Hitting the Mark: Crossing the Guadalupe River with the Second Vertical-Curved Microtunnel in the United States

The New Braunfels Utilities Surface Water Treatment Plant Discharge Water Line is a 30-in./24-in. diameter potable water distribution line that required a 413 LF trenchless installation beneath the Guadalupe River. This installation had tight alignment tolerances, was beneath a river with highly incised embankment conditions and a 20-ft surface elevation difference between shaft locations, was next to an active pump station, and had inconsistent subsurface ground conditions. Three installation methods were considered: Horizontal Auger Boring, Horizontal Directional Drilling, and Vertical-curved Microtunneling. The project team selected the vertical-curved microtunnel method which reduced risk and allowed for an optimized alignment compared to other methods. Ultimately, it was utilized in a successful installation that satisfied all parties.