- Heidi Groover
- A panel of WSDOT officials were met with skepticism from Council Members Mike O'Brien and Kshama Sawant at today's tunnel update.
One of the most telling moments during today’s update on sinkage in downtown came in the form of silence.
Officials from the Washington State Department of Transportation were explaining to the Seattle City Council (all but Council Member Sally Clark, who was absent) how they’re monitoring the area in and around Pioneer Square to find out how much ground settling happened last month, why it happened, and whether it has stopped.
“How much more data, how many of these points do we need to check?" asked Council Member Mike O’Brien. "What does that plan look like, and what is the time frame for getting that data so that there’s a level of confidence that we actually know what’s going on before someone makes a decision to do something"—like, say, keep on with the Bertha rescue effort—"that may adversely affect the viaduct or the buildings or the life [and] safety of people in this area?”
There was a pause as WSDOT administrators looked at each other and back at the council.
“That’s the big question,” project manager Todd Trepanier said before going back to talking about WSDOT’s ongoing monitoring.
The specific decision O’Brien is talking about there is whether Seattle Tunnel Partners, which has the contract to both design and build the underground tunnel meant to replace the aging Alaskan Way Viaduct, should stop dewatering the soil around the Bertha rescue pit in order to make it safe to keep on digging. And if they do stop the dewatering, what becomes of the project?
Dewatering, for everyone (including me) who's not a tunneling engineer, is the process of pumping water out of the area around the pit they’re digging in order to access Bertha, the boring machine that broke down (no one knows why) and needs to be fixed (no one knows how soon that'll happen) in order for the tunnel project to continue. It needs to be done to keep bad subterranean pressures from messing with the digging. But dewatering is also the suspected—though not confirmed—cause of the recent sinking, and the sinking is causing worries about the safety of the viaduct, the thousands of people who drive on it each day, and the historic buildings in nearby Pioneer Square. WSDOT or Seattle Tunnel Partners could decide to stop the dewatering. Then, the pit would be filled back in with either water or dirt, and the work would stop.
But, as O'Brien learned when he tried to ask, WSDOT can't say when it'll know if that's the right course of action. And it’s unclear what would happen to Bertha in that case, though WSDOT secretary Lynn Peterson says there are other ways to access the machine.
Other takeaways from the three-hour meeting:
• WSDOT says the tunnel project is 70 percent complete, but that doesn’t include the removal of the viaduct or the street connections.
• No one knows when the project will be done. “We cannot commit to a specific timeline,” Peterson (who called this a “pretty tense moment in this project”) told the council.
• WSDOT has told Seattle Tunnel Partners to temporarily stop digging at the Bertha rescue pit. Trepanier told the council the excavation is likely not the cause of the sinking, but WSDOT wants Seattle Tunnel Partners to come up with a plan for how they would turn off the dewatering pumps if they needed to. (Doing it too abruptly could cause new unforeseen problems in the soil.) Then he explained why, if the rescue effort is going to continue, this may actually be a bad thing: “Every day they’re not allowed to excavate is a day longer they must continue pumping. If the point is to try and minimize pumping, the smart decision is to get the excavation done and get Bertha into the shaft as soon as possible."
• The state’s contract with Seattle Tunnel Partners allows for up to 2 inches of total settlement throughout the construction process before the tunnel builders are required to do “additional strengthening to the viaduct.” (WSDOT was supposed to bring the city council a copy of the contract language today, but forgot.) The viaduct sank about 1.4 inches in November, which prompted this whole discussion.
• WSDOT has inspected 20 buildings in Pioneer Square. Four of them show some “cosmetic damage,” like cracks, sticking doors, or drywall dust on the floor since the settling. None of them have structural damage, according to the department. The agency will inspect 10 more buildings in coming weeks.
• Leaders at Seattle Public Utilities believe a 16-inch water pipe near First Avenue was bent thanks to this recent ground settlement. The pipe isn't leaking, but will likely have to be replaced.
• Mayor Ed Murray talked to Governor Jay Inslee about all this on December 4, when they agreed that “public safety is the top priority,” according to Deputy Mayor Kate Joncas. The mayor’s office has convened a group of leaders from city utilities, transportation, police, fire, and other departments to update each other on how the settling is affecting them and their plans in case of emergency. This is called a “unified command structure,” presumably because it helps add to the whole spy thriller/apocalypse vibe.
• It’s still not entirely clear, as O’Brien put it, “who makes the call when the viaduct is no longer safe.” WSDOT reiterated that they would shut down the viaduct if it was a threat to public safety, but it’s widely agreed upon that the viaduct is already unsafe. So, just how unsafe does it have to get to be shut down? WSDOT can’t seem to say. Not today and not in Peterson’s guest editorial in the Seattle Times this weekend. The Seattle Department of Transportation, meanwhile, has flatbed trucks loaded with all the equipment they’d need to “at a moment’s notice mobilize and close down the viaduct,” according to SDOT director Scott Kubly.
• In the face of all these unknowns, those who opposed this thing from the start say it’s time to pull the plug, and those who supported it are digging in. Council President Tim Burgess—who traded barbs with Council Member Kshama Sawant during the meeting when she called on citizens to “not forget where this whole boondoggle started”—released a statement after the meeting saying, “There’s no turning back at this point.”