Thursday, July 18, 2013

Did you feel that shake?

We sure did here out in Sunol Valley at our construction sites!  A small earthquake struck on July 15, 2013 at 12:02 p.m., which measured at a 3.4 magnitude, according to the U.S. Geological Survey (USGS).

According to the USGS, the epicenter was located 7 miles east of Milpitas and 9 miles northeast of San Jose, at a depth of 5.3 miles below ground.  The earthquake was triggered by the Calaveras Fault. This active fault is located near to, or in some cases underneath, crucial water infrastructure in the Sunol Valley, including: the  existing Calaveras Dam,  the treatment plant that filters water from the valley for our customers, the pump station that transmits water to and from the plant, and the major pipelines that transmit water from the Sierra Nevada and the Alameda Watershed to our Bay Area customers.

Why does this matter?
This is a reminder to us why our work to seismically upgrade these crucial water transmission facilities through the Water System Improvement Program is so important.  We work every day to ensure that we can provide water to our customers within 24 hours after an earthquake.
·         We recently constructed a fourth seismically-designed pipeline that crosses the Calaveras Fault to survive after an earthquake
·         We completed seismic upgrades to the nearby San Antonio Pump Station
·         Upgrades to the Sunol Valley Water Treatment Plant are nearly complete.
·         Construction of the New Irvington Tunnel and a replacement Calaveras Dam are underway.

Our system is more reliable today than it was 10 years ago. And it will be much more reliable, still, 10 years from now.

We hope that the earthquake we are planning for never happens. But if it does, we will be ready!  To learn how to make yourself and your family ready, visit

Crews completed work on the Alameda Siphon #4 Project in 2010, which crosses directly over traces of the Calaveras Fault.

The New Irvington Tunnel will provide us a new 3.5 mile seismically upgraded tunnel.  Workers are seen here standing a set in the new tunnel and expect final tunnel hole-thru this Fall 2013 with completion at the end of 2014.

Calaveras Dam is being replaced to provide a new earth and rock fill dam restoring the historic storage capacity of the dam to 96,850 acre feet (31 billion gallons of water) and will withstand a credible earthquake from the Calaveras fault. 

During construction at the Sunol Valley Water Treatment Plant, crews drilled almost 1,200 piers underneath the new treated water reservoir to anchor it into the hillside in case of an earthquake on the nearby Calaveras fault.


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