UV CIPP: High-Difficulty DN1200 Culvert Trenchless Rehab in North America

Project Background

A critical 1,200 mm (48-inch) reinforced concrete stormwater culvert in North America suffered severe structural degradation, classified as Fully Deteriorated. Because the pipeline ran alongside a major traffic corridor with an extremely high water table, traditional open-cut replacement was immediately ruled out—requiring a full structural, trenchless solution.

Key Challenges

Extreme Conditions & High Water Table: Groundwater sat flush with the surface, keeping the line fully submerged. Exposed, rusted rebar protruded into the flow line, presenting severe puncture risks.

Complex Geometry: The 89-meter run featured a sharp 45-degree bend, an intermediate access manhole, and steep slope variations up to 9.0%.

Heavy Structural Requirements: The final repair had to independently support AASHTO HS-20 heavy traffic loads with a 50-year design life.

Solution

The host pipe was thoroughly hydro-blasted to remove internal encrustation, followed by robotic cutting to trim all protruding rebar flush against the invert. Our DN1200 14 mm UV glass-fiber liner (styrene-free) was then deployed. Thanks to its exceptional tensile strength and radial flexibility, the liner navigated through the intermediate manhole and 45-degree bend without wrinkling or tearing. Once in place, automated UV light curing formed a tight-fitting structural pipe-within-a-pipe directly under fully submerged conditions.

Results

The 14 mm glass-fiber liner traversed the 45-degree turn cleanly, leaving a smooth interior profile with zero flow restriction. Post-curing inspections confirmed that the liner independently carries 100% of all dead and live loads, successfully delivering a fully rehabilitated asset engineered for a 50-year service life.