Monday, February 27, 2012

Lasers: Inline and On-Target


“Record Day of Tunneling: DS- Laser Road Header Blasts through Miles of Rock!”

This is what a headline could say in the year 2082 during the construction of the New New Irvington Tunnel. Today, lasers serve a much different but very important purpose of keeping tunnel excavation inline and on-target.


The alignment of the New Irvington Tunnel stretches 3.5 miles from the Sunol Valley to Fremont. At depths of up to 700 feet below ground surface, crews are working in four headings to excavate the new tunnel. With miners deep underground tunneling in four different directions, how do they make sure the tunnels line up? How do they keep from tunneling into Livermore or Union City? The answer: Lasers.


Inside of each tunnel heading laser beams cut through low light conditions and provide alignment control. The lasers are mounted on the left and right side of the tunnel near the tunnel entry and project their beams on the rock face that is being excavated. Crews operating the road headers keep the machine between these beams to stay on target. Surveyors are brought in between each tunnel set (typically four feet of tunneling) to verify that the alignment of the tunnel is accurate.

Laser Road Headers and Lightsabres may never become more than the wishful thinking of science fiction enthusiasts. But for miners and the 2.5 million people that depend on a safe and secure Hetchy Hetchy Water System lasers keep the New Irvington Tunnel on-target!

Wednesday, February 22, 2012

Then and Now

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 New Irvington 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:

Wednesday, February 15, 2012

Miracle Mile


Miracle Mile is a slight exaggeration but the New Irvington Tunnel Project surpassed the one mile mark last week with help of two record setting days of tunneling. Miners typically average 22.5 feet of excavation per day but ideal ground conditions allowed crews to tunnel a daily project record of 70 feet. Two days later miners set a new record and grinded out 83 feet on their way past this significant mile-stone!.

The new 18,600-foot (3.5 miles) tunnel is currently being excavated from three headings using road headers (tracked tunneling machines) and controlled detonations when necessary. Tunneling is estimated for completion in late-2013 with project completion in late-2014.

Check out www.sfwater.org/nit for weekly updates of tunnel progress.

Monday, February 6, 2012

Groundwater Monitoring Program Update

The New Irvington Tunnel project team is currently monitoring some local groundwater decline. So far, four properties south of the Sheridan Valley project area have been affected. It appears that these declines are related to tunnel construction and dewatering activities. We have initiated mitigation measures at each property and we are maintaining their water supply.

Our commitment to protecting the groundwater in Sheridan Valley has not changed. If tunnel construction causes a decline in groundwater levels that affect an individual’s property, we will initiate the contingency measures defined in each site-specific Groundwater Management Plan. The project team continues to keep a close eye on groundwater levels and will take appropriate actions to maintain water supply.

If you notice any change in your water system, please contact the SFPUC’s 24-hour Answer Line (866.973.1476). Contacting the answer line will ensure the appropriate team members respond to you in a timely manner.

Should you have any questions or concerns, we will host question and answer coffee sessions next week:

Thursday February 9
4:00 PM to 6:00 PM
Sunol Jazz Café
11986 Main Street
Sunol, CA

Friday February 10
7:00 AM to 9:00 AM
Sunol Railroad Café
11882 Main Street
Sunol, CA

If you cannot attend either of those sessions, please contact Francis Zamora at 925.232.4059 or fzamora@sfwater.org. We are always available to answer questions and address your concerns.

Friday, February 3, 2012

Draft EIR for Proposed San Antonio Backup Pipeline Project Now Available for Public Review and Comment

The SFPUC reached a key milestone recently with the release of the Draft Environmental Impact Report (EIR) for the proposed San Antonio Backup Pipeline Project in the Sunol Valley. The document is now available for public review and comment. Later this month, the SFPUC and the San Francisco Planning Department will host two public hearings related to the Draft EIR, one in Sunol and one in San Francisco. Please see additional details below.

Draft EIR Public Hearings:

Wednesday, February 22, 2012 at Sunol Glen School (11601 Main Street, Sunol) starting promptly at 6:30 pm.

Thursday, February 23, 2012 at San Francisco City Hall (Room 400, 1 Dr. Carlton B. Goodlett Place, San Francisco) beginning at 12 p.m. or later.
(Call 415‐558‐6422 the week of the hearing for a recorded message giving a more specific time).

Public Comments on the Draft EIR will be accepted from January 25 through March 12, 2012.

Written comments should be addressed to: Bill Wycko, Environmental Review Officer, San Francisco Planning Department, 1650 Mission Street, Suite 400, San Francisco, CA 94103; provided by fax to 415‐558‐6409; or emailed to Steve.Smith@sfgov.org.

To view or download copies of the proposed San Antonio Backup Pipeline Project Draft EIR, click the following links.

Volume 1

Volume 2

Thursday, February 2, 2012

Airplane in Flight

Rebuilding our water system has often been compared to repairing an airplane in flight. With 2.5 million people relying on safe, high quality water- the Hetch Hetchy Regional Water System must continue to operate even as it is systemically upgraded to meet seismic standards. The work currently taking place at the New Irvington Tunnel Project is an excellent example of the balancing act that takes place.



The major water transmission pipelines that connect into the New Irvington Tunnel can only be taken out of service individually, and for short periods of time in winter, when demand is typically low. This allows for other waterlines to continue to operate while individual ones are under construction. This also means the construction team only has a limited window of time to complete their work before waterlines must come back into service.



This winter workers have the challenge of replacing three waterlines between October 2011 and May 2012. Each line must be completely drained before workers can demolish and remove the 70 year old concrete and steel pipes. Workers then install new welded steel pipe connections as large as 102” in diameter. The waterlines are then buried until the new tunnel can be connected to them. A fourth waterline will be taken out of service next winter when water demand is again low.



Crews are working hard and are on track to meet the tight schedule this year As we move forward with the New Irvington Tunnel’s critical seismic safety upgrades, we will continue to provide the same high quality water to our customers at the same time.