Abstract

The ability to regularly deliver safe drinking water is a constant challenge to municipalities. According to the Canadian National Research Council reports, the present estimated cost across Canada for replacement and rehabilitation of water mains is at least $15 billion. Therefore, selecting the best repair and/or rehabilitation scenarios is essential to optimize the quality of the existing water mains and to minimize rehabilitation losses. Current research identifies several rehabilitation methods for water mains, which are classified into three main categories: (1) repair (i.e. Open trench, sleeves); (2) renovation (i.e. slip lining, cement lining, epoxy lining, CIPP); and (3) replacement (i.e. pipe bursting, micro-tunneling, directional drilling, auger boring, open cut). Stochastic life cycle cost (SLCC), using Monte Carlo simulation approach, is utilized to compare the current new installation and rehabilitation methods, so that the optimal scenario can be accommodated for different types of water mains (i.e. Cast Iron, Ductile Iron, Concrete, PVC, and Asbestos). Data, related to the cash flow of each scenario, are collected from contractors and municipalities in Canada. Results showed that using "Open Trench" and "Slip-Lining" are the best methods for "repair" and "renovation" categories, respectively. However, the best method for "replacement" category is pipe bursting for small pipe diameters (<30'') and open cut for large pipe diameters (>30''). Accordingly, a maintenance plan is developed to manage repair, renovation, and replacement decisions. Current research framework will assist municipality engineers to select the optimum rehabilitation scenario for each type of water main. In addition, it will assist them to properly manage their assets, which guarantee better quality of life for the society.