Six more pontoons for the new 520 bridge will float out of their casting basin at Grays Harbor on Saturday morning, the third batch since work began there in early 2012.
Four of them are the giant lengthwise pontoons that are each 360 feet long and 11,100 tons — comparable to the bulk of a large Washington state ferry. They will be fastened mid-lake.
Two of them are smaller supplemental pontoons, to be grafted alongside the six-lane floating bridge to add stability. In all, 18 have been built at Grays Harbor so far, and 20 in Tacoma.
This new set will be moored in the harbor for several weeks, before being towed around the Olympic Peninsula to Lake Washington. Two pontoons from the second batch are also still waiting in the harbor.
There isn’t enough room on the lake to store them right now, one reason being that cracks in four earlier pontoons needed repair, causing delays in the assembly workflow.
The federal government shutdown shouldn’t affect the pontoon transport, said 520 spokesman Andrew Richardson. Recently repaired Pontoon W made it through the Ballard Locks a day earlier, and even with limited staff and hours, it appears the locks can handle pontoons, he said. However, a routine maintenance closure at the locks is planned for November, he said. Meanwhile, temporary pontoon-moorage sites are being added on Lake Washington, he said.
Various cost increases, including not just pontoon repairs, but design changes and some delays on the Eastside approach highway, are estimated to cost up to $378 million, chewing up the cash reserve for the entire corridor, and raising the total price to $4.25 billion. State transportation managers have said they’re trying to negotiate the costs downward. Those talks should be concluded by the end of the year, state Department of Transportation project manager Julie Meredith told the Seattle City Council this week.
On Sunday night, a barge and crane for the non-floating part of the bridge, near Foster Island, became uprooted from the soft lake bottom, and floated nearly to the shoreline at Laurelhurst. Follow-up inspections found no damage to the equipment nor to the bridge, Richardson said.