Integrated Pipeline (IPL) Section 17 Trinity River Tunnel Crossing

Completed in 2022 by Southland Contracting, the Integrated Pipeline (IPL) Section 17 Trinity River Tunnel Crossing Project consisted of the installation of approximately 11,700 linear feet of 108-inch steel water pipe of which 2,600 linear feet was tunneled under the Trinity River through mixed geology. During initial excavation and support of the tunnel heading, while under the river, the crown of the tunnel differed substantially from what had been reported. Accordingly, our forced stopped working to discuss the circumstances with the Owner and our Tunneling Consultant and arrive at a conclusion for mitigation of the conditions. During the discussions and resolution, the owner requested additional geotechnical investigation and ultimately the condition was resolved by relocating the tunnel away from the specific conditions and down another 38 vertical feet to a more competent geology, conducive for the tunnel. Additionally, the tunnel was increased to a 15 feet 6-inch diameter and was lined with Precast Concrete segments cast by our forces. The concrete segments were cast on site with our segment forms. Additional unique features include that the tunneling was done at a 6.6% grade. The tunneling also included a river crossing of approximately 700 feet underneath the Trinity River with 50 feet or less of ground cover.