The Washington State Department of Transportation has begun the second round of soil testing for the proposed bored tunnel to replace the Alaskan Way Viaduct.
The soil samples and other geotechnical information gathered by crews will inform the design of the tunnel and boring machine. When testing is finished this fall, tunnel engineers will have soil samples every 100 to 400 feet along the alignment, to depths of 100 to 300 feet below the surface.
“These samples will help us plan where ground stabilization should take place prior to the start of construction and where monitoring equipment can be installed,” said Ron Paananen, Alaskan Way Viaduct Program Administrator. “It will also provide important data to the tunnel designers and contractors so they can complete their work.”
Transportation department representative said it will maintain access to businesses near each work zone and conduct the majority of work during weekdays and daytime hours. The soil testing will take place along the bored tunnel alignment on First Avenue between Soouth Royal Brougham Way and Virginia Street and northeast of Virginia Street and First Avenue, following the proposed bored tunnel alignment as it continues toward Aurora Avenue North.
Approximately 50 holes will be drilled for soil sampling and testing.
Businesses, residents, drivers and downtown visitors should be aware the holes will be generally in or near the sidewalks and parking lanes; some work will take place in traffic lanes as well. Crews will begin each boring by drilling a shallow test hole, which will take approximately one business day. They will return to each location to drill a more extensive boring that will take five to 15 business days to complete.
Up-to-date information about the drilling locations and schedule will be available on the project Web site.
In May, Gov. Chris Gregoire signed into law ESSB 5768, which approved the SR 99 bored tunnel. The program team is completing environmental review plans and other contracting work so that tunnel construction can begin in 2011.
