Workers begin inspecting Seattle tunneling machine

  • Fri Jan 17th, 2014 7:25pm
  • News

Associated Press

SEATTLE — A Washington Transportation Department spokeswoman says workers have begun a close-up inspection of the cutter face of a giant machine that got stuck 60 feet underground while digging a highway tunnel under downtown Seattle.

Spokeswoman Laura Newborn says the inspection started late Friday afternoon and work will continue this weekend. The Seattle Times reported that teams of five to six people will clean and examine the cutter in three-hour shifts, working in air at 1.4 times atmospheric pressure. Then they will spend an hour in a tank aboard the tunnel drill, to gradually decompress to normal pressure.

Drilling was halted Dec. 6 by a blockage. Since then, crews have pumped water away from the surrounding soil and sprayed in a clay slurry to help form a crust so compressed air could be pumped in, providing a gap where workers can inspect the cutter.

The state has said that a buried steel pipe is only partly to blame for the stoppage. An independent expert told state senators that the workers’ inspections should solve the mystery.