This $12.4 million project for the North Texas Municipal Water District involves 2,534 linear feet of 118-inch excavated diameter tunneling. The tunnel will consist of 4-flange liner plate and will house 84-inch steel carrier pipe. It will be driven through Austin chalk with a double-shielded, open-faced, gripper-type machine with articulated steering.
Tunneling was completed on Jan. 6, 2021. Stiver Engineering provided tunnel design services for the project. We performed analysis and design of launching and receiving shafts and the tunnel liner. The shafts were designed to extend through the transition between the soil and rock layers. The top 30 feet of the shaft was designed using ring beam and liner plate. Rock anchors and shotcrete were used in the bottom portion of the shaft in the limestone.