Pennsylvania Township’s Manhole Rehabilitation Results in Large I&I Reduction

Frequently, we read of large municipalities dealing with inflow and infiltration (I&I); however, I&I plagues every size system. It is a costly problem even for small systems. The Upper Yoder Township Authority (Township) located at the foothills of Laurel Mountain in Pennsylvania was settled in 1820. Historically, the area was part of the extensive coal mining region in western Pennsylvania, but today it is largely a suburban community of just more than 5,000 people. They have been working to reduce I&I from their sanitary sewer system for numerous years.

Discovery

As with a large majority of I&I related rehabilitation projects, the Township’s first priority was to address the problems plaguing the main line sewer pipes by implementing a cured-in-place pipe (CIPP) program. Unfortunately, the project did not produce the reduction in I&I they were hoping for. Hydrophilic end seals were not installed on the ends of the CIPP, which allowed for the water to travel the annulus space between the host pipe and the liner and enter the sewer system at the manhole penetrations.

Manhole rehabilitation and replacement was the next item of business. These essential underground structures face a myriad of challenges, from environmental stressors to corrosion and degradation. The need for effective, long-lasting solutions is paramount. The Township previously used cementitious coating on their manholes, but it was not effective at resolving the I&I nor did it hold up very long. They also used a chimney seal material (as an attempt to seal the adjustment area between the top of the manhole and the manhole frame, where either adjustments rings and/or bricks were used). This material was not holding up in the sewer environment either.

The Township learned of a nearby sewer authority who had been having success with their manhole rehabilitation program. They had a contract through Advance Rehabilitation Technology (ART), using OBIC Armor. ART is a Bryan, Ohio-based company and a certified installer of OBIC products. Based on the recommendation of the other municipality’s success, the Upper Yoder Township Authority decided to give OBIC Armor a pilot project.

Manhole Pilot Project

According to James Rutledge, project manager for the Upper Yoder Township Authority, “The Upper Yoder Township Authority started with 14 of the worst manholes in the system that needed replaced as a trial. These manholes had no invert channels left and half of the benches were missing.” ART was awarded the contract to install OBIC Armor for a pilot project. The Township would monitor the manholes for one-year before they decided on how to proceed.

This project was going to be challenging. Not only were these manholes identified to be completely replaced but some were also located along a stream bed adding to the problem.

“When you are told that your success of a project is being judged based on the worse manholes in a system that is normally not good.” said ART business development manager Rusty Hesselschwardt.
“Doing a demonstration or pilot type project for a municipality or sewer authority is the best way to sell them on OBIC. Especially when they learn that the material and installation are both back by a 10-year warranty,” he says.

OBIC Armor is a multi-layer polyurea liner system: a game-changing solution for manhole rehabilitation. Manholes, by virtue of being underground, are subject to ground movement. Over time, this can lead to cracks and other structural issues. Polyurea coatings are both flexible and durable, allowing them to move with the ground without cracking. This flexibility ensures that the coating remains intact, and the manhole structure remains protected, even in changing environmental conditions.

Manhole Action Plan

Prep: Everyone in the coating business knows the key component to a successful project is surface preparation. Once the ART crew had cleaned the manholes with high-pressure water, work commenced to temporarily stop the infiltration using OBIC’s own brand of grout products. The next step was to reconstruct or build the invert channels and benches.

Adhension Layer: Following the cleaning and drying of the manhole, a base layer of OBIC 1000 (polyurea) is applied to the host surface. Polyurea adheres effectively to a variety of substrates, including concrete, brick, fiberglass and even metal. It also bonds nicely to CIPP liners, which ensures a watertight seal at the manhole. The surface is tack free in approximately 20 seconds.

Surfacing Layer: Following the base layer application, the surface is sprayed with OBIC 1306, a closed cell foam that aids in smoothing out uneven surfaces and adds structural enhancement to the system.

Final Layer: To finish off the multi-layer system a final layer (or topcoat) of OBIC 1000 is applied. At this point in time the current date and OBIC name are imprinted into the liner. This serves to document the start of the 10-year warranty period. OBIC Armor boasts superior chemical resistance, protecting the manhole from corrosion and other chemical-related damages. Traditional rehabilitation methods, like cementitious linings or epoxy coatings, can leave joints or seams where materials meet. These weak points are often the first to degrade, leading to leaks or structural failure. With OBIC, the application is seamless, eliminating any potential weak points and providing an impenetrable barrier against groundwater infiltration and exfiltration.

Conclusion

After the one-year evaluation process no I&I was occurring in the manholes and OBIC Armor was doing its job. The Township approved the remaining 76 manholes in that basin to be lined with OBIC. Rutledge reported that the manhole lining in the one basin has shown an approximately 60 percent reduction in flow.

Manhole rehabilitation is essential to maintaining the reliability and functionality of our underground utilities. There are very limited products on the market that will offer a 10-year warranty and if they do, it does not cover the cost of labor. Traditional methods, while effective in the short term, often don’t offer the longevity and resistance needed to ensure a long operational lifespan. OBIC Armor provides an innovative solution to these challenges, offering a myriad of advantages that make it the ideal choice for municipalities. Its rapid cure times, chemical resistance, flexibility and cost-efficiency are just a few of the reasons it’s quickly becoming the gold standard in manhole rehabilitation.

Michael Hoffmaster is the director business development at OBIC. Photos provided by Michael Hoffmaster.