On Wednesday, August 31, the Sonoma County Water Agency (Sonoma Water) will be using heavy equipment to investigate the conditions of a 16” pipeline, which is leaking, near the Verano Avenue bridge. The pipeline, known as the Sonoma Valley Aqueduct, serves the City of Sonoma and the Valley of the Moon Water District (VOMWD).
No service interruptions from tomorrow’s work are expected to Sonoma or VOMWD customers. Traffic controls will be in place.
A leak in a mainline valve of the aqueduct was discovered on August 17. Sonoma Water crews found that a chunk of concrete from a retaining structure adjacent to the bridge abutment had dropped onto the underground pipeline. (The bridge abutment is intact and structurally sound.)
The leak is releasing between five and 10 gallons of water per minute. The water is seeping into the banks of the creek and not directly flowing into Sonoma Creek. Planning began immediately to repair the leak. The Sonoma Water Board of Directors declared an emergency on Tuesday, August 30, which allows for expedited contracting and purchasing.
“Today’s action ensures that the work can get started as soon as possible and that we can stop the loss of our precious water,” said Sonoma Water Director and Sonoma County Supervisor Susan Gorin.
Given the location of the leak, the complexity of removing the concrete resting on the pipe, and worker safety concerns, Sonoma Water determined that all materials and parts should be in place prior to repairing the pipeline. Due to supply chain issues, Sonoma Water is waiting on a few critical parts to arrive. Once all materials are onsite, the repairs will be scheduled.
“While we regret the loss of even one drop of water during this drought, the safety of our workers, the integrity of the pipeline and ensuring our community’s water supply are paramount. We don’t want to start a repair job until we know that all equipment and materials are on hand when we shut down the aqueduct,” said Sonoma Water General Manager Grant Davis.
Argonaut Construction will assist with the investigation and repair, which will begin on August 31, with an examination of the existing pipeline to assess conditions before repairs start. The full repairs will require two temporary shut-downs of the aqueduct. Planning is ongoing with the City of Sonoma and Valley of the Moon Water District to ensure that impacts to water service will be minimized during the shutdowns.
Environmental resources staff conducted an immediate assessment and found no observations of fish or other species mortality in Sonoma Creek and found no chlorine in the creek. As a precautionary measure, the water is being dechlorinated onsite. The California Office of Emergency Services, San Francisco Regional Water Quality Control Board and regulatory agencies have been notified of the leak.
Sonoma Water provides water supply, flood protection and sanitation services for portions of Sonoma and Marin counties. Visit us on the Web at www.sonomawater.org