Tunnel crews are drilling eight wells 120 feet into the ground to create an environment safe for workers, but the work won't be completed until next week.
By lowering groundwater pressure, workers will be able to safely enter the excavation chamber at the front of the tunnel boring machine. The high pressure combined with loose soils have made it unsafe for workers.
In a release, the Transportation Department said workers will hopefully inspect the obstruction late next week.
The machine was halted Friday by the mysterious obstruction. It may be a huge boulder, but so far WSDOT said it's all speculation until they are able to get eyes on the obstruction.
The boring machine is 60 feet under the streets and about one-tenth of the way into the planned 1.7-mile tunnel that will carry Highway 99 traffic and replace the Alaskan Way Viaduct.
So far "Bertha" the boring machine has completed 1,000 feet of tunnel and workers have continued some work on the tunnel even as the machine is stopped.