Feeling Steamy at Calaveras Dam

Among many other fascinating geological features present at the Calaveras Dam project site, a geothermal steam vent has recently been exposed during construction. Although typically associated with volcanic activity, steam/gas vents are also frequently found near large active faults, like the Calaveras fault, which is within 1/4 mile of the project site. There is also evidence of past geothermal activity in the vicinity of this vent. As seen in this photograph, there are areas of hydrothermally-altered bedrock (gray sandstone stained yellow) and holes where former vents, now dormant, were once active.

The construction team continues to monitor the temperature and the gaseous emissions of the present feature, and has created a cautionary exclusion area around it, but, as seen in this video, there has been no adverse effect to construction activity. We will keep you posted on our findings!

The Rim Fire in Yosemite and a Sunol Valley Update

The Rim Fire, which started in the Stanislaus National Forest on Saturday, August 17th, has been widely reported during the past week. The fire has spread to 179,481 acres as of this writing, and more than 3,000 personnel have been dispatched to combat the fire. As of this writing, the fire is 20% contained.

The fire has since spread into the Tuolumne Watershed, and the environs of the Hetch Hetchy Reservoir, which is the source of 85% of the drinking water we provide our 2.6 million customers. There continues to be no change or impact to water quality or delivery from the Hetch Hetchy Reservoir. We continue serving high quality water to our customers.

The water delivery system and the recent upgrades completed in the Sunol Valley as part of our multi-billion dollar Water System Improvement Program have increased our ability to continue to serve our customers even during such an event as this. Why?

• Hetch Hetchy water is being pumped to San Antonio Reservoir in the Sunol Valley as we speak to ensure we have as much water here in the Bay Area as possible, in case Hetchy supplies should become unavailable to us.
• The pumps that send Hetchy water to San Antonio and to the Sunol Valley Water Treatment Plant were recently upgraded as part of the San Antonio Pump Station Upgrade.
• The Sunol Valley Water Treatment Plant Expansion and Treated Water Reservoir upgraded filters and outlet works at the plant, and recently finished construction of a new treatment basin.

In short, should Hetchy supplies become unavailable to us because of the Rim Fire, or need to be treated, we have completed enough infrastructure upgrades in the Sunol Valley to filter and provide 160 million gallons of water a day to our Bay Area Customers for up to 2 months.

This incident underscores the urgency to complete the remaining water system upgrades in the Valley: New Irvington Tunnel, San Antonio Backup Pipeline, and a replacement Calaveras Dam.

So, when the next large incident occurs -- we will still be ready!

For up to date information on the rim fire, please visit sfwater.org/RimFire.

San Antonio Pump Station









Water being filtered at the Sunol Valley Water Treatment Plant

Less than 1,000 feet to go!

It’s an exciting time here for the New Irvington Tunnel Project team.  As of August 14th, we have 886 feet of mining left to go!  The hole-through of the entire 18,860 ft tunnel is expected sometime this Fall 2013.  After we hole-through, construction is not quite done yet.  Miners will start preparing the tunnel for the installation of 8.5 ft diameter steel pipe, installed in 50-foot sections and welded together inside of the tunnel. We anticipate final completion of the New Irvington Tunnel at the end of 2014. Upon completion of the seismically-upgraded New Irvington Tunnel, the SFPUC will take the existing tunnel out of service for an inspection to assess the need for future maintenance and repairs.

We plan on hosting an Open House for the project on September 25, 2013.  All are invited to see our tunnel progress and project updates. Stay tuned for the invite!

For more information on the New Irvington Tunnel Project, subscribe to our blog, or call our 24 hour answer line at 866-973-1476 or email mle@sfwater.org

Tunnel workers pouring invert concrete

Vargas East Final Steel Liner looking west

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 72hours.org

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.

 

Celebrating Summer at the Sunol Water Temple

With the sun shining, a soft breeze moving through the Valley and the Sunol Water Temple as the backdrop…. it was the perfect June afternoon in Sunol. For those who stopped by to join us, it was not only a chance to socialize with neighbors, but an opportunity to engage in lively conversations with SFPUC team members about the construction work in the Valley. Guests were able to play with rock samples from the Calaveras Dam, learn about future fire system upgrades for the town, marvel at historic photos of the Valley, check out a conceptual model of the proposed future Watershed Center, and even test their knowledge of the Valley by answering a trivia question to win a prize!

Thank you to those who were able to attend our summer open house! See you all around the Sunol Valley!

Calaveras Dam Project Continues to Dig Away

Today the Calaveras Dam workers celebrated yet another milestone since construction began in August 2011.  Over 3 million cubic yards of soils and rock have been excavated to make room for the replacement dam.  The team enjoyed lunch on top of one of the disposal sites, where they have moved and compacted nearly 20% of the 3 million cubic yards of materials. 

Imagine the weight of 96 fully loaded Titanic ships--- this is the approximate equivalent weight of the 3 million cubic yards of soils and rock that have been excavated and moved to disposal sites around the project. 

By the end of the project, the Calaveras Dam Replacement Project will have moved more than 9 million cubic yards of soils and rock.  About 3.5 million cubic yards of the materials will be used in the construction of the new dam, while the remainder will be disposed of onsite.  As we celebrate today, we still have a lot of heavy moving to look forward to!

Calaveras Dam workers are acknowledged by Earthwork Superintendent Sam Aiello for moving over 3 Million Cubic Yards

View of the Calaveras Dam foundation today
where major excavation has taken place to make room
for the future replacement dam

Series #2 Do you Know Your Tap Water? – Local Waters

Second in our series of ‘Do you know your tap water’, begs the question, OK, 85% from Hetch Hetchy, straight through the Sunol Valley to our customers… but what about the rest?

 
The rest of the water supply comes from local reservoirs. In the Sunol Valley that includes two: Calaveras and San Antonio Reservoirs. Calaveras, when full, is our system’s second largest drinking water reservoir, second only to Hetch Hetchy Reservoir. It also stores only local watershed waters from the Arroyo Hondo and Alameda Creek. San Antonio Reservoir, on the other hand, stores water from San Antonio Creek, and we can also store Hetch Hetchy water there as well.
 

Calaveras Reservoir, shown here prior to the start of construction of the Replacement Calaveras Dam, stores local water only.

 San Antonio Reservoir Stores both Local Watershed Waters and Hetch Hetch Hetchy Water

We must filter the water from these local reservoirs at our Sunol Valley Water Treatment Plant before we send it to our customers.

Some facts about local dams and reservoirs that you may not know:

• The dam at San Antonio Reservoir is called Turner Dam, after former SFPUC General Manager, James H. Turner.

Turner Dam

• When originally constructed in 1925, Calaveras Dam was the largest earth-fill dam in the world.

Existing Calaveras Dam. The New dam is being constructed directly downstream of the existing one. The site looks very different today!

 

• Both reservoirs support habitat for many rare and endangered species. Each reservoir also has a nesting pair of bald eagles. Learn more about them here.

Catch up on the Do you know your Tap Water series.

See you around Sunol Valley!