The Seattle Times

Ellen M. Banner / The Seattle Times

Friday, June 27, 2014

Losing competitor for 99 tunnel making drill bigger than Bertha

Mud spills from a clamshell scoop Friday near the stalled Highway 99 tunnel-boring machine. Crews are building a ring-shaped shaft 120 feet deep and 83 feet in diameter to reach the buried drill. They push steel tubes into the soil and extract the muck within, making room for concrete to be poured down the tubes. As of Friday morning, 31 of the 80 new pillars that will form the shaft were completed. In September, the tunnel drill is supposed to grind through the south side of the shaft into open air, where a crane is to lift the entire 2,000-ton cutter drive to the surface for repairs.