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SEWER PIPELINE PERFORMANCE INDICATORS
Citation:
Tafuri*, A N., M D. Royer*, AND P. Stahre. SEWER PIPELINE PERFORMANCE INDICATORS. Presented at 2000 Joint Conference on Water Resources Engineering & Water Resources Planning & Management of the American Society of Civil Engineers-Urban Water Resources Research Council sponsored session, Minneapolis, MN, July 30-August 2, 2000.
Description:
Wastewater collection systems are an extensive part of the nation's infrastructure. In the United States, approximately 150 million people are served by about 19,000 municipal wastewater collection systems representing about 500,000 miles of sewer pipe (not including privately owned service laterals connecting buildings to sewer mains). As these systems become older, more preventive maintenance and renewal are required. For municipalities to cost-effectively plan, organize, and implement this effort, they require improved information on structural conditions, decision-making tools, operation and maintenance (O&M) practices, and techniques for repair and rehabilitation. Experiences with exemplary European wastewater collection systems are potential sources of novel and efficient maintenance and renewal practices.
Although a lot of money has been spent trying to increase the knowledge about the structural condition of wastewater infrastructure, our knowledge is still very limited. Pipe age is a factor; however, it is usually a combination of several factors that causes failures and influences maintenance decisions, making the situation very complex. To effectively manage maintenance and rehabilitation programs, managers need a quantitative picture of the condition and performasnce of their systems. Conceptually, this quantitative picture can be generated through the selection of performance indicators (e.g., overflows/year/mile), followed by collection of the required data (e.g., overflows/year, miles of sewer), and computation of the performance indicator value (e.g., 0.3 overflows/year/mile). Performance indicator trends can be used to monitor conditions and performance within a system over time (e.g., increase in overflow rate over last 5 years) or over space (e.g., sub-system X overflow rate is 75% greater than sub-system Y) and between separate systems (e.g., system A overflow rate is 50% higher than "similar" system B). Managers can use these indicators to identify, quantify, and justify areas requiring increased or decreased labor emphasis. There have been several attempts, both here and abroad, to develop and apply performance indicators; however, benefits and associated costs of using them have not been well documented.
This paper will discuss procedures to optimize the O&M of wastewater collection systems, including European approaches for diagnosing and analyzing systems, and non-hydraulic models for predicting system integrity.