Caring for Underground Assets
The Water Authority operates and maintains a regional water delivery system capable of delivering more than 900 million gallons of water per day. The system consists of 310 miles of large-diameter pipeline, 1,600 aqueduct-related structures, and approximately 100 metering/flow control facilities. It also includes a state-of-the-art water treatment plant, hydroelectric facilities, pump stations, flow regulatory structures, and a dam with a 24,000 acre-foot reservoir.
Each year, the Water Authority develops an Aqueduct Operating Plan to communicate and coordinate with member agencies. The plan incorporates on-going efforts to optimize the delivery, treatment and storage of water in the San Diego region and is a coordinated effort with the Water Authority and its 24 member agencies, the Metropolitan Water District and other key stakeholders. The goal is to manage the water demands of San Diego County and coordinate maintenance activities and system shutdowns so that all portions of the systems are managed safely and efficiently.
Pipelines Require Continual Monitoring and Maintenance
Like all infrastructure, pipelines need vigilant assessment and upgrades to keep doing their jobs day after day, year after year. It’s no easy task, given the fact that they are buried in both urban, suburban and rural settings – and the fact that they are almost constantly in use. That’s why the Water Authority prioritizes monitoring and maintenance to ensure that the pipelines can continue to carry their precious cargo for decades to come.
Pipeline Relining
Approximately 82 miles of Water Authority pipelines are pre-stressed concrete cylinder pipes. Made from a combination of steel and concrete, PCCP was first used during World War II to help minimize the use of steel, appearing highly resistant to corrosion and able to provide unparalleled inner pipe strength. However, numerous catastrophic failures have occurred with these pipes worldwide. In response, the Water Authority instituted a proactive pipeline relining program in 1991 to reinforce the pipes with steel liners. In addition, in 2003 the Water Authority began utilizing an innovative technology, using carbon fiber, to conduct urgent pipeline repairs, helping ensure a safe and reliable water supply to the region.
Pipeline relining is used on long stretches of pipelines and involves inserting new steel liners into an existing pipeline. The new liners, which serve as new pipelines, are anticipated to last approximately 50 to 75 years. Relining the existing pipelines with steel is a quicker, more cost-effective alternative to excavating, removing, and replacing an entire pipeline. To date, the Water Authority has relined 47 miles of PCCP within its service area.
Urgent Carbon Fiber Repairs
Carbon fiber is a synthetic fiber originally developed in the early 1960s for use in the aerospace industry. Because of its light weight, strength, and speed and ease of installation, it is used in small sections of pipes that are in need of urgent repairs. While currently not as cost-effective as using steel liners to reline longer sections of pipelines, carbon fiber sheets are adhered to the interior of a pipe’s wall, fortifying the pipe and allowing it to quickly be put back into service. Most urgent carbon fiber repairs can be completed within 30 days.
While most relining work is conducted inside the pipe, minimal impacts to the immediate community can occur. In all cases, the Water Authority continuously works to minimize impacts to nearby residents, including noise, dust, traffic and limited access near work sites. When work is complete, areas impacted by construction are restored to their original condition or better.