Politics & Government

Pot Holes and Frost Heaves and Sink Holes, Oh, My!

Montville DPW Chief Says Water Is the Culprit

When the weather is good for maple sugaring, it’s ideal for potholes, frost heaves and sinkholes. So right now, we are in the prime time of the season for these road changes.

Department of Public Works Director Donald W. Bourdeau explained how these road-changing events come to pass.

When asphalt is new, Bourdeau says, it is dark in color, and filled with oil. In the same way that a teenager is strong and flexible, a young road is strong and flexible, too.

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As time, traffic and weather take their toll, the road surface dries out and becomes increasingly brittle.

“Alligator cracks,” those long, undulating breaks in the road surface, begin to develop. This is the beginning of all three road problems, Bourdeau says.

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Pot holes

“Water gets in, freezes, and expands, over and over,” Bourdeau says. “As time goes on, it’s a continuous process.”

Every time the water freezes, it expands, pushing the edges of the crack farther apart, and opening up the road surface deeper and deeper. Eventually, the water will make its way to the bottom of the asphalt.

Beneath the asphalt is a mix of gravel and what Bourdeau calls “fines,” fine particles of sand and soil that make a bed for the asphalt.

The water will continue its process of freezing and expanding at night, and melting and making its gravitational way downwards during the day.

In time, it will take the “fines” with it, Bourdeau says, leaving a slight depression in the gravel bed beneath the asphalt surface.

When something heavy, like a truck, drives over at the right place and the right speed, the weight of the truck will push down on that depression, and the surface of the asphalt will split and break off, and there’s your pot hole.

“Once there’s a depression,” Bourdeau says, “then there’s nothing to keep it from breaking.”

Frost heaves

Frost heaves work in much the same way, Bourdeau says, except that they begin underneath the surface.

Soil, and even the gravel used for the bed beneath the asphalt, contain water. As the days warm and the nights freeze, the water in the gravel expands and contracts. Over time, this action will cause the gravel to shift and settle. When the water freezes, it expands, and, Bourdeau says, will move in the direction that’s easiest for it to go.

“That is up,” he says.

As the water freezes and pushes up, it pushes the asphalt with it, and you get a frost heave.

Sink holes

Sink holes are like frost heaves with extra water.

Often, Bourdeau says, they begin with a broken water or sewer line, or with flooding. Water is introduced, and when it flows out, it takes a big amount of soil and gravel with it, leaving a large gap unseen beneath the surface.

Something heavy passes over it, and everything on the surface falls into the depression beneath.

Repairs

It’s tough to make repairs while the weather is cold, Bourdeau says. For starters, the hot asphalt plants shut down for the winter, he says. The patching material the town uses does not stick as well as hot asphalt, but it will work until the weather warms and the permanent repairs can be made.

The Montville DPW is responsible for 119 miles of road, Bourdeau says, and urges citizens to call his department to report pot holes. The number is 860-848-7473, or you can email bmissios@montville-ct.org


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