EIGHT OF THE Bay Bridge eastern span's 16 contracts have been completed, including interim retrofits of the existing span, a pile demonstration project, an archaeological excavation, one of the tower's foundations and the geofill.
The $8 million geofill project, completed in 2003, involved building and stabilizing a roadbed along the muddy Bay shore, north of the existing toll plaza. The new bridge's Oakland approach will be built on top of the geofill.
"We had to excavate very unstable soils and install this highly innovative drainage system," said Hal Stober, president of contractor Gordon N. Ball of Alamo. "Theoretically, it's earthquake-proof."
The work included placing 50,000 tons of riprap -- boulders from Syar Industries in Vallejo and reused material from the shoreline.
A key concern was liquefaction, which in strong shaking can make water-logged sandy materials behave like a liquid and cause extensive damage, such as what happened to San Francisco's Marina district in the Loma Prieta earthquake.
Subcontractor Nilex installed about 34,000 earthquake drains to help avoid such problems.
"It's high profile because it's the Bay Bridge project," said Nilex manager Jimmy Foster of Bay Point, a second-generation piledriver whose son and nephew currently work for Kiewit.
Nilex, which had eight employees on the job, also installed thousands of plastic wick drains to draw out water and accelerate consolidation.
"If you didn't put in the wick drains, it would take 30 years for that to settle out," Foster said.
Then came 72,000 cubic yards of fill -- soil from East Bay construction sites -- which posed another challenge. "If we put in the fill too fast, it was possible to destabilize the mud and essentially cause a huge failure," Stober said.
Gordon N. Ball had 25 employees on the geofill job -- two-fifths of its work force. It took about two years because they had to work around the tides to comply with environmental restrictions.
"We had to work in low tide," Stober said. "Every day the shift would change 30 minutes to an hour. Sometimes we were working at night."
In the end, Caltrans was happy with the job, he said.
"We've worked all around the bay, but we've never done one to this scope," Stober said. "We did it to everyone's benefit. We did our work. We met Caltrans' timetable and budget. We accomplished something that was very, very difficult."
W2 foundation
Perhaps the most difficult job on the new Bay Bridge will be building the signature tower. Self-anchored suspension bridges are rare -- only 21 have ever been built.
The Bay Bridge's single-tower, self-anchored suspension bridge would be the world's largest -- if it's built. On Sept. 30, the state rejected the only bid to construct the tower, which came in at a budget-busting $1.4 billion -- double what Caltrans estimated.
While politicians will consider in December whether to redesign the tower, already one of its foundations has been built and a contract has been awarded for its other two foundations.
The $177 million job for the tower's two marine foundations -- awarded to KFM -- is still in its early stages, but the $24 million W2 foundation on Yerba Buena Island -- awarded to West Bay Builders of San Rafael -- was finished in October.
"We're extremely happy with W2," said Brian Maroney, Caltrans' chief of toll bridge design. "They did a good job for us."
The project took 16 months to complete -- four months longer than expected. It took dynamite teams three months to blast through solid rock and create two 90-foot-deep holes for the foundation.
The holes were filled with two massive concrete pours of 5,000 cubic yards each, enough to cover an average Best Buy store, one yard deep. The first pour, in early January, lasted 36 hours from Friday night to Sunday morning.
"That's over 500 trucks of concrete. We had to have it coming from San Francisco and Oakland," said Joe Hass, West Bay Builders senior project manager. "We never could've done it during the week."
Pleasanton's RMC Pacific Materials supplied the concrete. At various points, ice, liquid nitrogen and cold water were used to keep the concrete cool and prevent cracks.
West Bay Builders had up to 20 employees on the project, usually two shifts working six days a week, but sometimes it was three shifts or seven days a week. The 200-employee firm, whose biggest job is a $42 million contract to build a high school in Stockton, also has another $9 million Bay Bridge contract and a $19 million contract on the new Benicia Bridge toll plaza.
"We're anxiously awaiting more (bids) from Caltrans," Hass said.
The temporary detour
The Bay Bridge's new eastern span will have side-by-side decks for the Oakland approach, skyway and tower sections, but the bridge needs to be double decked so drivers can pass through the two-level tunnel on Yerba Buena Island.
Before the island transition can be constructed, part of the existing bridge must be demolished and a temporary detour built.
The $71 million detour contract was awarded to C.C. Myers. Construction began in July and is scheduled to be finished Oct. 27, 2005.
C.C. Myers is perhaps best known for rebuilding the Santa Monica Freeway bridges after the 1994 Northridge earthquake, working around the clock to finish the project in 66 days -- 74 days ahead of schedule. The 27-year-old Rancho Cordova firm also won two other Bay Area bridge contracts of $64 million apiece -- replacing the Crockett interchange on the new Zampa Bridge and reconstructing the Interstate 680-780 interchange on the new Benicia Bridge.
The detour is a tough project. Space is tight. The slope is steep. And the project eventually will have two tie-ins to the existing bridge, a tricky job involving lane closures and strict penalties for any reopening delays -- up to $60,000 every 10 minutes.
"I personally think it's the most challenging engineering," Caltrans' Maroney said. "This is going to be what I call surgical. It's got to be very well timed and very well choreographed. It's structural surgery."
C.C. Myers' team includes structural engineering firm Imbsen & Associates, which has an office in Oakland, and geotechnical firm Geomatrix Consultants of Oakland.
"Being named on a team like this certainly adds to our credibility," said Marion Thatch, marketing manager of Geomatrix, a 350-employee geotechnical, seismic and engineering services firm with annual revenue of about $70 million.
Geomatrix, which also was the lead geotechnical engineering subconsultant on the new Zampa Bridge, has six employees working on the detour. The $400,000 job has included analyzing the island's soil and rock conditions. Based on Geomatrix's recommendations, some bridge columns will be supported by steel pipe piles while others will be supported by drilled shafts.
"It's temporary, but it still has to function," Geomatrix principal engineer Mark Freitas said. "We'd like the project to be in the headlines, but not our name to be in the headlines." Alec Rosenberg can be reached at (510) 208-6445 or [email protected]. |
