Object Blocking Giant Tunnel Borer Was an 8" Diameter Pipe 141
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."
Re:"Presume" there's no pipe? (Score:4, Interesting)
The problem could be serious in terms of time and effort, though. The machine is meant to only go forward -- there is no reverse. Repairing the bits on the face of the machine will require excavating a large void in front of the machine just to create room for the repair work itself. That probably means old and slow classic mining techniques will need to be used.
Re:underground stuff is still really poorly mapped (Score:5, Interesting)
You're spot on with that, look around quickly and you'll find dozens if not hundreds of stories about fiber, water, sewer, and NG being cut because *insert company* laid it out differently than what was in the plans, then refused to update said plans, or even come out and mark. In my own backyard(southern ontario) we still run into things like wood sewer pipes, in use but unmarked. Plank roads with the cast belting retrofit anywhere between 8" to 4' under the road surface, and early 1930's cast iron water and sewer pipes that are still in use, but not documented.
Re: Reading and comprehension skills (Score:5, Interesting)
Anyway:-
(i) The "brown M&Ms" clause *wasn't* at the end of the contract- where it would have been more likely to stand out- it was (presumably intentionally) hidden amongst all the other countless (but important) technical requirements.
(ii) The clause also stated that if it was not followed *the entire show would be forfeit*. That's a rather major penalty, and one anyone who'd actually been paying atention would be almost certain to want to avoid by following it to the letter. Hence its effectiveness as an indicator.
(iii) You also omit *why* it was so essential that the technical requirements were followed closely. (I could summarise that, but I'd probably just end up rewriting paragraphs that are more effective in context anyway; just read the blooming thing!
Re:underground stuff is still really poorly mapped (Score:5, Interesting)
Part of my line of work involves calling in "locates" prior to digging. This is generally done on behalf of our customer. Most of the time, people are happy and welcome the security of knowing where things are in the ground behind their house. On occasion, there's the idiot individual that refuses based on some kind of principle or that a locate was already done five years ago. In those cases, we tell them we can either leave the trees in their yard for them, the install costs forfeited, and they can dig the holes and plant the trees themselves, or they can have the locate done so none of the crew guys have to worry about smacking a natural gas line with a skid steer.
Maps and plans are useless. The only way to know what is in your dirt is to have a locate done and most municipalities will/should do this at no cost to the home owner. This also gives you indemnification in the event that you do end up hitting something that needs repair (so long as you dig within the time frame allowed).
Re:underground stuff is still really poorly mapped (Score:5, Interesting)
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.
Correction/confusing summary (Score:5, Interesting)
The tunnel that Bertha's digging isn't another project — the whole reason for digging the tunnel is to replace the Alaskan Way Viaduct. See here [wa.gov].
The wells were drilled in 2002 to study the ground after the 2001 Nisqually quake. But that's a related project, because the Nisqually quake is the reason why we got to thinking about a replacement for the Alaskan Way Viaduct.
Am I making sense? I hope I'm making sense. At any rate, the story summary needs updating.