Tunnel boring off to slow start
Published 10:32 pm Wednesday, January 2, 2008
King County’s expensive tunneling project continues to grind its way underground from Bothell to the future Brightwater treatment plant in Maltby.
It hasn’t hit full stride, though.
Since it launched Oct. 9, the tunnel boring machine named “Luminita” has traveled just 380 feet and is still in King County.
About 4,500 cubic yards of sand have been carted out.
“We hoped to have gotten 1,000 feet further, but we’ll catch up to that,” said John Kennedy, the contractor’s project manager.
The project is still in start-up mode, and tunneling gear is being moved into the tunnel, said Judy Cochran, a King County project manager.
When crews seriously start mining clay, sand and peat, they’ll be pulling out about 1,000 cubic yards a day, Kennedy said. That’s enough to fill 50 dump trucks a day, each outfitted with trailers that carry an extra 10 cubic yards of dirt.
Carbide-tipped cutters are chewing a 20-foot-diameter tunnel. The three-mile trek is expected to be complete in November this year.
In all, a 13-mile tunnel is planned to link the treatment plant to an outfall in Puget Sound.
Tunnel construction is estimated to cost $450 million and be completed in 2010. The entire project is estimated to cost $1.7 billion.
For more information, go to dnr.metrokc.gov/WTD/ brightwater.
