Mysterious object block Seattle tunnel progress

It was revealed today that Bertha was stopped when a huge steel pipe became entangled in its cutting head. The nearly month-long delay in tunneling was caused by a steel well casing left underground in 2002. The well was made to assess the groundwater situation along the tunnel route, long before the tunneling part of the project got underway. It has not been explained why the pipe had not already been removed some time ago.
blogs.seattletimes.com...

Hi Ross 54,
Thanks for the updates which you posted. It is good to know what caused the delay. That must be the most expensive piece of pipe for quite a while.

A buried steel pipe is mostly to blame for stopping the giant tunnel-boring machine Bertha, which has been stuck since Dec. 6 along the Seattle waterfront near South Main Street.

As you can see I emphrasised the "mostly" which I think is strange to word it that way. If it was mostly the steel pipe, then perhaps there must be something else as well.

I would assume they have ground radar and all kinds of gismos on the front of that thing pointing forward so that there would be no surprises in the few yards in front of the cutting heads.

Anyway, I guess we need to keep watching as they remove the steel pipe and find out what else there was.
It may be a good idea to contact the reporter and find out why they used that phrase and if there is anything more.

Alternate sources mention other possible factors that could have impeded Bertha. Soil conditions, wear on the cutting head surfaces, other objects in the tunnel or lodged inside the machine. The latter two would likely be more fragments of the well casing, which Bertha appears to have twisted into fragments before it was stopped.

NowanKenubi
Here is the image of the head of the most boring machine in the world. You have to wonder what made it stop...

Picture is from popsci article rickymouse linked and that works in east Canada.

Just the way my mind works, but the first thought I had when I looked this over was: "I'm gunna DRILL you Quade!! I'm gunna GRIND YOU UP!!

According to the Seattle Times story there are a few weird points:

• They said the pipe is only "mostly to blame."
  
  
• They said that Bertha cannot chew through steel.
  
  
• They knew a steel well casing pipe 8 inches in diameter and 115 feet long was buried in exactly this place in 2002. It's even shown in their specifications.
  
  
• They say they presumed it wasn't that pipe that stopped Bertha [even though Bertha was stopped exactly where the pipe was known to have been] because such pipes are normally removed.
  
  
• They say they continued to presume the pipe was removed even though for months they had been seeing pieces of other steel pipes that were not removed passing through Bertha's conveyor system and even though Bertha previously shoved another piece of unremoved 55-foot long steel pipe through the surface.
  
  
• They don't say why the other pipes were in pieces in Bertha's conveyor system if Bertha can't chew through them.
  

It seems like a whole lot of presumption and denial of the evidence before their eyes if it was really a pipe they knew of all along. And it has cost the project a great deal of time and money. So it should be fairly easy to tell whether this is the truth or is a cover story:

• If it's the truth, one or more heads should roll.
  
  
• If heads don't roll, it might be a cover story.
  
  
• And if the people responsible all get commended for a job well done, they're either the governor's nephews or maybe it really is the secret underground Starbucks or Microsoft galactic base. [Or my son says giant diamonds)
  

The New York Times weighs in on recent developments in Seattle. Has the advantage of perspective, via distance. It looks as if everyone responsible assumed that someone else had removed that obstructive well casing, because that was how things were supposed to be done...
www.nytimes.com...

Other bits and pieces:

seattletimes.com...

Bertha is unable to chew through steel. A railcar or metal beam would need to be plucked out. It’s unknown whether the blockage will lead to cost overruns. Tunnel builders might conceivably file a claim based on “differing site conditions” that state studies didn’t predict. The Highway 99 contract includes contingency funds for such cases.

The contingency fund is 20% apparently but they have had that labour dispute which stopped tunnelling for some weeks too.


in the comments section

Currently the tunnel is behind schedule. They are considering options like increased work hours to get the project back on schedule. Right now they can still get it back on time, but at some point in the near future that won't keep them on time. The only reason it is still on budget is because STP and the other contractors are still working out the price tag and who is paying for the last two issues.

www.tunneltalk.com...]Dewatering to help deal with stuck Bertha 20Dec2013

The 17.5m diameter machine currently stands about 60ft (18m) - still with only just one TBM diameter of cover - below the junction of South Jackson and South Main streets, to the west seafront side of the viaduct (Fig 1). On Wednesday of last week (18 December), crews were able to turn the machine's screw conveyor and remove some material from the excavation chamber to allow a quick view through one of the man locks at the top of the machine, states the WSDOT release. It continued that "nothing extraordinary" was observed in the chamber before it began to fill quickly with water and the lock door had to be closed.

I think it is strange that none of the steel pipe was found in the conveyor system. They had found steel pipe before which had got chewed up, so I guess this one is a lot bigger than that previously found. I know nothing about this subject, but 18m beneath the surface as mentioned above seems very little. I cannot help feeling that some of the high-rise buildings on top of this are going to sink or have cracks appear.


Here’s a recap of what crews have been up to since the blockage occurred

* On Dec. 7, our contractor, Seattle Tunnel Partners (STP), began prepping the machine and surrounding environment so crews could inspect the cutterhead and excavation chamber safely.
* On Dec. 17, a brief visual inspection of a small section of the excavation chamber and cutterhead found dirt, sand and cobbles – nothing unusual.
* Over the holidays, STP crews were on-site to drill dewatering wells, maintain the machine and switch out cutting tools on the machine’s face.
* Earlier this week, STP drilled 17 small-diameter, exploratory holes near the front of the machine to see if they could identify an obstruction. They encountered obstructions in four of the holes.
* On Jan. 2, the water pressure was low enough and enough soil was removed from the excavation chamber to inspect the top 15 feet of the chamber.
* This inspection showed an 8-inch-diameter steel pipe protruding through one of the many openings in the cutterhead. We believe the steel pipe is a well casing installed by WSDOT in 2002 after the 2001 Nisqually earthquake to better understand how groundwater flows through this area. The location of this pipe was included in reference materials in the contract.
* We also believe at least some of the obstructions found by the exploratory holes are pieces of the 2002 steel pipe, which could be a contributing factor in the delay of boring.
* Other potential factors include changing soil conditions that may have caused excessive wear of cutting tools, potential objects in front of the cutterhead or objects in the lower portion of the excavation chamber that still aren’t visible.


Next steps
STP is considering several options to remove the steel pipe and identify other potential obstructions.
...

reply to post by qmantoo


Thanks for the up-date.

And the arguments about who will pay begin...

bertha News

WSDOT secretary defends Bertha, Seattle tunnel despite longstanding concerns 16Jan14

Washington's transportation secretary is again defending the Seattle tunnel project, despite telling lawmakers in a letter Wednesday there have been a number of concerns since the tunneling machine launched in July.

WSDOT Secretary Lynn Peterson told lawmakers she has asked for answers to questions about the project including why the world's largest tunneling machine was operated at "extremely high temperatures" before it was shut down in December after running into an obstruction, and what the contractor is doing to make sure it can deliver on the project as promised.

But Peterson refused to criticize the contract or the contractor during an interview Thursday with KIRO Radio's Dori Monson, insisting WSDOT is just keeping oversight.

"If we weren't strong owners, we wouldn't be doing what we've been doing since the actual construction of the machine itself, which is ask the hard questions," Peterson said. "We just want to make sure that before Bertha goes any further below Seattle that we have all the answers we need to feel confident that she can make the entire run."

Seattle Times blog posts about Bertha


WSDOT: Bertha can be fixed and will complete tunnel project 13Jan14

Seattle's tunnel: SR's got 99 problems, but the steel pipe ain't one

“All of our ground investigation out in front of the machine has been inconclusive,” he said.

Trepanier said the pipe might not be the only problem. “I think maybe that is a contributing factor," he said. "But there are other issues that are being dealt with and wanting to be understood at this point in time on why this machine stopped.”

There have been difficulties, he said, with material not flowing correctly through the machine and wear to its metal teeth, which weigh about 1,200 pounds each.

“I don’t necessarily agree with the word stuck,” Trepanier said later, referring to Bertha’s current status. “The cutter head turns, you can mine with this machine. It would be like driving in your car and the warning light is coming on and telling you to stop.”

Bertha tunnel crews go ‘hyperbaric’

Teams of five to six people will clean and examine the cutter in three-hour shifts, working in air at 1.4 times atmospheric pressure, the paper said. Then, the crew members will spend one hour in a hyperbaric tank aboard the tunnel drill to gradually decompress to normal pressure.

In order to prepare the examination area, workers had to pump out groundwater away from the surrounding soil. A ‘slurry’ of bentonite clay was sprayed in, to stick to the soil walls, allowing a water and air-resistant crust to form. The procedure allows compressed air to be pumped in a 5 foot chamber, pushing outward to prevent water and soil leaks, the Times reported.

The state DOT has said that a buried steel pipe is only partly to blame for blocking Bertha, but managers would not describe their other theories when asked earlier this week.

reply to post by qmantoo


Thanks for the updates! Since it's apparently still inconclusive whether the pipe is the only thing stopping Bertha, I guess that means I can still keep hoping it's found the secret underground Starbucks or Microsoft galactic base.

dreamingawake
Interesting wonder if the block has something to do with the old streets/Seattle underground.

Seattle underground is very cool to explore.

reply to post by HoboHumpinSloboBabe


Heh. I was a tiny little kid when I saw Five Million Years to Earth and it scared the living daylights out of me.

A link, below, to the latest on Bertha and the tunneling project in Seattle. It still sounds as if the steel pipe was the main source of the trouble. They will attempt to begin tunneling again, soon. With luck they may hold the delay to two months, or even a bit less.
seattletimes.com...