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Plans to jump-start the Alaskan Way Viaduct‘s tunnel boring machine were disclosed by Washington State Department of Transportation officials at a Seattle City Council meeting on Monday.

The , developed by the project’s contractor, Seattle Tunnel Partners, call for digging a 120-foot-deep and 83-foot-wide circular access pit in front of the stalled tunneling machine nicknamed Bertha. It has been stuck under South Main Street in downtown Seattle since December.

A second row of 7-foot-wide concrete pillars will be built around the pit to supplement an existing row of pillars built at the beginning of the project.

Spaces between the pillars will be filled with jet grout, creating a watertight and safe workspace in the access pit, said Matt Preedy, WSDOT’s deputy administrator for the Alaskan Way Viaduct Replacement Program.

“The tunnel boring machine will be advanced forward until it is exposed in the interior of the shaft,” he said. “It will then be disassembled from above.”

A circular hole at the top of the shaft will need to be big enough for crews to remove Bertha’s cutter head and its entire inner main drive, Preedy said. The surrounding area will be monitored, he added.

“The effects of construction on the viaduct and buildings in Pioneer Square will be monitored to make sure that the viaduct and other infrastructure are responding consistent with the engineer’s predictions,” he said. “We don’t anticipate that making that into a solid wall is going to have any long-term effect on how the groundwater behaves in the area.”

Seattle Tunnel Partners is finalizing the conceptual plan, according to WSDOT spokeswoman Laura Newborn. She said it was too early to speculate on when Bertha will move again, though STP project manager Chris Dixon is targeting Sept. 1.

For more information about the project, visit .