Contractors building a new highway tunnel under downtown Seattle have started digging a 120-foot pit to rescue a stalled boring machine named Bertha.
Seattle Tunnel Partners also is pumping out groundwater as it digs the 80-foot-wide pit near the Seattle waterfront.
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The $80 million, five-story-tall boring machine overheated and came to a stop last December after digging about 1,000 feet, or about 10 percent of the planned Highway 99 tunnel route. An investigation found seals in the cutting head were damaged.
A crane will lift the cutting head from the pit for repair. Tunneling could resume in March.
Information from: Seattle Daily Journal of Commerce, http://www.djc.com/