Los Gatos Weekly-Times

Officials say a buckling pipe at Lexington poses no threat

By Jeff Kearns

Santa Clara Valley Water District engineers are checking out a 1,500-foot-long pipe that runs through the middle of Lenihan Dam at Lexington Reservoir after a visual inspection revealed that sections of the pipe were starting to buckle. Data collected over the past 11/2 weeks continue to show no evidence of any imminent threat to public safety, according to the water district's Mike Di Marco.

Divers entered the 52-inch-wide pipe last week to conduct a series of pressure tests and install pressure gauges.

"That's going to give us a clue what's happening inside the dam itself," water district spokesperson Mike Di Marco said. "This isn't something we expected to find."

Engineers aren't sure what caused the problem, which is the third instance of buckling in the pipe since the 1989 Loma Prieta earthquake.

Di Marco said that the district has theories about the cause, but hasn't found anything conclusive yet. One theory is that the steel used to build the pipe in 1952 may have been of inferior quality because the Korean War was on at the time. Other theories engineers are investigating are that an air vent connected to the main pipe may not be big enough, and that the problem may linked to recent seismic activity or changes in the soil in the earthen dam.

For the sake of the fish in Los Gatos Creek, reservoir water is being pumped over the spillway to keep the creek flowing while the outlet pipe is closed for inspection.

Di Marco says the reservoir will not be drained, however, so that the engineers and divers can keep testing the pipe. "There's no chance of draining it at this point, but we may in the future to get the fix done," he said.

Once the water district figures out what the problem is, the next step will be to figure out how to operate the dam if the pipe is still closed when the winter rainy season begins. "If we get so much rain that we can't release it, the reservoir will spill sooner than anticipated," Di Marco said.

Local police, fire and other emergency agencies were alerted to the situation at the dam, and the water district has partially activated its Emergency Operations Center, Di Marco said, in order to create a communications channel for the various agencies and officials involved in the process, as well as other officials. Officials are holding conference calls each morning and afternoon to keep other agencies and cities informed about the work going on at the dam.

The public is being asked to stay away from the dam so as not to jeopardize the investigation. Water district crews are working around the clock; testing is being conducted in cooperation with the Division of Safety of Dams, a state regulating agency.

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