The Los Angeles Department of Water and Power (LADWP) has 7,200 miles of water main in its water distribution system. The large diameter water mains that make up backbone of the system were installed early in the history of the City. For the most part, these were installed before 1940 when the City was much smaller than the sprawling urban City that it is today. As a result of the City's growth, these large diameter watermains known as trunklines, are now buried in streets that support very high traffic volumes. Replacement of these trunklines is a very difficult undertaking, with much disruption to surrounding communities. The LADWP undertook a Pressure Testing Program to determine which of these trunklines were in need of repair or replacement. Any trunkline that could not withstand a pressure test of 1.5 times the working pressure without repeated leaks would need rehabilitation or replacement. This paper discusses the decision making process to choose a TITE-FIT rehabilitation method over the standard replacement method for two existing trunklines. The TITE-FIT process was utilized to rehabilitate 4200-feet of 24-inch diameter welded steel trunkline, as well as 3800-feet of 36-inch riveted trunline, with a High Density Polyethylene (HDPE) liner. The contractor chosen to accomplish this task was ARB Inc. The liner was fused into 1,000-foot long sections from 50-foot lengths of HDPE as they were delivered to the site. The liner then went through a symetrical reduction process, which temporarily reduced the diameter of the liner by 10%, thereby allowing the liner to be pulled into the existing pipeline like the normal sliplining process. After the liner was in place it expanded back to its original diameter achieving a TITE-FIT liner. The TITE-FIT liner allows the existing pipeline to stay in service for at least 50 years or more, at approximately 1/3 the cost of standard replacement techniques with minimal social disruption.
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