Tucson Water's Strengthening Approach to Address Thrust Restraint for PCCP

Since 1999, Tucson Water has had an active PCCP asset management program utilizing inspection and advanced structural materials such as carbon fiber. The program strategy includes precision inspection methods that identify distressed pipe segments and proactive rehabilitation of those segments. In January 2013, separation of several pipe segments located at bends in an 84-in. PCCP line was identified. The separation of the joints was due to combined loading issues at the bends, specifically inadequate thrust restraint. The pipe sections with inadequate thrust restraint were strengthened using carbon fiber primarily applied in the longitudinal direction to address the identified issues. The use of the trenchless repair method was favorable due to the difficulty of excavating in the distressed pipe region. The application of carbon fiber for this design condition was a significant advancement beyond typical CFRP rehabilitation, which involves reinforcement primarily in the hoop direction. This paper will provide valuable information and insight into the use of CFRP to address thrust restraint.