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Fold and Form: Trenchless Rehabilitation of 1.5 km Deteriorated Sewer Mains in a Densely Populated Neighborhood

The project site is a mature, densely populated residential neighborhood that has been occupied for many years.

Project Overview

  • Pipeline Type: Municipal Sewer Mains

  • Pipe Diameters: DN200 – DN300

  • Total Length: 1,500 meters (1.5 km)

  • Technology Deployed: Fold-and-Form Lining Technology

  • Project Status: Successfully Completed / Fully Operational




Background & The Challenge

The project site is a mature, densely populated residential neighborhood that has been occupied for many years. Due to constant chemical corrosion from municipal wastewater and natural ground movement over time, the underground DN200–DN300 drainage network had severely deteriorated, creating a critical infrastructure risk for the community.

Prior to intervention, a comprehensive CCTV robotic inspection revealed a combination of severe structural defects:

  • Structural Cracks & Fractures: Wall integrity compromised by years of corrosion.

  • Joint Misalignment & Displacement: Widespread joint failures leading to active groundwater infiltration and exfiltration.

  • Localized Collapses: Structural deformation impeding hydraulic flow.

  • Heavy Blockages: Accumulated debris causing frequent backups and local flooding.

The Major Constraint: The pipeline runs directly beneath the community's primary traffic corridors, paved driveways, and established green landscaping. Traditional open-cut excavation was entirely out of the question. Cutting open the roads and destroying the gardens would result in weeks of traffic gridlock, extreme noise pollution, high restoration costs, and severe disruption to the residents' daily lives.



The Solution: Fold-and-Form Lining

After a rigorous joint evaluation by municipal engineers and Anyue’s technical expert panel, Fold-and-Form Lining was selected as the optimal trenchless solution.

The installation process was executed with precision:

  1. Preparation & Cleaning: The host pipes were thoroughly jetted, cleaned, and cleared of all heavy blockages using high-pressure water equipment, followed by a pre-lining CCTV verification.

  2. Liner Insertion: The PVC liner, pre-folded in a factory-controlled environment to reduce its cross-sectional profile, was pulled smoothly through existing manholes into the target pipeline segments.

  3. Expansion & Curing: Utilizing pressurized steam, the liner was heated to its forming temperature, causing it to unfold and expand tightly against the host pipe wall. Once cooled, it formed a jointless, high-strength, close-fit independent structural pipe.



Results & Business Benefits

The project achieved flawless execution, meeting all engineering and environmental benchmarks:

  • Zero Excavation, Zero Disruption: The entire 1.5-kilometer pipeline network was fully rehabilitated without a single square meter of green space being destroyed, and without closing the neighborhood's main access roads.

  • Rapid Asset Lifecycle Extension: The structural integrity of the sewer mains was restored to an independent Class III structural level, extending the pipeline’s operational lifespan by an estimated 50+ years.

  • Optimized Hydraulic Flow: The seamless inner surface of the new liner significantly reduced the friction coefficient, enhancing fluid dynamics and preventing future blockages despite the tight DN200-DN300 diameter constraint.

  • Maximum Cost Efficiency: By eliminating the costs associated with road reinstatement, landscaping restoration, and prolonged traffic management, the client achieved a highly favorable return on investment (ROI).



Contact Our Engineering Team

Need a resident-friendly, zero-dig solution to restore your aging pipeline infrastructure? Contact Anyue today for a technical consultation.

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