Manholes are critical access points that keep your sewer and stormwater systems functioning properly. They endure constant exposure to corrosive gases, groundwater infiltration, and heavy surface loads from traffic above.
But manholes don’t announce they’re failing with a megaphone. Problems develop gradually, often going unnoticed until they become expensive emergencies that disrupt operations and threaten system reliability.
Most manhole failures show warning signs long before they reach crisis levels. Recognizing these early indicators can save you thousands in emergency repairs and prevent costly system disruptions.
Here are five critical signs that your manholes need rehabilitation before it’s too late:
1. Water Infiltration Around Pipe Connections
What to look for: Water seepage or standing water around areas where pipes enter the manhole walls, especially after rain events.
This is one of the most common early warning signs of manhole deterioration. When water infiltrates through compromised joints, it signals that the watertight seal has failed. The best time to inspect is immediately after heavy rainfall. Look for wet spots, mineral deposits, or actual water flow around pipe connections.
The risk: Unchecked inflow and infiltration lead to soil erosion around the manhole structure, potentially causing settlement or collapse.
2. Root Intrusion and Vegetation Growth
What to look for: Roots growing through manhole walls or unusual plant growth near manholes.
Where water goes, roots aren’t far behind. Root intrusion creates a destructive cycle where small cracks become larger openings that allow more water and vegetation to enter. This is particularly problematic in older brick construction.
The risk: Root systems actively widen cracks and can cause significant structural damage, leading to wall degradation and potential collapse.
3. Corrosion and Deteriorating Interior Surfaces
What to look for: Pitted concrete surfaces, exposed rebar, crumbling mortar joints, or strong sulfur smells inside the manhole.
This indicates that sewer gases are combining with bacteria to produce sulfuric acid, extremely corrosive to steel, concrete, and mortar. Corrosion typically starts at the top, where gases concentrate, then works downward.
The risk: Advanced corrosion compromises structural integrity and accelerates once it reaches rebar in concrete structures.
4. Surface Settlement Around Manholes
What to look for: Cracks in pavement radiating from the manhole, settling around the rim, or uneven surfaces creating trip hazards.
Surface settlement indicates that the soil around the manhole chimney has been compromised by water infiltration. When water washes away supporting soil, the ground can no longer support surface loads properly.
The risk: Continued settlement can cause complete structural failure, creating safety hazards and expensive emergency repairs.
5. Unusual Odors or Gas Emissions
What to look for: Strong sewer odors around manholes or visible gas emissions, especially during weather changes.
While some odor is normal, persistent strong smells indicate that the manhole’s seal has been compromised. This allows sewer gases to escape and indicates broader structural problems.
The risk: Gas emissions signal that protective barriers are failing, often indicating deterioration.
The Cost of Waiting vs. Proactive Action
Emergency manhole repairs often cost 3-5 times more than planned rehabilitation because they require immediate response, traffic control, and temporary bypasses. Nobody wants to make other people sit in unnecessary traffic jams.
Many facility managers delay sewer maintenance because they assume repairs mean excavation and major disruption. Today’s trenchless technology eliminates these concerns.
Modern Trenchless Solutions
At Shenandoah, we use polyurethane injection (chemical grouting) that requires absolutely no excavation. Our technicians inject specialized polymers through the manhole wall or from the surface. The polyurethane expands up to 25 times, filling voids and hardening surrounding soil while creating a watertight seal.
Stay Ahead with Proactive Maintenance
Manhole rehab is most effective when done proactively, before minor warning signs become major failures. Our IRM (Inspection, Restoration, and Maintenance) Program helps you stay ahead with scheduled inspections and strategic maintenance.
With over 45 years of experience, Shenandoah has the expertise to assess your manholes, identify potential problems, and provide cost-effective solutions that keep your systems running reliably.
Ready to assess your manholes before problems escalate? Contact Shenandoah today to schedule an inspection and learn more about how our trenchless rehabilitation services can protect your infrastructure investment.
