– Re: Four Teams Short-Listed for $5-Billion Tappan Zee Bridge Rebuild
In Reply To
The Sacramento Bee
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SACRAMENTO, Calif. -- A builder of the new San Francisco-Oakland Bay Bridge failed to disclose that a 19-foot section of concrete in the foundation of the span's signature tower had not hardened before it was tested. By keeping quiet about the problem, the builder prevented further examination or repair.
The Sacramento Bee found descriptions of the apparent defect in records provided by Caltrans last fall to reassure the public about the overall stability of the suspension segment of the bridge's eastern span. Experts said the problem, combined with other construction and testing lapses by the California Department of Transportation and its contractors, raises new questions about the structural integrity of the bridge.
Kiewit-FCI-Manson, a joint venture, built the foundation as part of a $177 million contract. It did not provide the problematic 2007 test results until after a Bee investigation in November showed that a Caltrans employee skipped required test preparation for separate checks of the same foundation and fabricated results on other structures.
The agency plans to open the $6.5 billion structure, the costliest public-works project in state history, by Labor Day 2013 to an estimated 100 million drivers annually. Caltrans said the bridge is sound and can withstand any anticipated earthquake.
Beyond the large area of suspicious concrete in one of the reinforced underground foundation piles, a Bee examination of Caltrans records found numerous other problems with the piles, and gaps in essential data. Experts who reviewed concrete and engineering records for The Bee questioned the ability of the main tower foundation to resist an extreme earthquake -- the reason for building the new bridge.
Among The Bee's findings:
Two of 13 piles that rise out of the Bay to hold up the tower contain suspect and inadequately tested concrete. Sonic-wave tests revealed a 19-foot section of poor concrete in Pile 3, in a location subject to profound seismic forces. When tested, the concrete had not hardened to the required strength. It was not retested. For unclear reasons, Pile 8 either received no sonic test or builders could not locate the test report. Jobsite inspection diaries also show construction abnormalities in that pile.
Sonic test reports contained more than 20 errors. Among other slips, they misstated which piles were tested, test dates and pile measurements. Experts said the unusual volume of mistakes casts doubt on the reliability of testing for both the problem pile -- Pile 3 -- and others deemed free of defects.
Builders treated the piles with an additive meant to increase concrete strength, but known to cause soft or poor-quality concrete when overused -- one possible explanation for the 19-foot anomaly. Although batching computers should ensure mixing precision, records for a different pile show unexplained mixing errors by a concrete plant computer.
Caltrans and its experts said the bridge is safe. Many of their supporting assertions were contradicted by agency documents. For example, a Caltrans panel asked to review the work said sonic tests proved that the piles were of sound construction, despite the Pile 3 problem and the lack of testing for Pile 8. Panelists relied heavily on tests of what they called "full scale" mock-ups. Those models actually were a small fraction of the bridge piles' size. Independent experts said the mock-ups offered invalid comparisons.
Larry Olson, president of Olson Engineering, based in Wheat Ridge, Col., which conducted the sonic tests, declined to comment without permission from Kiewit Corp., based in Omaha. Neb. Kiewit referred all questions to Caltrans.
Olson Engineering detected the problem concrete in Pile 3 in 2007, calling it "a batch of concrete that has not fully set at the time of testing" or "a very poor area of concrete." The company suggested new sonic tests. None was conducted, according to Caltrans.
"The most likely cause for the (19-foot) anomaly is concrete that didn't cure," or harden, said Les Chernauskas, general manager of Geosciences Testing and Research Inc., a Massachusetts company that specializes in sonic testing. Chernauskas, who examined hundreds of pages of technical documents for The Bee, co-authored a seminal paper used to develop standards adopted by Olson and most similar companies.
Through a spokeswoman, California Gov. Jerry Brown declined to answer questions about whether Caltrans has kept his office informed of ongoing concerns about the bridge, or if the agency enjoys his confidence for its construction and testing oversight. The Governor's Office deferred all questions to Caltrans.
Rather than provide engineers or executives for an interview, Caltrans spokeswoman Tamie McGowen responded in writing to Bee questions. "Substantial evidence," including tests of the small mock-ups and the other bridge piles, indicates that the abnormal concrete in Pile 3 eventually hardened properly, she wrote.
"We are confident in the structural integrity of the main tower foundation and that the bridge will perform as designed to handle an extreme earthquake," McGowen said. A panel of engineering experts hired by the agency to re-evaluate the safety of the foundation concurred.
Chernauskas expressed skepticism about that conclusion. No one knows if the problem section ever hardened to its required strength, he said, because of the failure to retest.
"The way that they conducted the testing program, and the results, do raise some serious issues with respect to the quality of the concrete," said a university professor and expert in deep foundation testing, who also reviewed the documents at The Bee's request. He spoke anonymously for fear of jeopardizing business relationships with contractors for Caltrans, among the nation's largest public-works funders. A chief concern, he said, involves the absence of sonic data for Pile 8 and the location of problem concrete in Pile 3, toward the top of the pile, "subject to the most significant loads during an earthquake."
"If you had (two) out of 13 piles with major zones of defective concrete," the professor said. "(It) could result in a very large movement of that tower in an earthquake...How that would affect the performance of the bridge structurally is a big question mark. No matter what anyone tells you, no one can answer that question without doing some very rigorous analysis."
Using computer modeling, "you simulate the potential defects and see whether that would have any impact on the overall system," said Cumaraswamy Vipulanandan, an internationally known deep-foundation expert at the University of Houston, as a way to test "how much the factor of safety in the design would be reduced."
Getting to structures beneath a mammoth 525-foot tower might require drilling through the bridge footing to extract core samples -- a significant engineering challenge. But Chernauskas, Vipulanandan and the other professor who reviewed the data said such an effort might be vital to determine whether the bridge could stand up to the most extreme earthquake.
Kiewit built the Bay Bridge piles in 2006 and 2007 and had relatively little experience with this kind of deep foundation. It had struggled on previous jobs, according to Caltrans records obtained by The Bee
Kiewit began building foundations for the Benicia-Martinez Bridge shortly before taking on the Bay Bridge project. Records show that Caltrans engineers recommended rejection of nearly all the Benicia piles built before awarding the Bay Bridge contract to the Kiewit joint venture. Those piles, almost one-third of the Benicia job, were deemed either too flawed for use without repair or required retesting due to construction errors. After Caltrans awarded Kiewit the Bay Bridge contract, engineers similarly recommended rejection for more than 80 percent of the remaining Benicia piles.
Soon after the Bay Bridge sonic testing, Kiewit-FCI-Manson provided Caltrans with results for six of the 13 piles. They showed only minor problems. It failed to deliver the other sonic reports, including one showing the huge anomaly. Caltrans did not request those tests, McGowen said, which technically were not required by the construction contract.
Because the company declined to comment, its motives for withholding test data remain private. Substantial repairs on a giant pile can cost up to $1 million.
Thomas W. Joo, a University of California, Davis law professor and contract authority, said that even if Kiewit and its partners had no contractual duty to report the sonic data, they could face legal liability for "straight-up bad faith."
"If it's a matter of public safety, the calculus is different," he said. "The whole thing is colored by what's at stake."
By providing findings for six piles, the builders could have "engendered a duty to disclose" more fully, Joo said. "Partial, misleading disclosure is a species of fraud."
Questions Arise About Builder's Work on Bay Bridge Foundation