Evaluation of emergency repair attributes for sewer infrastructure management

Emergency response to sewer failure can result in considerably higher costs than scheduled rehabilitation. As part of their Local Sewer Rehabilitation Strategy, the City of Edmonton, Alberta initiated a strategic plan for initiating a proactive approach for rehabilitating their sewer network. An analysis was performed on historical repair data in order to gain a better understanding of the difference between emergency rehabilitation costs compared to scheduled rehabilitation costs. The emergency and scheduled cost distributions were fitted against different theoretical beta distributions resulting in a statistical comparison. The analysis revealed the emergency mean cost to be approximately 55% greater than the scheduled mean cost. Additionally, the variance of the emergency distribution was found to be three times greater than that of the scheduled distribution. This suggests that investment into a proactive approach that attempts to maximise the life span of a sewer infrastructure system, while responsibly replacing deficient pipe sections prior to an emergency system failure, could result in tremendous costs savings.