A North Carolina contractor was tasked with upgrading aging drainage infrastructure that would involve installing new manholes, drainage pipes and constructing a new headwall. The upgrades would help control the storm runoff from a nearby neighborhood and prevent future structural drainage failures. The excavation site presented several challenges with nearby powerlines and adjacent structures. The contractor required a protective system that could provide the necessary vertical clearance to accommodate the new 84-inch reinforce concrete pipes while also allowing the necessary open span area needed for the tie-ins. In addition, the protective system would need to account for two new manholes that would be cast in place.
The contractor would need to ensure that the protective system did not damage the power lines during the system’s installation, which had resulted in the exclusion of a few of the contractor’s options on the project. The contractor turned to National Trench Safety for review of the site and additional options to safely provide shoring on the project. NTS presented a few potential solutions, while the contractor elected to use of 10-ft shields paired with arch spreaders. The combination allowed the contractor to have additional work space and adequate clearance that kept the spreaders above the 84-inch RCP; a solution that could not have been achieved with conventional eight feet tall trench shields. The solution allowed the contractor to assemble the system outside the work area and then move the system into place with the assistance of an excavator. The contractor was extremely satisfied with the trench shields.