Caltrans was warned of Bay Bridge leaking before span opened
By Jaxon Van Derbeken | San Francisco Chronicle
Updated 8:00 am, Friday, April 24, 2015
Caltrans knew the new Bay Bridge eastern span's supposedly watertight steel support structure leaked in the rain as early as 2012 — more than a year before the bridge opened — and warned that the water could cause corrosion, documents obtained by The Chronicle show.Ultimately, the problem got worse despite patches made when Caltrans first identified the leaks. Experts warn that every year water accumulates in the span, its steel deck and vital components could degrade because of possible rust and hydrogen-fueled corrosion.
Caltrans didn't acknowledge that the bridge leaked until January 2014. The first leaks, discovered nearly two years earlier, left water standing inside more than two dozen massive steel boxes — 90 feet wide and as much as 120 feet long — that are welded together to form the road decks.
Caltrans engineers first noticed the problem after the winter of 2011-12, documents show. Water was apparently entering the span in small gaps between the hollow steel bridge decks and the cross beams that link them together.
'Ponding' water
"Water is entering and ponding in the interior," Caltrans senior bridge engineer Darryl Schram warned in May 2012 in a memo to Tony Anziano, then the head of Caltrans' toll bridge program. "To prevent corrosion of the bridge interior, water intrusion and ponding must be reduced and/or eliminated."
At the time, Schram proposed a modest $373,000 plan that involved drilling more holes to allow water to drain out of the bottom of the steel decks and cross beams. He also recommended improving the seals on connections between the deck sections and the cross beams.Caltrans officials say the plan initially appeared to work. "The bridge didn't leak in the winter of 2012-13," Bill Casey, the agency's supervising engineer on the Bay Bridge project, said in an interview this week.
But more water was to come, through hundreds of holes in the deck that were drilled so guardrails could be bolted to the steel structures. Those holes were covered and the rails had not yet been installed when the first leaks became apparent in 2012, Casey said. But by late 2013, shortly after the span opened and the guardrails had been put in place, crews had found roughly 900 leaks.
Downplayed problem
When The Chronicle asked about the problem in early 2014, Caltrans officials said they had expected some leakage all along and had incorporated drainage holes, called weep holes, to let the water escape out of the bottom of the steel boxes.
They did not mention the earlier leaks, however, and downplayed the risk from corrosion, despite photographs taken inside the steel structures that showed a brown, sludge-like material. Caltrans dismissed it as the product of steel shavings left behind from earlier work.
In late January 2014, the executive director of the Metropolitan Transportation Commission, Steve Heminger, complained that the leaks and other corrosion-related problems — including brittle bolts and water seepage onto steel that supports the bike path — were part of a pattern that "smacks of utter carelessness." He also criticized Caltrans officials for waiting two months after they spotted the leaks to alert him to the problem.
Heminger declined to comment this week on the documents indicating that Caltrans had failed to notify his agency for nearly two years, not two months.
Caltrans indicated in contract documents that it was to blame for the guardrail leaks by agreeing to a contractor's request to eliminate steel plates that were supposed to divert water away from the rails. The fix for the leaks, which included more caulking around the bolt holes and the steel plates used to anchor the rails, has failed to stop the problem.
Standing water problem
The bridge still leaks, officials acknowledge, and water is pooling near high-strength steel rods that secure the main cable. Caltrans has installed dehumidifiers to reduce the threat of corrosion to the rods, but officials say the standing water needs to be eliminated.
Fixing the leaks will require a redesign of the bolted connections that hold down the guardrails.
Experts say the fact that the leaks problem has yet to be solved three years after it was discovered is troubling.
"Dealing with critical factors like this takes time, money and knowledge — in this case, they don't seem to be willing to devote any of the three," said Bob Bea, a UC Berkeley civil engineering professor emeritus who studies failures in major infrastructure projects.
Active corrosion
Lisa Fulton, a Berkeley-based corrosion expert who has studied the bridge, said the fact that the standing water had been present for years bolsters her conclusion, based on the photographs taken inside the steel structure, that there is active corrosion.
"Every day there's water there's more metal loss, we're eating into the safety factor," Fulton said. "They are aware of the risk because they have acknowledged they need to fix it, but they haven't fixed it."
Source: www.sfgate.com/bayarea/article/Caltrans-was-warned-of-Bay-Bridge-leaking-before-6220861.phpRead my blog at http://eclecticarcania.blogspot.com/
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