WSDOT responds to 520 pontoon problems

In response to KOMO’s reports on a range of construction issues with the first six pontoons for the new 520 Bridge, WSDOT said Friday the cracking problems in particular are fixable. From Mike Lindblom at The Seattle Times:

Despite the discovery of cracks in the first batch of pontoons produced for a new Highway 520 floating bridge, state Secretary of Transportation Paula Hammond said Friday she expects all six to be made watertight.

That includes the critical east endpiece, known as Pontoon W, which left the casting basin on Grays Harbor near Aberdeen on July 30 while water seeped through an exterior wall.

“I have no reason to believe we are going to reject pontoons, even W,” Hammond said….

In followup inspections this week, by engineers for contractor Kiewit and the state Department of Transportation (DOT), Hammond said it appeared seeping had stopped on W — perhaps the wall is still curing and “apparently the concrete continues to heal.”

Apparently the leaks were discovered before the pontoons were floated out of the casting basin in July. WSDOT, contractor Kiewit and their insurer decided it would be best to tow the pontoons to Lake Washington to make the necessary repairs:

The decision to release the pontoons from the basin, and fix them later, was in part motivated by a desire to make room for the second batch, Hammond said

The night the pontoons floated out, Ziegler and Hammond didn’t mention the W cracks. Ziegler said there would be underwater inspections and patching if needed, before their trip to Seattle.

Kiewit-General-Manson changed strategy — choosing to tow them and make followup repairs in Seattle instead of leaving them exposed to saltwater and tides. The team got permission from insurer Lloyd’s [of London] after it determined the pontoons would make the trip, DOT officials said.

There was no word in the Times report about missing steel rebar at the pontoon end joints or potential $90,000/day cost overruns.

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  1. Pingback: WSDOT: More construction quality problems for ‘Pontoon W’ | montlaker

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