Selection and Concentration of Pipeline Mains for Rehabilitation and Expansion of Water Distribution Network

This paper proposes a strategy for rehabilitation and expansion of water distribution network (WDN) in developing countries. The main framework of the pipe network rehabilitation is formulated based on the “selection and concentration” of trunk/limb mains pipe strategy. The strategy is to select more appropriate pipeline, diameter and material of pipe mains to ensure cost effectiveness and adequate water pressure. Meeting the objective of the strategy, this study developed Hybrid Genetic Algorithm(HGA) model. HGA-I is applied considering rapid growth of the future water demand. HGA-IIa focuses on selection and concentration of trunk/limb mains pipelines, and HGA-IIbis applied to determine appropriate diameters for water demand in interim plan years. Life Cycle Cost Analysis (LCCA) is applied to identify the potential cost of a project alternative. This analysis proposes the most effective combination of pipe material and diameter of each pipe main. The application of this method may be appropriate for water authorities in planning rehabilitation and expansion of a WDN. They can easily clarify the optimal combination of pipeline, diameter, and material of trunk/limb mains pipes in the network that will result in the minimum life cycle cost over the entire upgrading project period.