Event-Based Approach to Optimize the Timing of Water Main Rehabilitation with Asset Management Strategies

Abstract

Municipalities with limited budgets will have to rehabilitate their stock of deteriorated water mains in the coming decades. Optimization and asset management offer municipalities the opportunity to plan the rehabilitation of their water mains in a more rational manner. The aim of this paper is to develop a new event-based approach to optimize the timing of water main rehabilitation. The approach incorporates a new gene-coding scheme and covers the full range of decisions about pipe replacement, duplication, lining, new pipe installation, and asset management strategies (infrastructure adjacency and quantity discounts applied to the installed pipe). The new approach is applied to the Fairfield water network, and results suggest that applying a budget constraint prohibits early investment in pipe rehabilitation with a resulting increase in leakage, pipe breaks, and energy costs. Applying pipe discounts decreases capital and operation costs and favors pipe lining over pipe replacement and duplication in the Fairfield network. A sensitivity analysis suggests that uncertainties in demand, leakage, and break growth rate have a moderate to significant impact on capital and operation costs.