Date:  Tuesday, November 18, 2008

Contact: Messay Shiferaw, WSDOT Engineer, 206.440.4689
Jamie Holter, WSDOT Communications, 206.440.4698
 

 

BLACK DIAMOND – WSDOT is closing the 80-year-old State Route 169 Green River Bridge for at least six months due to concerns over public safety. After reviewing extensive data gathered by electronic sensors in the landslide zone near the SR 169 Green River Bridge in Black Diamond, WSDOT geotechnical engineers have determined the structure is vulnerable to significant land movement.

Closure

• WSDOT maintenance crews will close the SR 169 Green River Bridge tonight at 7 p.m., Nov. 18. The bridge may remain closed for up to six months for significant long-term repairs.

“I can’t emphasize enough that this closure is about safety,” said Paula Hammond, Secretary of Transportation. “We will do what is necessary to keep the public safe and preserve the bridge.”

WSDOT geotechnical engineers believe the soil supporting the bridge is showing unusual movement that could be aggravated by recent heavy rain. They are concerned that the soil may not be able to support one of the southern most bridge piers. If the soil slides, the pier could move with it.

“The geotechnical experts watched the slide through the weekend and determined that something had accelerated the rate and direction this slide is moving,” said Lorena Eng, Regional Administrator. “At this point it appears that last week’s heavy rains saturated unstable soil under the bridge, and that soil is now moving. With the next storm set to hit Wednesday, we do not want to take any chances with safety.”

Next steps
The long-term repairs will take place in two stages.

• First, crews will remove excess water by clearing trenches, unplugging manholes and installing pumps to help drain water from the unstable hillside.
• Secondly, crews will excavate the soil that is putting pressure on the bridge pier. They will dig out a section of roadbed 30 feet deep and 300 feet long just south of the bridge and replace it with lighter weight material.

All the work will be done as an emergency contract and will cost about $10 million. This is a rough estimate as the details have not been worked out.

Local drivers, emergency services and freight
The Kummer Bridge is vital to the communities of Black Diamond and Enumclaw. It carries an estimated 9000 trips each day including emergency services and law enforcement.

Detours
There are two detour routes: one for passenger vehicles and one for commercial trucks. Drivers can download the maps at: www.wsdot.wa.gov/Projects/SR169/GreenRiverRepair/Detour.htm

Drivers can follow project progress at: www.wsdot.wa.gov/projects/sr169/greenriverrepair/