WSDOT to spend $100M to fix 520 pontoons

SEATTLE — The Washington State Department of Transportation has decided how to fix four faulty pontoons for the new 520 floating bridge.

One of the pontoons, a 360-foot-long, 11,000-ton section, is going to have be towed to Portland for repair.

Another similar-sized pontoon will be taken to Harbor Island on Elliott Bay to be fixed.

Sending the floating sections to multiple dry dock locations will speed up the time it takes to fix the cracking cement on the pontoons.

Two additional sections will stay on Lake Washington, next to the existing bridge.

Steel coffer dams, which are basically portable dry docks, will be slipped underneath the pontoons and the water will be pumped out so the cracks can be filled and fixed.

The repairs are going to cost an estimated $100 million, plus months of delays. That expenditure will eat up most of the money the Department of Transportation saved by going with a lower bid for the bridge's floating sections.

Engineers are going to have to inject an epoxy into the cracks and they will use some high tension cables to pull the concrete together.

After that, workers will wrap the damaged sections with a carbon fiber material.

It is expected to take months to fix the problems.

Late Friday, another pontoon will be towed through the Ballard Locks to Lake Washington.

KIRO