Consequence of Failure of Sewers (COFS) Model for Risk-Based Asset Management Using Analytical Hierarchy Process

The deterioration and subsequent failure of sewer pipes impacts the community, the environment, and has significant economic consequences for utility owners. As a result, it is vital that sewer utilities have a robust methodology that accurately assesses the consequences of sewer pipe failure. The aim of this paper is to present a consequence of failure of sewers (COFS) model that uses a weighted sum multicriteria decision making method based on sewer expert opinion to assess the economic, social, and environmental consequences of sewer pipe failure. The first part of this paper briefly reviews methods used in practice to assess the consequence of failure (CoF) of sewer pipes. The proposed methodology is presented next, where the analytical hierarchy process (AHP) is used to develop the COFS model by incorporating a series of internal and external pipe factors. When incorporated with probability of sewer pipe failures, the COFS model is useful in determining the risk of sewer pipe failures to budget and prioritize maintenance actions more efficiently. The final part of the paper presents a short example where the model was applied to a 54-inch diameter reinforced concrete sewer pipe segment.