Near Carter Street in Chattanooga, Tennessee, a round, culvert pipe in extremely poor shape was failing due to inadequate design for the current load conditions it was experiencing. A quick, efficient solution was needed.
The existing culvert had been severely compromised due to overloading from years of piling foundry sand from a nearby site. This additional load greatly exceeded the designed height of cover anticipated for the original pipe. Given the relatively rapid deterioration being experienced by the culvert, Chattanooga needed to find a structural solution in a very short period of time.
With approximately 50’ of cover on the pipe at its highest point, the engineer of record, Arcadis, determined that a trenchless rehabilitation method would be most efficient and cost-effective. With manufacturing and design support provided by Contech Engineered Solutions, 240 LF of DuroMaxx®
steel reinforced polyethylene (SRPE) liner pipe was sliplined into the both ends of the culvert with a segment of Contech 2-Flange Tunnel Liner Plate (TLP) through the middle area where the greatest deflection and highest fill occurred. The invert of the TLP was lined with concrete to help the hydraulic efficiency of the culvert and make the transitions smoother from end to end.
The contractor, Chase Plumbing, was able to push the DuroMaxx liner pipe through both ends of the host pipe via skid rails to facilitate proper placement of the line pipe sections, including blocking and bracing as required. The 24' long pipe segments also allowed for fewer joints which were joined through a welded-coupler method providing a watertight solution. Once inserted and joined, the pipe was grouted in a multiple-lifts utilizing factory-installed grout ports included with the DuroMaxx liner pipe. Having had previous experience with installing DuroMaxx liner pipe, Chase was able to insert the liner pipe into the host, join, and grout the entire structure quickly. They monitored each lift to ensure the pipe was properly aligned and the curing process was successful.
April Van Dusen, project coordinator for Chase Plumbing, commented, "Chase has worked with Contech on several projects and relied upon their knowledge and host of products to provide effective solutions to challenging jobs such as Carter Street. The plan had to be flexible due to the structure size changing over the course of the project. DuroMaxx (SRPE) liner pipe and Tunnel Liner Plate were chosen to slipline the culvert.
The installation went smoothly, and the overall project was a success that met the needs and expectations of the owners."
The accepted proposal included a two product solution that not only addressed the overloading condition but structurally relined the outfall for a combined sewer overflow system so it can continue its job unimpeded. This project provides an excellent example of incorporating multiple products to cost-effectively solve a problem.