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Object Blocking Giant Tunnel Borer Was an 8" Diameter Pipe

Posted by Soulskill on from the at-least-it-wasn't-zombies dept.

An anonymous reader writes "A few weeks ago we discussed news that a tunnel boring machine measuring 57.5 feet in diameter was halted underneath Seattle after running into a mysterious object. Project engineers have now figured out what the object is: an 8-inch-diameter pipe. In 2002, researchers for another project — the replacement of the Alaskan Way viaduct — drilled down into the ground to take water samples. They used the 115-ft-long pipe as a well casing. As it turns out, this well site was listed in the contract specifications given to all bidders for the tunnel's construction. In addition, the crew manning the machine noticed that it was chewing up pieces of metal, and they removed part of the pipe and kept going. Only later did they realize that significant damage had been done to the machine's cutting face. Officials aren't sure how long repairs will take, or how much they will cost."

9 of 141 comments (clear)

  1. Reading and comprehension skills by petteyg359 · · Score: 5, Funny

    Looks like somebody forgot to RTFM.

    1. Re:Reading and comprehension skills by cold+fjord · · Score: 5, Funny

      Looks like somebody forgot to RTFM.

      In this case they get to RTFM: Repair The Fine Machine

      --
      much of left-wing thought is a kind of playing with fire by people who don't even know that fire is hot - George Orwell
  2. underground stuff is still really poorly mapped by Trepidity · · Score: 5, Insightful

    Even recent stuff tends not to be recorded in a nice way, like a computerized 3d model that can be used to keep all the data in one place and plan excavations. Instead it's often just a list of things in freeform text, like "well site at [lat,long], dug 2002, depth 115 ft". And older stuff is even less well documented; nobody really has an accurate map of what's under NYC.

    --
    10 PRINT CHR$(205.5+RND(1)); : GOTO 10
    1. Re:underground stuff is still really poorly mapped by sjames · · Score: 5, Funny

      That's why you should always carry a foot of fiber in your pocket.

      If you're ever stranded in the middle of nowhere, just bury the fiber. When the backhoe shows up to break it, hitch a lift.

    2. Re:underground stuff is still really poorly mapped by Solandri · · Score: 5, Interesting

      That happened at the hotel I used to work at. One of the tour buses entering hit and knocked over a gate, which hit an electric utility pole. I never got the next part of the story straight, and probably nobody knows for sure. But the underground piling holding the gate bent and burst an unmarked gas line as it shifted underground, and somehow a spark from it or the power pole lit the gas.

      The ensuing fire required 2 fire trucks, 4 Gas Company trucks, and one Edison truck on-site as they tried to figure out what to do. The hotel was over 100 years old and the break was before the meter so in a section of pipe that was the Gas Company's responsibility. They couldn't find any records of where they had originally installed the gas lines, so they couldn't simply go upstream and turn a valve to shut off the gas, at least not without shutting off gas to the entire neighborhood. They had to bring in special equipment to trace the pipe underground several hundred feet upstream to the main pipe under the road. They determined no shutoff valve had been installed when the line was first constructed. So they picked a good spot between the fire and the road, dug down (with shovels so as not to cause another break), and spliced in a new shutoff valve. The fire burned for over 2 days while they did all this. The gate was ruined. The power pole was a write-off and Edison had to install a new one. I spoke with the Gas Company guy in charge of the whole thing and he said this was the biggest incident he'd ever been involved in in his 30 year career, and it was the main topic of discussion for several days among all the Gas Company branches in the entire Southwest U.S. We were just fortunate the fire was in a remote location and didn't spread.

      Always document your work.

  3. Was expecting an alien spacecraft... by K.+S.+Kyosuke · · Score: 5, Funny

    But it turns out that the boring machine found a boring object! (Why am I not surprised?)

    --
    Ezekiel 23:20
  4. Re:"Presume" there's no pipe? by gman003 · · Score: 5, Informative

    But for a $1.44B hole in the ground, I'd want to make damn sure every inch I dig through presents abolutely no risk whatsoever.

    And how do you suppose they are to do that? The only real way to see exactly what is underground is to dig a hole. Sonar only gets you so far, records are sketchy and incomplete, at the end of the day the only way to be 100% sure there's nothing in the way of digging a hole is to dig the damn hole.

    This was a fuckup, sure, but it's on the scale of "we hit something we knew we were going to hit (although not exactly where), we removed it when we hit it, but it turns out it fucked up the drill head when we tried to drill through it." I wouldn't bet on this causing the whole billion-dollar project to fail - it's most likely to be a couple hundred grand, maybe a few million in repairs. And that's coming out of the contractor's profits, not from the state, most likely.

  5. Re:"Presume" there's no pipe? by Cryacin · · Score: 5, Funny

    Yeah, that'll probably work something like this...

    Welcome to Alaskan Way Viaduct customer support. Your call is important to us. We are receiving a higher than expected level of calls at the moment and thank you for your patience. You're approximate waiting time will be 30 minutes.

    4 hours later
    Pleased to be welcome to Alaskan Way Viaduct customer support, how may I help you?

    "Hello, Alaskan Way Viaduct project officials? This is STP. The DOT says you bore a hole in the ground in 2002. We're just calling to make sure you guys removed the pipe."
    Pleased to be sorry, sir, I do not know what you mean about DOT.

    15 minute explanation later...

    Pleased to be putting you through to my manager

    2 hours later

    This is Alaskan Way Viaduct level 2 support, how may I help?

    "Hello, Alaskan Way Viaduct project officials? This is STP. The DOT says you bore a hole in the ground in 2002. We're just calling to make sure you guys removed the pipe."

    The documentation states that the pipe has been removed sir.

    --
    Science advances one funeral at a time- Max Planck
  6. Bits are replaceable; it's the rest of the face... by Anonymous Coward · · Score: 5, Informative
    The cutting bits are designed to be replaced; it's a PITA process but it's very much a normal operating procedure. (They're bolted in from the back; the top picture on the tunnel boring machine wikipedia page shows a machine with all the bits removed.)

    The problem is if there has been damage to the rest of the face, the support structure around the bits. This is not accessible while the machine is in operation, particularly for an earth pressure balance machine like they're using. (Required when there's lots of groundwater or a need to minimize surface disturbance, such as in an urban area.)