St. George water main break swallows car and closes a block of 100 South
This one was because of a water line break, according to St. George public works director Cameron Cutler.
“It was really just a coincidence that it happened during the storm that we had,” he said. “We didn't have any flooding anywhere else.”
Actual sinkholes form by rainfall eroding the ground to form a cave that eventually collapses, said Bill Johnson, a geology professor at the University of Utah. Other so-called sinkholes, like the one on 100 South, are caused by infrastructure problems and aren’t considered geological hazards.
“They’re under pressure and a jet of water will remove whatever's in front of it,” Johnson said. “While that process is kind of akin to a sinkhole process, it occurs over a short time, right, it occurs over hours to days and creates a puddle that can be dangerous.”
In this case, Cutler said the water found its way to the surface and took out sediment and asphalt causing a hole to form. For the past few years, he said the city has been taking stock of its aging underground infrastructure. He said they’re addressing areas of concern and keeping an eye on other older pipes.
“For the most part, our roadways, our systems are pretty good,” he said. “We just have these small waterline breaks or something like that cause a little issues here and there.”
Recent rain in St. George comes after 92 consecutive days without precipitation, according to the National Weather Service. More rain and the potential for flash flooding is expected in the coming days.