Project Background

Critical Pipeline 4 Repairs Completed in North San Diego County

In August 2019, Water Authority crews detected a leak in the 90-inch diameter Pipeline 4, one of five major pipelines the agency operates. The Water Authority’s second aqueduct contains Pipelines 3, 4, and 5, which crosses Moosa Creek in the northeast portion of San Diego County. The leaking section was near Camino Del Rey in Bonsall, in an area with no adjacent homes or businesses.

Water Authority staff dewatered the pipe to determine the cause of the leak. Preliminary investigations found that a weld seam connecting a steel pipe section to pre-stressed concrete cylinder pipe separated in an area of very high water pressure. Additional analyses and inspections concluded that inadequate pipeline support in this area resulted in significant stress on the pipeline and the weld seam separation.

The Water Authority worked with contractors to find a fast and innovative solution – installing a carbon fiber liner to give the pipeline several more years of service. Repairs were completed in fall 2019. The newly installed carbon fiber liner will give the pipeline several more years of service while a longer-term solution for the aqueduct is developed and deployed.