MANHOLE LINING
For Corrosion Protection And Structural Reinforcement
what are MANHOLE LININGS?
Manhole lining is a proven, high-strength solution for rehabilitating and protecting aging underground infrastructure. ArmorThane’s manhole lining systems create a corrosion-resistant, leak-proof barrier inside existing manhole structures. Our spray-applied polyurea and polyurethane protective coatings provide both corrosion protection and structural reinforcement, extending the service life of manholes, lift stations, and other critical sewer assets.
WHAT IS
MANHOLE LINING?
A manhole lining is a continuous coating applied to the interior of a manhole to form a new protective surface. These protective coatings (often advanced polyurea or epoxy coating formulations) bond to the concrete or brick walls of the existing structure, sealing out moisture and corrosive agents. A manhole liner creates a corrosion-resistant inner shell that shields the host structure from chemical attacks, water infiltration, and physical wear. ArmorThane’s manhole lining systems are spray-applied, meaning they can be installed without digging up the existing manhole – known as the trenchless manhole rehabilitation method. The coating quickly sets, forming a durable cured-in-place manhole liner that conforms exactly to the manhole’s shape. This process restores aging concrete manholes and similar structures to like-new conditions without the expense and disruption of full replacement.
WHY DO MANHOLES NEED LINING?
Underground sewer system structures endure harsh conditions. Concrete manholes and lift station wet wells are constantly exposed to sewage, stormwater, and corrosive sewer gases. Over time such an environment causes chemical attacks on the concrete or metal surfaces.
- CORROSION AND CHEMICAL DECAY: Sewer gases like hydrogen sulfide (H₂S) rise into manholes and get converted into sulfuric acid by certain bacteria. This process is called microbial-induced corrosion, and it aggressively eats away at concrete and mortar. Unlined surfaces lose strength as acid dissolves the material, compromising the manhole’s structural integrity. Additionally, industrial chemicals and runoff can further corrode surfaces, and without a protective liner, these structures will continue to deteriorate.
- WATER INFILTRATION: Cracks, porous walls, and failed pipe joints in manholes allow groundwater to leak into the collection system. Groundwater infiltration adds excess water to the wastewater system, which can overwhelm pumps and the wastewater treatment plant. A leaking manhole also indicates infiltration issues that can erode surrounding soil or allow sewage to exfiltrate, so stopping unwanted water infiltration is critical to maintaining an efficient wastewater system and preventing sewer line overload.
- STRUCTURAL WEAR AND LEAKS: Repeated freeze-thaw cycles, heavy traffic above, and old age cause many manholes to develop fractures or spalling concrete. Such defects reduce the manhole’s load-bearing capacity and overall structural integrity, and, if not addressed, minor damage can escalate to severe failures. Lining provides needed structural reinforcement, bridging gaps and adding strength to keep the structure sound.
THE BENEFITS OF ArmorThane's
MANHOLE LINING SYSTEMS
Applying a manhole lining is an ideal solution for aging sewer and stormwater infrastructure because it addresses multiple problems at once:
CORROSION RESISTANCE
AND CORROSION PROTECTION
Our linings form an inert barrier that is highly resistant to sewage acids, gases, and other types of harsh chemicals. Polyurea offers exceptional acid resistance, shielding the substrate from sulfuric acid and other corrosives, and this corrosion protection prevents further decay of the underlying concrete or steel. Unlike bare concrete, a lined manhole withstands decades of exposure to hydrogen sulfide and other chemical attacks without deteriorating.
LEAK PREVENTION
AND INFILTRATION CONTROL
A seamless (literally, without seams) ArmorThane liner stops leaks in their tracks. It adheres to every inch of the manhole interior, sealing cracks, joints, and pinholes. By eliminating groundwater infiltration, the liner prevents excess water from entering the sewer collection system during rain events or high water table conditions and mitigates infiltration issues that can lead to overburdened lift stations and treatment facilities.
STRUCTURAL REINFORCEMENT
Our high-build polyurea adds significant structural reinforcement to the manhole. Once cured, the liner has high compressive and tensile strength, effectively creating a new pipe-within-a-pipe. It bonds monolithically to the existing walls, restoring integrity even if the substrate was partially deteriorated, and this added high-strength layer re-establishes the manhole’s structural integrity, enabling it to handle soil loads and traffic stress like a new structure.
EXTENDED SERVICE LIFE
Combining these benefits means manhole lining greatly extends a structure’s service life. A quality liner can add decades of use to a deteriorated manhole, providing a long-term solution that delays or avoids full replacement.
APPLICATIONS: WHERE MANHOLE LININGS ARE USED
In municipal wastewater systems and collection system networks, most manholes are constructed of concrete or brick. Lining these manholes restores deteriorated surfaces and protects them from future corrosion. Cities across the United States are incorporating linings into their manhole rehabilitation projects to renew aging sewer infrastructure without costly excavation. Our solutions have been implemented from small towns to large metropolitan sewer systems, with consistent success in stopping leaks and corrosion.
Storm drain manholes and catch basins can also be lined to prevent leaks and deterioration. Even though stormwater is less corrosive, linings protect against erosion and groundwater intrusion in these structures.
Sewage lift stations (pump stations) are deep manhole-like structures that house pumps, making them prone to severe corrosion from concentrated sewer gases, with even greater consequences. Lining a lift station wet well provides robust corrosion protection and leak sealing under those extreme conditions. The high-strength liner helps maintain the wet well’s shape and structural integrity, and utilities often line their key lift stations to avoid catastrophic failures and environmental spills.
Primarily used in wastewater systems, the same linings can protect concrete tanks at a wastewater treatment plant or valve vaults in water distribution systems. Many of ArmorThane’s coatings are certified safe for potable water contact, making them versatile beyond sewer applications.
THE MANHOLE REHABILITATION PROCESS
- ASSESSMENT AND SURFACE PREPARATION: First, the manhole is inspected and cleaned of any debris or loose material. If there are active leaks, preliminary manhole repair (such as grouting cracks) is performed to stop water ingress. Surface prep ensures the substrate is in good condition for coating and is essential for a high-quality installation.
- APPLYING THE PROTECTIVE COATING: Next, technicians spray-apply the liner material to all interior surfaces of the manhole, including walls and the bench. The polyurea coating builds up to the desired thickness, forming a new manhole liner that bonds to the structure. The liner cures rapidly in place, essentially becoming a cured-in-place manhole lining.
- CURING, INSPECTION, & RETURN TO SERVICE: ArmorThane’s polyurea cures extremely fast – within seconds it forms a rigid, seamless liner. Crews then inspect the cured liner to ensure full coverage and a complete seal. The rehabilitated manhole can often be put back into service the same day, since no excavation or lengthy drying is required, and this quick turnaround minimizes downtime for the collection system. The entire trenchless manhole rehabilitation procedure is typically completed in a matter of hours per manhole. ArmorThane’s trained certified installers follow strict quality controls during each project to ensure long-lasting results.
RELATED CONTENT
FAQ FREQUENTLY ASKED QUESTIONS
Yes. A spray-on manhole liner forms a continuous, joint-free seal over cracks, seams, and around pipe inlets, effectively sealing a leaking manhole from the inside. This stops groundwater infiltration and exfiltration by creating a watertight envelope. By eliminating infiltration issues, the liner keeps excess water out of the sewer line and prevents sewage leakage into soil. Stopping leaks helps preserve surrounding roadbeds and keeps the wastewater system more efficient.
Yes, a quality manhole lining system significantly enhances a manhole’s strength. ArmorThane’s polyurea liner adds structural reinforcement to the existing walls, thanks to its high bond strength and tensile strength. It can bridge gaps and hold together sections of deteriorated concrete, essentially creating a new structural wall inside the old one. While extremely damaged manholes may need additional repairs, most linings can return an aging structure to good condition with improved structural integrity.
Manhole liners provide a long-term solution, often extending a manhole’s service life by 20-50 years or more. They withstand continuous exposure to sewage and temperature swings without significant degradation. Once lined, the manhole typically needs little maintenance over decades. This extended lifespan makes lining a very cost-effective approach compared to repeated minor manhole repair or full replacement.
PROTECTING YOUR SEWER INFRASTRUCTURE CONTACT ARMORTHANE
Investing in professional manhole lining is an effective solution to prolong the life of your underground assets and avoid emergency failures. It rehabilitates each existing manhole without excavation, drastically reducing downtime and cost.
ArmorThane is a leader in trenchless manhole rehabilitation, providing industry-leading products and expertise to municipalities and contractors on manhole rehabilitation projects. All our installations are handled by trained, certified installers for quality results. We proudly support our partners with reliable, high-performance protective coating solutions for sewer infrastructure rehabilitation. So if you are ready to protect and strengthen your manholes and lift stations, we’re here to help. Contact us today to learn more about our manhole lining systems, technical training programs, and partnership opportunities. Our team will work with you to implement the ideal solution for your needs, helping you to achieve safer, longer-lasting infrastructure and peace of mind for years to come.
ABOUT THE AUTHOR
TYLER GLECKLER
I am a chemist with a specialization in nanotechnology and applied materials chemistry. My work has focused on the characterization of optoelectronic materials, namely including semiconductor nanocrystals.
