New pipe for qqueduct
A section of new pipe is laid during the rehabilitation project. Courtesy SDCWA

The San Diego County Water Authority has completed a major rehabilitation project on the historic First Aqueduct in North San Diego County, it was announced Thursday.

The project renovated and replaced dozens of structures on two large- diameter pipelines which delivered the first imported water to the San Diego region in 1947 and remains a part of the regional water delivery system. The construction contract for the project was worth approximately $30 million.

“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 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 rehabilitation of the aqueduct was part of the water authority’s proactive asset management program, which includes continually assessing the agency’s 310 miles of large-diameter pipeline and making the upgrades necessary to continue serving the region. That work is funded through water bills paid by residents and businesses across the county.

The First Aqueduct project began in early 2019 and included replacing 14,500 linear feet of lining on the steel pipe sections of a pipeline, removing 16 associated structures and retrofitting 46 structures, all while ensuring regional water service remained safe and reliable.

In addition, redundant connections to six flow control facilities were added between the two pipelines with the intention to improve the aqueduct’s operational flexibility.

Over the past two years, the water authority had four coordinated shutdowns in collaboration with member agencies and communities in North County intended to create minimum impact on nearby neighborhoods and water users.

Work on the project was completed Jan. 12 and a report will be presented to the authority’s board at its March meeting.

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 San Diego County Water Authority is a public agency created in 1944 which delivers wholesale water supplies to 24 retail water providers, including cities, special districts and a military base.

–City News Service