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00000181-fa79-da89-a38d-fb7f2a000000Bertha, the world's biggest tunneling machine, is a five-story-tall monstrosity of drilling tasked with digging out the tunnel for State Route 99 to replace the Alaskan Way Viaduct. It's journey to the center of the earth underneath downtown Seattle began in July 2013, and since then the project has seen its fair share of successes and failures.Follow the progress of the $3 billion megaproject with KUOW.

Waterfront Project Nearly Complete, But That Last Stretch Is A Doozy

Seattle City Councilmember Mike O'Brien, longtime opponent of the waterfront tunnel, has been pushing Washington State Department of Transportation officials to be more transparent.
KUOW Photo/Joshua McNichols
Seattle City Councilmember Mike O'Brien, longtime opponent of the waterfront tunnel, has been pushing Washington State Department of Transportation officials to be more transparent.

Pioneer Square sank more than an inch, and Bertha the giant tunnel boring machine is still stuck, but state officials are putting on a happy face.

Washington State Department of Transportation officials returned to the Seattle City Council Monday to discuss worst-case scenarios for the waterfront tunnel project. Bertha, stuck under downtown Seattle for nearly a year, was mid-rescue when officials realized that buildings were settling deeper into the ground.


But officials offered an optimistic view of the project – and assured residents and business owners that their creaky buildings are perfectly safe.

“To date, the buildings that we’ve looked at, there’s no indication of structural damage at all. And the damage that has been identified is very cosmetic,” said Todd Trepanier said of the state transportation department.

Ann O’Meara, who works in Pioneer Square, sits half a block away from the site where contractors are digging a massive pit to rescue Bertha. The land beneath her feet sank about 1.3 inches recently.

“I had a few friends ask me yesterday if I can feel myself sinking while I’m at work because they know that I work in Pioneer Square,” O’Meara said. “And I said 'I can’t, but I believe it is happening.'” 

At the City Council meeting, Trepanier said the ground has stopped settling. And he offered good news: The citywide waterfront project – of which Bertha is a part – is 70 percent complete.

But that last 30 percent is going to be the hardest, according to Seattle City Councilmember Mike O’Brien. “We’ve gone a thousand feet out of a two mile tunnel digging project. And the machine is stuck and we haven’t figured out what’s actually wrong with it or how we’re going to repair it. To imply that somehow we’re mostly done with this is, I think, misleading at best.”

What Keeps Project Managers Awake At Night

Monday morning, state officials described a collection of hypothetical nightmare scenarios that could further delay the project.

If the viaduct settles more than two inches total, contractors would be forced to fix it. The state could be liable for some of those costs.

If the ground water pumps stop working, the pit could turn into a muddy mess.

There’s a water main that Seattle Public Utilities says is close to breaking due to all the ground settlement. That has to be replaced.

There’s less money to help people move through downtown once the viaduct comes down. The state’s mitigation funds earmarked for mass transit have already been spent. An early viaduct closure due to further ground settlement could dump a lot of cars downtown and put a lot of pressure on Metro Transit.

Meanwhile, Washington officials are expanding the area they monitor for ground settlement. They’re going to start looking further east, uphill from the proposed tunnel route. They want to see just how far this ground settlement thing goes.

Last weekend, state officials asked contractors to stop digging the pit meant to access the stuck drill. They gave no indication of when work would restart. 

[asset-images[{"caption": "In this diagram, the blue dotted lines show how far the groundwater table has been drawn down beneath the Bertha access pit.", "fid": "106918", "style": "placed_wide", "uri": "public://201412/Groundwater.JPG", "attribution": "Credit Shannon & Wilson, Inc/Washington State Department of Transportation"}]]