A construction company was awarded the installation of a double-barrel 66-inch storm drainage project on a high-in-traffic area composed of a recently rehabilitated interstate highway and existing crossroads. Once the project is finalized the new drainage lines will provide the proper amount of water flow to drain and reduce the potential of stagnate water contributing to floods in the area. The contractor would be using a boring machine to minimize excavation needs on the site and prevent disturbance to the existing infrastructure. The project would require a linear run of 40-ft with a width of 20-ft wide and a depth of 16-ft for the bore pit. The receiving pit would require a linear run of 24-ft with a width of 12-ft and a depth of 20-ft. The Competent Person on-site classified the moist, dense, clay soil as Type-B and Type-C.
The excavation cut was located on a median adjacent to active traffic running east and westbound of the project site. The protective system would need to provide an open span area for the large diameter casings while securing the underground for the workers. Additionally, the protective system would need to support the integrity of the adjacent active roads taking into consideration the loads stressed by vehicular traffic on both ends of the excavation cut.
After carefully reviewing several protective systems, the contractor selected a slide rail system for the project. The slide rail system is a unique, flexible underground safety system that works well with the installation of large diameter pipelines due to its modular flexibility. The slide rail system for this project would be composed of guide frames on each end incorporating 3 to 12 bays and a conforming triple bay tie back system, providing the workers with an open span area. The contractor was very impressed with the flexibility provided by the slide rail system and the safety provided during the storm drainage upgrades.