Water supplier to spend $300,000 on pipeline vulnerable to earthquake
A 60-year-old pipeline that supplies much of Ventura County with imported water will soon get a closer look to help reduce the risk it fails during an earthquake.
Roughly 75% of the county’s population gets imported water through the Thousand Oaks-based Calleguas Municipal Water District. The agency receives the imported supply from Metropolitan Water District in Los Angeles via an 8-foot-wide tunnel through the Santa Susana Pass – one found to be vulnerable to earthquake damage.
Calleguas then provides water to communities from Simi Valley to Oxnard.
"We get all our water from Metropolitan Water District through this one, single connection," said Fernando Baez, Calleguas' engineering manager. "So, it is of the utmost importance that we make sure that we are making it reliable."
This week, the Calleguas board voted to hire Brierley Associates to assess the tunnel's condition and evaluate the need for improvements. The work is expected to cost roughly $307,000. It will include detailed mapping, high-resolution video and 3-D modeling. Ground-penetrating radar will be used to locate spots where steel reinforcement exists.
Officials postpone survey
In 1962, crews cut through sandstone and shale to construct the 1.3-mile tunnel that stretches from Chatsworth to Simi Valley.
The area has several faults nearby, and a 2019 study confirmed the tunnel could be susceptible to significant damage during a worst-case scenario earthquake. Depending on the degree of shaking or displacement of faults, the tunnel and entrances could crack or even collapse.
Calleguas officials planned a more detailed analysis four years ago, but the work had to be postponed after errant flows forced a temporary evacuation. Metropolitan has since replaced a leaky valve and Calleguas made improvements to better isolate any such flows.
Quake knocks out water supply
In 1994, the Northridge quake knocked out Calleguas' water supply for three months. The quake didn’t damage the tunnel but other facilities. The agency made it through the shortage but came close to not having water, officials have said.
Calleguas is working to build a pipeline to connect to the Las Virgenes Municipal Water District, a neighboring agency that gets imported water from Metropolitan upstream from the tunnel.
That connection could allow Calleguas to temporarily get imported water during a shutdown or if something happened to the tunnel. Construction is expected to wrap up next year.
Cheri Carlson covers the environment and county government for the Ventura County Star. Reach her at cheri.carlson@vcstar.com or 805-437-0260.
This article originally appeared on Ventura County Star: Ventura County water supplier to spend $300,000 on critical pipeline
