Friday, February 28, 2014

Lined, Then Sealed, Then Delivered This Fall. The New Irvington Tunnel Reaches Another Milestone

Imagine an 8.5 foot in diameter steel pipe roughly the length of a tractor trailer. Now imagine gently placing it into a 14-foot tube the length of 1½ Golden Gate Bridges? Now weld each of them together from the inside of the installed pipe in less than two months.

Well, that is EXACTLY what we did. This week the New Irvington Tunnel contractor completed the installation of a total of 14,600 feet (2.7 miles) of the welded steel liner into the tunnel. The 50 foot segments were all installed from the Sunol Valley and transported with a customized pipe placer westward into the tunnel. This completes the steel lining for the entire 18,660 foot (3.5 miles) New Irvington Tunnel.

What’s next? More grouting! Our teams will mobilize in March to prepare the tunnel to place cellular grout into the space between the steel liner and the excavated tunnel. This will effectively backfill the space between the tunnel pipe and tunnel wall, sealing it off to prevent water from seeping into or out of the tunnel.

We plan to bring the New Irvington Tunnel into service this fall, when drinking water will officially be transmitted through the new tunnel. Final project completion of the New Irvington Tunnel Project – including above ground restoration - is expected in mid-2015.

The New Irvington Tunnel will provide a seismically designed connection for water supply for 2.6 million bay area customers. 

50 ft segments of steel liner being delivered
Photo credit: Robin Scheswohl

View of steel liner from inside of Alameda West Portal
Photo credit: Robin Scheswohl

Welding work taking place on steel liners
Photo credit: Robin Scheswohl

Wednesday, February 26, 2014

A Tale of Two Geary Road Bridges

It has been more than 80 years since the original Geary Road Bridge was built over Alameda Creek, connecting park users and lease holders to Sunol Ohlone Wilderness Park trails in the East Bay Regional Park District.  Over time the first Geary Road Bridge was unable to support the weight of large vehicles, forcing trucks to drive through Alameda Creek at that location. So, the San Francisco Public Utilities Commission constructed a new bridge that recently opened to the public. The new Geary Road Bridge is highway grade, which protects Alameda Creek by eliminating the need for large vehicles to drive through the creek. 

The amazing contrast of the old and new bridge is depicted in the photo above that was composed of two photos shared with us on Twitter by @RHMImages, a landscape and rust photographer.  Thanks @RHMImages for the fabulous photos!

Friday, February 21, 2014

Whales in the Sunol Valley?

Since construction began at the Calaveras Dam, team paleontologists have had some remarkable finds from ancient shark teeth to marine mammal vertebrae all collected during the excavation of over 4 million cubic yards of earth over the sediments that were once an ancient sea floor.  

Just this week, project paleontologists found a portion of an ancient whale skull in the slope above the spillway excavation of the new dam. The skull is almost a yard long and relatively intact, except for a small portion of the right rear section which is missing. Our paleontologists are still researching the find but initially assess the fossil to belong to a Mysticete (or baleen) whale, from the family of Humpback, Grey or Blue whales that live in the oceans today and forage on plankton. This fossil was discovered in the temblor sandstone formation which makes it over 20 million years old.

The project takes important steps to salvage these paleontological finds for educational purposes. The critical construction work to build a replacement dam has not been affected and continues, while we discover amazing fossils to add to the rich history of this valley.

Paleontologists Bruce Hanson and Jim Walker work on uncovering fossils at Calaveras Dam. Photo credit: Robin Scheswohl

In November 2013, a collection of bones including vertebra from a marine mammal were discovered on the lower portion of the Spillway.  It appears to show a complete cross section of the body, neural arch and measures 15 x 7 centimeters. Some of the other bones appear to be ribs. None of the specimens found interfered with construction activities and the specimen still remains in the rock.

Friday, February 14, 2014

Pipe Installation for Backup Pipeline Approaches Finish Line

Sprinting to completion, crews have been working hard to install the pipe for the new 1.3 mile-long San Antonio Backup Pipeline, and it is paying off - they are almost done!! To date, about 85 percent of the 5.5-foot-diameter pipe has been installed in the ground for the new water pipeline. With the bulk of the pipeline installation behind them, crews have begun construction of some of the small above-ground structures and the discharge pumps at the quarry storage pond at the north end of the site. Once they cross the finish line in 2015, the San Antonio Backup Pipeline will add operational flexibility to our Sunol Valley water transmission system that currently serves 2.6 million customers.

The first 50- feet-long pipe segment was delivered in August 2013. 

 Crews prepare to set the pipe in the trench.  

Once installed, the pipe segments are welded together to secure them in place.

Monday, February 3, 2014

The New Geary Road Bridge to Open on Feb. 7

We are excited to announce that the new Geary Road Bridge will be ready for use on Friday, Feb. 7th! The new 150-foot-long concrete and weathered-steel bridge has replaced an old bridge that was unable to support the weight of the large vehicles that use it regularly. It crosses Alameda Creek downstream of Calaveras and Alameda Creek Diversion Dams, and is located within the East Bay Regional Park District’s Sunol Ohlone Wilderness Park leased lands. This new bridge will protect Alameda Creek at this location by eliminating the need for large vehicles to drive through the creek’s low-water crossing. Planting and restoration of the site are underway. 

Thanks to the East Bay Regional Park District staff, park visitors, private landowners, lease holders and all members of the public in the area for their patience during construction. To see how the new Geary Road Bridge was constructed , take a few moments to check out our project video: