The purpose of the distribution system is to deliver adequate quantities of water at sufficient pressure under continually changing conditions. From time to time there are factors, situations and occurrences that disrupt this theory. Some of these instances occur more frequently than desired. Often municipalities and utilities are faced with making decisions that affect the bottom line. The goal is to maximize continuous service of the equipment in the system at the lowest possible cost to the utility.
Rehabilitation is the application of infrastructure repair, renewal, and replacement technologies in order to return optimal functionality to a drinking water distribution system. The most important task to make this successful is the planning and prioritizing of the needs, tasks, work and financing of the project or projects. The average age of distribution infrastructure is 50 years old. It is estimated that $325 billion would need to be spent in the United States from 2007-2027 in order to update the infrastructure in the distribution system. Currently 1 million miles of pipe services the 273 million people in the United States.
When thinking about rehabilitation in the distribution system, one should consider the current condition of the system as well as the extent of critical repairs needed. Knowing the system’s condition can easily be tracked through good maintenance records. The ability to inspect and assess the condition and deterioration rate of each element of the system is critical to the rehabilitation decision making process. In the maintenance records, problem areas can be tracked and monitored for performance and problems. This can help a municipality decide whether to choose partial or full rehabilitation. Many operators may say “Well I am not involved in any of this.” You should be. As the operator most of you are certified by the state and trained by your municipality in distribution system operations. It is good for you to know this information as well as make yourself available for questions and solutions in your area of expertise. Developing good relationships between operators, superintendents, mayors and councils can result in significant progress in distribution system efficiency.
As these conditions are analyzed by people that are familiar with the system by using sound asset management principles, sound decisions can be made on the rehabilitation approach suitable for the entire system. Some of these principles include Performance Assessment, Deterioration Rate of Assets and Life Cycle Analysis. Major areas that are monitored under the performance assessment are the main break frequency, main break severity, water quality issues and poor hydraulic characteristics. Many systems have shifted the focus of their performance assessment analysis to improved leak detection to reduce water loss, reducing repair costs and using predictive models for deterioration based on pipe materials, ground conditions and failure history. Using these methods in conjunction with maintenance logs can give a good indication of the system’s deterioration of assets rate. Once this data is obtained and organized, a life cycle cost can be established. Life Cycle Cost is the calculation of the total project cost for a distribution system improvement project that includes initial cost, annual operation costs, as well as maintenance and replacement costs over the life of the project. This will reveal to those managing the system which approach they can afford or whether they should extend the life of the system or replace it. This is a starting point for assessing rehabilitation vs. replacement. Future blogs will show analysis and scenarios that will give insight on how to effectively use data obtained from the tools mentioned above.