We are Stronger and Safer Together – National Safety Week

This week is National Safety Week. Which means construction contractors across the country emphasize one of the most important factors of the job -- SAFETY. Right here in Sunol Valley, we have over 150 workers working on projects such as building the replacement Calaveras Dam.

At the Calaveras Dam Replacement Project, crews have worked over 140,000 safe working hours since the beginning of the year, without any recordable safety incidents.  A recordable safety incident is when a worker requires medical treatment beyond first aid and there is a loss time on the job. Our last recordable incident was in October 2014. This is well below the industry average.

Why is this record special? Because our construction crews at the Calaveras Dam Replacement Project work multiple shifts – both day and night – working with huge machinery, excavating earth and rock, on a very complicated job site in challenging conditions. As we continue work to complete the project, we applaud the joint venture of Dragados USA, Flatiron Construction, and Sukut Construction for making safety a priority here at Calaveras Dam during National Safety Week.

Check out our time lapse capturing excavation work since the beginning of the project:

Before sunrise, the Calaveras Dam crews get together for their daily morning safety tailgate 

A New Bridge for the New Year

We at the Calaveras Dam Replacement Project have been talking a lot about the new spillway under construction at the dam. And why not? It is as wide as a six lane freeway, with walls that are 40 feet tall, and it is 1500 feet long. We placed over 50,000 cubic yards of concrete into the structure to date, and it has been the major focus of activity at the dam for over a year.  Spillways allow dams to safely discharge water without overtopping. This is a key safety feature of any dam, particularly Calaveras Dam as it is an earth and rock fill dam.

Last week we sent out a traffic notice for users of Calaveras Road to be aware that three large trucks would be making a very special delivery for our favorite spillway – its bridge. So special that it had to be trucked in six sections all the way from Ohio.

The spillway bridge will allow future personnel to drive across the top of the spillway safely and access the top of the new dam and outlet works at the toe of the dam. Crews used special cranes to begin installation of the bridge this week. We will be completely done with the spillway this spring.

 

Photos courtesy of Lead QA Inspector Glen Gorski and QC Engineer Shary Truong

Calaveras Dam Welcomes the US Society on Dams Conference

It is fitting that the SFPUC helped host the annual meeting of the United States Society on Dams (USSD) this last week in the same month as the anniversary of the 1906 Great Earthquake and Fire. The group finished their week of technical sessions and presentations on dam safety in extreme events with a field tour of a dam in construction.

That would be our very own Calaveras Dam Replacement Project. The project will construct a new seismically designed earth and rock fill dam right next to the existing, which will be able to withstand the maximum credible earthquake on the Calaveras fault.

The USSD Conference attendees peppered the Calaveras Dam Replacement Project Team with questions.  We appreciate that the SFPUC project team members, the Construction Management team from Black & Veatch, Design team from URS, and the contractor Dragados USA/Flatiron/Sukut Construction shared their experiences with their industry colleagues. 

Then the Calaveras Team returned to the current work at hand, which is continuing the major excavation work on the new spillway and stilling basin, as well as mechanical and electrical improvements to the new intake Tower.

When complete in late 2018, the replacement dam will enable us to bring the Calaveras Reservoir back to historic capacity, storing approximately half of the Hetch Hetchy Regional Water System’s local Bay area water supply.

This somber anniversary for the 1906 Great Earthquake reminds us to ensure our families are prepared for the next big earthquake. Visit 72hours.org, or http://www.redcross.org/ca/san-francisco/ to learn more. 

 SFPUC Project Manager Susan Hou discusses the critical upgrades to the Hetch Hetchy Regional Water System

Project Manager Alberto Benlloch from the joint venture of Dragados USA/Flatiron/Sukut Construction points out to the tour the excavation work to-date of over 4 million cubic yards of material

Aerial view taken on March 23, 2014

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!

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

Fascinating Fossil Finds at Calaveras Dam

Every day, our scrapers dig soils and earthen materials to make room to build the replacement Calaveras Dam.  We have special staff who monitor high sensitivity areas during construction searching for paleontological and cultural resources, which are protected by federal and state laws.  Construction crews also attend environmental training about the identification and protection of paleontological and cultural resources. Calaveras Dam project teams have discovered fascinating finds within our construction site. 

What are Paleontological Resources?

Paleontological resources include: remains of prehistoric/extinct plants and animals, petrified wood, fossil leaves, fossil remains of vertebrate and invertebrate organisms, fossil tracks and track ways, and plant fossils, typically of Pleistocene Epoch (> 12,000 years ago) or greater age. 

What have we found?

Fossilized plants such as wood, leaves, and a pine cone have been salvaged from the site.  Invertebrates uncovered include: scallops, clams, snails, barnacles and worms.  We have also found shark teeth that are still being analyzed but may be related to a great white shark although much larger (Think “Jaws” and then some).

Our most fascinating finds are linked to prehistoric marine mammal(s).  This includes an intact portion of a backbone of a whale.  These finds are still being analyzed by experts.

Why?

Most of the fossils have been found in the 20 million year old marine sandstone called the Temblor Formation.  The Sunol Valley area was below sea level in the Pacific Ocean about 20 million years ago and has since been uplifted along with the rest of the Coast Ranges. Life along the old coast was similar to today, with abundant clams, mussels, sea worms and other invertebrate organisms living in the sand. But the fossils also document significant differences from today’s relatives and provide important information about the details of evolution and environments of the plants and animals represented by the fossils.  We continue to work to preserve and protect these neat findings every day.

Fossils & Shark Teeth discovered at the Calaveras Dam Replacement Project Site

Seashells and Secant Piles

A recent trip to the Sunol Valley by SFPUC photographer Katherine DuTiel produced a photo that, by striking coincidence, looks remarkably like one taken on the Bay Division Pipeline Project on the Peninsula.

Look closely to see which is which!





Shown here is the receiving shaft of the Bay Division Pipeline micro tunnel section on the Peninsula. The project was forced to tunnel under a culturally and environmentally sensitive area at the end of this 9 mile pipeline. The secant wall in the shaft consists of a series of drilled piers filled with concrete. They are arranged concentrically to provide a continuous concrete wall that supports the shaft.



The Sunol Valley area was covered by the Pacific Ocean about 20 million years ago. Life along the old coast was similar to today, with abundant clams, mussels, sea worms and other invertebrate organisms living in the sand. The sandstone formation that represents the old ocean deposits is called the Temblor sandstone, and contains fossils from this old coastline. The photograph shown above is a fossil scallop collected by geologists at the Calaveras Dam Replacement Project.

What do Dams and Space Shuttles have in common?

The Calaveras Dam Replacement Project work site is a busy place on an average day. Machines both large and small are in constant motion, moving soils and materials from one side of the site to dispose of them on the other.

However, this Wednesday around lunchtime was different.  Work paused, for a short time, to celebrate the team’s achievement of another milestone. The team has moved a total of 2 million cubic yards of rock and soils since the project began in August 2011.  As the team enjoyed its well-earned pizza lunch to celebrate, we wondered how much dirt they’d just managed to move.

2 million cubic yards of dirt weighs as much as 1,656 space shuttles. It weighs as much as 1,175 Saturn V Rockets and weighs as much as 18,225 Boeing 747’s.

Here’s another question: Why? Building a dam is similar to painting a house, in that the majority of the work goes into the preparation. The team needs to remove all the loose materials on both sides of the valley and the valley floor so the new dam will be built upon a solid base.  The Calaveras Dam Replacement Project will have to move more than 9 million cubic yards of soils and rock during construction. 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.

Two down, only seven million more cubic yards to go! And the crew is geared up, full of pizza, and ready to get going. 

Our Calaveras Dam work crews take a few moments to celebrate the important milestone of excavating
over 2 Million Cubic Yards of materials

As seen almost daily, a scraper moves soil and rock materials excavated at the project site

For more project info, please email mle@sfwater.org or call our 24 hour answer line at 866-973-1476

Calaveras Dam Replacement Project - Winter Update

Project Update

In mid- June of 2012, during excavation of the large hill known as “Observation Hill” on the left side of the valley (if you are looking downstream, standing with your back to the reservoir), the Contractor encountered unexpected geologic conditions that could contribute to the instability of the left abutment and spillway area as designed.  These features were not visible at the ground surface, and were not apparent during the extensive pre-construction geotechnical investigations. Therefore, the excavation cut slope in “Observation Hill” has been re-designed to “lay back” the slope to a flatter slope in order to produce a final slope that will be stable during construction and over the entire life of the new dam.

What this Means

1)    Additional Materials to Move - Approximately 3 million cubic yards of additional material that was not originally anticipated now needs to be excavated and moved to disposal sites around the reservoir. We are working with the environmental regulatory agencies to secure disposal sites for these materials within the designated construction areas. No additional materials will be hauled off site on public roads.

2)    Extended Construction Schedule - Because of the additional time needed to excavate these additional materials, we anticipate a 25 month delay in the project, which would put the completion of construction activities at the end of 2017.

3)    Impact to Project Cost, not to WSIP Overall Cost – Based on preliminary projections, the cost of the project will increase by approximately $133 million. These additional costs are offset by savings recorded on other projects and favorable bond financing so the overall Water System Improvement Program (WSIP) is still forecasted to be completed within the currently approved budget of $4.6 billion.

4)    Calaveras Road Shutdown Delayed - The second scheduled closure of Calaveras Road will be postponed until 2014, at the earliest. The duration of the closure remains 18 months, Monday through Friday only, but the specific dates will be determined when the contractor completes re-sequencing of the construction schedule.  We will notify you in advance of the closure period.  Join our road closure notification mailing list by emailing: mle@sfwater.org or calling our 24 hour answer hotline at (866) 973-1476.

Environmental Review

We are currently working with the regulatory agencies to amend the permits for these changes. The San Francisco Planning Department will distribute an Addendum to the Final Environmental Impact Report in mid-December 2012. To obtain a copy of the Addendum, please visit www.sf-planning.org, or contact: Chris Kern, San Francisco Planning Department at (415) 575‐9037 or email at chris.kern@sfgov.org.

Project Background

The San Francisco Public Utilities Commission, owner and operator of the Hetch Hetchy Regional Water System, is building a new dam to replace the existing Calaveras Dam in the Sunol Valley. Calaveras Reservoir, impounded by the Calaveras Dam, is our system’s largest drinking water reservoir in the local Bay Area. When full it provides more than half of our Bay Area storage capacity for 2.6 million customers. The existing earth fill dam is 87 years old and is located within 1,500 feet of the Calaveras earthquake fault. In 2001 we lowered water levels in the reservoir to less than 40 percent of normal operating capacity in response to seismic concerns.   The Calaveras Dam Replacement Project is the largest project of the $4.6 billion Water System Improvement Program (WSIP) to repair, replace, and seismically upgrade key components of the Hetch Hetchy Regional Water System.

Work Completed to date

Construction began in August 2011 to build a new earth and rock fill dam adjacent to the existing dam. Since then, the Contractor has moved nearly two million cubic yards of earth and rock materials to make room for the new dam. Crews have prepared disposal sites, constructed a soldier pile tie-back wall to stabilize a landslide in the right abutment (the right side of the valley as you face downstream from the dam, away from the reservoir), and began injecting cement grout deep into the joints in the rock of the dam’s foundation. The team has excavated to the new dam’s foundation and has started to build the new dam. In addition, we have begun construction of connecting outlets from the reservoir, and successfully completed the first 2-month closure of Calaveras Road in spring 2012.  However, there is still a great deal of work that lies ahead, with the project only 26% percent complete as of November 2012.

For more project info, contact us at our 24 hour answer line at (866) 973-1476 or email mle@sfwater.org 

We are Building the Dam!

We are rocking out here at Calaveras Dam.  Not so much to the sound of music but to the sweet sound of haul trucks loading and dumping rock fill.  This week marks a big step towards building the new replacement dam. We dug down to the dam foundation back in August 2012 and we are now officially filling in rock material in the foundation for the new replacement dam. The fill material consists of rocks 30 inches in diameter, being moved at approximately 4,500 yards per day. Our bull dozers are equipped with GPS (global positioning system) units which detects the proper thickness levels as the materials are placed.  The first phase of fill material will be completed at approximately 100 feet.

Haul truck places fill material into the Dam Foundation

Bulldozer uses GPS technology to level rock material for the replacement dam

Rendering of New Replacement Dam with first phase of rock fill being placed

(Not to scale)

For more project info, contact us at our 24 hour answer line at (866) 973-1476 or email mle@sfwater.org

Calaveras Dam Replacement Project Team Reaches Milestone

The Calaveras Dam Replacement Team has been working hard since early April, scraping away at existing earthen materials to excavate for the dam foundation.  This week, the team has reached 1 million cubic yards of materials excavated, which would cover an entire football field 60 stories high.  A total of 7 million cubic yards of excavation is required for the entire project.  Approximately 3.5 million cubic yards will go into the construction of the new dam.

Our team has been operating scrapers daily, excavating approximately 20,000 cubic yards per day.  The scrapers operate with hydraulics using a blade which then scrapes materials into a drop can, carrying an average of 28 cubic yards per trip.  These materials are then moved to disposal areas within the project site. 

The Calaveras Dam Replacement Project Team Celebrates the first

Million Cubic Yards of Earth Moved on July 13th

Construction Manager Jordan Sukut representing the general contractor Dragados USA/Flatiron/Sukut Construction congratulates the field team on the milestone

For more project info, contact us at our 24 hour answer line at (866) 973-1476 or email mle@sfwater.org

Scraper, scraper, scraper.

The Calaveras Dam Replacement Team has been working hard since April, scraping away at existing earthen materials to excavate for the dam foundation. We have now reached the highest point of the dam foundation for the future replacement dam. This point is located in the right abutment, an area located to the right when looking downstream from the dam. By July 2012, we anticipate to move close to 1 million cubic yards of materials. Our scrapers are excavating approximately 20,000 cubic yards per day. The scrapers operate with hydraulics using a blade which then scrapes materials into a drop can, carrying up to 30 cubic yards per trip. These materials are then moved to a disposal area within the project site. The scrapers are about 11 feet tall and the project is operating 12 scrapers for the excavation work.

For more project info, contact us at our 24 hour answer line at (866) 973-1476 or email mle@sfwater.org

View of Right Abutment Area

Scraper working in Right Abutment Photo courtesy of Robin Scheswohl