Epoxy Coating for Buried Concrete Manholes
Introduction
Five buried concrete water interceptors had been left uncoated since installation, resulting in progressive surface degradation and water ingress. The client required a proven protective lining system to restore structural integrity, halt further deterioration, and extend the service life of the assets.
Our Solution
Following inspection, active leaks were arrested by injecting a closed-cell polyurethane resin into voids and cracks; on contact with water, the resin expands to seal the defect. Concrete defects were then ground back using a diamond grinder to achieve a sound surface profile, followed by high-pressure water jetting to remove laitance, friable material, and surface contaminants. A cementitious fillet detail was installed at all transitions before two coats of penetrating epoxy primer were applied to improve adhesion and prevent outgassing. Raven 405 — a plural-component epoxy lining system with over 35 years of service in the water and wastewater sector — was then spray-applied to the specified thickness using a lorry-mounted fixed-ratio plural-component pump. A high-voltage spark test was conducted across all coated surfaces to identify pinholes or holidays, which were repaired by hand and retested to confirm a fully continuous film.
Key Benefits
- Active water ingress arrested prior to coating using closed-cell polyurethane resin injection
- Diamond grinding and high-pressure water jetting ensured a clean, sound substrate for optimum adhesion
- Raven 405 epoxy lining provides proven resistance to H₂S attack and chemical degradation
- Plural-component spray application ensured consistent film build across all five chambers
- High-voltage spark testing confirmed 100% holiday-free, continuous coating film
- Asset lifespan extended without the need for structural replacement
Conclusion
All five interceptors were successfully relined and returned to full service. UCL Ltd's capability in substrate preparation, leak arrest, and Raven 405 spray application demonstrates a complete, in-house solution for the rehabilitation of buried concrete wastewater assets.
