Shrinking Clay Soils a Headache for Cities too

Business is good for area foundation repair contractors because the drought is so bad. The same expansive clay soils that are now shrinking from lack of water and moving home foundations are also causing water mains to shift and break at the city level.

For homeowners it’s even more important to keep those soaker hoses going around the concrete foundations.

Here is part of a report from Wendy Hundley and The Dallas Morning News:

Friday, July 28, 2006

Bone-dry soil.

Officials say the ongoing drought is causing the bone-dry soil to shrink and shift. The ground movement puts pressure on buried waterlines, causing them to rupture, spilling millions of gallons of precious water and frustrating conservation efforts.

Richardson, which usually has five waterline breaks a week, has had to repair 26 lines since last Friday. Road crews have been temporarily reassigned to help with the repairs. “It’s pretty much unprecedented,” said Michael Wanchick, assistant city manager for development services.

In Dallas, crews have repaired 700 more breaks this year than they had by this time last year. Arlington has had 122 ruptured pipes since June 15. Mesquite has had 187 waterline breaks since June 1, about twice the normal number.

Garland has had 60 this month. “Normally for July in a wet year, we have around 20 a month,” said Robert Ashcraft, water distribution manager for the Garland Water Department. “It’s even above normal for a hot, dry year.”

With cities limiting watering to once or twice a week, the sudden changes in water pressure when everyone turns on the sprinklers can cause further damage.

“Everyone is using so much water the velocity of the water is putting stress on the pipes,” Mr. Ashcraft said.

In Arlington, most of the breaks are occurring in the eastern part of the city, which has high concentrations of clay soil, said John Durbin, interim assistant director of utilities.

The western part of the city has more sandy soil that tends to shift less than clay soil as it dries out.

“When it gets real dry, the earth starts to shift and crack down to where our mains are,” Mr. Durbin said. “Some of our older mains can’t take it.”

Older waterlines, made of inflexible cast-iron, break more easily than the newer pipes made of PVC or reinforced concrete.

“We have several hundred miles of pipes installed in the ’50s and ’60s,” Mr. Durbin said, noting the city is gradually replacing older lines with plastic pipes.

Last week, a main break in Royse City caused a flood of phone calls to City Hall from people wondering why their water pressure had suddenly dropped.

“We’re being plagued with main breaks, but that’s common all over North Texas right now,” said Karen Philippi, city manager of Royse City. “Even as the ground shrinks, our pipes can’t stretch.”

Officials say they’re being alerted to the breaks by homeowners who see water bubbling out of lawns or city workers who notice water running out of cracks in streets.

Was this a danger SimCity? I don’t remember. I barely remember yesterday.

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