Meeting the Challenge of Pipeline Emergency Repair

The Metropolitan Water District of Southern California (MWD) is the nation's largest provider of treated drinking water. Each day during a normal year, MWD moves more than 1.5 billion gallons of water through its distribution system. Since nearly 19 million Southern Californians rely on Metropolitan for up to half of their water supply, it is important to make the system as reliable as possible.To maintain the system, each year MWD schedules shutdowns to perform inspection, maintenance and repair on various pipelines and facilities throughout the system. However, when unanticipated problems arise that puts the water delivery system or public at risk, an emergency pipeline repair is required. Close cooperation among MWD's in-house engineering, fabrication and construction workforce makes it possible to have the pipeline repaired and returned to service in a short time. There are also times when a pipeline shutdown is not feasible, requiring an emergency repair without service disruption. This paper provides an overview on the various emergency repair methods MWD uses to repair Prestressed Concrete Cylinder Pipe (PCCP), precast or cast-in-place reinforced concrete pipe and steel pipe. For structural repairs of PCCP and precast concrete pipe, the repair methods include removing the distressed pipe and replacing it with steel pipe, inserting a steel liner inside the pipe, or installing carbon fiber reinforced polymer (CFRP) liner. For water leaks in precast or cast-in-place reinforced concrete pipe, the repair methods include installing internal EPDM rubber seals, installing fiber reinforced polymer (FRP) lining, or external crack injection. For steel pipe, the repair methods include welding on steel patch plates, installing a steel outlet, or installing internal or external steel bands.