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spledeus
(@spledeus)
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Posts: 2635
January 11, 2018 2:46 pm  

41°41'8.08"N

69°57'46.40"W

Veterans001

A few years ago, I set a DH in the middle of the concrete slab over a utility vault hanging out in the side of a hill overlooking the ballfield.  We have run some static on it over the years without issue.
Yesterday afternoon the crew setup a total station and it would not hold an angle.  They would zero out and the station would move about 4 minutes.
This morning they went out with the backup total station and had the same issue.  They setup on the sidewalk about 20' away and had no issue.

There used to be a siren nearby.  When I was a kid it would go off at noon everyday.  I do not recall when they took it down, but perhaps they placed it in the vault.  I don't even know if the thing had a big magnet in it.

I have a call in to the Town Staff to get into the vault to see what the deal is.  It is a great point for GPS and Total Station.

J. Thaddeus Eldredge, PLS, CFM
Eldredge Surveying & Engineering, LLC


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Bill93
(@bill93)
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Posts: 4495
January 11, 2018 3:17 pm  

Does 'utility vault' mean lots of electrical power, perhaps a monster transformer? I can see that putting out electric and magnetic fields that could affect some equipment in close proximity.

Did you try a brass transit?  See if its compass buzzes.

Or maybe you're just at a weak spot in the space-time fabric.  No telling when or where you will find yourself if it gives way. 😉


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Dave Karoly
(@dave-karoly)
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Posts: 9322
January 11, 2018 3:28 pm  

Backsight on 00-04-00

Problem solved.

I thought it my duty to exhibit things as they are, not as they ought to be. -Alexander Hamilton, August 13, 1782


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Loyal
(@loyal)
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Posts: 2673
January 11, 2018 4:30 pm  

"Perilous to us all are the devices of an art deeper than we possess ourselves."
Gandalf, The Two Towers


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RADAR
(@dougie)
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Posts: 4043
January 11, 2018 5:03 pm  

Are you walking around on the vault? Maybe, if the lid isn't sitting on the structure right, it might wobble a little. 

It's probably somewhere in your set up...

I never did a day's work in my life. It was all fun.--Thomas A. Edison

Citius, altius, fortius


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spledeus
(@spledeus)
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Joined:6 years  ago
Posts: 2635
January 13, 2018 5:37 am  

The vault contains the 2" service and water meter for the irrigation of the ball field.  The top appears to be stable.  The electrical for the field is off 3rd base (2 large above ground electrical boxes), this is off centerfield.  

  • After the storm I will have to try out the old brass compass that we have never use for anything more than decoration.

J. Thaddeus Eldredge, PLS, CFM
Eldredge Surveying & Engineering, LLC


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Mark Mayer
(@mark-mayer)
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Joined:8 years  ago
Posts: 2363
January 13, 2018 7:51 am  

That vault lid is flexing a little when you stand on it to set up your instrument.  Either that or your tribrach is worn out and unstable. 

EDUCATION, n. That which discloses to the wise and disguises from the foolish their lack of understanding.

EXPERIENCE, n. The wisdom that enables us to recognize as an undesirable old acquaintance the folly that we have already embraced.


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RADAR
(@dougie)
2,500+ posts Registered
Joined:8 years  ago
Posts: 4043
January 13, 2018 9:19 am  

Try setting up a robot on it, and see if that helps...

No one walking around, near it, while it spins the angles.

I never did a day's work in my life. It was all fun.--Thomas A. Edison

Citius, altius, fortius


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Peter Lothian
(@peter-lothian)
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Posts: 193
January 15, 2018 1:02 pm  

Is the concrete top integral with the sides, or is it a separate piece?  If separate, there may be some ice in the joint, causing it to rock a bit when the weight distribution on top changes.


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