San Diego County Water Authority
San Diego, California, United States
The San Diego County Water Authority (Water Authority) is a public wholesale water provider serving 24 member agencies. Together, these agencies serve 3.3 million residents across the San Diego region.
The Water Authority has a robust asset management program in place to protect its 310-mile (500 km) transmission network. Some of their largest mains are made of prestressed concrete cylinder pipe (PCCP) manufactured more than 60 years ago.
The Water Authority prevents service disruptions by proactively detecting age-related defects with innovative inspection and monitoring technologies. Using this approach, they are extending the life of their transmission mains and improving service reliability for the San Diego community.
The Water Authority’s PCCP transmission mains range in diameter from 66 to 96 inches (1675 to 2440 mm). They provide a critical supply of water, making shutdowns or failures extremely expensive and disruptive. A single 10-day shutdown costs the agency approximately US$100,000.
The Water Authority was one of the first agencies to take a proactive PCCP management approach. They began an aggressive condition assessment program in 1992. This early program relied primarily on internal visual and sounding inspections. In 1999, the agency began using electromagnetic technology to detect broken wire wraps — the principal structural component of PCCP.
While successful in identifying distressed pipe sections, these inspection methods do not provide the ongoing rate of pipeline deterioration. Regular inspections reduce the risk of failure significantly, but they can also miss rapid wire break deterioration.
The Water Authority was an early adopter of acoustic fiber optic (AFO) monitoring. Since 2006, the agency has monitored their PCCP in near-real-time with Xylem’s SoundPrint® AFO platform. Today, they monitor over 29 miles (47 km) of pipe.
SoundPrint AFO is a long-term monitoring solution that continuously detects wire breaks. This advanced warning system helps the Water Authority take preventive action to avoid large-scale failures.
The AFO system includes a specially designed fiber optic cable deployed inside the pipeline. The entire length of the cable is acoustically sensitive and acts like a long sensor.
A data acquisition system collects and processes the monitoring data. Artificial intelligence and expert analysts review the data, identify events of concern, and convey actionable information to the Water Authority. Data is also available on a map-based web portal where the agency can view individual pipe history.
The Water Authority’s operators also actively review the monitoring data. Two possible wire breaks within one hour or five possible wire breaks within 12 hours trigger an executive decision-making process. Over 10 years, the agency captured more than 1,400 distinct wire break events.
Installing acoustic fiber optic (AFO) cable
“We have relied heavily on the SoundPrint AFO system over the years to provide oversight of imminent pipe failures and as a long-term planning tool that drives our pipeline rehabilitation program. This simply would not be achievable without the rate-of-change data obtained by continuously monitoring PCCP pipelines.”
Operations & Maintenance Manager for Asset Management at San Diego County Water Authority
Before installing the SoundPrint AFO system, the Water Authority was inspecting their pipelines every three to five years. While monitoring is a significant investment, the Water Authority achieved a favorable payback period through savings associated with fewer shutdowns and inspections. This also means fewer interruptions for customers and less damage from repressurizing the pipeline after an inspection.
Continuous monitoring also significantly reduces the risk of failure. The Water Authority has averted two potential catastrophic failures by responding to increasing wire break activity with a planned repair. Avoiding even one pipeline failure could prevent between $1.2 million and $10 million in damage costs. Catching the early signs of failure also enables the agency to use localized, cost-efficient repair methods.
Rate of deterioration data strengthens remaining useful life modeling to support long-term planning and asset management. This has been critical for the Water Authority’s PCCP rehabilitation planning schedule. Repair prioritization helps the Water Authority spend capital and maintenance funds wisely. In some cases, monitoring has enabled the agency to defer replacement based on defensible data, maximizing pipeline life and asset value.
The Water Authority is a national leader in using advanced technology to protect the San Diego region’s large-scale water infrastructure. Monitoring has improved the agency’s ability to manage long transmission mains with limited impact on water delivery.
The Water Authority continues to realize savings and gain valuable insights from their investment in AFO monitoring. This translates to benefits for the San Diego community, where water is one of county’s most precious resources.