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Rev Mike

Submitting a recovery to the NGS

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I realize that this information must be here somewhere but I am having trouble locating it...

 

I have been looking for benchmarks for a while and I am finally at the point where I am interested in reporting to the NGS.

 

1. I was looking for a link on where to do so.

 

2. Are they only interested in specific marks or just anything in the datasheet archives?

 

3. Any tips on doing this the correct way.

 

4. Interested in perhaps seeing this procedure as a pinned topic.

 

Thanks in advance for any help.

 

- Rev Mike

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A good place to start would be to jump over to the National Geodetic Survey forum and read the Pinned FAQ topic at the top. It should answer most of your questions.

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1. I was looking for a link on where to do so.

 

Submitt a Recovery Report Page

 

2. Are they only interested in specific marks or just anything in the datasheet archives?

 

Anything in their database except the Landmarks like water towers, church spires etc. To many of them are gone or changed to not be of use anymore except for historical purposes. If its destroyed, they would like that info but to report it still there is not necessary.

3. Any tips on doing this the correct way.

 

Look at the reports sent in by others, that is the best info. If you put the Lat and lon you find for marks in the descriptive text, they will capture it and update the scaled positions. SCALED POSITIONS ONLY, anything that has an adjusted Lat and Lon is not wanted.

 

4. Interested in perhaps seeing this procedure as a pinned topic.

Edited by Z15

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2. Are they only interested in specific marks or just anything in the datasheet archives?

 

Anything in their database

Except...they don't want reports on intersection stations unless one can prove that the station was destroyed, right?

 

Patty

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A couple more quick questions:

 

To report a destroyed disc to Deb, the Mark Recovery form states... "If you have found the actual marker separated from its setting, you can report the point as destroyed"

 

If the disc is still in its setting but totaled does that constituted a destroyed?

 

Example:

48c337c2-8ee1-4e43-8943-829ca50cf8d1.jpg

 

If a disc set in a concrete post is found with the post knocked over and buried (not in original location) is that considered destroyed?

 

The wording on the form seems pretty specific but these could often go different ways.

 

- Rev Mike

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Generally for us amateurs, a post knocked over is Destroyed and a stem that remains in position is Found Poor.

 

The pros generally won't want to use a remaining stem for many projects, but might if nothing better is around. It is still a reasonably good horizontal position, or a useful vertical elevation for coarse work.

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Rev Mike -

 

We have asked this kind of question of Deb Brown at the NGS. We have asked it about both horizontal control marks and vertical control marks. Her answer to us has indicated that if we have found anything that we're sure was a remnant of the monumentation to post found poor. The examples have included a vertical control where a disk had been mounted on top of a square cement post and what was found was only the lower section of the post - no disk, no hole, no stem. Yet, she said to log it as found poor.

 

This is not to be taken lightly and to log found -poor for any hole in cement or any broken cement post in the vicinity of where a mark was supposed to be. It has to be really good evidence of the monumentation of the correct marker. I would go so far as to say that if the disk isn't found, then a photo of the suspected remains should be sent to Deb (as was done in the cases above) and let her decide and tell you the answer. Until she says it could be logged as found-poor, then it's a not-found.

 

I think that having a goal to get some marks categorized as Destroyed is not good. The NGS leans hard over toward the idea of getting things logged as either not-found or found-poor, rather than destroyed. This direction of leaning should therefore be used by us as well.

 

This leaning makes logical sense. If a surveyor needs to use an existing mark, then a revised go-to, possibly with GPS handheld coordinates in the case of a vertcal control for the obvious remains of the mark, is better than the mark's existence being hidden (not published anymore) because of its being previously categorized as destroyed. The surveyor will want to be able to make their decision in the field whether or not to use the mark, based on the specifications of their particular project.

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Hi Rev Mike--

 

When I looked at your image, I said to myself, "Boy! I've got one that looks almost identical to that!"

 

So I went back to my photo file and figured out my photo was for MY2614. Then, sure enough, I saw that you were the guy who had logged it just before me, as destroyed. At that time I don't believe you had your image posted however.

 

I called it "Found, Poor" (given that the stem was solid and the apparent plumb point had survived) and reported one of the three RMs as found as well. If I went back today (with a little more smarts and some better equipment) I'll bet I could get at least one more of those pesky RMs as well! :D

 

What's a nice guy like you who signs "PA" doing knocking around up here in MA? I'm in Winchester.

 

-Paul

Edited by pgrig

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Dupe. Sorry, server is very slow and said I had timed out. :D

Edited by pgrig

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I have no goal to submit marks as festroyed here and since I am finally submitting to the NGS for the first time I figured I would ask here first before doing anything.

 

What's a nice guy like you who signs "PA" doing knocking around up here in MA? I'm in Winchester.

 

I do spend quite a bit of my time in MA these days even though I do live in PA.

I just got back from two weeks around Burlington where I looked for a "few" benchmarks.

 

I am still seeing those MAGS discs in my sleep.

 

- Rev Mike

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In one of those FAQs they metioned they only accepted NAD83 data. My GPSr was set to WGS84 when I made a waypoint for a scaled BM. I read some old posts saying they ARE the same and some that say they are NOT the same in North America. Should I take the trouble to try to convert it before submitting?

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Unless your handheld unit is different from any reported here so far, it will read the same in WGS84 and NAD83. Try writing down the coordinates of several waypoints, switching datums, and comparing the new display. If there is any difference, let us know what model you have.

 

In the future there may be recreational grade units where it does make a difference, so it is good practice to select the right datum.

 

WGS84 and NAD83 were originally defined to be identical within the accuracy of the data available at that time. It has since been found that there is an average of about 1 meter difference between them. Also, the definition of WGS84 is fixed to the average of points all over the earth's surface. NAD83 is fixed to the average of points on the major North American tectonic plate. So there is 1 or 2 centimeters per year drift between them. Californians and Alaskans have a bigger drifts to deal with.

 

People who can get repeatable values at that level of accuracy need to do it right. There is a conversion tool HTDP on the NGS site that you might play with. It will probably tell you there is about a meter difference. However, all data has error at some level, so the way points in NAD83 are fitted to the data may mean that the NAD83 coordinates for individual marks have a little different shift from WGS84.

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When reporting to the NGS use WGS84 datum on your handheld device. Since the NGS accepts reports that include "HH" coordinates and all recreational GPSrs use WGS84 as the default datum, that is what will be expected when a surveyor reads the datasheet and sees "HH" coordinates.

 

Remember that logging the benchmark is to allow the next person to seek that benchmark to find it quicker and easier. The difference between the 2 datums is less than a normal walking stride, so it will have no noticeable effect on the next recovery.

 

John

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While I was waiting for my GPS to arrive I had my eye on a few easy monuments on local overpasses that hadn't had a recovery posted for a while. By the time I got my GPS a CalTrans survey crew came through here and used them and put up witness posts. They're still going up and down this section of the highway and are about one step ahead of me. It's been at least three weeks and I haven't seen any new recoveries posted for those monuments. Should I wait a bit longer and give the pros a chance to submit a recovery or should I not worry about it?

 

thnx

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While I was waiting for my GPS to arrive I had my eye on a few easy monuments on local overpasses that hadn't had a recovery posted for a while. By the time I got my GPS a CalTrans survey crew came through here and used them and put up witness posts. They're still going up and down this section of the highway and are about one step ahead of me. It's been at least three weeks and I haven't seen any new recoveries posted for those monuments. Should I wait a bit longer and give the pros a chance to submit a recovery or should I not worry about it?

 

thnx

Recoveries submitted to the NGS often take a month, occasionally 2 months before they are published. They are often (but not always) done in a batch shortly after the start of a new month. Also, I would guess not every team would bother to submit every recovery. They have too much else to do to pay their expenses. They are more interested in their own projects and probably marked these (with witness posts) because they will have ongoing work in the area in the near term.

 

Take it easy, wait a few month and then check back.

 

Any pros here have a take on this subject?

Edited by Papa-Bear-NYC

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You didn't really say, but by all means, log them on Geocaching.com, if you haven't. Assuming they are on there.

Edited by Klemmer & TeddyBearMama

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