Site Specific Engineered System Proves Cost Effective for Contractor

The contractor was installing sanitary sewer pipe in a Gulf Coast Florida city as part of an eventual road expansion project.  The project comprised several open trench/cut linear runs ranging from 40’ to about 196’, all with varying widths.  The contractor’s Competent Person had classified the soil as a Type C soil composed of a sandy soil mixture with some shell fragments.

Additionally, the sewer lines would be installed into “jack and bore” casings under a heavily traveled road.  The pipe elevations within the existing median had been engineered to allow for an appropriate camber because the construction area would become filled with dirt for an elevated roadway to be constructed.  Given the presence of an existing roadway, the varying lengths and widths of the excavations required, the contractor needed a comprehensive shoring plan to fulfill the project.

The contractor contacted NTS about the potential for a customized, NTS engineered trench safety plan for this project.  NTS’ team of experienced engineers assessed the site information provided by the contractor to develop a comprehensive system that would be composed of Steel Trench Shields, and Sheeting Guide Frame Panels for use adjacent to the roadway and slide rail.  Where many projects may only use one type of protective system, the combination of multiple systems allowed the contractor to effectively manage productivity and rental cost, while ensuring workers would be protected.

As is common with Trench Shields, they were used for the longer, uninterrupted linear runs of pipe.  The Steel Sheeting Guide Frames were added to address the areas that faced existing manholes or where adjacent to roadways or needed a line to traverse the trench plane along the linear runs as well as the boring pits.

The Slide Rail System was used along portions where the soil conditions worsened and a more proactive, yet time productive system was needed to support the trench walls throughout excavation.

The contractor was very satisfied with the equipment and thoroughness provided by the engineered trench safety plan and the support provided by the servicing NTS branch.  The engineered plan presented the contractor with an optimal shoring configuration for the project that maximized production, while balancing cost.