An Integrated Field Implementation Framework for Gravity Sewer Asset Management Using Standardized Condition Assessment, Defect Coding, and UV-CIPP Rehabilitation

Abstract

Aging gravity sewer networks require rehabilitation strategies that are technically reliable, economically sustainable, and minimally disruptive to urban environments. Although ultraviolet-cured-in-place pipe (UV-CIPP) technology has become an established trenchless rehabilitation method, published literature rarely describes how condition assessment, standardized defect coding, rehabilitation execution, and quality assurance are integrated into a unified field implementation workflow.

This paper presents an integrated field implementation framework developed from practical experience gained across multiple municipal gravity sewer rehabilitation projects. The framework combines systematic CCTV inspection, defect classification using the Water Research Centre (WRC) Manual of Sewer Condition Classification (5th Edition) and EN 13508-2, structured rehabilitation planning, UV-CIPP installation, and post-installation quality verification.

The methodology was applied during the rehabilitation of more than 120 km of gravity sewer pipelines ranging from DN150 to DN2000. More than 4,500 structural and operational defects were documented using internationally recognized coding systems, supporting the successful installation of over 280 UV-CIPP liners. Practical implementation challenges, quality assurance procedures, and lessons learned are presented to demonstrate how standardized workflows improve inspection consistency, rehabilitation planning, and construction quality.

Rather than introducing a new rehabilitation technology, this study contributes a practical implementation framework that integrates existing engineering standards into a repeatable workflow suitable for municipal sewer asset management programs. The paper also discusses the emerging role of AI-assisted inspection systems as complementary tools for improving future defect recognition and reporting efficiency.