Life-cycle cost based rehabilitation plan for water mains

According to the Canadian National Research Council reports, the renewal and rehabilitation of infrastructure across Canada is estimated to be at least $15 billion. Life cycle cost is an essential approach to distinguish alternative rehabilitation strategies for water main rehabilitation. Therefore, Life-cycle cost is used to compare different alternative strategies among water main rehabilitation techniques. Current research identifies several rehabilitation methods for water mains, which are classified into three main categories: (1) repair (e.g. open trench, sleeves); (2) renovation (e.g. slip lining, cement lining, epoxy lining, CIPP); and (3) replacement (e.g. pipe bursting, micro-tunneling, directional drilling, auger boring, open cut). Stochastic life cycle cost (SLCC), using Monte Carlo simulation approach, is used to compare different rehabilitation scenarios within the same alternative. Data, related to the cash flow of each scenario, are collected from contractors and municipalities in Canada. Results show 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 rehabilitation plan, based on SLCC, favors repairing with "Open Trench" until the breakage rate reaches 0.5 breaks/ km/year then replaces the main.