Wednesday, December 26, 2012

Calaveras Critters on the Move!

If the television show Unlikely Animal Friends were to film an episode at the Calaveras Dam Replacement Project, they would have no trouble identifying symbiotic animal relationships all over the Southern Alameda Creek Watershed. Our personal favorites are ground squirrels and the threatened California Tiger Salamander.

Tiger Salamanders live underground in the burrows of other animals, quite often the burrows of ground squirrels. When the rains come to the watershed, the California Tiger Salamanders leave their burrows and make a beeline for a nearby pond where they can meet a mate and lay eggs. 

Problem is, there is a large dam construction project in the way. Our biologists placed tubs at strategic locations around the site. As they walk the perimeter of the project on a daily basis, they take the captured salamanders and relocate them to pre-designated places offsite. 

They often make sure to stick the Tiger Salamanders into ground squirrel burrows that are stable.  The ground squirrels do not seem to mind their amphibious neighbors, and provide the added benefit of digging out the tunnel should it collapse. Otherwise the salamanders would be trapped by cave-ins and might perish. Who knew?
Photo courtesy of Pete Trenum, Elkhorn Slough


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

Tuesday, December 11, 2012

Calaveras Dam hosts Delegation from one of the Largest Dams in the World

On November 30th, the Calaveras Dam Replacement Project team was honored to host a high level delegation from the Three Gorges Corporation from China.  Along with representatives from the United States Geological Survey (USGS), seven members of the Three Gorges Corporation visited the Calaveras Dam Replacement Project for a site tour.

The Three Gorges Dam and Calaveras Dam – both the existing and the new on under construction – are very different. Three Gorges is a concrete dam that is one of the biggest hydropower-complex projects in the world. Located on the Yangtze River in China, the Three Gorges complex sits on granite bedrock, which provides favorable topographical and geological conditions for dam construction.  Three Gorges Dam stands 594 feet tall, 7,661 feet wide, and has the capacity to hold 31,900,000 acre feet of water or over 10 trillion gallons of water. 

Calaveras Dam, both existing and the new one, on the other hand, are earth and rock fill. When constructed in 1925, Calaveras Dam was the largest earth and rock fill dam in the world. The foundation of both dams is a unique geologic mixture of Franciscan mélange and Temblor Sandstone.  In comparison, the replacement Calaveras Dam will be 220 feet high, 1,210 feet wide, and will hold 96,850 acre feet or 31 billion gallons of water. 

Despite the differences in the dams, the two teams found a great deal in common to discuss. The teams shared their respective knowledge about seismic reliability, fishery passage improvements, and overall dam safety. Calaveras Dam was one of many stops in the United States for the delegation. We wish them well on the rest of their journey.

Three Gorges Corporation Executive Vice President Mr. Fan Qixiang
and San Francisco Public Utilities Commission Regional Project Manager Dan Wade

The Three Gorges Corporation Delegation, members of USGS,
and the Calaveras Dam Replacement Team at the crest of the dam

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

Monday, December 10, 2012

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) 5759037 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 

Friday, December 7, 2012

Filling the Void

Last week, crews digging the New Irvington Tunnel excavated an astounding 92 feet in just 3 days. This feat was all the more surprising given that the tunnel was passing through a fault zone where miners excavating the original Irvington Tunnel encountered an enormous amount of groundwater pouring into the tunnel. So much so that it was dangerous for the workers. What was different this time around? Grout.


Crews knew they had entered this zone when they probed 100 feet ahead of their tunnel face and found large amounts of groundwater. Before crews could do any mining forward, they had to inject 66,000 pounds of grout (think liquid cement) into the rock ahead of them to fill cracks and voids in the earth. That’s enough to fill up the water tank pictured below! Grouting fills these voids and keeps groundwater out of the tunnel. It keeps our miners safe and allows tunneling to continue.


Grout is taken by rail to tunnel heading and mixed inside of the tunnel. In November alone, approximately 423,000 lbs. of cement was injected into rock fractures, filling cracks ranging up to 1.5 inches in width.

As of December 4, 2012, over 13,100 feet has been mined. With 5,500 feet to go we expect tunnel expect tunnel excavation to be complete by mid-2014. For those that remember our Road Header Rendezvous Challenge we’ll have another one next year to celebrate NIT’s final hole-through!

Thursday, December 6, 2012

Successful Team Work Sees Sunol Plant through Technical Conversion


Recently, the project team at Sunol Valley Water Treatment Plant successfully completed one of the most technically challenging shutdowns of the Water System Improvement Program (WSIP). In order to upgrade the technical monitoring and control systems for the treatment plant, the entire operating system, that monitors and controls the water flow as it relates to plant operations, was taken off line for two-weeks. This shutdown meant that operators at one of the two treatment plants in our regional system were without the ability to monitor the instruments and processes throughout the plant to treat water as usual. This shutdown also required the team to thoroughly inspect all the critical elements of the plant’s treatment process to ensure they could run manually without the controls system to deliver water to customers, if necessary.

 
One of the unique aspects of WSIP construction is that all projects must be completed without any water service interruption to our 2.6 million customers. More than 120 system shutdowns must be performed to accommodate WSIP construction. 

Since the original treatment plant was constructed in 1964, many of the instrumentation and control systems had reached their maximum data capacity. As new facilities are being constructed and others upgraded, there was no room to incorporate new communication and control signals from the new facilities into the existing controls system. To remedy this overload, the existing data on Programmable Logic Controllers (PLCs) were “split” into separate PLCs to create the needed space and capacity. PLCs are like mini industrial computers that help the operators run the treatment plant. During this “split”, new programming codes for this data were loaded and tested.  

Crews worked overtime to ensure the pipe work was completed on time, so it did not delay the treatment plant system coming back on line. In fact, the team successfully completed this shutdown in 12 days, two days ahead of the scheduled 14-day shutdown. This critical shutdown required a detailed System Outage Request (SOR) plan prior to the shutdown identifying contingency options, man-power requirements, material requirements, and detailed work activity schedules to help ensure this critical shutdown was completed without impacts to the water system.   

Simultaneous with this technical shutdown, the contractor had to complete several large diameter pipe tie-ins at the plant (shown above). 

“Completing this technical work in a tight time frame was not an easy feat, but the team was up for the challenge,” said Paul Gambon, System Operations Manager of the Water Supply and Treatment Division. “The complex nature of this shutdown required close coordination, extensive planning beforehand and excellent communication among numerous project team members and the operations staff,” Gambon explained.

Team members from the following groups were involved with the coordination of this shutdown and contributed to its success: Construction Management team; Shutdown Coordination team; Water Supply and Treatment Division; Water Quality Division; SVWTP Operations team; City SCADA group; City IT/Communications group; Shimmick Construction Company Inc. and Transdyn Incorporated.


As of November 2012, the overall Sunol Valley Water Treatment Plant Expansion and Treated Water Reservoir project is 90 percent complete. The project is expected to be complete by June 2013.

Wednesday, December 5, 2012

Reminder: NIT Project Open House Tomorrow


REMINDER

Please Join Us for Coffee at the
New Irvington Tunnel
Project Open House

Thursday December 6, 2012
4:00 PM to 6:00 PM

Mission Coffee
151 Washington Blvd
Fremont, CA

Please stop by and check in on the progress of the new tunnel.  Our project team is available to answer your questions and listen to your comments.  

Project Update
Over 13,100 feet (out of 18,660) has been tunneled to date.  Workers completed the installation of 102-inch diameter steel pipe at the Irvington Portal that will eventually carry drinking water from the Hetch Hetchy system to 2.6 million Bay Area customers. 

Installation of the waterline connection to the new tunnel at Irvington Portal near Mission Boulevard continues.  We expect the connection fully installed by January 11, 2013.

The New Year will also begin the countdown to the completion of tunneling.  Excavation is scheduled for completion mid-2013.  The steel pipe liner will go into the last sections of the tunnel by the Fall of 2013.

We look forward to seeing you at the open house!
Please call 866-973-1476 or email fzamora@sfwater.org for
more information. You can also visit www.sfwater.org/nit or
www.sfwater.org/sunolvalley for project updates.