Already rusting...

Bay Bridge: Hundreds of leaks, possible corrosion

Jaxon Van Derbeken, San Francisco Chronicle

By Jaxon Van Derbeken

A supposedly watertight steel chamber supporting the roadbed of the new Bay Bridge eastern span sprang hundreds of leaks during the first big storm of the rainy season, Caltrans officials said Monday. They denied that the water was already causing damage to the $6.4 billion project's backbone structure, but one expert who viewed photographs of the steel said they showed signs of "active corrosion."

"We're taking this issue very seriously - it is something that, if left unaddressed over several years, could become an issue," said Richard Land, Caltrans' chief deputy director, as he ventured into the hollow chamber beneath the suspension portion of the bridge Monday to survey some of the leaks that materialized over the weekend.

Land invited the media along one day after The Chronicle reported that water was leaking into the steel structure beneath the 0.3-mile section where the bridge deck is suspended from its signature tower.
Caltrans officials said they consider the leaks to be a manageable problem. However, they conceded Monday that they have yet to figure out all the reasons why the steel structure is leaking, and so they have not yet devised a solution.

Suspicion first focused on caulking where the suspension span's four steel guardrails - two in each direction - meet the steel support structure 2 inches beneath the roadway. Construction plans originally called for the guardrails to be laid in a continuous line of caulk, but with Caltrans' permission, lead contractor American Bridge/Fluor decided instead to lay the guardrails atop the steel and apply caulk along the outside.

Caltrans said the caulk may be failing to keep water out, but they downplayed the possibility. However, the structure has sprung leaks in other places, officials said.

Among the likely sources of infiltrating water are holes drilled into the hollow guardrail system to install the electrical conduits for lights on the suspension span's cables, officials said. Water may also be coming in where square service panels are bolted on the hollow guardrails.

Whatever the source, experts say the steel on a leaking bridge could be prone to corrosion.
"We see no signs of corrosion," Land insisted Monday as he examined one location where water was dripping from bolts that connect the guardrails to the steel support chamber.

Near where Land was speaking, patches of brown sludge and a white, powdery residue had formed where water was visible. Andrew Gordon, a spokesman for the bridge project, said the sludge could be the result of steel shavings breaking down, but not evidence of corrosion to the steel structure itself.

Some experts, however, weren't so sure, noting that the powder is indicative of the failure of the zinc-based primer designed to protect the steel. If that's the case, they said, the brown sludge is probably corrosion from the structure itself.

"That's shocking - steel should not even be showing red rust," said Lisa Thomas, a Berkeley metallurgist who recently wrote an analysis of the corrosion cracking risk to bridge bolts like those that failed on the span in March. Thomas reviewed the photos of the brown-and-white areas provided by The Chronicle and identified it as "active corrosion."

"You shouldn't be seeing that - no way," Thomas said. She called Caltrans' suggestion that the sludge was from steel shavings "a ridiculous notion." John Scully, a corrosion expert at the University of Virginia, said Caltrans "can't eliminate all the infiltration points. They are going to have some issues here - as to long-term implications, this will be in the high-maintenance category."

Land said Caltrans can apply zinc-rich primer to help ward off rust on the bridge. However, Scully said the zinc in primer is not designed to handle standing water, only water in the atmosphere.Zinc dissolves when it comes in contact with water in the air, preventing rust from forming, Scully said. But "with standing water, the zinc will be used up in its function," he said.

Land said the leaks that have materialized so far are not a major cause of concern. "It's not realistic to not have these issues show up," he said. "I'm confident we're going to get on top of this fairly quickly, although it may involve a little work."

A series of issues has developed during and after the construction of the Bay Bridge's new $6.4 billion eastern span. Most of the bridge was manufactured in China and shipped over, some US made parts have broken and the quality of the Chinese parts have been brought into question.