AWWA ACE58205

The pathways through which water quality can be compromised in the distribution system may be classified into five major categories: intrusion of contaminants into the distribution system; regrowth of bacteria in pipes and storage tanks; water treatment failure; leaching of chemicals or corrosion products from system components (pipes, storage tanks, liners, etc.); and, permeation of organic compounds through plastic pipe and pipe components in the system. The characterization and quantification of these risk factors is complex and highly uncertain. The current inability to precisely quantify these risks may require the usage of a quantitative-qualitative framework. In this paper a framework for aggregative risk analysis is proposed for water quality failure in the distribution system. Each basic risk item is expressed by fuzzy numbers, which are derived from the product of the likelihood of a failure event and its consequence. The fuzzy numbers capture vagueness inherent in the qualitative (linguistic) definitions. A multi-stage hierarchical model for water quality failure is developed. An analytic hierarchy process is used for estimating the weighting scheme for grouping risk items. The framework is demonstrated with a simplified structure of risk hierarchies for water quality in distribution systems. Includes 11 references, tables, figures.