Assessment and Renewal of Water Distribution Systems

Water utilities use their distribution systems to deliver high-quality water to customers, in spite of breaks, corrosive deterioration, and other forces. These aging and invisible water distribution networks, spread over large areas with multiple connections and points of access, require large allocations of capital resources for renewal. The engineers and operating crews in utilities work in tandem with planners, information technologists, and finance staff to gather and utilize the data required to make effective decisions about maintenance and renewal. Often, these operations must be conducted in the midst of congested urban areas, without disrupting daily life. This report is about the specific tasks involved in water distribution system capital management locating, assessing, planning, repairing, and renewing water distribution systems. The report came about as a result of the Awwa Research Foundation's (AwwaRF's) project Synthesis Documents on Infrastructure Integrity (2001, RFP 2772), which aimed to help utilities assess the knowledge they need for distribution system capital management and to evaluate the available research-based tools. The report is a synthesis of knowledge and the suggestions of utility and other professionals about renewing distribution systems. In addition to utilities, the report is aimed at policy makers, and at the water supply research and development community (including AwwaRF), to help the water supply industry plan a responsive research agenda for distribution systems. Information presented in this report was gleaned from the project 's literature survey, utility visits, surveys of experts, and three workshops. We also learned about practices in several different countries and in allied fields, including oil and gas and wastewater. The report covers a broad range of technologies, from technology-based assessment tools for operators to capital strategy planning methods. The first topic, condition assessment (the "science" and engineering side of distribution system management), addresses locating assets, diagnosing failures, learning about deterioration mechanisms, and measuring condition. The second topic, planning and prioritization (the "management" side of distribution system capital management), requires the utility to find funding sources, relate to governing boards and the public, and provide management and financial accountability. The third topic (the "construction" side of distribution system capital management), comprises the physical work of maintenance, repair, and renewal.