A Texas contractor was awarded the construction of a cast-in-place pump station. The project would require an excavation cut of 91-ft in length, with a width of 27-ft, and a depth of 20-ft. The geotechnical report classified the wet sandy soil as Type C-80. The excavation cut would be located inside a refinery adjacent to several operational lines and distillation towers. The contractor was concerned with the pressure loads exerted from the nearby structures including the amount of groundwater found in the area.
The contractor would require a modular protective system that could provide an open-span work area in a tight environment while providing a height-free clearance as the concrete structure would stand 10-ft above ground level. Additionally, the protective system would be required to secure three walls of the underground excavation with the exception of one treated as an open end. The open end would allow the contractor to easily supply material into the excavation and manage the construction of the concrete structure.
The complexity of the project would persuade the contractor to seek the assistance of an engineering shoring expert. NTS was able to assist the contractor and after carefully reviewing several shoring options, the contractor selected a site-specific slide rail with a dual system 80 tie back. Site-specific engineered systems provide a high degree of customization that allows for certain protective devices to be modified for unique applications. For the initial phase, it was determined that a slide rail system with rolling struts would be the best solution thanks to its modular capabilities. The rolling struts would be used until the cast in place reach its pre-determined height to be later switched to a system 80 tie-back with custom-made H-beam caps. For the final phase, the H-beams were welded onto the end caps to support both ends of the slide rail system. The system 80 was composed of two braces placed at ground level on the outer perimeter of the slide rail secured by clamps. Once the project has been completed and the pump station is fully operational, the structure will adequately remove chemicals and impurities from the water allowing the refinery to safely reuse this valuable natural resource. The customer was impressed with the modular and customization capabilities that proved to be a cost-effective solution.