Rehabilitation of the Orange County Feeder

The Metropolitan Water District of Southern California (MWD) owns and operates the Orange County Feeder. The Orange County Feeder is a 36-inch-diameter steel pipe with coal tar enamel lining. A nine and half mile-long stretch of the pipeline was originally installed in the 1940s using refurbished steel pipe with coal tar enamel lining and coating. The lining in this stretch of the pipeline has reached the end of its useful life. This project involves removing the coal tar enamel lining, installing internal butt straps at every joint, and lining the pipe with mortar. The biggest challenge associated with removing the coal tar enamel is that coal tar can’t be removed with a traditional abrasive blast because it tends to melt. The only practical way to remove the lining is with a high-pressure water blast. The project also replaced old boiler type manholes (which were difficult to maintain) and valves that had reached the end of their useful life. MWD took a comprehensive approach to the rehabilitation so that all components in need of refurbishment were rehabilitated at the same time as the lining was replaced. To perform construction the pipeline had to be accessed every 1500 feet along the length of the pipeline to install the construction equipment. These access locations had to be installed in some of the busiest streets in the city of Santa Ana. The design team developed construction and traffic plans so that the pipeline could be accessed while minimizing impacts to businesses and the public. The construction of the pilot project was recently completed which was about 2 miles long. The construction was successful in removing the lining, installing the buttstraps, installing a new mortar lining, installing new manholes, and valves.