Over the years the City of Denver has seen tremendous traffic growth resulting in a negative impact for daily commuters. As a result, new infrastructure would be needed to alleviate and improve the flow of traffic. The improvements would consist of expanding the freeway with the addition of two new HOV lanes in each direction, and the construction of new bridges and exit ramps. Additionally, the new construction would require upgrading the existing utility lines to adjust for the growing infrastructure in the area.
The utility upgrades would be located adjacent to a live freeway and presented several challenges. Due to the complexity of the construction, a well-known contractor was tasked with upgrading the existing 36-inch utility lines, which would require an excavation cut of 20-ft in length, with a width of 24-ft, and a depth of 12-ft. that the competent person on site would classify as clay soil as Type-B. After addressing the scope of work, the contractor would require a device that could provide paramount support and address the pressure loads originated by the adjacent freeway which sat 6-ft away. Additionally the contractor would need a securing device that could provide the proper clearance for the pipe installation.
The contractor contacted National Trench Safety (NTS) and after carefully reviewing several protective options the contractor selected a slide rail system with a sheeting guide frame. The slide rail system is a modular protective system, typically installed by dig and push method. Panels are threaded along the interior grooves of the slide rail posts at the top of the excavation and brought to depth ahead of the excavator’s cut. Sheeting guide frames are installed by threading short steel panels with interior grooves of the corner posts at the top of the excavation. Steel sheets are then inserted through the interior grooves to the total excavation depth to provide a proactive support which in this case was around the utility line tie-ins. This project was the first time the contractor had used the slide rail system with a sheeting guided frame and came away very impressed with the system’s shoring capabilities. Once the utility phase has been completed the contractor will move to the other phases of the project