Risks and Rewards in Completing a Design/Build Tunneling Project

The Robertson Umbenhauer Water Treatment Plant referred to as the canal water treatment is over 75 years old and is in downtown El Paso. The plant is wedged between the Rio Grande River and the BNSF railyard. The railyard is over 100 years old, making infrastructure improvements near the plant challenging. To address aging infrastructure, El Paso Water wanted to replace existing transmission lines from the plant and build a new pump station. To mitigate risk, El Paso Water elected to use a design/build delivery method on this project. To put the risk in perspective, the project required a 66” diameter, 570' long tunnel across 18 active tracks under the railyard. It also required a second 315' tunnel across a TxDoT roadway. To compound the complexity, the Border West highway project by TxDoT had overlapping traffic control with this project. To facilitate construction of both tunnels, a single large entry shaft was constructed within the railyard. This created its own set of challenges coordinating with railroad personnel for access, safety requirements, and storing material and equipment. Any excavation within the railyard had its own risk as the yard had several abandoned pipelines mixed in with active pipelines that had been installed over its 100-year life. The experience gained on this project can provide several lessons learned and some innovative ways to monitor and track settlement in congested and difficult work areas.