San Diego County Water Authority Completes First Aqueduct Rehab

A major rehabilitation project on the First Aqueduct in North San Diego County was completed last week by the San Diego County Water Authority. The $30 million project included renovating and replacing dozens of structures on two large-diameter pipelines.

The First Aqueduct project began in early 2019 and was one of the most complicated pipeline retrofits in the Water Authority’s history. The upgrades included replacing 14,500 linear feet of lining on the steel pipe sections of Pipeline 1, removing 16 associated structures and retrofitting 46 structures. In addition, redundant connections to six flow control facilities were added between the two pipelines to improve the aqueduct’s operational flexibility.

“The First Aqueduct delivered imported water to our region for the first time more than 70 years ago, and it remains critical to water supply reliability for our region to this day,” said Gary Croucher, chair of the Water Authority’s Board of Directors. “Coordination across Water Authority departments and collaboration with our member agencies allowed us to complete this extraordinarily complex project and ensure these pipelines operate for generations to come.”

The Water Authority’s Engineering Department provided construction management and inspection for the retrofit. Before the pipeline was returned to service, secondary tie-in connections to flow control facilities were added, and crews removed bulkheads that were used to isolate pipeline sections during the rehabilitation work. Once the work was completed, staff inspected all work areas in the pipeline to ensure they were clear of construction debris.

After the bulkheads were removed, the Operations and Maintenance team disinfected the highly impacted work areas and then refilled the aqueduct to prepare for a second disinfection of both pipelines with chlorine. Water samples at locations throughout the aqueduct were collected and analyzed to ensure the system was safe to return to service. Once all the samples passed analysis, all flow control facilities were placed back in service and the aqueduct was returned to normal operations.

The Water Authority will begin rehabilitation of the Southern section from Escondido to its terminus at San Vicente Reservoir in Summer 2022.

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