OPTIMAL LOCATIONS OF ISOLATION VALVES AND BOOSTER CHLORINATION STATIONS IN AN URBAN WATER DISTRIBUTION NETWORK

Abstract

Urban water distribution networks (UWDNs) are critical infrastructures that provide essential services in an urban setting. Ensuring the quality of water inside this water distribution network (WDN) is critical, as this is the closest point before human consumption. To address these problems, appropriate disinfection procedures must be implemented that can prevent possible contamination concerns while maintaining water quality standards. Chlorination is widely used for disinfection in WDNs. However, delivering high doses of chlorine from storage tanks can pose challenges, especially for residents near overhead service reservoirs, leading to increased chlorine consumption and wall decay. To address this, booster chlorination (BC) stations with smaller doses are desirable. Furthermore, these networks often face challenges due to aging infrastructure, increasing demand, pressure drops, cross-connections, back-siphonage, breakages, leakages, and biofilm release. Such challenges make safeguarding water quality and preventing frequent breakdowns difficult, disrupting services to downstream users. Installation of isolation valves (IVs) at strategic locations can reduce such adverse impacts by isolating small segments of the network and expediting repairs, which in turn contribute to water conservation and leak control. However, identification of these optimal number of IVs, and their placements, as well as the optimal number and locations, and chlorine dosages of BC stations, is a disturbing question for researchers. This study addresses these interconnected challenges by focusing on these two key aspects. In the first aspect, this study proposes a methodology to assess the optimal number of IVs in a UWDN and identify their placement in the best of the worst possible scenarios. Based on the network topology and the associated IV costs, it identifies the optimal numbers and their places to minimize the maximum undeliverable demand. The methodology is illustrated with the help of a small WDN. Thereafter, the proposed methodology is applied to a real-type UWDN. The results indicate that the optimal number of IVs for the case study is 10, which should be placed at strategic locations to reduce the maximum undeliverable demand to 18% of the total demand.