Jan. 4 project update: Bertha bores toward the access pit wall

Posted on Jan 4 2016 4:32 PM
Seattle Tunnel Partners pushed the SR 99 tunneling machine forward in the access pit Monday, digging the 6.5 feet needed to build the tunnel’s 161st concrete ring. As of Monday afternoon, the machine’s cutterhead was positioned near the northern wall of the 120-foot-deep pit. 
STP is preparing to mine through the approximately 15-foot-thick concrete wall in the coming days. Once beyond the wall, crews will begin tunneling through native soils that will serve as the next stage of STP’s testing process. This section of the tunnel route includes an underground wall that was built to protect the Alaskan Way Viaduct while crews continue to test the machine.
Look for another progress update after crews have tunneled through the pit wall.
Soil-removal barge arrives at Terminal 46
With excavation underway again, STP is resuming its operation for removing excavated material from the tunnel. This is done via a conveyor belt that extends from the tunnel to the edge of the Port of Seattle’s Terminal 46. Material that contains concrete from the access pit wall will be hauled away by truck. Clean material – which crews will encounter once outside the access pit – will be taken by barge across Puget Sound to a reclamation site near Port Ludlow. There, the soil will be used to fill an old quarry.
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