Topeka, Kansas, has approximately 760 miles of sanitary sewers, and despite a proactive approach to maintenance, the inevitable deterioration of certain infrastructure assets is still a problem. Like many other cities, Topeka perennially faces the common problem of manhole damage caused by H₂S corrosion.

Today’s market offers an unprecedented range of solutions for utility asset protection. For manhole rehabilitation in particular, solutions can range from quick, temporary fixes for emergency situations to a plethora of sound rehabilitation options that provide long-term solutions. When considering solutions, numerous factors come into play.

A “quick fix” in the form of a cement repair can sometimes serve the purpose and be cost-effective, but depending on the severity of deterioration of the structure, that is not always optimal. Investing in a long-term solution, while sometimes more costly upfront, ends up saving cities in the long run due to its long-standing effectiveness. Long-term asset protection was the city of Topeka’s goal, ultimately leading officials to explore structural epoxy lining solutions for their manholes.

The right approach

Topeka city engineers first met with Epoxtyec, a company that specializes in manhole rehabilitation solutions, in the spring of 2020.

“Topeka’s engineering meeting was one of the first COVID-19 virtual meeting sessions for Epoxytec that took place during the initial lockdown. For what had previously been in-person meetings, this new virtual platform gave me the opportunity to easily educate and inform engineers from the city of Topeka and throughout the nation about the growing field of structural liners,” says John Thompson, Epoxytec’s national sales manager. “Structural liners have a unique place in the world of manhole rehabilitation. They provide long-term asset protection from environmental elements in greatly deteriorated structures where traditional liners have failed.”

Epoxytec, which was recently acquired by Tnemec Company, has been manufacturing performance coatings for lining water and wastewater systems for over 30 years. Its product line has grown with specific attention to structural liners, specifically Epoxytec’s CPP products. Unlike traditional thin film coatings, where outgassing and inflow and infiltration can wreak havoc, these structural coatings are designed for low-pressure resistance, to hold back I&I, and seal against hydrostatic pressure, all properties designed with manhole rehabilitation in mind. In addition to its structural properties, one of the product’s most desirable features is that it can be spray-applied up to 3/8 inch thick (375 mils) using a heated rig. This method of application expedites the turnaround time for projects and supports a much faster return to service.

“These products have been highly engineered to be easy to use,” Thompson says.

A spray-on system that would provide structural strength was exactly what the city was looking for. And the final determining factor in Topeka’s decision was the certification process. To become certified in the application of Epoxytec’s CPP Sprayliner, contractors must attend training sessions to ensure that they understand industry standards, specifically AMPP (formerly NACE and SSPC) for surface preparation and application in the water and wastewater industry.

Having completed training and met Epoxytec’s standards, Memphis-based Hill Services was well qualified for this project. The company has been providing industrial maintenance, services and repairs nationwide for municipalities as well as industrial facilities and power plants for close to a century. As one of Epoxtec’s certified contractors, Hill Services provides expertise in manhole rehabilitation with a focus on structural liners.

Getting to work

The Topeka project began in the fall of 2021 and lasted roughly three weeks from start to finish. The structures included several significantly corroded brick manholes and concrete junction boxes. Surface preparation started with hydroblasting to meet SSPC-SP13/NACE No. 6 standards, and a surface profile of ICRI-CSP 5 with a minimum pH of 9, a preparation standard required for proper application of the sprayliner. Leaks were sealed, and then concrete repairs were made using Epoxytec’s Mortartec Ceramico, a hybrid cementitious epoxy mortar.

“This [surface preparation] is one of the most vital aspects of successful manhole rehabilitation,” says Ed Ward, the Hill Services manager who oversaw the project. “Without a sound substrate, the entire project is jeopardized.”

Once the surface was prepared, CPP Sprayliner was applied, using Hill Service’s heated spray rig to reach 125-200 mils. The completion time for each manhole was approximately two days, including one day for surface preparation and one day for coating.

Quality and detail

While a rehabilitation project like this may not be particularly glamorous, it’s a good example of quality products and execution solving problems and bringing good results. Officials in the City of Topeka were highly involved in all aspects of the project and Epoxytec representatives were on site during various stages of the job. There was solid teamwork throughout, from the engineers to the applicators, all emphasizing quality and detail.

The end result of the rehab project was the return to service of the manholes, with protection for an estimated 10 years or more, and long-term cost-savings over other solutions.