AWWA IMTECH59626

The Orange Water and Sewer Authority (OWASA), located in Carrboro, North Carolina and serving the Towns of Chapel Hill and Carrboro, and the University of North Carolina at Chapel Hill, maintains a proactive program for rehabilitating and/or replacing water lines in the service area. In a given year, as much as 5% of the system may be targeted for replacement. Staff had used performance (recent breaks and leaks) and pipe material (e.g., a goal to replace asbestos cement pipe) as the primary criteria for selecting and developing rehabilitation and replacement projects. OWASA wanted to improve upon the traditional approach to water line rehabilitation and replacement, by prioritizing projects in the service area and more efficiently planning the Capital Improvements Budget (CIB). OWASA retained the professional services of Earth Tech to develop a dynamic AccessTM-based model that prioritizes water lines needing replacement. The model input consists of physical data on the distribution system, and service level criteria based on industry and local standards. To insure the highest quality input possible, OWASA and Earth Tech worked together to: develop an accurate system wide inventory; establish service levels and performance criteria for individual water mains; and, ensure "buy-in" by stakeholders on the water main prioritization criteria. Through these efforts, an "OWASA specific" dynamic water main prioritization model was created, and is currently in use for planning the fiscal year 2004 CIB. This paper: describes the processes and challenges of assembling the system inventory, establishing performance criteria, and developing the model; describes how the model output is being used in capital project planning; and, emphasizes the dynamic aspects of the model, including new data input and level of service changes. Includes figures.