Water Infrastructure Asset Management: A Methodology to Define Investment Prioritization

Abstract

A key component of water supply infrastructure asset management is the establishment of investment priorities: how to decide among investments of different types, values, functions, and physical conditions? The decision may be straightforward in some cases, but in most situations managers find themselves in the situation of having to adopt subjective criteria. Nowadays, decision making needs a comprehensive approach that takes into consideration cost of building, operating, maintaining and disposing of capital assets over their life cycles. Conversely, factors such as improvement of customer level of service, improvement of system reliability, or minimization of negative impacts of the infrastructures on the society and on the environment should be incorporated into the investment prioritization process. This was the motivation for a project promoted by the water utility EPAL, S.A. and jointly developed with a research team. The objective was to define a conceptual model and develop an operational tool able to assist decision-makers in the prioritization of water distribution system investments. In this context, an integrated decision support tool was developed taking into account direct, indirect and external costs during the life cycle of the assets. The model includes different points of view and service goals important for water infrastructure asset management (e.g., quantity and pressure, water quality, reliability, water losses, energy, operation and maintenance, and environment) and was developed for different infrastructure components (water mains and service connections, treatment facilities, pumping stations and service reservoirs). The model was implemented into an MS Excel-based application that allows for input data and report production. Detailed tests were made for the three most common types of investments identified by the involved water utility. Sensitive analyses were carried out and conclusions drawn about the most important and critical points of view for each case. Based on the results of the model applied to this set of investments, three different alternative approaches for investment prioritization are analyzed and discussed. The paper describes the principles of the conceptual model, summarizes the main features of the computer application, discusses its applicability, strengths and weaknesses and presents some recommendations for further development.