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Benchmarks Destroyed During Construction

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I looked all over the NGS site but could not find what a person would do if there is a need to remove a benchmark due to construction, etc. There are a number of benchmarks in my area that have been destroyed due to road construction, railroad signal changes, and other things., and I just wondered what action the builder must (or "should") take to make sure the benchmark involved is returned to NGS. I would guess the answer is "nothing" since there are so many benchmarks that have been removed for construction but no note is made in the NGS database.

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No answers yet. Hmmmm


I asked an engineer here at work and he didn't seem to really know either, but said they would "reset" them if they could. That doesn't quite answer it for me, as I know there would have to be some NGS forms to fill out, etc., etc., etc., before that could be done. Oddly enough, he was unaware of two (of three) benchmarks located on our company's property! And to add more of a twist, those marks are on a piece of property we were thinking of developing a year ago, and even had plans drawn up for the development. Those plans were only sketches though, so it is quite possible nobody even really walked the property or looked at a USGS map of it.

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NGS is suppose to be contacted.

On this one they still have not got the discs yet on the Azimuth and Reference and now I do not know where they are,I even contacted NGS.



A search in this same area will yield Monett Triangulation Station that was moved by landowner request,another is Golden Triangulation Station


There are also several others around here that I dont have the quick link to that have been moved at the request of the landowners due to new construction.


Others just get plowed over in some cases.

Mainly because no one knows they are there, they have not been updated in several years in most cases. :rolleyes:

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I talked to another person in our company and he was aware that it is illegal to remove them but said that if we had land surveyed it would be the surveyor's job to deal with any destroyed, or "to-be-destroyed" benchmarks. I suspect a lot of benchmarks get destroyed when a responsible party is not involved--for instance, when a local building was torn down--someone simply hired a company with a backhoe and a dump truck to do what they do best... end of benchmark.

Others mystify me, such as the replacement of a bridge on a state road. Wouldn't SOMEONE from the state have found that benchmark and reported it to NGS? Obviously not, as it is simply marked "not found" in the database.

And then there are the ones I simply don't believe are gone, as there has been no modification to the area where they are listed as mounted--how would a benchmark in the middle of BFE, mounted in a rock outcropping on the railroad, have simply disappeared? Once all this dang snow melts I will certainly be out there looking for some of those. It is that sort of "find" that appeals to me most.

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NGS does not have the manpower to replace these marks. They seek out cooperation from States and private companies to preserve these marks. It is in the best interest of every engineer and surveyor to preserve these marks. That said, the engineers in our organization could have cared less.


I don't see where you are located but check here for the NGS state advisor. State Advisor's Contact him and he may be able to find someone who will care. My agency DOT, would do everything we could to preserve them or relocate them. Bench marks, those will elevation only are not to difficult to relocate, other horizontal control stations require more work and are often let go.


btw-when a mark is reset, relocated etc, the accuracy is down graded. For instance, if a 1st order mark is reset, it will downgraded to 3rd unverified data. There is just no way to control the quality of the reset work, no matter how diligent the reset it.




Edited by elcamino
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I am in PA, so we don't have a state advisor.


My original post was mostly curiosity about how benchmarks get destroyed, and nobody bothers to report it. After reading your post and talking to our internal engineering staff, few people really care, including those in the industry.


There was a post here somewhere saying benchmarks were outdated and would be replaced by GPS, but of course GPS won't give the accuracy needed to survey a plot of land--I can just see a deed stating "+-30 feet due to GPS accuracy". That sort of accuracy could reduce my land ownership by half!


Benchmarking is something I just discovered, so I have a whopping 3 finds to my credit. Based on other posts here I plan to inform NGS of my finds/not finds.

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Thanks elcamino for the scans--very helpful... 'tis a shame that too few people follow them.

And gbod, I read that thread (it was what I based my statements on) but it should be read by anyone who goes benchmarking and wants to know the importance of finding these marks.


Of course, it is really cool to see that piece of history there too, and to be the first to log it! Can't deny that.

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