A $25.3 million Pipeline 5 relining project is under way in North County to improve the reliability of the San Diego region’s water delivery system. The project involves rehabilitating approximately 2.3 miles of one of the San Diego County Water Authority’s regional wholesale water pipelines in eight segments along a 9.5-mile stretch through the community of Fallbrook.
Construction work will be done in phases and completed in summer 2019. When finished, the Pipeline 5 Relining Project will help extend the service life of this vital piece of infrastructure for more than 75 years. Generally, relining construction rehabilitates segments of pipelines based on their age and the need for improvements.
Relining process advances in well-planned stages
Construction activities in Fallbrook began September 19 with the installation of protecting fencing, establishing an entrance to the construction area, and clearing the site of all vegetation and debris for safety. The relining itself will begin in November.
In broad terms, the relining process begins with dirt being excavated to create an access portal or work area. The construction crews will conduct most of the work underground, inside the pipe. They will access the pipe by excavating, establishing, and entering the pipeline through nine access sites, or portals. The portals will be 25-foot by 60-foot excavated pits, spaced approximately 525 to 2,500 feet apart. At each portal site, 40 feet of existing pipe is removed to permit access inside the pipe to install relining materials.
The work involves removing 20-foot sections of old concrete pipe at each portals. Then, new steel liners are inserted into the existing pipe using a specialized pipe cart. Liners are installed into the entire pipe section. Once installed, the joints of the liner pipe are welded together. Each new steel liner is coated with a cement mortar lining. Finally, portals are backfilled and — after pipeline disinfection — the pipe is ready to be put back into service.
Community kept informed about project’s progress
Much of the construction work associated with the project is in Water Authority rights-of-way. Some portals within the unincorporated San Diego County portion of the alignment will be in undeveloped areas.
As people living and working in the area begin to see the activity, project team members will be available to address questions or concerns. Contact information including 24-hour phone numbers, email contacts, and website links are posted on nine informational signs along the construction route. Construction workers on site will also have contact information to pass out on request.
Pipeline upgrades ensure safe, reliable water supplies
The Water Authority’s large-diameter pipelines extend approximately 310 miles to convey water throughout western San Diego County. Approximately 82 miles of these pipelines were installed between the early 1960s and late 1980s with pre-stressed concrete cylinder pipes, or PCCP, made from a combination of steel and concrete. First used during World War II to help minimize the use of precious steel, this pipeline type is used extensively around the world.
Numerous failures of similar pipes nationwide prompted the Water Authority to take proactive measures to reinforce its PCCP type pipelines with steel liners in an strategic, multi-decade program starting in 1991.
In addition, in 2003 the Water Authority started using an innovative carbon fiber technology to conduct urgent pipeline repairs, helping ensure a safe and reliable water supply to the region.
When the Fallbrook project is finished, the Water Authority will have rehabilitated approximately 47 miles of PCCP — more than half of the total in the Water Authority system.