Friday, June 19, 2015

A Snapshot of our Spillway Chute and Stilling Basin Today


Spillways are important safety features on any dam. They allow for the safe discharge of high water in a reservoir around a dam.  And the new spillway at the Calaveras Dam Replacement Project is no different.

Work began on our spillway in March 2014. A total of 40,000 cubic yards of concrete, equivalent to one football field filled six feet deep, will be used to build the structure. All of the concrete is being supplied by our on-site concrete batch plant. The concrete is placed into the spillway in sections, or slabs. This spillway requires a total of 170 slabs, and we only have 18 more to go.

The spillway chute is 60 feet wide, equivalent to a five lanes of a highway. The slabs are strengthened with reinforcing steel bars and the entire structure is anchored to the bedrock to resist movement during an earthquake. 

The quality of the concrete used in the structure is key. It has to be kept at a cool temperature while it cures in order to prevent cracking. Sunol Valley in summer is anything but cool. That means our crews often begin cement pours at 2 o'clock in the early morning, the coolest time of the day.

The spillway is expected to be completed later this year. This will be a major milestone for the project to complete this important feature of the dam.


Friday, June 12, 2015

Construction Advisory: New Irvington Tunnel

To our Irvington Portal neighbors:
We wanted to inform you of some very important construction activity affecting your neighborhood.


Project Update
The New Irvington Tunnel is now in service delivering water to our 2.6 million Bay Area customers.  With the new tunnel in service, we were able to take the old Irvington tunnel out of service for inspection and repairs. Both tunnels will remain in service during normal operations. The construction team has begun restoration of the above ground facilities. The contractor has demobilized and restored the southern portion of the property. The contractor has removed the sound barriers (shown in yellow) on the south section of the site.  (See map)
Starting as early as June 15, 2015, the contractor will begin the process of removing the remainder of the sound barriers at the Irvington Portal project site.  The sound barriers will be removed at the locations shown on the map in blue. The sound wall removal work is estimated to be completed by early July 2015.


Map of sound walls to be removed

What to Expect:
-       The work involves removal of the panels and digging around the concrete foundation. Workers then remove the foundation and cut or pull the steel beams out. The excavated area would then be backfilled.

-       Noise associated with sound barrier removal will include the operation of heavy equipment, back up alarms, and concrete breakup. The soil backfill will also require compaction where the steel beams and foundations have been removed.
 
Removal Hours:
Sound barrier removal will only take place Monday through Friday from 7:00 AM to 7:00 PM.  We will continue to monitor noise and vibration in this area to ensure full compliance with strict noise and vibration standards set forth in the project’s Environmental Impact Report.

What’s Next

-      Installation and burial of permanent portal facilities and security improvements will be completed by the end of June 2015.

-      Once the sound walls are removed, topsoil will be trucked in and spread throughout the disturbed areas of the site.

-      Site restoration for the remainder of the site will be throughout the summer and be completed by early Fall 2015.  This includes paving, fencing and hydro-mulching of the disturbed areas. 

-      An iron wrought fence will be installed at the Mission Road entrance sometime in Fall 2015.

-      Full project completion for the New Irvington Tunnel is currently scheduled for Fall 2015.

Questions?
We sincerely appreciate your patience and cooperation.  Please call our 24-Hour Answer Line at 866-973-1476 if you have questions or comments or email mle@sfwater.org