Pressure Zone Water Audits for the East Bay Municipal Utility District:Evaluating Water Loss Using AMR and Leak Detection

摘要

Water system audits are becoming an integral tool in determining performance of water systems throughout the United States. The recent popularity of Automatic Meter Reading (AMR) has enabled a new level of detail to be analyzed for these water audits. AMR devices equipped with data-logging functions allow for the hourly comparison of system supply vs. customer demand. This information leads to a better understanding of the nature of water losses and whether they are real losses such as system leaks or apparent losses such as meter error or water theft. In this study, East Bay Municipal Utility District (EBMUD), in cooperation with Water Prospecting and Resource Consulting (WPRC), has completed detailed audits of two pressure zones within EBMUD’s system in order to determine the true nature of lost water. Evaluation of leaks, flushing activities, system meter error, customer meter error, theft, leaks from one zone to another, or combination thereof were conducted. The data tools used in these audits were hourly consumption from AMR-equipped customer meters, hourly operations data from EBMUD’s Supervisory Control and Data Acquisition (SCADA) system history of pumping plants flow rates and reservoir level indicators, as well as test results from meter flow testing. Acoustic leak detection with Permalogs and leak noise correlators and customer meter testing were used in two pressure zones to evaluate further the real and apparent losses noted from the data analysis. The Holly Pressure Zone was selected because of its discrepancy between billed consumption and reported water delivery to the zone. The Round Hill Pressure Zone was selected because of its fairly low discrepancy. Audit of these zones were first conducted by comparing billing records based on bimonthly meter reads and average supply rates from SCADA system records. After a supply vs. demand discrepancy was identified, the audit process formally began. The audit process allowed EBMUD to get a much more accurate interpretation of system losses on an hourly basis and to reduce apparent losses that were partially skewing the system data. The steps taken to analyze the data and evaluate the systems’ losses are outlined in the following paper.