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A major challenge for society in the 21st century will be replacement, design, and optimal management of urban infrastructure. It is estimated that the current worldwide demand for infrastructure investment is approximately three trillion dollars annually. A Drinking Water Infrastructure Needs Survey conducted by the U.S. Environmental Protection Agency estimated that community water systems nationwide have an immediate need of $12.1 billion in infrastructure investment, primarily to protect against microbiological contamination. This paper presents equations that can be used to estimate the cost of system construction, expansion, and rehabilitation and repair for distribution system components. Equations have been developed for installation of new pipe, trenching, embedment, and the other unit operations that are required to replace or construct new distribution system components. Equations have also been developed to estimate the cost of cement mortar lining, sliplining, and corrosion control. These equations can be used in an additive manner to estimate the cost of all of the unit operations required for replacing or laying new distribution system piping, and for a limited set of rehabilitation and repair options. CE Database keywords: Water supply; Costs; Water distribution; Rehabilitation; Regression models; Pipes.

There is growing concern over the need to rehabilitate, replace, and repair drinking water distribution systems and wastewater collection systems in the United States. A recent survey conducted by the U.S. Environmental Protection Agency found that $138 billion will be needed to maintain and replace existing drinking water systems over the next 20 years. It is estimated that $77 billion of this expenditure will be dedicated to repairing and rehabilitating pipelines. Given the cost and disruption caused by replacing distribution system pipe using conventional open trench technology, utilities are beginning to increase the application of rehabilitation or trenchless replacement technologies to extend the life of existing pipes. This paper discusses the various types of technologies that can be used for rehabilitation and repair of drinking water distribution components. It also presents representative costs that can be used by utility managers to estimate order-of-magnitude budgetary costs for rehabilitation and replacement of distribution system components. DOI: 10.1061/(ASCE)0733-9496(2002)128:4(303) CE Database keywords: Water distribution; Costs; Pipes; Rehabilitation; Excavation; Trenching; Replacement.

A major objective of drinking water treatment is to provide water that is both microbiologically and chemically safe for human consumption. Drinking water chlorination, therefore, poses a dilemma. Chemical disinfection reduces the risk of infectious disease, but the interaction between chemical disinfectants and precursor materials in source water may result in potentially harmful by-products. Chlorine consumption results in the formation of by-products, and the loss of chlorine residual reduces protection against potentially pathogenic bacteria. Therefore, much effort has been invested in characterizing the loss of chlorine residuals in raw and treated water. This paper presents a mathematical model based on the use of two second-order terms for predicting this loss or decay. DOI: 10.1061/(ASCE)0733-9496(2002)128:2(152) CE Database keywords: Pottable water; Chlorine; Mathematical models; Prediction.