Replacing the Los Angeles Department of Water and Power’s Aging Infrastructure: Design of the City Trunk Line North Project

Los Angeles Department of Water and Power (LADWP), the nation’s second largest municipal water utility serving over 4 million residents, is upgrading its aging infrastructure, including the existing Los Angeles City Trunk Line (LACTL). The existing LACTL was the first pipeline to serve the City of Los Angeles with water from the Los Angeles Aqueduct. It was completed in 1914 and is a 72-in. riveted steel pipeline with a total length of 63,440 ft. Approximately 28,900 ft of LACTL will be replaced by the City Trunk Line North Project, which is split into Units 1 and 2. Both Unit 1 and Unit 2 will be 54-in. in diameter and will be installed using open cut, slip lining, and micro-tunneling methods. Unit 1 crosses six fault lines and will be a combination of earthquake resistant ductile iron pipe and welded steel pipe, while Unit 2 will be entirely welded steel pipe. The entire City Trunk Line North project is expected to complete construction by 2030.