A contractor was performing a grease trap system installation in Northeastern Illinois. The new installation required a 16-ft linear run, with a width of 12-ft and an excavation depth of 18-ft. The competent person on site had classified the soil as a Type C-60 consisting of a sandy soil mixture. The site conditions for this project presented several challenges. The contractor’s primary concern was directed toward the unstable soil resulting, in part, from the close proximity to Lake Michigan. The contractor would need to select a protective system that could provide proper support while accounting for the high water concentration in the soil due to the proximity to a large body of water. In addition, to need to account for water concentration in the soil, the project scope would require a moderate vertical clearance to allow for an efficient installation of the two vault grease trap systems. The contractor would also have to accommodate construction for a new five story building that was being built adjacent to the excavation site.
After reviewing several protective systems for the project, the contractor ultimately selected a Steel Sheeting Guide Frame System. The system is installed by setting corner posts and sliding steel panels along the posts to provide a frame at the top of an excavation. This upper frame typically covers the first 4-ft of an excavation. The steel panels have interior grooves that allow steel sheets to be inserted through the grooves and pushed to the necessary depth for the excavation according to manufacturer’s tabulated data and/or a site specific plan.
The progressive installation of the system, from setting the frame at the top of the excavation to then inserting the sheets, allows for minimal soil disturbance, which was important for this project due to the existing building. The Steel Sheeting Guide Frame System also provided an open span work area needed for an efficient installation of the grease traps as well as providing the crew a safe protective system for the project.
The contractor was very satisfied with this system and the productivity gains it provided.