Winter at Calaveras Dam

There is plenty of work happening during this winter season at the Calaveras Dam Replacement Project.  Although our construction team is not working on the dam’s embankment, they're keeping busy with other important construction projects that need to be completed before spring. Here is a glimpse of the work in progress.

Our team is working hard to construct some of the support facilities. Support facilities such as: the stream maintenance vault, the downstream toe electrical building and all of the electrical equipment are needed to operate the outlet works.


V34 Vault


Electrical Panels for Stream Maintenance Vault


Electrical Panel in Downstream Toe Building

Our team continues to prepare the left abutment foundation. Part of this job entails removing a temporary tieback retaining wall. This temporary tieback retaining wall was needed during the construction of the spillway to support an ancient landslide.



Tie Backs

During the past two weeks, our team has been working hard installing the last of our piezometers. For more information on our internal and external instrumentation, reference our November 7, 2017 and December 15, 2017 blog posts.



Drill Rig for Insturmentation



Piezometer

Our crew is working hard to finish these projects before the spring time. As you can see, there is a lot of activity happening in the winter months.

See you around the valley!

A Celebrity at the Alameda Creek Diversion Dam

There was a celebrity in our midst at the SFPUC's Alameda Creek Diversion Dam, the site of the Fish Passage Facilities Project. Field Biologist Chris Pattison spied this California Red-legged frog recently near the construction site and moved it to a safer location.



"Why is this frog famous?" you ask.

Could it be because the California Red-Legged frog (Rana draytonii) is a federally threatened species? 

Or that they are found almost exclusively in California?

Or that they were once a common meal for miners during the Gold Rush?  

Give up?

It has the distinct honor of being the Official Amphibian for the State of California. Read more in this blog post from 2014.

It is heartening to know that these really special frogs are still hopping around the Alameda Creek Watershed.

See you around the Valley!

Photo Friday from January 9, 1913

Happy Photo Friday!

While the East Coast of the U.S. experiences frigid temperatures and some frightening weather event called a 'bomb cyclone', we in the Bay Area, have been experiencing relatively mild temperatures. 

This was not always the case, however. For this Photo Friday we delve back to photos taken almost exactly 105 years ago, on January 9, 1913. 

On that day the crews constructing the first Calaveras Dam found their work site covered in snow. 

The site was so remote back then that the crews lived on site. Here is the watershed keeper's house and another worker's cabin.

Shown here is a barn, corral, and nearby cottage. 

It might be foggy out there today, but at least it isn't snowing!

Happy long weekend and see you around the Valley!

Sunol Valley's Native Residents - California Tiger Salamanders

Photos curtesy of Bill Stagnaro

It has started to rain in the East Bay! And with the first major rain fall of fall and winter appears a native Sunol Valley resident - the California Tiger salamander (Ambystoma californiense). 

These ever smiling amphibians are very elusive and hard to find. They are not really smiling but appear to be because of their wide mouth outlined in yellow. An adult California Tiger salamander can reach 7.5 inches or more in length.  Adults are black or dark grey, with oval to bar-shaped spots ranging in color from white to yellow. Juveniles are dark olive green in color and do not generally have any lighter markings. The best time to spot them is at the beginning of the rainy season.

The California Tiger salamanders found in the Sunol Valley are a federally threatened species. These beautiful amphibians have a complex life cycle that requires them to have different types of habitats. During mating season, they like to live in vernal or stock ponds. The juveniles and adults live in grasslands and oak woodlands, mainly living underground in the burrows made by other animals.  It is not uncommon to find California Tiger salamanders cohabiting with a family of ground squirrels.

During breeding season they will travel a mile or more to a nearby pond to breed. Although they may live as long as 10 years, they may reproduce only once. Females lay eggs singly or in small groups. Its larvae require significantly more time to transform into juvenile adults than other amphibians. Around late spring, salamanders leave the ponds to find burrows.

You most likely will never spot a California Tiger salamander during the hot summer months that’s because they are in estivation. Estivation is basically another word for “summer hibernation.” During this time they enter a dormant state and will not come out of their burrow until late November or the rainy season.

Photo curtesy of http://www.sonic.net/~shwand/amphibians/california_tiger_salamander.htm

If you’re ever spot a California Tiger salamander in the Sunol Valley,  smile back at it and count yourself lucky to have spotted it.

See you around the Valley!

Happy New Year Photo Friday: A Year's Work

The start of any new year is a good time for reflection. For us here at the Calaveras Dam Replacement Project, we are reflecting on how much progress we have made in 2017. Below are two pictures of our project, one at the beginning of the year and one taken a couple weeks ago.

Calaveras Dam at the beginning of 2017:



We were months into building the dam itself, and the foundation, and outlet pipeline are still above ground.

Calaveras Dam in late 2017:




As you can see from the picture above, we made tremendous progress on construction of the replacement dam itself. The team is more than half way up with the building of the replacement dam, whose final grade you can see rising up more than 110 feet. The foundation and outlet pipe are completely buried now under the new dam.

To date, our project is 89% complete. Our New Year's goal is to have the entire project completed by mid-2019.

From all of us, we wish you and yours a Happy New Year!

See you around the valley!

Photo Tuesday at Sunol Valley Yard

Photo Tuesday at the Sunol CorporationYard

Today's post is about the SFPUC's Sunol Corporation Yard, which is located near the Sunol Water Temple.  In the last year, we have been constructing badly-needed upgrades to the Corporation Yard that is home to our Water Supply and Treatment East Bay operations and our Natural Resources personnel. 

Here are some photos of our progress.

Shop #5 will house plumbing and electrical supplies

Iron workers at the job site


The Sunol Yard Long-Term Improvements are expected to be completed by the end of 2018.  During construction, the Sunol Water Temple will be closed to the general public.

We hope you are having a wonderful Holiday Season.

See you around the Valley!

Piezometers and Inclinometers - Part 2

Piezometers and Inclinometers

This week’s blog is Part 2 of our instrumentation series. Piezometers and inclinometers are two types of internal instruments used to measure a dam’s movements. Both of these instruments will be installed in the new Calaveras dam.

Piezometers

A piezometer is an instrument that monitors the ground water through the dam’s core and into the downstream drainage blanket and downstream rock/soil shell. A piezometer helps to ensure that the ground water surface does not erode the toe of the dam (the bottom downstream part of the dam). It also helps track the water level in the underline bedrock foundation.

Image courtesy of http://www.briodydrilling.ie/services-monitoring.asp

How Piezometers Work

An open stand-pipe piezometer is an open pipe (see picture above) that permits water to enter. The water level is measured and compared to other piezometers surrounding the dam’s face. These types of piezometers are called open-stand piezometers. We also have automated piezometers called Vibrating Wire Piezometers (VWP’s). VWP’s are data collection devices. We will have a total of 17 VWP’s and 14 open-stand pipe piezometers at Calaveras Dam.

Image curteosy of http://www.slopeindicator.com

Inclinometers

An inclinometer is an instrument that measures the movement of a slope with respect to gravity. Slopes on dams are built to be stable but still need to be monitored for possible movements. Inclinometers verify the stability of dams, dam abutments (sides) and upstream slopes during and after a reservoir filling.

How Inclinometers Work

Inclinometers measure the orientation angle of an object with respect to the force of gravity. This is done by means of an accelerometer, which monitors the effect of gravity on a tiny mass suspended in an elastic support structure. When the device tilts, this mass will move slightly, causing a change of electrical charge between the mass and the supporting structure. The tilt angle is calculated from the measured electrical charge. You will always find inclinometers in pairs or sometimes in 3’s. Two inclinometers placed at Calaveras Dam.

Image curtesy of i-astm.com

Piezometers and inclinometers will play an important role in Calaveras. Once they are placed, they will need to be monitored and observed on a frequent basis.

See you around the valley!