Texas limestone could make Texas vulnerable to sinkholes

Texas may be more susceptible to sinkholes than you think.

Overnight Monday, a sheriff’s deputy was killed in San Antonio when the road opened up and swallowed two cars. The sewer line underground is now being investigated.

No one was hurt in a Northwest Austin neighborhood back in June when ten foot sinkhole opened up on a Sierra Blanca bridge.

“(it was) Ten feet in diameter, I would say 15 feet down to the pipes. So you literally could have lost a car inside this hole,” said resident Rick Hoffman.

Hoffman said it took only “four to five inches” to “generate a sinkhole that big.”

Both instances had active, underground water from excessive rain.

“We think of material and water underground as sometimes just sitting there, but it doesn’t sit there. It can do quite a bit. It can chemically react with the rocks around it and it can physically move the rocks that are down there,” said Dr. Elizabeth Catlos, an associate professor of geology at the University of Texas.

Dr. Catlos said sinkholes happen when rock or soil are removed from underneath a surface causing a collapse. The amount of underground limestone in Texas, mixed with a small amount of acidic water, makes sinkholes in Texas more likely than in other places around the U.S. -- especially after days of rain.

“During major rain events the water table goes up, it’ll interact, maybe with loose soil and then the ground catastrophically sinks down,” said Catlos.

Hoffman said the city was able to repair the bridge in about a week’s time.

Dr. Catlos said infrastructure developments adds to underground water that could deteriorate foundation and cause a sinkhole.