The Need to Proceed: Condition Assessment of 60-Inch PCCP in Houston, Texas

As part of a continued focus on operational efficiencies and reliable customer service the City of Houston established a Condition Assessment Program (CA) as a means to initiate a proactive approach for extending the useful life and enhancing the functionality of its water system infrastructure. Since 2001, both catastrophic failures and corrosion-related leaks have significantly impacted the City's water transmission system. These failures and leaks required these major transmission lines to be taken out of service for extended periods of time. These failures occurred unexpectedly and without prior warning. In response to these previous failures and leaks the CA program utilized a systematic process to prioritize its existing large diameter lines for future assessment. On the basis of the following criteria a 60-inch PCCP transmission line (the South 60), was identified as the highest criticality and priority for assessment. The South 60 water transmission line conveys approximately 35 MGD of surface water from the City's East Water Purification Plant (EWPP) to areas south and west of downtown Houston. The South 60 service area includes the Texas Medical Center. The South 60 consists of approximately 30,700 LF of steel pipe (from the EWPP to approximately 1,500 LF and 29,000 LF of PCCP. Condition assessment of the South 60 was performed in conjunction with a planned project to replace air release valves (ARV) along the same line. Improvements to the ARVs along the South 60 were recommended as part of a previous study to support the City's effort to achieve compliance with Texas Commission on Environmental Quality (TCEQ) regulatory requirements. Because of the nature of work required, the ARV project also included contractor support services for condition assessment of the South 60. By combining the ARV improvements with condition assessment of the South 60, the City optimized the work activities to isolate and shut down the pipeline.