Inspection Prioritization Framework and Implementation for Combined, Sanitary, and Storm Sewers

Timely inspection of sewer pipelines is necessary to track pipelines’ conditions and to also respond to intervention needs in case of major operational and structural defects. Asset owners usually confront difficulties in determining the annual sewer inspection needs they need to achieve annually while balancing budgets, and risks associated in case pipelines are not inspected. Risks of failures associated with these pipelines, if they occur and critical, are costly due to potential consequences on the society, environment, and economy. Proper management of these networks begins with understanding their risks in case pipelines failed which will then aid in prioritizing pipelines for inspections in the short- and long-term periods. Therefore, the main objective of this paper is to develop a risk-based matrix that will identify the inspection frequency of sewers depending on their criticality and conditions. As part of this paper, a four-point scale criticality model development will be discussed, which was then implemented on the city of Hamilton sewer network. The results of the vulnerability analysis and condition grading will be summarized to associate the findings of both criticality and conditions with sewer inspection frequency. The sewer funding needs are analyzed based on a 20-year period, identifying pipelines that need to be inspected in the short-, medium-, and long-term. While this paper will summarize the findings of the project completed for the city, this paper will assist other asset owners in implementing a systematic criticality framework and a risk-based decision matrix to determine the time of inspection per sewer pipe in their network to better allocate inspection budgets.