Leaks Found In Some Pontoons For New 520 Bridge
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 Department of Transportation.
Construction flaws were found in the first pontoons floated out of dry-dock in Aberdeen after being built, KOMO-TV reported (http://is.gd/3wO02E) Thursday after reviewing transportation department video and documents.
Also on Thursday, department Secretary Paul Hammond announced changes in the pontoon construction team to improve oversight and coordination. The changes were part of a review of the first cycle of pontoons that the agency conceded shows more cracking than expected.
The state has not yet accepted any of the pontoons from the contractor. The equipment will have to meet specifications for the new bridge expected to be completed in 2014 and last 75 years.
“We won’t accept the pontoons from out contractors until we are satisfied they meet contract specifications,” Hammond said in her statement.
The new bridge will replace an existing 49-year-old bridge that officials say is vulnerable to an earthquake.
The planned, six-lane bridge is the centerpiece of a 13-mile project costing more than $4 billion to improve Highway 520 between Seattle and its eastern suburbs.
It’s difficult to confirm whether 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, Pierce said.
An inspection of the pontoons was continuing.
“These are manageable issues,” Pierce said.
Some of the leaks are related to cracks that developed during 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 possible changes, he said.
The transportation department is particularly concerned about pontoon W, the big end piece on the east side of the bridge, The Seattle Times reported (http://is.gd/qxQKbW ).
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.
In 1990, the Interstate 90 floating bridge on Lake Washington sank in a storm because some hatches had been left uncovered during renovation. In 1979, half of the Hood Canal bridge sank in a windstorm.
Copyright 2012 The Associated Press.