Eventually They All Go Down

In 2018, as part of a conventional design, bid, build project two circular shafts were started for a trenchless crossing of a United States Army Corps of Engineers (USACE) controlled body of water. After four years, the seal slab was finally installed on the second shaft, resulting in two shafts for launching and receiving the proposed tunneling machine. The project was a performance-based design and had specific requirements for this crossing that were different from all other trenchless crossings included on the project. With continued support and work by multiple consultants, contractors, and subcontractors, the work has reached a stage that tunneling will finally start and hopefully be completed in the near future. The risk associated with underground crossings can vary, and careful consideration is needed to ensure success. This paper will dive into details and issues impacting the design, bid, and construction process for this challenging shaft and provide risk mitigation methods for municipalities hoping to decrease risk inherently associated with underground trenchless crossings as part of performance-based design, bid, build projects.