Optimal Pipe Replacement Accounting for Leakage Reduction and Isolation Valves

Decisions about pipe replacement in water distribution systems usually involve multiple rationales dealing with economic effectiveness, hydraulic consistency and management targets. In addition to these, rehabilitation planning should also take into account the effects on customers of temporary service disruptions during interventions and the potentially achievable leakage reduction subsequent to asset renewal. A multi-objective genetic algorithm is used here to identify a set of "optimal" replacement schemes that consider work allocation based on the position of existing isolation valves and leakage reduction. The effectiveness of ranking of pipes according to their frequency of selection among MOGA solutions in terms of Pareto dominance and practical use for water managers is demonstrated. The benefits of considering segment isolation due to planned/emergency interventions is discussed by comparing solutions obtained with different sets of objective functions. Finally, it is shown that including leakage reduction among the objective functions allows for a faster improvement of network performance in terms of both water savings and average system pressure increases. Analysis is performed on a real medium-size water distribution network.