Logs and other debris rushing downriver in a swollen Cedar River formed a logjam against the footbridge to Riverview Park, forcing the City of Renton to close the bridge.
A structural engineer inspected the bridge Wednesday. A contractor has been contacted about removing the logjam, perhaps as early as today (Thursday) or Friday.
“It’s quite tricky,” Todd Black with the City of Renton Community Services Department, said of removing the logjam. The bridge is narrow and has a wooden support structure.
Complicating the removal, too, was the continued high level of the Cedar River. Seattle Public Utilities is continuing to lower the level of the Chester Morse Reservoir on the upper Cedar River to create storage for the next big storm expected late this week.
The high water also affected the Boeing Co.’s ability to move 737s around its Renton production plant. Boeing has two bridges that span the Cedar. The high water forced the company to raise the bridge on the plant’s south end. But that stranded three 737s so they couldn’t be moved to the flight line.
However, Thursday morning Boeing had a five-hour window during which it could lower the bridge and move the three 737s. The bridge was raised again to accommodate flow and to allow debris to flow under. It will remain in that position into Sunday, said Boeing spokeswoman Debby Arkell.
Last weekend’s heavy rains sent the Cedar River into a Phase 4 Flood Alert, although no major flooding was reported in Renton. As usual, the Cedar River Trail was closed because of the high water.
No logs or other debris collected against any of the bridges in downtown Renton. In the massive January 2009 flood, logs piled up against downtown bridges and had to be removed.
“Right now, it’s my opinion that the bridge is not in any imminent danger,” Gregg Zimmerman, the city’s public works administrator, said Wednesday of the Riverview Park footbridge.
However, his concern was that more logs and debris would stack up, putting more pressure on the bridge supports.
It’s likely the Cedar’s level won’t return to normal seasonal levels until next Wednesday or so, said Tom Fox, water resources business area manager for Seattle Public Utilities.
Seattle owns and operates the Masonry Dam on the upper Cedar River and the Chester Morse Reservoir behind it. The Pineapple Express’s rains in the Cascades filled the reservoir to the point that water was spilling over the spillway. SPU made no releases of water that contributed to the high flow, Fox said.
SPU now must work to lower the reservoir level in advance of the next storm late this week. The forecast calls for about two inches of rain.
“We need to get it down as quickly and as reasonably as we can,” Fox said. Zimmerman said he agrees that opening up storage space in the reservoir is “really important.”
Fox pointed out that without the dam and reservoir, the Cedar would have been flowing at about 10,000 cubic feet per second, causing massive flooding.
