SEATTLE - Severe frost damage is the newest problem to plague the 520 Bridge project - a project that's already late and over budget. Now, the KOMO 4 Problem Solvers have discovered freezing temperatures caused micro-fractures on one of the concrete pontoons.
On our first trip last Monday out to the Aberdeen casting basins where contractor Kiewit is building the pontoons, we found crews scouring the top deck of Pontoon B or Bravo with high-pressure water. The 120 foot section of concrete froze after being poured during freezing temperatures on February 5th, and at least the top layer was crumbling.
"Contractor had some issues with his cold weather protection," said WSDOT Engineer Dave Ziegler, "and the next day, through our quality process, we determined that we had a problem."
Pontoon Bravo is just one of 77 floating concrete boxes that will hold up the new 520 bridge being built across Lake Washington. A Problem Solver investigation first exposed problems with the pontoon construction in 2012.
Last year the state said the problems were its fault - and just last month Transportation Secretary Lynn Peterson confirmed the contingency fund was exhausted and taxpayers are on the hook to pay for repairs and delays saying, "the total cost of the design errors will be approximately $208 million."
The problem with Bravo according to WSDOT, is the frost damage created "micro-fractures" making the concrete unacceptable. We weren't allowed onto the section because of the on-going work but we asked Ziegler to tell us what the crews were doing. "They're working to remove the damaged concrete so they're using hydro demolition to remove that top layer that was damaged."
Though Ziegler clearly described the activity we were watching as hydro-demolition, Problem Solver sources told us it was not true commercial hydro-demolition. When we later asked WSDOT about that, they admitted what they showed us was just what an on-site sign said: "hydro-washing". They said the demolition machine broke down before we arrived but was back in service the day after we were onsite.
WSDOT's Ziegler also told us the bad concrete was only on a thin, surface level. "The concrete that's damaged is being removed, the remainder of the concrete meets the contract requirements." We asked him if the concrete was strong enough to last, "correct."
In spite of that, by week's end, Kiewit began work to remove the entire 120 foot section that had been frozen. Jackhammers working at the ends will just remove concrete and leave the steel rebar. But in the center, large saws are cutting out entire pieces and both the rebar and the concrete will have to be replaced.
This is the first time WSDOT has forced the contractor to remove a major, poured-in-place section of concrete. Ziegler said Kiewit originally wanted to repair rather than replace.
"DOT evaluated those repairs and determined that none of them would give us the 75 year life span that we were looking for."
As for who pays for the job? A Kiewit spokesman told us they take, "full responsibility" for the damage.
This cycle of pontoons was scheduled to be floated out in April but, with this new construction damage, that schedule could be delayed. This is the fourth of six cycles of pontoons being built in Aberdeen.
The overall completion of the 520 floating Bridge has already been delayed by over a year.