Area cities are seeing fewer water main breaks than usual, thanks to some combination of mild winters and replacement of old cast iron pipes.
Usually, Mankato averages between 40 and 60 of the disruptive and costly breaks a year, but had only about 32 in 2013, Infrastructure Supt. Tony Talamantez said. North Mankato and St. Peter have had fewer breaks than normal, as well.
Deep frost is the enemy of water pipes, and it’s forming whenever the weather stays below freezing, Talamantez said. Despite the bitter cold of recent days, two relatively tame winters may have played a role in the trend.
But the replacement of the old pipes, typically during street projects, with more flexible plastic pipes and more fatigue-resistant ductile iron has also greatly reduced the number of breaks.
“About the only time you see newer pipe break is if it’s installed incorrectly,” Talamantez said.
In St. Peter, there have been no water main breaks this winter due to the weather, which is a bit unusual, Public Works Director Lew Giesking said.
“We’ve got a program to upgrade from cast-iron to ductile iron,” he said.
Giesking said pipes break not simply because of the cold, but because one area freezes before another area, creating a difference in pressure.
“The idea is you lay water main in a bedding, so there’s equal pressure all around,” he said.
Likewise, North Mankato has had fewer than normal, though it’s partly a matter of luck, Public Works Director Brad Swanson said.
“My overall sense of it is we’re probably below average,” he said.
But even that assessment may have been enough to invite some bad luck. A water pipe broke Friday morning in upper North Mankato near Noretta Drive.