Our faults … | SierraSun.com

Our faults …

Greyson Howard
Sierra Sun

Emma Garrard/Sierra Sun file photoRon Rose of the Dam Safety Assurance Program points to the fault in Martis Valley last month.

MARTIS VALLEY “-The Army Corps of Engineers, as part of a study into the safety of Martis Creek Dam, dug two trenches in Waddle Ranch this fall. What they found, two earthquake faults, lends credence to the dam’s ranking of one of the six riskiest in the nation.

The dubious ranking, derived by the Corps, came because water is seeping under the dam through a loose glacial till, which in a worst-case scenario could result in failure and flooding in Reno.

“We found a fault in each trench,” said Ron Rose with the Dame Safety Assurance Program of the corps. “They are two separate faults, but probably related, and they do trend towards the dam.” Rose said in a previous interview it could be four years, in a best-case scenario, before the corps can come to a decision, on repairing, rebuilding, or removing the dam.

The Corps did not find any charcoal near the faults for the purpose of carbon dating, which would have indicated when the last earthquake was, and how much of a risk it presents to the dam, Rose said. Other dating options are being pursued.

More trenches will be dug both up and down stream from the dam to further map the faults, and an aerial map will be made of the surrounding landscape, Rose said.

Other work around the dam will be slowing down or stopping for the winter, said Veronica Petrovsky with the corps.

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This means the dam will once again be open to the public as drilling operations cease this week, Petrovsky said.

Well, it wasn’t yesterday. Officials know that much. But officials did not find any charcoal near the faults for carbon dating, which would have given the corps an indication of when the last earthquake was. Other dating options are being pursued.