How Glanville Trenchless Uses Manhole Spraying to Prevent Water Infiltration
Water infiltration—groundwater seeping into wastewater networks through damaged or aging manholes—poses major challenges for utilities. It increases treatment costs, overloads sewer systems during storms, and contributes to environmental pollution through storm overflows. Glanville Trenchless, a division of Glanville Environmental, tackles this problem using advanced manhole spraying and sealing technologies designed to create long‑lasting, watertight protection from within.
This article explains how manhole spraying works, why it is effective, and the benefits over older rehabilitation methods.
What is Manhole Spraying?
Manhole spraying is a trenchless rehabilitation technique where specially formulated grout or mortar is applied to the interior surfaces of a manhole. The material is sprayed in controlled layers to seal cracks, rebuild structural strength, and form a watertight barrier.
Glanville Trenchless use a method involving wet spraying using a grout pump, compressor, mixing system, high‑pressure hose, and spray head to apply a smooth, plastic‑consistency grout in multiple passes, each layer between 5–10 mm thick.
In 2025, Glanville further enhanced this process by investing in state‑of‑the‑art manhole spray equipment capable of applying coatings centrifugally from above ground—coating shafts up to 10 metres deep without confined space entry, improving safety and efficiency.
How Manhole Spraying Prevents Water Infiltration
Water infiltration occurs when groundwater enters the sewer network through cracks, deteriorated joints, or porous manhole walls. Glanville’s spray-applied liners combat this in several ways:
1. Sealing Cracks, Joints, and Defects
Spray-applied mortar fills voids and seals gaps that allow groundwater to seep into the system. This restores the manhole’s watertightness from inside the structure.
2. Creating a Continuous Protective Coating
Each sprayed layer bonds to the next, forming a seamless barrier that stops both infiltration (water entering the system) and exfiltration (wastewater leaking out).
3. Rebuilding Structural Integrity
Spray-applied liners strengthen weakened manholes, protecting against soil erosion, root intrusion, and corrosion—major causes of infiltration failures.
4. Providing a Fully Automated, Consistent Seal
The new centrifugal spray equipment ensures an even coating and watertight finish with minimal manual intervention, significantly improving reliability.
Benefits of the Glanville Trenchless Manhole Spraying Method
Our approach delivers advantages far beyond traditional excavation-based repairs or manual patching.
1. Faster and Less Disruptive Than Excavation
Trenchless manhole rehabilitation avoids digging, meaning roads, footpaths, and properties stay open and undisturbed—an advantage also reflected across the wider trenchless industry.
2. Enhanced Safety
With the new equipment, operators spray manholes from above ground, eliminating the need for confined-space entry, a major safety risk in traditional repair methods.
3. Improved Environmental Protection
Sealed manholes prevent sewage exfiltration, reducing the risk of soil contamination and protecting watercourses—key concerns highlighted in large-scale infiltration reduction programs.
4. Reduced System Overload and Spill Incidents
By blocking groundwater inflow, utilities minimise system surcharging during heavy rainfall. Nationwide, infiltration reduction has already prevented thousands of overflow events, demonstrating the impact of effective sealing.
5. Lower Maintenance and Lifecycle Costs
Properly sealed manholes reduce debris entry, odour issues, corrosion, and structural damage—significantly cutting long-term maintenance expenses.
6. Consistency and High-Quality Finish
Automated centrifugal spraying produces a uniform lining, improving durability compared to manual trowelling or small hand-spray tools.
How It Compares to Previous Methods
Traditional Methods
Manual patching and mortar repairs, inconsistent and prone to failure
Full manhole reconstruction requiring excavation
Time‑consuming, labour-intensive process
Limited effectiveness for deep or narrow manholes
Higher lifetime costs due to shorter-lived repairs
Manhole Spraying
Automated, even, multi-pass spraying ensuring watertight seals
No-dig rehabilitation, minimal disruption
Fast, safe, two-operator process with above-ground operation
Centrifugal spray system coats shafts up to 10m deep efficiently
Long-lasting protection with reduced maintenance needs
Glanville Trenchless has significantly advanced the field of manhole rehabilitation by integrating modern no‑dig technology with innovative spray systems. Their manhole spraying approach offers:
- Superior infiltration protection
- Safer, faster, and more consistent application
- Lower operational and environmental risk
- Greater durability than traditional repair methods
With infiltration being a major factor behind storm spills and sewer network failures, Glanville Trenchless has the capability to deliver high-quality, trenchless manhole sealing, which strengthens the resilience of wastewater systems across the UK.