The Implementation, Outcome, and Lessons Learned of “Design Considerations for Dual 96-in. 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 mi of dual 96-in. diameter transmission pipeline, pig retrieval station, flow distribution basin, sedimentation basin, and approximately 24 mi 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: It contains grooves for stop logs to stop the pig once it exits the vault and provides open access for pig retrieval. 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. The purpose of this paper is to discuss the constructability of the pigging retrieval station that allowed for a reduction of footprint, ease of construction, and differential settlement solutions.