How to do an impossible survey

Gyro.?ÿ Years ago I almost bought a military surplus version for shooting LiDAR verification points.

Smoke and mirrors.

The gyro would be the HOT setup, but maybe not in the budget.

Look up "plumbing a shaft," that's how it was done in the [good] old days.

All ya need to 2 HEAVY plumb bobs, 2 buckets of oil, some piano wire, and misc. survey stuff.

Loyal

You can use a sonde with an EML (electromagnetic locator).

Alternatively, you can try drilling upwards. There are techniques to do this.?ÿ

That is exactly how my Mining Engineer friend described it. You do need a reasonably large shaft.

The Weisbach Method. Used it in '79 to transfer control down a shaft at a molybdenum (sp) mine in New

Mexico.

Depending on how deep the shaft is, some plumbing pipe, and cheap laser pointers could be effective. Build it top side, index it, and put it down the shaft.

N

Go to end of tunnel. Drill up to surface. ?ÿDone.

Come on Holy Cow.?ÿ I showed you and a 100 other Kansas surveyors how to do this on a Saturday morning in Pittsburg, KS many years ago.

Remember my little demo in the front of the room with a Wild T-1A and a Wild objective pentaprism.?ÿ It is THE perfect accessory for a job like Daryl's.?ÿ The pentaprism is clamped onto the objective end of the telescope and the counterweight fits over the eyepiece of any old Wild instrument.

I have one that I could "loan" out and Scott Zelenek has one.?ÿ Old timers here may recall some photos that Scott posted using his pentaprism with an old-style Wild T-2 and a split-bubble telescope attachment to plumb the outer steel girders on the Freedom Tower.?ÿ His application was a unique way to use an objective pentaprism.?ÿ The Wild folks designed it to transfer bearings down shafts.?ÿ In addition to the pentaprism, the only other items one needs to transfer a bearing down a shaft are two 4-5 ft. graduated staves (as the Swiss call them).?ÿ The most time consuming part of the work is building a platform at the top of the shaft to set the tripod on that also has openings to see the marks on the staves at the bottom of the shaft.

Otherwise, as mentioned earlier, a gyro can determine the direction of the drift to within 20 to 30 arc-seconds.

?ÿ

How deep is the tunnel?

Why not vacuum excavate?

Was simply reverse engineering the problem, Gene. ?ÿFrequently, our linear thinking tendencies complicate finding solutions.

Was just teasing you HC.  ???? 

My big concerns are how safe is that "tunnel" and confined space issues regarding breathable air.  I often go underground, but those occasions are at metal mines that have ventilation systems; at a minimum a vent bag that goes past where I will be.

Don't count on me to volunteer. ?ÿNot my cup of tea. ?ÿWill gladly allow others to do what they enjoy.

Donƒ??t drill up into a sewer pond or septic tank.

That would be the S###'s.

No s### Sherlock!

I hope you're also going to rescue that guy buried next to the tunnel!?ÿ?ÿ?ÿ I think I saw this worked out in an episode of "Hogan's Heros"..?ÿ I'll find the link for you.?ÿ

Not sure how deep the tunnel is but what if you went into the end and drove a rebar up, then used the magnetic locator?

Sonde.?ÿ

It's a small transmitter that can then be located at surface. Used to trace pipes. Sorry it's not really a surveying solution. Your friendly neighborhood pipe camera-ing outfit probably has one.?ÿ

Once you've got that a hole can be bored into the end of the tunnel and a plumb dropped. Then you will have 2 points to work with down below.

BTW- 1999 called - they want their long bob and bucket of oil back. Laser Plumbs can be purchased at HD for under $100.