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City Trunk Line South – Unit 3

Client: Los Angeles Department of Water and Power (LADWP)

location: los angeles, ca

Project Value: $51M

Project Description: This project, located in the heart of the San Fernando Valley, replaced a 90-year-old segment of the City’s aging water infrastructure. The scope included installing 1,290 feet of 60-inch steel pipe via the open cut method, with an average depth of 16 feet, primarily using beam and plate shoring, along with installing 4,186 linear feet of 60-inch steel pipe via 82-inch micro-tunneling. Located in the North Hollywood area of Los Angeles, the project runs north to south along Whitsett Avenue from Vanowen Street to Magnolia Boulevard. We used three jacking pits and five receiving pits, with a depth of 30 feet, to push both the casing and welded steel piping for the micro tunnel drives. We also installed seven maintenance holes and crossed hundreds of existing utility lines with numerous relocations. To ensure that there was no settlement, we monitored surface elevations continuously throughout this three-year-long project. Due to poor soil conditions in specific areas, 1,076 linear feet of the 82-inch micro-tunnel required that W.A. Rasic Construction perform soil grouting from the street surface. The soil grouting ahead of the tunnel operation ensured soil was stabilized and that no ground settlement occurred. Monitoring involved using various elements, including 18 extensometers, 11 utility monitoring points, 26 slope inclinometers, and surface deformation points every 150 feet along the pipe route. Noise levels occurring during work hours were kept to a minimum using sound-dampening barriers to shield residences and other noise-sensitive receptors from direct exposure to construction. Project mitigation measures allowed for maintaining a one-hour average noise level below 75 dBA. Since this project was in a major metropolitan area, we focused on supporting and protecting existing utilities and restoring paving and other improvements in seven distinct phases, which required W.A. Rasic Construction to perform six trunkline tie-ins.