Modeling of the deterioration timeline of sewer systems.

Sewer deterioration, prevalent in municipalities throughout Canada, prompted the Quebec provincial government to implement a 1% renewal rate of the conduit facilities as to meet the goals of the national water plan adopted in 2002. Some of the most affected municipalities are usually the ones already under tight budget constraints, and cannot therefore afford the use of CCTV inspections in assessing the state of their sewage systems. This paper proposes a probabilistic model devised to survey the current conduit deterioration state caused by maintenance and operational conditions. Based on the multinomial logistic regression, this model - successfully applied to a case study in Quebec - shows the temporal deterioration of conduits for different material types. On average, it correctly predicted 54% of outcomes for transition probabilities involving both condition classes 1 (excellent) and 2 (good), and it showed a 59% correct prediction for class 3 condition (fair). This model is a recommended tool - applicable in combination with current exploratory techniques - for an effective prevention of conduits failure. [ABSTRACT FROM AUTHOR]