Despite a halt to the longshore union’s picketing Tuesday, tunnel-boring machine Bertha needs a few days before it can restart.

One might expect drilling to begin immediately, given that Seattle Tunnel Partners (STP) had four weeks of delay to prepare. But it’s not that simple, contractor and state officials say:

Workers need a couple days to finish adjustments that were under way on large mixing arms that stir the excavated muck, right after it passes through Bertha’s rotary cutting face, said Chris Dixon, project manager for STP. This work was going to happen later anyway, when Bertha stops in a so-called refuge area between Sodo and the Alaskan Way Viaduct this fall. Dixon now hopes to skip the refuge and keep drilling northward.

Conveyor parts need to be fixed, where muck will be sometimes lifted from a temporary stockpile on Terminal 46, and moved to barges, said KaDeena Yerkan, spokeswoman for the state Department of Transportation (DOT). The work couldn’t be done earlier without crossing an International Longshore and Warehouse Union (ILWU) picket line, so it’s happening this week, she said.

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Workers have to be rescheduled from other jobs on-site, said Yerkan.

Complicating matters, STP began the week hunkering down for another delay of two or three weeks, and sent some workers to build an alternate muck-handling bin that would let trucks remove soil via Alaskan Way South, bypassing the docks.

The green light to drill caught managers by surprise, Dixon said Tuesday. “The whole landscape changed,” he said. “We’re very happy with the news. It’s very positive. It’s uplifting the spirits of the people on the project.”

Rumors and tips abound regarding the supposed real reason Bertha is idle — anything from electrical flaws, to an inability to chew through concrete grout in the soil. All of these, the project officials vehemently deny. But if Bertha does have mechanical flaws, those will be manifested, before too long.

When restart is imminent, Yerkan said, the DOT will announce it online, through email, or through Bertha’s Twitter feed.

Mike Lindblom: 206-515-5631 or On Twitter @mikelindblom