Corrosion found inside the 520 Bridge pontoons

SEATTLE -- Are taxpayers going to face higher long term costs despite the state's latest repairs to the new 520 bridge pontoons? Those repairs will already cost taxpayers hundreds of millions. Now the KOMO 4 Problem Solvers have uncovered exclusive new evidence showing serious corrosion in those first pontoons.

We brought in outside experts to review our evidence. It's a series of photos that have never been seen by the public. They show just how serious the water damage to the pontoons really was. They show exposed and corroded rebar. They also show holes, some several inches deep, in the concrete, caused either by the corrosion or by construction problems.

Our year and a half long Problem Solver investigation starting in 2012 originally showed cracks and leaks in the first pontoons designed to hold up the new 520 floating bridge. And it prompted deeper investigation by the state. Our exclusive photos show just some of the defects then uncovered by the state's investigation.

As a result, two pontoons, Pontoon W and Pontoon T, were repaired in dry dock last summer. But as Washington State Department of Transportation Floating Bridge Manager Dave Becher showed us this month, Pontoons V and U can't be moved off the lake, so they're being repaired in a special steel coffer cell that creates a sort of dry dock on the water. Of the repairs, Becher told us, "It's actually gone very well, I think it's exceeded our expectations."

Becher took us down inside the coffer cell to look at the first set of completed repairs on Pontoon V. Inside we examined the repaired walls and asked Becher to explain the process. The main focus of the repairs is cracks on the end walls and bottoms of the pontoons. He told us the cracks had been injected with epoxy, and new cross-pontoon tension rods had been installed to squeeze the walls together and. As a final step, carbon fiber mats were rolled over the entire section.

"We're almost done at this end of the pontoon, it looks good, the repairs have gone well and we're pretty happy with what we've seen," Becher said.

After our initial Problem Solver investigation, WSDOT acknowledged the problems in a February 2013 news conference and blamed them on their own design errors. They have since admitted the errors will cost taxpayers more than $200 million in extra costs.

While examining the Pontoon V repairs, we asked Manager Becher about the long-term effects of the corrosion and holes we saw in the photos.

"It was really more surface rust than anything else, you just need to clean that off, and basically patch it back with a really high strength grout material, and we've done that in a number of locations and it wasn't anything that we didn't expect," he said.

But we wondered, could the patches really hold up? Our sources inside WSDOT told us no way, not without significant extra maintenance costs. So we sent our photos to two engineers outside of Washington who have expertise in corrosion and bridge construction. Dr. William Hartt is a Professor Emeritus with Florida Atlantic University. Christopher Bradbury is a licensed structural engineer with 15 years experience in bridge and building construction.

"It can be repaired," Bradbury told us. "There's a lot of repair strategies that can be done, but it doesn't solve the problem of what other damage; other corrosion that's going to be in that bridge."

Both experts echoed the concerns of our WSDOT sources about how long patch repairs will last. Bradbury added, "corrosion can be hidden."

Bradbury and our WSDOT sources told me that, even with repairs, the damage seen in these pictures indicates that over the long-term the pontoons will require extra maintenance.

"I think there's going to be a lot more maintenance costs," said Bradbury, "because the corrosion is already there; once it starts you can't stop it," he said.

WSDOT disagrees and insists the repairs will make the pontoons strong enough to last, with normal maintenance, for 75 years. Additionally, WSDOT and Dr. Hartt believe an electrical system designed to provide power to the bridge will also help prevent corrosion.

"The stray current protection: there is some benefit to protecting the rebar from corrosion," Becher said.

The repairs to Pontoons V and U on Lake Washington should be completed by June, and WSDOT hopes to put the costly problems with the first pontoons squarely behind them. Only time will tell if fears over extra maintenance costs - at taxpayer expense - will come to pass.