Features & Highlights
- Use of specialized Earth Pressure Balanced tunnel boring machine (EPB TBM) to cut through rock and subgrade below ground water table.
- Five different tunnels each with unique requirements and challenges
- Tunnels were mined under 2 state highways, 2 creeks, a lake, and a Union Pacific railroad.
- This project was designed and built to have a 100 year service life.
Project Overview
This project with Tarrant Regional Water District (TRWD) helps deliver 350 million additional gallons of raw water to north central Texas residents every day. In total, the IPL 19 Long Tunnel Project consists of over 43,000 linear feet of 84” steel pipe waterline with 12,360’ of trenchless installation using a precast segmented concrete liner or steel casing. To complete the project, the Sundt team and joint venture partner Taylor Bros. had to secure specialized equipment to carefully manage the challenging geotechnical conditions.
The project totals 10,944 linear feet of Earth Pressure Balance Tunnel Boring Machine (EPB TBM) tunnels, 1,727 linear feet of micro-tunneling runs and 191 linear feet of hand-mined tunnel.
For the two largest tunnel segments, each about one mile long consisting of vertical and horizontal curves through mixed geology, the team acquired a highly specialized EPB TBM from Germany. This 144-inch cylindrical EPB TBM excavates the earth with a rotating cutting wheel while hydraulic cylinders continuously advance the machine forward. Once the excavation is complete, the extracted materials are carried out by conveyor belt and transported back to the launch shaft where they are safely removed. In addition to excavating, the TBM also works to install the segmented, precast concrete shoring system that lines the tunnel.
Each of the five tunnels presented their own unique requirements and challenges. The first segment, the Cedar Creek tunnel, required the team to break through rock formations as well as account for serious flood risk. The next section, Stream A Tunnel, involved a low cover under the stream channel. The Royall Blvd tunnel was installed by slurry micro tunneling using a Micro-tunnel Boring Machine (MTBM). Construction of deep shafts and open cut on both sides were carefully planned and executed to cross under existing utilities, the Union Pacific Railroad, and Texas State Highway 31, locally known as Royall Blvd. The fourth tunnel segment, the Hollywood Lake tunnel, is the longest segment of the project at 5,900 feet. It was mined with the EPB TBM, which was launched from the eastern limits of the tunnel and mined to the west. The final stretch of the project is the SH-155 tunnel that was mined with the Slurry MTBM and required careful coordination with highway and utility crossings.
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