Last weekend’s freezing cold snap caused five water mains toburst around the city, but it’s not actually the cold that’sresponsible.

It’s the ground itself.

Brookhaven Water Department Assistant Superintendent Keith Lewissaid damage done to five city water mains that cracked since Fridayafternoon was caused by movement in the earth as the groundexpanded in the cold. Extreme weather changes – like last weekend’s20-degree cold snap – cause the ground to shift weight on thepipes, he said, resulting in breakages.

“If it’s going from cold to hot, wet to dry – anytime you have achange in the weather, the ground shifts,” Lewis said.

Contrary to popular belief, ice formation is not what causesmains to burst – that condition only affects smaller pipes likeoutdoor faucets.

The 6-inch pipes are buried anywhere from 3 to 8 feet below thesurface, while the ground’s freezing level is generally 6 inches,Lewis said. Likewise, the big pipes move a large volume of water,operating at around 60 pounds per square inch (psi), making itimpossible for ice to form inside.

Damage to the big metal pipes is minimal, but it doesn’t takemuch.

A hairline fracture is enough to cause water to jet out from thepipe, and Lewis said a leak could go unnoticed for more than a daywhile water is pushed to the surface, making the leak visible.Beginning Friday around 3 p.m., five mains burst around the city,at Adam, Court, Monticello, North Jackson and Railroad streets.

No city residents experienced outage and water pressure was notaffected, Lewis said. The last of the five breaks was repairedMonday afternoon, a simple task that requires bolting on a metalsleeve with a rubber gasket that contains the leak.

“It’s digging down to them that’s the hard part,” Lewis saidwhile his men dug into the earth with shovels and a backhoe.