Red Phone: What happens if dam breaks?

“Red Phone, is there an alarm system in place to warn nearby residents in the event Anderson Dam should fail in an earthquake? You know, something like cities along the Pacific Coast have in the event of a tsunami.”

Red Phone: Dear Is There an Alert, Red Phone received a similar call last year and contacted Marty Grimes, spokesman at the Santa Clara Valley Water District, which owns and operates the dam.

He said they do not have an alert system such as those in place for tsunami threats. “However, we are working to implement a ‘tailwater alarm system’ so that we can be automatically notified if there are unusual changes in flow below the dam,” Grimes said.

“In addition, we have various sensors that monitor the dam remotely. These sensors would alert us if there are unusual pressures or movement within the dam.” If there were an imminent failure of Anderson Dam, the district would notify downstream neighbors, such as the cities of Morgan Hill and Gilroy and they would initiate their own evacuation plans, as necessary.

“We coordinate with downstream agencies and perform regular exercises to test our emergency plans,” he said. “In the event of a large earthquake, we would have a team of trained inspectors perform a visual examination of each of our dams to assess damages.

These inspectors report back to the District Emergency Operations Center, which issues updates to the downstream public safety agencies.” You should also know, good caller, that the water level of Anderson is kept below 57 percent of capacity as a safety precaution while a seismic study is underway. According to Grimes, a seismic retrofit of Anderson Dam to make it seismically safe won’t begin until 2015 and should take three years to complete.

In February, the cost of the retrofit project was bumped from $110 million to an estimated $185 million. Hope that answers your questions, good caller.

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