Site work for a water / sewer project in Los Angeles, California. Completed plans call for site work for a water / sewer project.

Sewer HC Remodeling for the City Trunk Line North Unit 1 Project The proposed project would be located in the northeastern portion of Los Angeles (Figure 1). The new trunk line would originate at the LADWP Van Norman Complex in Sylmar and terminate adjacent to the Tujunga Spreading Grounds in Sun Valley. The trunk line alignment generally extends north from Tujunga Spreading Grounds along Canterbury Avenue until Branford Street. At Branford Street, the trunk line alignment would be realigned east to Arleta Avenue and then continue north to Brand Boulevard. The trunk line would then be routed west along Brand Boulevard and San Fernando Mission Boulevard to Stranwood Avenue, continuing northwest on Stranwood Avenue into the LADWP-owned Van Norman Complex property. The proposed project would be located in the northeastern portion of the San Fernando Valley in the City of Los Angeles with the trunk line originating at the LADWP Van Norman Complex in the Granada Hills community of Los Angeles and terminating adjacent to the LADWP Tujunga Spreading Grounds in the Sun Valley community of Los Angeles. The Los Angeles Department of Water and Power (LADWP) proposes to replace the northern extent of the existing Los Angeles City Trunk Line (LACTL) with approximately 33,000 linear feet of 54-inch-diameter trunk line (the City Trunk Line North [CTLN] Project, also referred to herein as the project or proposed project). The CTLN would originate at the LADWP Van Norman Complex in the Granada Hills community of Los Angeles and terminate adjacent to the LADWP Tujunga Spreading Grounds in the Sun Valley community of Los Angeles, where it would connect to the existing City Trunk Line South (CTLS). The original LACTL was installed in 1914 to serve the City of Los Angeles with water delivered by the Los Angeles Aqueduct to the Lower San Fernando Reservoir (later renamed the Lower Van Norman Reservoir), located in what is now the Van Norman Complex. The LACTL traversed the eastern San Fernando Valley from the reservoir to the Santa Monica Mountains, providing direct supply to areas of the eastern Valley as well as functioning as a primary transmission conduit for water for central areas of the City through connections to the Franklin Reservoir Tunnel and, later, the North Hollywood Pump Station. The portions of the LACTL from Tujunga Spreading Grounds to the Franklin Reservoir Tunnel have been or are in the process of being replaced under the CTLS Project. The portion of the LACTL that would be replaced by the CTLN is a 72-inch-diameter riveted steel pipeline, which, at over 100 years in age, has severely corroded. Since 2000, it has experienced numerous leaks and ruptures, including a major collapse of approximately 400 feet of the pipeline within the Van Norman Complex. With the completion in 2012 of the new Sepulveda Trunk Line and Parthenia Trunk Line, as well Units 1 and 2 of the CTLS, trunk line supply pathways were established to bypass the northern portion of the LACTL. However, in order to maintain supplies to the service areas adjacent to the northern portion of the LACTL, it was converted to function as a distribution mainline, fed with restricted supplies from the Van Norman Complex on the north and Tujunga Pump Station on the south. This has reduced the operating pressure on the line and, thus, minimized the potential for leaks and ruptures (Figure 2). Nonetheless, even functioning as a distribution mainline, this northern portion of the LACTL is reaching the end of its service life. Therefore, to avoid further leaks and ruptures and the associated loss of service and potential damage created, it must be replaced. As mentioned above, the Sepulveda and Parthenia trunk lines now provide a connection from the Van Norman Complex to the CTLS to deliver water to areas of the City to the south, but the proposed CTLN is required to continue to reliably provide water to the communities currently served by the northern portion of the LACTL. In addition to this requirement for direct water supply to adjacent communities, seismic evaluations have indicated that the Sepulveda Trunk Line, which is located west of the LACTL, is crossed by several active earthquake faults that traverse the northeast San Fernando Valley. The relatively large surface displacements that could be created by these faults have the potential to cause severe damage or rupture to the Sepulveda Trunk Line, resulting in the possibly loss of service to areas of the City. Therefore, replacing the LACTL with the 54-inch-diameter CTLN (rather than a 36-inch-diameter mainline that would be required for local distribution purposes) would provide trunk line system redundancy and resilience to help maintain service resulting from potential damage to one or more trunk lines during seismic events. The proposed route for the CTLN is depicted in Figure 3. It would originate at the northern end within the Van Norman Complex, where it would follow the alignment of the existing LACTL. The CTLN installation in the Van Norman Complex would be achieved by traditional open trench construction methods. This would entail removing the aboveground segment of the LACTL, excavating a trench approximately 10 feet in width and approximately 12 to 15 feet in depth, placing pipeline sections of nominally 40 feet in length in the trench, and backfilling the trench. After leaving the Van Norman Complex, the route of the CTLN would continue to follow the existing LACTL alignment southeast along Stranwood Avenue between Rinaldi Street and San Fernando Mission Boulevard. Because it would follow the LACTL, this segment of the CTLN would be installed via a "slip-lining method" involving the placement of the new 54- inch-diameter CTLN (the "carrier" pipe) within the larger 72-inch-diameter LACTL (the "host" pipe). Launching and receiving pits would be excavated at generally widespread locations, depending on the straightness of the alignment, from which the CTLN pipe sections would be fed through the LACTL. The slip-lining method of pipeline installation reduces the extent of surface disruption when compared to open-trench construction. The slip-lining segment would include the region beneath the San Diego Freeway (I-405). This would require several launching/receiving pits excavated within the roadway but would not involve disturbance of most of the street surface in this segment. Once reaching San Fernando Mission Boulevard, the CTLN route would diverge from the LACTL alignment, proceeding east along San Fernando Mission Boulevard and Brand Boulevard, southeast along Arleta Avenue, and southwest along Branford Street to Canterbury Avenue. Within this portion of the route, which would constitute the majority of the CTLN at about 27,000 feet, the pipeline would be installed entirely via open-trench construction because no host pipe (i.e., the existing LACTL) would be available to accommodate slip-lining. At major intersections, freeway underpasses, and flood-control channel crossings within this portion of the route, a jack and bore method would be employed, which involves installing the pipeline at greater depths from a launching pit and to a receiving pit, thus avoiding surface disruption between the pits.