48-inch Bachman Wastewater Interceptor

Completed in 2016 by Southland Contracting, the 48-Inch Bachman Lake Wastewater Interceptor Project is a noteworthy micro tunnel boring machine (MTBM) project situated in Dallas, Texas. This substantial undertaking spans a length of 6,010 linear feet, incorporating the installation of 52-inch cuts to accommodate 60-inch HOBAS fiberglass reinforced (FRP) Jacking Pipe. Furthermore, the project encompasses the execution of 2,206 linear feet of 48-inch open cuts across seven shafts, varying in depth from 40 to 60 feet. Notably, one of these seven shafts had to be meticulously constructed to be completely watertight, with stringent requirements allowing zero gallons per minute (GPM) seepage. The project’s challenges were further compounded by its urban location, where it encircled a lake, and traversed through diverse soil conditions. These conditions ranged from soft rock to running sands and gravel, as well as clay with high groundwater levels. Despite these complexities, the project was executed successfully, showcasing the team’s ability to navigate challenging terrain and meet rigorous standards in this critical infrastructure endeavor. The project passes through a very high-profile park and recreation center which demanded high attention and careful planning for park patrons, traffic control and tree mitigation. Southland partnered with an independent certified Tree Arborist to manage the sensitive health of the environment. Prior to any work, we conducted a hydraulic study of the interceptor system. The study showed that the line was close to private underground utility lines and a widely used public park. Furthermore, the park was located near the local airport. These factors made open cut construction too risky. After evaluating replacement options with multiple routes and reviewing various trenchless installation techniques, our team determined that micro tunneling would provide the ideal balance of safety and cost efficiency.