A south-central Texas contractor was tasked with the installation of fuel tanks. The project required an excavation of 85-ft in length with a width of 30-ft and a depth of 16-ft. The Competent Person on-site classified the hard clay rocky soil as Type-C-60.

The excavation site was located on the grounds of a new gas station and presented several challenges. The lack of open span area and the close proximity of a building structure hindered the chance of sloping or benching. The solution would require excavating vertically and securing the area with the use of a shoring system. The contractor would need a protective system that could provide an open-span area and secure the excavation without disturbing the adjacent structures.

The contractor contacted NTS and discussed a few protective options for the project,  after carefully reviewing the challenges the contractor selected an engineered cantilever beam and plate system. The cantilever beam and plate system is an application that offers a large free-span area. Generally, the cantilever beam and plate system is installed by drilling pilot holes to the required depth and inserting beams through the holes. Steel plates are then pushed to depth between the beams channels providing sufficient lateral protection. In this type of system, the protective system strength is derived from the depth of the beams and installed below the soil as well as the soil’s strength using engineered calculations. The plates are then used to transfer the structural support from adjacent beams to the soil walls.

Once the installation of the new fuel tanks is completed, the new gas station will store and sell fuel to its customers. The contractor was very impressed with the open span area, and the minimal footprint provided by the cantilever beam and plate system.