Love Your Local Stilling Basin

We have written a great deal about the spillway at the Calaveras Dam Replacement Project. Completed in 2016, this spillway is the width of a six lane freeway, and the height of a three-story building. The spillway's job is to protect Calaveras Dam by allowing water from Calaveras Reservoir to flow safely around, and away from, the dam in extreme high water events.

We have neglected to highlight an important component of a spillway - the stilling basin. Today, we'd like to generate a little love for stilling basins.  

A stilling basin is a structure that dissipates the energy of the water rushing down the spillway. Without a stilling basin, water coming out of the spillway could scour out the foundation of the dam, the base of the spillway, and nearby creek beds. In short, the stilling basin is a sort of bodyguard for the dam.

Stilling basins come in a variety of types, but generally fall into two categories: a straight drop for lower elevations, or an inclined chute. The stilling basin at the new Calaveras Dam is an example of the latter category. To be specific, it is a United States Bureau of Reclamation (USBR) Type II stilling basin.  Our stilling basin is approximately 200 feet long, 45 feet high and 80 feet wide.    

Water flowing down the new spillway of the new Calaveras Dam will drop 200 feet in elevation before it reaches the stilling basin at the bottom.The stilling basin creates a hydraulic jump to slow down the high velocity water before it slowly, and safely, discharges into Calaveras Creek.

A view of the new stilling basin at the Calaveras Dam Replacement Project

So, let's hear it for the humble stilling basin!

See you around the Valley! 

Loma Prieta Earthquake Anniversary Week - The New Irvington Tunnel

Happy Friday

This week marks the anniversary of the 1989 Loma Prieta Earthquake. 

We've been blogging about the San Francisco Public Utilities Commission's efforts to seismically upgrade our water system for many years now. The $4.8 billion Water System Improvement Program is more than 96% complete as of this writing. The water system that supplies water to 2.7 million customers in four Bay Area counties is much more earthquake ready today than it was 5 years ago. 

In honor of the Loma Prieta Anniversary week, we wanted to remember a post from October of 2013 when a crucial seismic project for the Water System Improvement Program achieved a huge milestone. Final hole through. 

Miners worked long hours in the New Irvington Tunnel .

The New Irvington Tunnel Project ,which went into service in February 2015, is a new 3.5 mile long seismically designed tunnel. We mined the tunnel from different directions, and the moment the two teams met underground to complete the digging is called Final Hole Through.

See the October 2013 Story here.

One of the three road headers that excavated the New Irvington Tunnel.

Have a great weekend, everyone.

See you around the Valley!

Calaveras Dam Embankment Celebration- Photo Friday

The replacement Calaveras Dam has reached its full height of 220 feet.

The month of September marked a huge milestone for the Calaveras Dam Replacement Project.  The new replacement earth and rock fill dam has finally reached its full height and is nearly ready to begin impounding water this winter. 

You might have read about it or seen it on the news.  We had many media outlets out at the dam on September, 21, 2018 to cover the occasion.  

Here are some photo highlights in honor of Photo Friday.

San Francisco Public Utilities Commission Vice President Vince Courtney addressing the crowd.

Sharon Tapia, DSOD, Division Chief addressing the crowd.  DSOD or California's Division of Safety of Dams regulate dams in California.  They were a key partner in the construction of Calaveras Dam. 

General Manager Harlan L. Kelly, Jr., was joined by SFPUC Commissioners, SFPUC Deputy General Managers, and representatives from the Bay Area Water Supply and Conservation Agency to make it official with a ribbon cutting. 

Here is the entire Calaveras Dam Replacement Project Team atop the new dam.








The project isn't completed, however. The crew will work on completing the approach channel, constructing access and roadways throughout the site, restoration and revegetation, placing instruments, and installing gates and security systems. 

The overall project is 94% complete and is scheduled to be completed in spring 2019.

See you around the valley!

Calaveras Road Closure Extended through November 2, 2018

The Closure of Calaveras Road to through traffic between Milpitas and Sunol has been extended from September 30, 2018 to Friday, November 2, 2018.

The road will reopen to all traffic, weekdays, weekends, and holidays starting Saturday, November 3, 2018.

Why:

The SFPUC has been working with the appropriate county agencies to secure final approval for renewed public access to the road after a portion of the road was built by the SFPUC to replace a portion undermined by a landslide.

Background:

We have been working since 2011 to replace the 93 year-old Calaveras Dam to increase the reliability of the Hetch Hetchy Regional Water System, which serves 2.7 million people in four Bay Area counties.

The closure of Calaveras Road began in July 2016 to protect public safety on the extremely narrow portions of Calaveras Road while large trucks utilized the road for construction.  

Road Closure Details:

Where: Calaveras Road just south of Geary Road (entrance to Sunol Regional Wilderness) to Oakridge Road near the Alameda /Santa Clara County line.

When: July, 2016 through November 2, 2018. The Road will be open on weekdays, weekends, and holidays starting Saturday, November 3, 2018.

For more information, visit sfwater.org/calaverasroad

Thank you for your continued patience. We apologize for the inconvenience.

The Rainbow Trout Count

It is that time again. Time for the Trout Count. Biologists with the San Francisco Public Utilities Commission have been working to estimate the total number of adult rainbow trout living in Calaveras Reservoir.



Sunol biologist Randy Renn trolling for fish on the reservoir.

Rainbow trout (Oncorhynchus mykiss) are a cold water species native to the rivers and lakes of North America. Like all native fishes, it’s important to preserve them and our ecological systems. Monitoring fish populations is an important part of protecting trout in Calaveras Reservoir.



Here is a good specimen from Calaveras Reservoir.

How do the biologists estimate the rainbow trout population size?

They use a technique known as mark and recapture. During spring, when adult rainbow trout migrate from the reservoir upstream to Arroyo Hondo to spawn, the biologists capture and mark as they can. During summer, after the adult fish move back down into the reservoir, the biologists fish for them and check for tags. Knowing how many trout were originally tagged in Arroyo Hondo, they can use the ratio of tagged to untagged fish caught in the reservoir to estimate the total number that are there.

Pictured here is Scott Chenu SFPUC Sunol biologist, with one of his catches.

Our dedicated biologists will continue track the fish through the end of September. After Calaveras Reservoir is refilled, they will check the population size again to see if there is a difference. 

Periodically tracking the rainbow trout population size is also important because it helps our biologists determine whether they are healthy and thriving or being negatively impacted by reservoir operations.

See you around the valley!

Photo Friday from Sunol Long Term Improvements

Happy Photo Friday!

The team working on our Sunol Long Term Improvements Project has been tasked with constructing a new corporation yard and offices to house SFPUC Water Supply and Treatment and Natural Resources staff near Sunol. These new facilities replace the old corporation yard and buildings, which were aging and in need of upgrading.  The teams housed here operate the East Bay water system as well as monitor the rights of way and 35,000 acres of SFPUC-owned watershed lands.

We dedicate this photo Friday to the tremendous progress the team has made this year.



Here is a view of the new administration building.

Workers are installing a new bioswale to catch and absorb water run off at the site.

And, here is a very modern looking canopy for equipment to be installed outside of the shop.

The Sunol Long Term Improvement Project is 75% complete. The project is expected to be completed by the end of 2018. 

During construction, the Sunol Water Temple will remain closed to the general public.

We hope you have a great Labor Day weekend! See you around the Valley!

Thank you, Jordan Erickson

Meet Jordan Erickson. He is a native of Maple Grove, Minnesota and was with us this summer as a student intern. Jordan is currently studying civil engineering at Iowa State University. During the summer. He was an integral part of the Sunol Yard Long Term Improvement Project team. Last week was his last week on the job.



He said that working as an intern for the SFPUC gave him a better perspective on the type of work he'll be doing in the future. One the most valuable things that it taught him was the importance of communication between the contractor and the owner.

When he is not busy working, Jordan enjoys playing sports and hanging out with his friends. We wish Jordan another successful year at Iowa State University.

Jordan is one of dozens of summer interns we at the SFPUC are delighted to host each summer. They are all fantastic, like Jordan. It is extremely important to help support the growth of future leaders in our industry.

The entire staff at the Sunol Yard Long Term Improvement Project would like to thank Jordan for all of his hard work.

See you around the Valley!