Tarrant Regional Water District and Dallas Water Utilities have partnered to design, build, and operate a pipeline to supply water to more than 1.8 million people in North Central Texas. Once completed, the Integrated Pipeline Project (IPL) will combine both utilities’ systems to deliver 350 million gallons per day of raw water and provide operational flexibility and drought protection for more than 5 million people.

Schnabel played a broad and important role in developing the guiding criteria for this major program. Our early planning work and feasibility design contributed to the development of the design manual utilized for this massive undertaking. When completed, the pipeline will extend 150 miles from Lake Palestine to Lake Benbrook with connections to Cedar Creek and Richland-Chambers Reservoirs. The alignment runs between 15–50 feet below ground, ranges in size from 84–108 inches in diameter, and crosses numerous railroads, interstate and state highways, county and rural roads, utilities, and waterways.

The pipeline’s development includes tunneling through marl, limestone, sandstone, and shale utilizing a variety of tunneling, trenchless, and ground support methodologies. Our work involved reconnaissance of undercrossing, reviewing available geotechnical information, and both anticipating and later evaluating ground response to tunnel excavation. We recommended appropriate tunneling methods and provided criteria for minimum ground cover, tunnel settlement, and monitoring for the IPL design manual. We also prepared geotechnical design memoranda for the more than 50 proposed tunnel crossings.