Unlocking the Importance of Manhole Maintenance

Manholes often escape the notice of the average person, yet their significance in the daily operation of society cannot be overstated. The Environmental Protection Agency (EPA) estimates that the United States boasts approximately 20 million manholes, translating to roughly one manhole for every 400 feet of pavement. These humble structures serve not only as gateways to sewer lines for maintenance and repair but also provide access to water, electricity, telephone, and natural gas facilities. Ensuring the upkeep of these manholes is paramount for the continued prosperity of our cities. Regrettably, many manholes are overlooked during sewer system maintenance, leading to severe deterioration. An estimated 20% of them are between 30 and 50 years old, with over 3 million in such dire condition that they demand immediate rehabilitation or replacement.

In Pima County, Arizona, 21 manholes initially constructed in the 1940s had previously undergone rehabilitation using a competitor's cementitious liner, which ultimately failed. As this liner eroded, it began losing bond adhesion to the substrate, with fragments falling into the sewage stream, posing a threat to the county's sewage processing system. These manholes necessitated the removal of the failed liner, reinforcement, and protection from Hydrogen Sulfide Gas. The restoration process involved grinding the surface of the manholes after removing the eroded liner, resurfacing the concrete with Quick-Set grout, and sealing all cracks with a low-viscosity crack injection polymer. CarbonSeal™ carbon fiber was saturated and installed, followed by the application of a vinyl ester topcoat to shield the carbon fiber from future erosion resulting from Hydrogen Sulfide gas exposure.

HJ3's carbon fiber system saved the county a remarkable 80% compared to the cost of replacing all 21 manholes. Furthermore, the system facilitated the repair of these manholes without necessitating any road closures, resulting in months of saved downtime and the prevention of nearly 62,000 gallons of water wastage that would have occurred during the manufacture of new manholes.

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