Design Considerations for Dual 96-Inch Water Transmission Pipeline Pig Retrieval Station and Flow Distribution Basin

The Luce Bayou Interbasin Transfer Project (LBITP) was commissioned by the Coastal Water Authority (CWA) as a regional water supply project to convey water from the Trinity River to Lake Houston. The LBITP consists of a raw water intake structure and pump station, approximately 3 miles of dual 96-inch diameter transmission pipeline, pig retrieval station, flow distribution basin, sedimentation basin, and approximately 24 miles of canal. The pig retrieval station consists of an underground vault housing expanded pipe sections to install steel cables for stopping the pipe cleaning pig valves and decant line. The vault is covered by a metal building with removable sections to facilitate access. Downstream of the vault, a concrete wye structure serves two purposes: (1) it contains grooves for stop logs to stop the pig once it exits the vault and provides open access for pig retrieval, and (2) it centers the flow of water and sediment entering the flow distribution basin. Design considerations included vault covering with a removable building, a Victaulic coupling system, a pig stopping system, and a flow distribution system design confirmed with computational fluid dynamic (CFD) modeling.