Leaks found in bridge pontoons
Changes made in construction, team; process under review
Friday, October 26, 2012
SEATTLE (AP) -- Small cracks have appeared in at least two the first six pontoons built for a new floating bridge in Lake Washington, but transportation officials said Friday the problem is manageable.
Leaks can be repaired and changes made in the construction of 61 remaining pontoons, said Steve Pierce, a spokesman for the Washington State Department of Transportation.
Construction flaws were found in the first pontoons floated out of dry dock in Aberdeen, where they were built.
WSDOT Secretary Paul Hammond on Thursday announced changes in the pontoon construction team to improve oversight and coordination in response to the review of the first cycle of pontoons.
The state has not yet accepted any of the pontoons from the contractor.
"We won't accept the pontoons from out contractors until we are satisfied they meet contract specifications," Hammond said.
The bridge is expected to be completed in 2014 and remain in operation for 75 years. It will replace an existing 49-year-old bridge that officials say is vulnerable to an earthquake.
The planned six-lane bridge is part of a 13-mile project costing more than $4 billion to improve state Highway 520 between Seattle and its eastern suburbs.
Pierce said that it's difficult to confirm if more than two pontoons were leaking because of temporary ballast water added for balancing, residual water left from concrete curing, missing plugs for bolt sleeves and hatch doors being left open.
Some of the leaks are related to cracks that developed in construction because of interior cables that are tightened for strength, Pierce said.
Changes in construction have been made, and experts are reviewing the process for other possible changes, he said.
WSDOT is particularly concerned about pontoon W, the end piece on the east side of the bridge. Some of the cracks are superficial, and some are structural, said Mike Cotton, a design-build manager for the department. Water hasn't been streaming in, but some cracks have allowed absorption and condensation, so water appears inside the pontoon, he said.
Washington has three floating bridges that are among the longest in the world -- two on Lake Washington and one across salt water on Hood Canal.