With an associate I need to as-built the invert of a 7,100 foot long tunnel/pipeline. We ran a level loop and topo survey through the tunnel two years ago. You could stand up in about half the length then and walk bent over in the rest (that hurts the back!). There is a 18 inch gauge RR through it and we were able to use that for access then. They are now installing a 54 inch diameter CMP pipe through the tunnel which is fixed in place with cellular concrete grout. They had some problems with the pipe floating in the grout starting out and the engineer per the contract wants the invert of the completed pipeline verified.
The 54 inch pipe will have hangers for a ten inch culinary water line at 10 foot intervals. These hang down 7 inches from the top. So there is about 4 feet vertical space.
Anybody here done something like this? It's been suggested that you can use some sort of cart to lay down on and then push pull yourself through the pipe with your equipment. If the hangers are sturdy enough I'm going to build some sort of ??tripod? to set instruments on that hangs from the top of the pipe so we can slide under. Another option is to make something that wedges across the pipe to support instruments.
Although I set benchmarks in the roof of the tunnel every 100 feet for the invert design and construction control, the way they are constructing will not allow us to use them or even transfer them into the pipe. So its a new level run through the pipe with invert elevations every 20 feet of so. I can work from both ends but that is still 3,500 feet in. There will probably be a little seep water running in the pipe also. The air inside the mountain is about 45 degrees F.
Suggestions on methods would be appreciated!
Short tripod and short instrument man...
Actually, he is about 6'4" or so. But we use that tripod for short setups, in this case to get under railings that were blocking the line of sight.
When we had to as-built a circular tunnel (that had a few curves), we used a two prism setup and took 8 shots around the tunnel every 50 feet or so. The difficult part was that they could only shut down flow for 2 hours at a time, so we had to set resection points on the tunnel wall using reflectorless every time we had to break down to resume flow, then come back in and use those to resect and continue...
You could use a shorter rod with a prism at the bottom and a prism at the top similar to what we did, and run a 3D traverse up the tunnel. For leveling, we have a 1m fiberglass bar coded rod and also a 50 cm invar strip, so you could run levels as well using the short tripod
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Definitely a scanner with paper sticky targets on the walls that have been precisely leveled and if possible good x & y values on them as well.
Well, first I'd low-ball the job to make sure I got it...
Well, first I'd low-ball the job to make sure I got it...
Nate, that is probably what will happen.
I would skip the level run and do it all with a total station.
What the heck, It sounds like you know where the 54" pipe is.?ÿ It's in the tunnel with a little room to spare. 🙂 Jp
What the engineer needs is the invert elevation?ÿ and station to certify they are in spec (flow line). Doesn't need to be straight horizontal.
If you dont need position
Once through with a digital level, low tripod and cut down staves front and rear
A digital level would probably work if the stationing can be kept good enough.?ÿ They will give you a distance reading to the staff.?ÿ Just not sure it will carry all the way though without accumulating to much distance error.
Leica Disto to measure distance?
I'm thinking survey stations on the roof. Leica spigots on a strong magnet might work, or drill and fix if you are allowed. Leica round prisms can then be orientated which ever way you need to transfer the levels forward. Then resection using a robotic total station on a short tripod or just a plate. On board camera would help with sighting the prisms behind you.
Then some kind if cart on a rope could be used for the invert shots. Or assistant with a short pole.
The hangers from the ceiling could get in the way of the shots to the roof prisms. Might need to fix them to the side wall.
Refraction will be strong. I suggest setting up under each prism location and getting a short vertical shot to it as well as the forward and back prisms. Can then take out the refraction by reciprocal sights.?ÿ
Sounds very claustrophobic. 54 inches sounds bigger than when you're actually in it. 3500 feet in. Be careful who you send in and a plan to get them out would be wise. Can carts run on the corrugated invert?
Sounds very claustrophobic. 54 inches sounds bigger than when you're actually in it. 3500 feet in. Be careful who you send in and a plan to get them out would be wise. Can carts run on the corrugated invert?
And what in the hell is the engineer who wants these as-builts gonna say when some 200 feet section in the middle does not quite meet his slope tolerance requirement?
Sounds very claustrophobic. 54 inches sounds bigger than when you're actually in it. 3500 feet in. Be careful who you send in and a plan to get them out would be wise. Can carts run on the corrugated invert?
And what in the hell is the engineer who wants these as-builts gonna say when some 200 feet section in the middle does not quite meet his slope tolerance requirement?
REDUCTION in PAYMENT.
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claustrophobic - I was worried about that before we did the topo through the tunnel but when I went in it didn't bother me.?ÿ What did hurt was walking where you couldn't stand up fully.?ÿ Very hard on the back.
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I'm considering building some sort of powered cart to travel thru the pipe.?ÿ Might be able to sell it to the contractor that needs to hang a 10 inch HDPE pipe thru the pipe and then the owner could use it later for inspection and other maintenance.?ÿ We all need something for sure.
REDUCTION in PAYMENT.
First, I apologize for this thread detour. ?ÿFeel free to ignore this line of questions. ?ÿ
Is the potential $ amount for reduction in payment to the contractor significantly greater than the $ amount to be paid to the as-built surveyor? ?ÿThat is one heavy weight on the surveyor??s shoulders.
What is the desired slope? ?ÿWhat is the acceptable tolerance?
How far out of tolerance costs how much money?
What good does this reduction in payment serve? ?ÿWill the pipe continue to function?
Again, I apologize for my insolence. ?ÿNo ill will is intended. ?ÿOnly curiosity, education, and understanding.
Thanks for listening.
Brad
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Not that this helps with the current problem, but what should have been happening during construction is a program of regular as-builts of the pipe as it was being layed. That way any problems could have been dealt with in a pro-active way.
By failing to build that into the project specifications the engineer has assumed?ÿ a degree of responsibility for any sub-standard results.
To the OP: Seems like you could incorporate a pipe laser (calibrated, not off the pipe crews truck). It's still setting up an instrument but, this device is made to occupy the invert of the pipe and give true slope (which I believe can be set to 0%).?ÿ
Use a steel tape ("box" or DOT depending on length) for stationing, right angle prism for offsets to each 'wall', and a steel ruler/ scale for measure ups or measure downs. mark the pipe on each side with keel/ scribe to preserve your stations.
No experience with this, just spit-balling. You could tie to your "out-of-pipe" control at each end of the tunnel. The keel (or even a scribed mark in the pipe walls) should last long enough to come back if you suspect a bust anywhere).
As I type this, it makes me ask: If the ONLY interest is slope along the pipe invert, you could have the engineer stipulate the appropriate asbuilt interval. You may not even need to track absolute station or elevation. Just confirm slope via the pipe laser, taped distances and measure downs w/ reasonable overlap between stations (marking pipe laser locations on the wall for returns).
maybe I've had a little too much coffee for this...
Oh, one last thing. Don't forget the skateboards. If the seep water is not too deep, they make for a good rolling seat/ equipment mover.
Not that this helps with the current problem, but what should have been happening during construction is a program of regular as-builts of the pipe as it was being layed. That way any problems could have been dealt with in a pro-active way.
By failing to build that into the project specifications the engineer has assumed?ÿ a degree of responsibility for any sub-standard results.
I agree with what you say and that is what I wanted to do.?ÿ Transfer the existing BM elevations into the pipe as it is being laid.?ÿ It's the construction process they are doing that causes this to be problematic.?ÿ They are grouting the pipe in 1200 foot sections.?ÿ This takes about a week.?ÿ They are limited on time as they can only work when water is not available to run through the tunnel.?ÿ They are already one year behind.?ÿ While they grout they are continuing to lay more pipe.?ÿ Until the pipe is grouted it's somewhat unstable and control set in there wouldn't be reliable. So we can work in there after the grout is set but will need to carry a whole new control.
To the OP: Seems like you could incorporate a pipe laser (calibrated, not off the pipe crews truck). It's still setting up an instrument but, this device is made to occupy the invert of the pipe and give true slope (which I believe can be set to 0%).?ÿ
Use a steel tape ("box" or DOT depending on length) for stationing, right angle prism for offsets to each 'wall', and a steel ruler/ scale for measure ups or measure downs. mark the pipe on each side with keel/ scribe to preserve your stations.
No experience with this, just spit-balling. You could tie to your "out-of-pipe" control at each end of the tunnel. The keel (or even a scribed mark in the pipe walls) should last long enough to come back if you suspect a bust anywhere).
As I type this, it makes me ask: If the ONLY interest is slope along the pipe invert, you could have the engineer stipulate the appropriate asbuilt interval. You may not even need to track absolute station or elevation. Just confirm slope via the pipe laser, taped distances and measure downs w/ reasonable overlap between stations (marking pipe laser locations on the wall for returns).
maybe I've had a little too much coffee for this...
Oh, one last thing. Don't forget the skateboards. If the seep water is not too deep, they make for a good rolling seat/ equipment mover.
Seems like a good possibility (laser and tape).?ÿ They are laying the pipe with a pipe laser.?ÿ The pipe is on a 3 tenths per 100 feet grade. I think they are allowed to drop to 2 tenths but the engineer doesn't want any low spots or humps that cause the water to pond.
