Abstract

The Federation of Canadian Municipalities (FCM) reported that approximately 55% of sewer infrastructure in Canada did not meet current standards. Therefore, burden on Canadian municipalities to maintain and prioritize sewers is increasing. One of the major challenges is to develop a framework to standardize the condition assessment procedures for sewer pipelines. Lack of detailed knowledge on the condition of sewer networks escalates vulnerability to catastrophic failures. This research presents a proactive methodology of assessing the existing condition of sewers by considering various physical, environmental, and operational influence factors. Based on historic data collected from two municipalities in Canada, structural and operational condition assessment models for sewers are developed using multiple regression technique. These models are utilized to generate deterioration curves for Concrete, Asbestos Cement, and Polyvinyl Chloride (PVC) sewers. A combined condition index (CCI) for sewers is developed, which integrates the combined effect of structural and operational conditions. The CCI is divided into 5 condition categories, ranging from "Acceptable" to "Critical". It is developed based on integrating the two major sewer condition assessment protocols adapted in Canada: WRc (Water Research Centre, UK) and CERIU (Centre for Expertise and Research on Infrastructures in Urban Areas, Canada). Unsupervised, self-organizing, neural network approach is used in order to develop the CCI and the integrated protocol. The developed regression models show 82% to 86% accuracy when they are applied to the validation data set. The CCI and integrated protocol are verified by municipal practitioners and experts of the CERIU sub-committee for developing a unified sewer condition assessment system. Based on the developed models, a web-based sewer condition assessment tool, coded in Java (version 5.0), is developed to predict structural and hydraulic conditions as well as the CCI. The developed models will assist municipal engineers in identifying critical sewers, prioritizing sewer inspections, and developing a unified sewer condition assessment system.