vermont) Stormwater Services. “The snow that was on top of the curb slumps back over the curb and froze, covering a lot of catch basins.”

Even after the catch basins and everything else thaws, a winter like this has lasting effects.

“The byproduct of this awful freeze-thaw effect has been terrible potholes, which the effect on our drainage system will be a significant amount of broken asphalt, dirt — people don’t realize with potholes, it shakes all the rust and dirt out as cars rumble over them,” Cate says. “We’ll probably have to jet more lines and increase cleanup in the catch basins. It definitely makes for a lot more cleanup in the spring.”

Flood potential and freeze-thaw conditions are expected to continue for several more weeks, at least.

“This is my third winter here; there’s by far more snow this winter than in previous winters, so it is really a concern, with all the local communities,” Kirkpatrick says. “It’s really just by chance how it all melts.”


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