sliplining Indiana culvert

Sliplining Proves to Be the Winning Solution for Indiana Culvert Rehab

In fall 2022, Infrastructure Systems Inc. (ISI), headquartered in Orleans, Indiana, was contracted to rehabilitate a failing corrugated metal pipe (CMP) culvert located in Huntington County, Indiana.

The existing CMP measured 177 in. width x 109 in. height x 290-ft length and had a paved invert that had been installed during a prior rehabilitation initiative. As is common with field expedient repair methods, the existing CMP continued to fail structurally due to material deterioration and the emergence of a severe barrel deflection.

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sliplining Indiana culvert

Earlier that year, during July 2022, Eric Kennedy (project consultant with InfraSteel, a division Precision Pipe & Products Inc.) met with David Salmon and Jon Stalker (ISI) at the culvert location in order to conduct a thorough site inspection and record all radii, rise and span measurements of the existing CMP.

This is a critical first step in determining the viability of a structural slipline, and gives Infrasteel culvert rehabilitation systems the ability to match the exact radii and shape of the existing structure. Upon completion of the site inspection, InfraSteel proposed installing a 168 in. wide x 99 in. high InfraSteel Arch liner to the project owner for evaluation and approval.

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The project owner and engineering team evaluated several slipline methods, Precision Pipe & Products’ InfraSteel design was selected as the preferred method to structurally rehabilitate the failing structure.
Once given the green light to proceed with the project, Precision Pipe & Products produced and provided a steel template to ISI that was shipped direct to the site. Due to the existing paved invert and lower haunch swells, ISI team members walked the steel template through the structure to confirm no areas of resistance and that the liner would provide the maximum water-way hydraulic area.

sliplining Indiana culvert

Upon field confirmation of the liner size, ISI provided InfraSteel with approval to manufacture the proposed InfraSteel 168-in. x 99-in. liner. Due to the overall structure length of nearly 300 ft, Precision Pipe produced the liner in 8- to 10-ft sections over a seven- to eight-week period. These lengths allowed for easy unloading and handling at the jobsite, which was a crucial factor in minimizing disruptions to local commuter traffic.

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Slipline rehabilitation projects typically follow a three-step process that begins with cleaning and dewatering the host structure. In conjunction with the fabrication timeline, ISI began the dewatering process by installing coffer dams on both the upstream and downstream side of the structure and utilized 6-in. pumps with a discharge rate of 1,000 gallons per minute. In addition to dewatering, site preparation also entails removing any debris and obstructions from the host structure.

sliplining Indiana culvert

The second step in the slipline process is the actual installation of the chosen liner solution. Because of the inconsistent grade of the existing paved invert, ISI elected to install a simple steel rail system that was used to insert the InfraSteel liner. Using a 460 excavator, ISI’s professionals positioned each InfraSteel liner section at the entrance of the host structure and used the excavator to push into the host barrel. In order to insert the liner past an area of delamination inside the host pipe, ISI installers removed portions of the deteriorated CMP and proceeded to push the 1-in. thick InfraSteel liner through without experiencing any major issues.

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The installation took approximately five days to load the existing structure and tac-weld the liner in place. Once the entire liner was positioned in the host structure, ISI utilized two welders (working simultaneously) to complete an average of four full penetration welds per day. This is a critical step in the installation process as the full-penetration welds ensure that the InfraSteel liner is fully connected and protected against any type of water intrusion, exfiltration or joint separation.

Once the Infrasteel liner was fully welded, ISI proceeded to fill the annular space with approximately 70 cubic yards of grout, securing the liner and filling any voids in the original CMP structure. Once the grout was cured, all internal bracing was removed, leaving one continuous leak proof smooth wall carbon-steel structure. ISI completed the project in just over 30 days and maintained zero disruptions to commuter traffic.

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Based on corrosion and abrasion rates the 1-in. thick InfraSteel liner meets load bearing requirements at the site, and delivers on an expected design life of 75 to 100 years. The structural liner will continue to serve the community of Huntingdon County for many decades to come.

Maintaining active culvert and storm-water structure inspection programs is paramount in preventing catastrophic failures or washouts. Bridging culvert failure begins with identification of dips/depressions in pavement, sinking guardrails or irregular waterflow. This is then followed up with further field assessments and structural prioritization where appropriate rehabilitation or replacement measures are evaluated and implemented.

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Alex Sherrod and Eric Kennedy are with Precision Pipe & Products Inc.

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