If you live or work in the Stone Oak area, you may have noticed two large water tanks taking shape near Las Lomas Elementary School just off of Hardy Oak Boulevard. But you’d be hard pressed to guess what’s going on 40 feet beneath the surface, where hungry-looking machines are gradually chewing their way through a solid limestone wall.
The massive tunnel is part of the Central Water Integration Pipeline, which will distribute water from the Vista Ridge project — San Antonio’s largest-ever non-Edwards Aquifer water source — when that drought-proof supply comes on line in 2020.
Meanwhile, two miles away near Cornerstone Church, more rock-eating contraptions are chomping away at the other end of the underground passage that will soon be home to a 54-inch diameter steel water main.
“Tunneling is expected to be complete by July,” said Alissa Lockett, SAWS director of engineering. “We have contractor crews working 24-7 to meet our deadlines so we can make sure to get the water into town in April 2020.”
The bulk of mechanical muscle is provided by a tunnel boring machine, or TBM. The 6-foot-diameter, worm-like apparatus is so big it has to be lowered down a shaft in pieces and assembled underground, Lockett explained.
“The TBM is the workhorse in this process,” she said. “Once the tunneling is complete, crews can begin installing the pipe, and that needs to be done by December 2019.”
When complete, the Vista Ridge project will deliver more than 16 billion gallons per year of groundwater from the Carrizo and Simsboro aquifers in Burleson County. That’s enough to meet about 20 percent of San Antonio’s water needs, helping secure our city’s water future for generations to come.