SAN ANTONIO – With the water from the 142-mile-long Vista Ridge pipeline set to start flowing in just over a year, work is underway on tunnels that will help bring that water into the existing San Antonio Water System.
Two main sections of underground tunnels will be used to help connect the Agua Vista Station in the Stone Oak area, where the pipeline ends and the water is treated, down to the Hollywood Park line by Loop 1604 and Voigt Drive. Of the more than 45 million gallons of water a day that will pass through Agua Vista each day, most will flow through the 54-inch pipe in those sections of tunnel.
Once the Vista Ridge work is completed, the pipeline is expected to bring in about 20 percent of SAWS daily water supply, said Alissa Lockett, the SAWS engineer overseeing the projects to integrate the Vista Ridge water into the SAWS system.
"As an engineer, this is a once-in-a-lifetime-type project to get to work on this fabulous opportunity to guarantee water supply for the city that I grew up in and to guarantee water supply for 50 years," Lockett said.
At the bottom of a 43-foot-deep pit next to Agua Vista, a roadheader is churning around the clock, except on Sundays. The enormous machine will dig through the limestone until there is enough space to bring in the cylindrical tunnel boring machine, 88 inches in diameter, which will slice up the rock with spinning discs.
Similar machines will work from Cornerstone Church on the other section of tunnel. Both will be connected in the middle through a trenched portion. There will also be a short portion under Loop 1604 that will be tunneled by hand.
SAWS said the contractor expects to be able to tunnel about 60 feet each day on either of the main sections.
One portion will pass about 50 feet under the Regan High School soccer field.
"Nobody that's playing soccer should even know that the tunneling is going on," Lockett said. "But we have a couple of vibration monitors and settlement monitors that are going to make sure that everything stays intact and nobody loses a soccer game because of this."
All Vista Ridge-related projects are expected to be "ready for water" by December 2019, Lockett said, and the water should start flowing all the way from Burleson County to SAWS users' taps by April 2020.