Abstract:
Water main breaks are a problem of concern to many water supply agencies. Breaks cause disruption in service, pose a potential danger when they reduce temporarily fire fighting capabilities, may cause damage to other services and to property, and incur substantial repair costs. Breaks may also cause a disruption in the normal work schedule and create an atmosphere of public concern that pressures the water supply agency. When a pipe breaks, the leak has to be located, the pipe exposed, and the leak fixed or a section replaced. When a length of pipe shows an increasing susceptibility to breaks, consideration should be given to replacing it entirely with a new pipe. The reasons for breaks are many and can be classi fied in several categories: 1. The quality and age of the pipe itself, including connectors and other equipment 2. The type of environment in which the pipe is laid e.g., the corrosivity of the soil, frost and heaving, external loads 3. The quality of the workmanship used,in laying the pipe 4. The service conditions, such as pressure and water hammer. An analysis of break data may help pinpoint the main reasons for breaks in a certain area of the network or in a specific pipe. Changes in pipeline design and construction policies may then be issued. This, how ever, does not solve the problem of a pipeline that is in service and exhibits a history of many breaks. There are essentially two ways of dealing with such a situa tion: to either repair or to replace the pipe. A rational decision to replace or not to replace a pipe at a particular time must be based on a comparison of the two alternatives: whether to replace the pipe, incurring the replacement cost and whatever future costs are associated with the new line, or to retain the existing length of pipe, at least for the time being, saving the replacement cost but incurring possible future costs of repair, disruption of service, and damages. The analysis required for such a decision must include a projection
