More tests planned for Warm Springs Dam

<p>A series of new tests are planned for Warm Springs Dam, where the U.S. Army Corps of Engineers is trying to determine why a monitoring well showed an unusual increase in groundwater.</p><p>“It is still somewhat of a mystery,” said Mike Dillabough, the Corps division chief of operations. “To quote one of the guys with a Ph.D. from Lawrence Livermore Laboratory, ‘It's a curiosity.'”</p><p>Dillabough stressed there are no concerns for the safety of the dam that forms Lake Sonoma, a source for water and recreation and a flood-control project for the Russian River.</p><p>“The face is absolutely good. There are no signs of any seepage of water on any part of dam, no signs of dampness except those we've known about for years and years,” Dillabough said. “It is monitored and photographed and we are walking it daily.”</p><p>The Corps will be planting electrodes into the face of the dam and using electrical currents to detect any water flow, Dillabough said. </p><p>Those tests are being devised by geophysical research scientists from UC Berkeley's Lawrence Livermore Laboratory.</p><p>Dillabough said they will also drill additional monitoring wells and install more piezometers, which measure the pressure of the core.</p><p>The dam is already fitted with 194 different physical and electronic monitoring devices.</p><p>On July 21, a monitoring well on the face of the dam 700 feet from the top detected an increase in groundwater. It was the only monitor that has shown any unusual measurement.</p><p>A chemical analysis found that it was groundwater and not water from the lake behind the dam.</p><p>The reading has spurred the Corps to intensify its monitoring and to bring in experts to try to determine what was happening, even though they do not believe there is a safety risk.</p><p>The compacted earth dam was built 25 years ago, at a cost of $330 million. The dam is owned by the Army Corps of Engineers and operated by both the Corps and the Sonoma County Water Agency.</p>