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What if somebody took a BM?


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I found a station mark toppled over today. The monument is on private property and next to a rural driveway. It was originally set flush to the ground but is now fully exposed and on its side (see pic). Does anyone really use these anymore? Will the owner really get fined or go to jail if their lawn mower bumps into or ‘disturbs’ the mark? What if their cousin from Canada comes to visit, cuts the driveway short with their travel trailer, and runs over the monument; Federal prison? If I were the home owner I would really consider removing the BM. Is there a legal remedy or governing management organization who oversees these that can be called to fix it? a4337f6f-b493-4830-abe2-f0eeddb6d512.jpg

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Benchmarks should be preserved if at all possible, but when they get disturbed so that they no longer mark the intended position to survey accuracy they are no longer of much if any value.


It costs thousands of dollars in professional time to establish or re-establish one to NGS standards. Not all marks are important enough that they will be re-established, and not all marks were that accurate to begin with, but they should be treated as important until proven otherwise.


I have never heard of anyone getting in trouble for accidentally damaging one, but people have been (rarely) fined or contractors made to pay for replacement if they have willfully destroyed an important mark.


The worst thing you can do with a mark whose position is destroyed is to put it back so it "looks" like it belongs there. That can fool someone and cause great expense. I heard of one case where a shopping mall under construction had to be redesigned because someone laid it out using a bad bench mark (without sufficient checking). In that case, they used a local elevation place-holder measured in from official bench marks. Unfortunately, the local mark was a fire hydrant that the city came along and replaced, but nobody on the project caught it until it became expensive to redesign and partially regrade. If you set that concrete post up again you are risking that kind of mistake.


If this mark is in the NGS data base, you would be doing everyone a favor by identifying its PID and sending pictures of the disk and the post to deb.brown@noaa.gov so she can record the fact that this mark (position) has been destroyed.

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I want so badly to make a crude joke about that subject... :-)

Don't worry - I'm running right to the forums - maybe the "out of context" thread. ;)


The above post was due to an Off Topic regular. Those in Off Topic have a huge sense of humor.....


Now, your answer to that picture of the mark you found out of the ground, not just tipped over. It has been totally removed from its "Flush with the ground" position. BUT, it is a triangulation station that has 2 RMs and an Azimuth mark also. It might even have an underground mark where the original station mark had been. This one might be taken out of the post and reset by a professional if they choose to do so. Two of the RMs have been redone already, so it has been used several times and marks redone so it could be used again.


So, I would leave it alone. If you want to tell someone about it, you could Email Deb at the NGS with the picture included.


Just do not take it without an OK by someone from the NGS - "National Geodetic Survey" who is the actual owner of that disk.


Read the "Documented History" on the Benchmark page - RD2436 Damacsus that tells you about the other marks and lets you know it is still a valid station if any of those RMs or Azimuth marks are still intact.





Edited by 2oldfarts (the rockhounders)
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Thanks, Shirley for figuring out which PID it was. I sort of assumed, incorrectly, that it was an elevation mark.


She is right, there could be an underground mark. Although the data sheet doesn't explicitly say so, that was pretty standard practice for several decades.


So if I were reporting what I now know to NGS, I'd not email, but just file a recovered POOR report and explain that the station mark was out of the ground but no one has checked for an underground mark.


No one at NGS is going to get terribly excited about this one. Triangulation stations are perhaps still useful, but not as important as precise elevation marks. GPS has to a large extent replaced the use of these for horizontal (lat-lon) but GPS cannot replace the use of accurate elevation bench marks. This one had a measured elevation at one time, but it is only VERTCON accuracy which isn't great, and a user would probably go to a better one if it wasn't too far away, even if this one had survived.

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You can tell the mark was not set properly. Its supposed to be much deeper in the ground but I suppose at the time the workers figured no one will ever know we only dug the hole 2 ft deep (instead of 5).


If its in an area prone to frost that could cause the mark to become unstable, even push it out of the ground and then its easily disturbed. Seen a few set this shallow before.

Edited by Z15
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As recently as 1975 this Tri Station was still flush, as set.




Suspect that the erosion after driveway widening to match up with the rebuilt highway is the main culprit.



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