Ready for the Rain

The rainy season is here! While we welcome the rain we also have to prepare for it.  Why? If left unchecked, rain water will travel through constructions sites (that uncover large amounts of dirt for their work) and pickup dirt and small rocks and anything else that is on the ground surface along the way.  The runoff then goes into storm drains and flows into the local water system causing harm to the Bay.

At the New Irvington Tunnel Project, the San Francisco Public Utilities Commission uses a series of Best Management Practices (BMPs) to minimize the effects of storm water runoff.  Our prevention methods include:

Erosion Control: Planting vegetation is an effective way to stabilize the soil by reducing exposure to erosion.  Stabilization prevents soil particles from detaching and becoming transported in storm water runoff. 

 Erosion control measures in place at the Vargas Shaft

Earth Dikes & Drainage Swales:  Earth dikes are temporary berms of compacted soil and drainage swales with shallow slopped channels. These easily installed measures divert storm water runoff away from soil that is prone to erosion and into controlled areas.

This drainage swale channels storm water away from erosion sensitive areas

Sediment Basins: Control areas such as gravel basins trap and collect sediment from storm water runoff before it enters our local water systems.

A gravel basin at the Irvington Portal

The SFPUC and our contractor, Southland Tutor Perini Joint Venture, work together to make sure stormwater runoff does not make its way into the local water system.  As a team we keep a constant eye to ensure the appropriate measures are in place and are effective. 

New Irvington Tunnel Project Open House

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 12,593 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.

We are Building a “Mini-Dam”...for the California Tiger Salamanders!

Prior to and during construction, the Calaveras Dam Replacement Project implements measures to avoid and minimize impacts to wildlife located in the Alameda Creek Watershed. 

Our Environmental team has taken proactive steps to protect and relocate the California tiger salamander (Ambystoma californiense) species since the start of the project.  The California tiger salamander (CTS) is an amphibian native to Northern California growing up to 8 inches long.  CTS have started to migrate at night from upland habitats to aquatic breeding sites, especially during the first major rainfall events of fall and early winter.

 California tiger salamander (Ambystoma californiense)

Wildlife exclusion fencing is strategically located along the boundaries of the construction work limits to deter wildlife from entering.  Also, water moistened buckets are placed in trenches between silt fences to catch the critters, which are later relocated to nearby ponds.

Just this week our approved biologist monitored berm repairs performed on a relocation pond for CTS.  The berm serves as a barrier which is positioned on the top of the pond, to reduce turbidity and maintain suitable conditions in the pond.  Permission was given by the California Department of Fish and Game to relocate 50 CTS to this location. 

As of today, 78 California tiger salamanders have been trapped and relocated to safer habitats away from project construction. With the repaired pond, we will be able to provide them a suitable and safe environment for breeding.

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

Repair work on Pond for California tiger salamander

Repair work on Pond for California tiger salamander

Photo of pond after work completed

Then & Now: Tunnel Lining

The existing Irvington Tunnel was built in the early 20th century and can no longer be taken out of service for repairs or maintenance without impacting the water supply to customers. The last time the old tunnel was inspected for maintenance was in 1966. Completion of the New Irvington Tunnel will allow us take the existing tunnel out of service for much needed maintenance. The new tunnel is designed to provide a seismically-strengthened or reinforced connection between water supplies from the Alameda Watershed to Bay Area customers

Here’s a quick look at tunnel construction then and now:

Then: In 1933, the existing Irvington Tunnel was lined with cast-in-place concrete. The average cost of house was $5,750, IT’S-IT Ice Cream was gaining popularity at San Francisco’s Playland-at-the-Beach, and baseball by the Bay was played at Seals Stadium. 

Now:  The New Tunnel will be lined with a total 18,660 feet of welded steel pipe..  After the pipe is installed, the pipe will be lined with cement mortar finish to protect the steel pipe from rusting, so the tunnel will serve drinking water for future generations.

At 102-inches (8.5 feet) in diameter, the pipes are the final liner of the new tunnel, through which the pristine drinking water from the Hetch Hetchy Reservoir and our East Bay Watershed will flow to the San Francisco Bay Area.

Just in case you’re curious about how things compare in 2012:  The average price of a home is $295,300, Playland-at-the-Beach is gone but IT’S-IT is found at your local grocer, and the World Series Champion San Francisco Giants play at AT&T Park! 

Check out the previous entries in NIT’s Then & Now series:

Then &Now: Mining Methods

Then & Now: Alameda West Portal

Calaveras Road: Increased Truck Traffic 11/13 thru 11/16

The Calaveras Dam Replacement Project will be expecting heavy truck traffic from November 13th through November 16th on Calaveras Road just south of Interstate 680 to the project site approximately 4 miles past Geary Road.  Dates subject to change dependent on weather conditions.

• Calaveras Road remains open to the public
• Haul trucks are expected from 7:00 a.m. to 5:00 p.m.
• Please drive safely on the narrow portions of Calaveras Road and please share the road
• Speed limit is 25 mph in construction zones

For more information:

24 hour-Answer Line 866-973-1476

Email us:

mle@sfwater.org or blauppe@sfwater.org

Follow us online at: www.sfwater.org/sunolvalley

Celebrating Sunol Valley History

This past weekend, the East Bay Regional Park District’s Sunol Pioneer Folk Festival hosted music, square dancing, horse rides, vintage arts and crafts, and us!

SFPUC staff really enjoyed sharing historic photos of the water system in the valley with attendees, many of whom already knew a great deal about our current efforts to upgrade this system for future generations.

We also tested attendees’ knowledge of local water system history. Here is a sampling of questions to your own knowledge!

1. In 1898, Spring Valley Water Company, the predecessor of the SFPUC, began drilling wells under what nearby East Bay Valley?

Answer: Livermore Valley. 100 wells, the first of which was drilled in 1898, drew water that was transmitted to Sunol via a pipe installed in 1909. The SFPUC stopped using the well field in 1949 to replenish the groundwater basin for the overlaying landowners. The water is still used by the City of Pleasanton and Zone 7.

2. We are busy constructing a replacement dam to the existing Calaveras Dam as we speak. True or False: the replacement dam is the THIRD dam to be constructed in this location.

Answer: True. The original dam, started in 1913, was constructed using a technology that had never been used on this sized dam before. The dam collapsed while the reservoir was being refilled in 1918. Spring Valley Water Company had to rebuild it using a different method. They left portions of the original foundation in the dam, however, which is why we have to rebuild it completely.

3. The existing Irvington Tunnel began construction 1928 and now provides water to 2.6 million Bay Area residents.  What yummy Bay Area tradition also began in 1928? 

Answer:  IT’S-IT ice cream treats.  Created by George Whitney it was sold exclusively at San Francisco’s Playland-at-the-Beach for over four decades!  So when the miners at the existing Irvington Tunnel needed a day at the beach they probably had an IT’S-IT.

Attendees check out historic artifacts excavated at the
Calaveras Dam Replacement Project this past year

Historic Photo of the Sunol Valley Pump Station located on Calaveras Road

November 3, 1966. Seismic retrofits of the pump station were recently completed.

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

 

What’s Underground?

Have you ever wondered what’s underground? Throughout construction of the New Irvington Tunnel (NIT) project, we’ve had the rare opportunity to encounter some of the most fascinating and diverse geological features in the world. From faults capable of generating huge earthquakes to ancient rock formations dating back to before man first walked the Earth, the unique geographic setting of the new tunnel leaves plenty to be discovered.

The Bay Area’s San Andreas Fault system featuring the Hayward Fault (middle to bottom right) and Calaveras Fault (bottom right)

The new tunnel is located in a seismically active part of California between the Calaveras and Hayward faults. Between these two major faults are several small faults that cross the path of the tunnel. These faults consist of very short sections of intensely fractured sandstone and fault gouge (fault rock rich in clay, characterized by a mixture of fine grain-like rock fragments). Due to their incohesive nature, these formations are extremely weak, a stark contrast to other materials encountered while digging through this section.

A sample cross section view of the new tunnel alignment. The red markings indicate fault zones that intersect the tunnel.

Briones formation contains fossilized shell fragments (circled in yellow)

During excavation, a majority of the ground encountered is part of the Briones Formation, which includes massive sandstone characterized by coarse, grain-like quartz sandstone and shell fragments. These rocks are extremely old, dating back to the Late Miocene Epoch nearly 12 million years ago! These rocks aren't just old, but they are so strong that drill and blast methods were utilized to mine through the tough ground.

This is only a glimpse of the geology hidden beneath Sunol Valley. So the next time you look down and ask, “What’s underground?”, keep in mind that that there are ancient rocks, ever-shifting faults, and whole lot more going on just underneath your feet.