Bay Bridge's new problem: leaks Water seeping under roadbed could cause corrosion, experts say

Caltrans officials check for water leakage along the steel safety barrier on the SAS bridge deck of the new eastern Bay Bridge span in San Francisco, Calif. on Thursday, Feb. 6, 2014. Engineers are monitoring areas where small amounts of water is seeping into the structure, a situation which is not uncommon, according to spokesman Andrew Gordon. less Caltrans officials check for water leakage along the steel safety barrier on the SAS bridge deck of the new eastern Bay Bridge span in San Francisco, Calif. on Thursday, Feb. 6, 2014. Engineers are monitoring ... more Photo: Paul Chinn, The Chronicle Buy photo Photo: Paul Chinn, The Chronicle Image 1 of / 14 Caption Close Bay Bridge's new problem: leaks 1 / 14 Back to Gallery

The just-opened eastern span of the Bay Bridge, already beset by questions about flawed welds and cracked steel rods, has a new problem: It leaks.

Rainwater is dripping into the steel structure beneath the road deck on the suspension stretch of the span, which is supposed to be watertight, Caltrans said. Outside experts say that could pose a risk of corrosion on a bridge that cost $6.4 billion and is supposed to last well into the 22nd century.

"That's a problem, a big problem," said Lisa Thomas, a metallurgical engineer who studies material failure at a laboratory in Berkeley and analyzed bridge rods that snapped last year. "They want it to last 150 years, but with water coming in, something is going to corrode until it's too thin and weak."

Caltrans says it has not found all the spots where water is getting into the cavernous steel structure. "You don't want any water inside," said Andrew Gordon, bridge spokesman. "So far, it's slowly dripping, but we are going to have teams of engineers and inspectors there this weekend to assess the problem."

At this point, Caltrans says, the problem looks manageable.

"Everything needs maintenance," said Bill Casey, the agency's resident engineer for the bridge project. "No bolting system will ever prevent water from coming in."

The leaks are happening on the self-anchored suspension portion of the bridge - the 0.3-mile section with two main cables that drape atop the bridge's landmark single tower.

Evolving plan

Unlike the rest of the bridge, which has concrete road barriers, the guardrails on the suspension part of the bridge are made of steel to save weight - but they are proving to be problematic.

When it drew up plans for the project in 2001, bridge designer T.Y. Lin International specified that the 2 1/2-foot-tall guardrails be bolted down through holes drilled in the underlying steel structure that supports the roadway.

The design called for a continuous line of caulk between the bottom of the guardrails and the steel structure. That way, water would not make its way through the bolt holes and into the hollow structure below.

But that posed a problem for the bridge's main contractor, a joint venture called American Bridge/Fluor: Once the barrier was placed onto a line of caulk, minor changes in its placement would be impossible.

"When you put the barrier down and there's caulk, you can't adjust it," Casey said, because that would break the seal.

Last year, Caltrans changed the plans, saying it was the "contractor's option" to apply the caulk outside the guardrails after setting them in place - much like a homeowner might lay down a bead of caulk where a bathtub meets a tiled wall.

Then construction crews applied waterproof epoxy coating over that bead of caulk. The 2-inch-thick concrete roadbed was put down next, which was supposed to add another layer of protection from water.

However, the caulking may not be watertight. The bridge opened in September, and within three months, it was clear that water was getting into the steel deck cavern when it rains, Casey said.

Shakeout period

Exactly where the water is leaking is unclear. It could be at holes in the caulk, Caltrans says, but it could also be coming through holes used to install electrical conduits near the guardrails. Casey said Caltrans needed a "monsoon" to send enough water pouring off the roadway to determine whether the caulking or something else is to blame - and until this weekend, such large storms have been lacking.

Casey said he doubts the caulking is the culprit, pointing out that rainwater would have to get past three levels of protection - the caulk, the epoxy coating and the roadbed.

"If you do it right, it should bond just fine," Casey said. "You would need all three systems to fail to get the water in there. I just don't see it."

He said the problem is expected to be resolved over the first five years of the span, known as a shakeout period. But in general, he said, the caulking will always need maintenance. "You do the best you can, but water will always find its way in," Casey said.

Corrosion expert Russ Kane of Houston isn't so sure Caltrans took the right approach. Kane has studied corrosion failures and prevention methods in the U.S. and worldwide, assessing the risks to the military, the petroleum industry and chemical manufacturers.

He likened Caltrans' choice during bridge construction to the options a plumber has when installing a faucet.

"With a sink faucet, to make a good seal that will last a fairly long time you put material down between two surfaces and you clamp it together," Kane said. "With a bead on the outside, there is nothing there physically to hold the caulk in place."

He does not share Caltrans' sanguine attitude toward the leaks.

"It's a bad situation," Kane said, because water naturally corrodes steel, and repeated dousings accelerate corrosion.

Tough problem to fix

Repairing the steel would not be easy. The metal is part of giant, hexagonal boxes welded together to serve as the bridge's backbone. Casey said the steel is primed, which should afford some level of protection. But experts said water and steel should never mix, because there is always a chance that pockets of corrosion can form that engineers don't see.

"People don't realize it takes three times more to fix something later rather than do it right for the first time," Kane said. "This is such a typical corrosion problem. People think they are saving a little money on the front end, but it ends up eating their lunch down the road."

Possible solution

One solution, he said, was contained in T.Y. Lin International's original plans for the barrier. Drawings show a channel between the concrete roadway and the steel guardrails that would have been lined with clay-filled asphalt.

"It is pretty effective, because the hot material (as the asphalt is poured) flows into all the nooks and crannies," Kane said. "It's similar to what they do on roofs - the stuff is sticky as all get-out and waterproof."

Casey said he did not know why Caltrans had abandoned that plan. T.Y. Lin International officials declined to comment for this story.

The leaks add to Caltrans' list of problems with the bridge, the first of which emerged last year when 32 steel rods that were supposed to hold seismic-stability structures in place snapped when they were tightened.

Those fasteners, like more than 2,000 other steel rods and bolts on the eastern span, had been made harder than Caltrans' standards normally allowed on bridges. The harder the metal, the more prone it is to being invaded by hydrogen and cracking, and hydrogen is present in abundance in a marine environment such as the bay.

Tests on bolts

Caltrans has been conducting tests for months to determine whether the steel fasteners are at an increased risk of failure.

Last month, a report commissioned for the Legislature said Caltrans had accepted hundreds of possibly defective welds on the bridge. Caltrans said the welds had been fixed and that the span is safe.

The leaks at the guardrails are not the first time Caltrans has discovered water on the span where it should not be puddling. In 2011, engineers discovered pools of water inside the supposedly watertight steel deck panels on the bicycle and pedestrian path on the south side of the span.

A recent Caltrans study downplayed the possibility of significant corrosion there, but recommended that the panels be drained, the water sampled for danger signs and the steel regularly checked for damage.

Kane said the study's authors may have downplayed the corrosion risk without the evidence to back that up.

"They didn't show the corrosion was not significant - but there is just no data there to support that," Kane said. "They make a statement, but they don't give enough for an independent assessment."

Caltrans says the water was drained from the bike path before the span opened in September. Officials said it is likely that much of the water got in during construction when the panels were left out and not properly protected from the elements.

'A huge blunder'

Thomas, the metallurgical engineer who has analyzed the bridge rods, said the waterlogged bike path deck panels and leaks in the steel deck superstructure show that the bridge builders didn't do enough to safeguard the span.

"Letting water get into those compartments is a huge blunder," she said. "Continual water intrusion means continual corrosion."