Public works director Kevin Tobeck said three water main breaks over the holiday weekend appear to be random coincidences, rather than a sign of systemic trouble in underground pipes.

He said crews are still testing valves to make sure there was no spike in water pressure that might have caused three mains to break in two days.

But the three water mains were not near each other, which suggests the breaks were unconnected, and one busted water main in south Tracy was a newer pipe made of iron, which is now the city’s standard.

“It may be one of those freak things,” he said. “Hopefully, that’s all it is.”

Pipes can break for all sorts of reasons, he said, such as a weak connection or problems with the soil.

The most recent water main to break was a concrete pipe that burst under a road in northern Tracy on Monday morning, flooding three blocks around Kavanagh Avenue in 3 feet of murky water. Tobeck estimated that pipe might be 40 or 50 years old.

The floodwater completely covered the sidewalks of three city blocks and extended a few feet onto neighbors’ lawns. No homes or cars were damaged, as far as public works employees knew, but the high-water mark reached the doors of some sedans parked on the roadside.

Isabelle Nnaji, 42, who lives almost directly in front of the 4-foot breach in the main, was returning home from a morning walk when she turned the corner from Tracy Boulevard onto Kavanagh Avenue and saw muddy water gushing from a sinkhole in the middle of the street.

“It was just pouring out, like a river,” she said. “And then it kept going and going until it covered all this street. We couldn’t leave.”

A team of six public works employees gave up their holiday weekend to fix the mess, which might have been caused by unusually cold water constricting an antique concrete pipe under the roadway until it burst, according to Wayne Bogart of the Tracy Public Works Department.

“People think that it’s the storm that caused it, but it’s really just a coincidence,” he said from the seat of his tractor. “It’s a change in water temperature.”

At its worst, the flood rose to 3 feet, Bogart said, and started pouring over the top of his rubber rain boots. From the sinkhole near the Tracy-Kavanagh intersection, the water ran a block and a half east on Kavanagh and a block in both directions on Sunset Way, a cross-street.

An iron pipe burst under the road Sunday in the Glenbriar subdivision south of Valpico Road, Bogart said. Tobeck estimated the pipe was about 15 years old, and the surge of water loosened the dirt and buckled the roadway, as it did on Kavanagh Avenue.

Another, smaller flood reached up to and over the sidewalks on 23rd Street, in north Tracy.

By the end of the day Monday, the broken mains had been fixed.

The final cost of the repairs in unclear, but money to fix broken pipes is set aside in the department’s roughly $140 million yearly budget, Tobeck said.