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Destroyed Or Not Found


Red_Cedars
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Red Cedars,

 

It is definitely not found, and here on GC.com you could log it as destroyed or as not found and say probably destroyed.

 

If you wish to log it with the NGS you will need to e-mail Deb Brown with the pictures and all other pertinent info and she will make the final decision.

 

Just curious, but what did the cover of the casing have stamped on it? Most in our area are stamped or cast with the word "survey" on them and that helps verify that you look in the right place.

 

Hope this helps,

 

John

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It seems strange that a disk and its concrete mounting could disappear leaving the tube in place. I presume you have checked distance from RM4 to be sure this is the right cover.

 

Can you estimate height relative to RM4, which was described as 0.5 foot higher than the station mark? If you don't have any fancier tools, you might be able to sight for that distance across a carpenter's level mounted to a camera tripod to a yardstick placed in the hole, and get an idea if you have dug far enough. There could have been regrading since 1976.

 

I don't think Deb will take a destroyed on this, and certainly not if you haven't gotten to a bottom in the hole.

Edited by Bill93
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It seems strange that a disk and its concrete mounting could disappear leaving the tube in place. I presume you have checked distance from RM4 to be sure this is the right cover.

 

Can you estimate height relative to RM4, which was described as 0.5 foot higher than the station mark?

 

...

 

I don't think Deb will take a destroyed on this, and certainly not if you haven't gotten to a bottom in the hole.

Yeah, I thought of that. Distance to RM4 checks out, as do the approximate distances from the nearby cross streets. The casing cover is not stamped, but "survey" can be made out in the casting.

 

I've e-mailed Deb with the particulars and supporting photos and will let her make the final decision when she returns. Personally, I'm all for "not found". To my way of thinking, that's just as good, if properly described.

 

Besides, I went looking for SD0855 right after not finding this one and SD0855 IS destroyed, without any doubt. I've posted photos and supporting documentation to Deb.

 

R_C

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R_C,

 

More often than not, NGS will not destroy a Survey Marker which was monumented as a disc, unless the destroyed disc is empirically shown as not just missing but actually in possession and separated from it's mounting or original location.

 

In other words, you could dig to the bottom of any hole a Survey marker was supposed to have been in and not find it, and NGS would only allow a not found for this, but if along the same hole was a concrete setting with a disc mounted in it, and the photos showed the disc and what was stamped on it, you could ask Deb if she felt that was enough supporting evidence to show it was destroyed, and if her eyes concur that all is matching and shown to be altered from it's original location, she can choose to call it destroyed.

 

Some markers, in fact the majority of those which are most likely destroyed will be forever not founds for lack of supporting evidence that shows them in destroyed condition.

 

Hope that helps R_C, and remember, Strange things happen. Your narrative on this station does leave some interesting clues. Perhaps you can revisit this on the next trip to Ocean Shores.

 

Good Luck, Rob

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My guess is that you have found the shut-off valve to that fire hydrant. The valve could easily be deeper than 2'. Keep digging!

 

I just found this same configuration last weekend at a geocache in Gig Harbor and the cap looked similar to yours.

 

Other possibility might be that the road level was raised since last recovery but that does not seem likely. Did you check the elevation differences between RM 4 and the station?

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About a year ago or longer there was an argument put forth that this condition could also be recorded on gc.com benchmarking as found. Not everyone agreed but the logic had merit.

 

The logic was that you clearly found evidence at the location but the monument was damaged or missing. It was suggested that the log might read: Found – damaged, or Found – destroyed.

 

Further qualification included that in order to log as Found in this situation there needed to be unquestionable evidence of the monuments exact location. Examples would be a concrete pier with the clear impression of the disk, or this topic's photo evidence if the measurements, elevations and descriptions match exactly.

 

A Destroyed log would be where it is very clear that all evidence of the marker was removed as in major regarding or complete demolition of the building, structure or sidewalks that the monument was located in.

 

A DNF would be when no clear evidence is available that the monument was destroyed AND no evidence such as a concrete pier or the casing in this topic was found.

 

For this topic example, however, I would want resolution to the 2' of digging not producing a marker.

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For this topic example, however, I would want resolution to the 2' of digging not producing a marker.

Good point. I should clarify. I removed all the sand in the casing to a depth of 1.5 feet. At that point, the bottom of the hole was tapering severly towards the center. The last .5 feet, while it did remain burried, was not sufficiently wide to be hiding a standard disk as described. It MAY have been hiding a stem, but even that is doubtful. I didn't have sufficient tools to remove what little sand remained in the casing, so probed the remainder. I suspect the depth to which I probed was the original mounting hole for the monument, but again, I can't be certain. I hit obstruction at about 2 feet in an area about one inch diameter.

 

The more we discuss this here, the more I'm inclined to go with my original thoughts of "not found" with a good description. But, I'll wait and see what Deb says when she comes back, even though we all suspect the same answer: "Not Found". :anibad:

 

R_C

 

Oh, and the casing I found was not the shut off for the hydrant. I found that as well. It's casing is marked "water".

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There could have been regrading since 1976.

:anibad:

 

You've obviously never been to Ocean Shores. I don't think they've put down new roads since they were new in the 60s. B)

 

Although you do raise a good point. They're actually starting to build new homes in the area, including adjacent to this mark. It may be that the mark was removed in anticipation of resurfacing the road. Time will tell, I suppose. It may be worthwhile to revisit this station in a year or so.

 

R_C

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I just got a reply from Deb.

 

Hi Steve,

 

Let's call this POOR/DISTRUBED and in the text portion of the form explain the extent of the problem.

Sounds to me like this supports the older topic suggesting that this could be logged on gc.com as:

 

Found - (Disturbed, Poor, Damaged, etc)

 

Hope I'm not straying too far off-topic.

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Okay we're all wrong.  :D

 

I just got a reply from Deb.

 

Hi Steve,

 

Let's call this POOR/DISTRUBED and in the text portion of the form

explain the extent of the problem.

 

Good question.

 

deb

 

So I'm off to log it. :D

 

R_C

R_C,

 

Before you take Deb's thinking on this as law, please consider my surveyors point of view.

 

This station you are discussing is a third order triangulation station. What this means to me as a Surveyor is that I have to set up a total station, an Optical Theodolite which has built in Computer and EDM, over this station and center the instrument with the optical plummet over the little dot inside the triangle... But there is no dot, no triangle, you cannot find a brass disc even.

 

Uh, I hate to be a killjoy, but I cannot accurately survey from this location if I cannot center my instrument exactly over this. Guessing would not give me the accuracy I need and throw all the measurements to other Tie in's off, so how can I use this station? How is it poor if there is no disk that you can find?

 

I would say nothing is forever. I mean, you did not find the disc. The disc itself is what I need in order to survey from this point. Ok, then why not report it as not found? If you return and find it later, you can file a found. These status changes can and do happen. People find markers that were not found all the time. Something that is poor must be examinable to determine a condition called poor, wouldn't ya think? That means to me that I would have to find it, see it and examine it in order to determine the markers condition is poor.

 

I honestly cannot conduct a survey from a monument I cannot find. I am not trying to hurt your score, but just get to the purest recovery you can make. If you have to read a disc to claim a find and you found no disc, then what else could it really be?

 

If I don't find one, I don't find it. It isn't a crime.

 

Just some food for thought. I am not meaning to be overly critical either. I hope it helps you see it as a Surveyor would. If we are asking Deb, that end user would be a Surveyor, not a game player trying to win a find, and they would find no disk to use. Yes?

 

Rob

Edited by evenfall
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I am not trying to hurt your score, but just get to the purest recovery you can make.

Just for the record, I "score" all reports the same. "Found", "Did not find", and "Destroyed" are all the same to me. In fact, I get more satisfaction from well reported DNF than an easy find. I'm just going with what I was told by Deb, whom I consider to be the final authority (even if I agree with you :ninja: ). I DO try to make the report as reasonable as possible. And I HAVE already submitted my recovery report. In the written portion (rather extensive) I included the fact that the disk was not found. Personally, I was surprised by Deb's response but went with it. As long as the problems are thoroughly described in the write up, I see no problem with her decission. FWIW, the text of my written report follows:

 

Found the Monument Casing as described. Casing was full of sand.  Removed all the sand in the casing to a depth of 1.5 feet. No monument was found. At that point, the bottom of the hole was tapering towards the center. The last .5 feet probed is not sufficiently wide to accomodate a standard disk as described. There may be remnants of a stem, but could not be confirmed. Probed to obstruction at about 2 feet depth in an area about one inch diameter. Searched for and found RM4 as described, except is now flush with surface. Description puts RM1 in an area that is covered by heavy brush, so did not search.

 

But just out of curiosity, under what circumstances would a mark be considered "Poor/Disturbed"? Wouldn't you have to "guess" with any such mark? If so, why do they even have that description?

 

(ebited for speeling)

Edited by Red_Cedars
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How is it poor if there is no disk that you can find?

 

I would say nothing is forever. I mean, you did not find the disc. The disc itself is what I need in order to survey from this point. Ok, then why not report it as not found? If you return and find it later, you can file a found. These status changes can and do happen. People find markers that were not found all the time. Something that is poor must be examinable to determine a condition called poor, wouldn't ya think? That means to me that I would have to find it, see it and examine it in order to determine the markers condition is poor.

 

I understand the surveyor's needs but I don't think we are bound by this interpretation for logging gc.com benchmarks. I have considered, for example, a concrete post (used for mounting a benchmark) as the station. If the disk is missing and the impression of the disk or some other conclusive evidence is available then the station could be considered as Found but is in Poor or Disturbed condition. I think this is what Deb's response was suggesting. Hence, a Found log would be appropriate, at least for gc.com.

 

For my concrete post example I don't think a recovery report to USGS would be misleading to future surveyors if it stated Poor or Disturbed condition. I suspect that would actually be more helpful than Not Found.

 

But... for the OP example, the mystery is still too great for me to consider it as having found the station. It is not possible to get concrete out of a pipe without damaging the pipe. It would make no sense that the monument would be removed but the pipe or a new pipe be placed back in the street, all without having to repair the asphalt. Three previous finders reported 9 to 12" depth. The measurements and elevations would have to be spot-on to consider this the actual monument station. If that were the case I would hope to be able to dig deeper.

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Found the Monument Casing as described. Casing was full of sand.  Removed all the sand in the casing to a depth of 1.5 feet. No monument was found. At that point, the bottom of the hole was tapering towards the center. The last .5 feet probed is not sufficiently wide to accomodate a standard disk as described. There may be remnants of a stem, but could not be confirmed. Probed to obstruction at about 2 feet depth in an area about one inch diameter. Searched for and found RM4 as described, except is now flush with surface. Description puts RM1 in an area that is covered by heavy brush, so did not search.

After reading your report and re-reviewing your photos and the recovery notes I'm thinking that you have found the station and because I think you did a fair job of assessing the measurements to the street and witness post references.

 

You didn't mention that you found concrete in the hole but the tapered hole down to 1" diameter sure sounds like it could be damaged concrete to me. Staining from the sand makes it look like you were digging in harder soil but, again, your description makes it appear to be concrete.

 

Your description could be consistent with someone taking a heavy prybar and hand jackhammering out the concrete around the disk until the disk popped free. Lot of work and a strange sort of vandalism but it sure reads like it to me. Hard to tell the diameter of the pipe from the photos but if it left 1" or more of concrete exposed around the disk this might be a possibility. Fun puzzle! Thanks.

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Hard to tell the diameter of the pipe from the photos but if it left 1" or more of concrete exposed around the disk this might be a possibility.

:lol: The pipe diameter is one measurement I didn't take. :D But if I had to guess, I'd say it's about 8 inches diameter. Given a "standard disk" (say 4 inches for the big ones from Berntsen) as mentioned in the description, that would leave 2 inches around the disk if centered in the pipe. That seems like it'd be enough to chisel. But yeah. It'd be a lot of work.

 

Also, keep in mind that this mark was first placed in 1927. The casing over it wasn't placed until a few decades later when the city of Ocean Shores was platted and the street put in. So the concrete was probably NOT stuck or fused to the pipe casing at all.

 

Jeeze, the trivial history you pick up in this hobby . . . :ninja:

 

R_C

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Red -

 

First, I commend you for a good bit of work. Your search for BROWN and the discussion it engendered is just one of a million reasons why this hobby/game/avocation/activity is so much fun.

 

It also highlights the "standards" situation we face. We have had discussions about the "gamers" vs the "serious" hunters, about GC.com reporting vs the NGS reporting, and now, Rob's excellent introduction of "surveyors'" standards vs. "non-surveyors'". In this case, you have ended up reporting a mark as NOT FOUND in GC, but FOUND-POOR in NGS. Up until recently, I would have considered that impossible (that the "standard" for a hobbyist would be, in effect, more demanding than the standard used by the keepers of the official database). But I agree with your reporting of this station.

 

The key is, I think, not whether the results of the hunt are reported as FOUND, NOT FOUND, etc. etc., but, in such cases as BROWN, what the acompanying words describe. Certainly, all interested parties (ranging from the fun folks to the professional surveyors) would understand what station BROWN's status is by reading your comments (both at CG and NGS) and viewing your photos at GC.

 

Recently, I did some benchmark hunting among the old shore batteries at Fort Monroe, VA. I came across several GC/NGS datasheets that had CGS recovery descriptions for listed (assumed existing) stations that clearly indicated that the stations were destroyed (in the common meaning of that word) fifty years ago. But the stations live on in the database. This (and the example of BROWN) tell me this: The NGS database is, first and foremost, NOT a list of EXISTING geodetic control points, but a list of LISTED points. While most points described as existing may, in fact, exist (in the common, physical meaning of that word)(and subject to validation by current recovery), many don't. For them, "existence" (not classified as DESTROYED) is a term of art employed by Deb et. al. for their particular purposes (or the results of limitations that they impose on themselves for their purposes).

 

So, Rob is correct when he says that the NGS' characterization of a station's status may not be, in fact, controlling or even useful for many purposes. But Deb owns that NGS database and controls the status there. Any discrepancy between Deb's characterization and the needs of the rest of the world is resolvable with good comments.

 

Interestingly, the example of BROWN suggests that the GC.com database (or, at least, that part of it created by the observations of "serious" [i can't think of a better word here without running the risk of giving grievous offense to some]) benchmark hunters could/would provide more relevant information to both hobbyist and professional surveyor than the Gov't's official database. Cool.

 

I still don't think that I could bring myself to "find" something for NGS purposes but fail to find it for the purposes of my hobby, but the possibility certainly is there. And, as I said above, I think your log(s) for BROWN are correct.

 

!! Too much coffee this morning?

 

Again, good job on BROWN.

 

Will

 

p.s. Maybe Deb wanted to keep BROWN in the database for reasons other than geodetic control?? :ninja:

 

Edited in futile attempt to conform to Standard English.

Edited by seventhings
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I tried to read most of this but may have missed some.

 

Do not assume to mark to be dead center in the box. Things could have shifted. I know from experience, we placed a similar box over a BM disk in a concrete headwall of a culvert along US-41. The property owner wanted to fill in the ditch with a pipe for a parking lot. I know for a fact we had the disk center in the box as I checked it after the paving was done, 2 ft below the blacktop lot. Jump ahead about 15 yrs and we are back in the area looking for a BM. So we go to this one and cannot use it. The box is now shifted and most of the disk is so close to the edge of the box we cannot plump a rod on the disk anymore. The surface is what likely shifted..

Edited by Z15
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Red Cedars,

 

The reason the NGS (Deb Brown) says found in poor condition is because the station is a Triangulation station and the reference mark is available to use for resetting the station mark. The original station mark may be gone, but it is still useable if the surveyor resets using the RMs.

 

Maybe we should put more trust in Deb's judgement?

 

 

John

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Hi Steve,

 

Let's call this POOR/DISTRUBED and in the text portion of the form

explain the extent of the problem.

 

Good question.

 

deb

Weird.

 

Could it be that finding irrefutable remains of the monumentation/mounting is a Found/POOR in the NGS database? In many cases, we have found pieces of cement, witness posts with nothing findable nearby, holes in cement, etc. that were NOT irrefutable remains of a monumentation and therefore a NOT FOUND. But this case is different in that the monumentation is, at least deemed by Deb, to be the correct monumentation. Apparently what we would think of as a 'gray area' siding on NOT FOUND, Deb finds an area within this 'gray area' that sides on FOUND/POOR.

 

It has become quite clear that Deb and the NGS generally stay away from classifying PIDs as Destroyed unless the evidence is extremely compelling. In this case, no disk was found separated from its mounting. So, the decision is left to: FOUND vs. NOT FOUND.

 

We have already seen a case where Deb has classified FOUND/POOR for a very obvious mounting near a railroad (I forget the PID, but recall the picture) that had supported a vertical control disk. The surveyors said here that such a situation might have been usable (in the most rough sense imaginable) if it was a horizontal control mark since the center of the remaining monumentation could be approximated. They said that a vertical control in such a condition (gone) could not possibly be useful (the entire top of the monumentation was gone). Yet Deb said to report FOUND/POOR. The present case is vaguely similar.

 

Being a person of 'specifications', I am obviously inclined to analyze this case toward determining what the specification Deb is using actually is. (I've already picked on the NGS for not having 'rules' spelled out in explicit text so there's no need to do that again.)

 

However, this mark recovery thing is complex and not every little contingency and 'gray area' shading can be nailed down with concise 'rules' and specifications. Fortunately, not all recovery information is in the report-type coding. The text allows a surveyor or anyone else to further evaluate the coding by reading the text.

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How is it poor if there is no disk that you can find?

 

I would say nothing is forever.  I mean, you did not find the disc.  The disc itself is what I need in order to survey from this point. Ok, then why not report it as not found?  If you return and find it later, you can file a found. These status changes can and do happen.  People find markers that were not found all the time.  Something that is poor must be examinable to determine a condition called poor, wouldn't ya think?  That means to me that I would have to find it, see it and examine it in order to determine the markers condition is poor. 

 

I understand the surveyor's needs but I don't think we are bound by this interpretation for logging gc.com benchmarks. I have considered, for example, a concrete post (used for mounting a benchmark) as the station. If the disk is missing and the impression of the disk or some other conclusive evidence is available then the station could be considered as Found but is in Poor or Disturbed condition. I think this is what Deb's response was suggesting. Hence, a Found log would be appropriate, at least for gc.com.

 

For my concrete post example I don't think a recovery report to USGS would be misleading to future surveyors if it stated Poor or Disturbed condition. I suspect that would actually be more helpful than Not Found.

 

But... for the OP example, the mystery is still too great for me to consider it as having found the station. It is not possible to get concrete out of a pipe without damaging the pipe. It would make no sense that the monument would be removed but the pipe or a new pipe be placed back in the street, all without having to repair the asphalt. Three previous finders reported 9 to 12" depth. The measurements and elevations would have to be spot-on to consider this the actual monument station. If that were the case I would hope to be able to dig deeper.

I work in the Survey field and use these monuments for a living, But I digress. Perhaps your right. If it is not found, Perhaps it is really Poor or disturbed.

 

If a Geocacher writes an email to someone who is an NGS employee for their opinion, in hopes of making the best recovery they can to the NGS so that the recovery which will remain on the datasheet forever will be as best it could be, then how is this tremain to the purposes of playing games at geocaching? R_C was dealing with an NGS question not a Game Question.

 

R_C, It may be easier to ask NGS type questions over in the NGS Forum in the future. There is a lower likelyhood that others will misinterpret our intentions there. In any case, If one is talking to Deb Brown at the NGS, I feel it is safe to assume you are talking about trying to make an NGS recovery, Not simply a GC.com Game recovery.

 

Digging nearly 2 feet deep in a monument casing when the Datasheet claims it should be nearer the surface is pretty telling... Digging in a monument casing is rarely fun anyway. R_C claims the pavement looks to be pretty vintage, and so I doubt any overlays would make it deeper. He should have found it as described, yet he didn't. Like I said, It can always be amended back to a found good or poor if someone finds it, but I feel R_C tried pretty diligently and did not find it...

 

Again as I said, If I cannot find a disc, I cannot survey from it. It is not Poor, It is not there and that = not found. Just my take. But what do I know. I 'm just a guy who wastes time for poor Stations that aren't really there!

 

:ninja:

 

As always,

 

Rob :lol:

Edited by evenfall
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Found the Monument Casing as described. Casing was full of sand.  Removed all the sand in the casing to a depth of 1.5 feet. No monument was found. At that point, the bottom of the hole was tapering towards the center. The last .5 feet probed is not sufficiently wide to accomodate a standard disk as described. There may be remnants of a stem, but could not be confirmed. Probed to obstruction at about 2 feet depth in an area about one inch diameter. Searched for and found RM4 as described, except is now flush with surface. Description puts RM1 in an area that is covered by heavy brush, so did not search.

After reading your report and re-reviewing your photos and the recovery notes I'm thinking that you have found the station and because I think you did a fair job of assessing the measurements to the street and witness post references.

 

You didn't mention that you found concrete in the hole but the tapered hole down to 1" diameter sure sounds like it could be damaged concrete to me. Staining from the sand makes it look like you were digging in harder soil but, again, your description makes it appear to be concrete.

 

Your description could be consistent with someone taking a heavy prybar and hand jackhammering out the concrete around the disk until the disk popped free. Lot of work and a strange sort of vandalism but it sure reads like it to me. Hard to tell the diameter of the pipe from the photos but if it left 1" or more of concrete exposed around the disk this might be a possibility. Fun puzzle! Thanks.

Again, I just want to point out that this is a Third order station with a Brass disc, inside a monument case. If you find the Case but there is no disc inside, guess what? it is not a find.

 

It is a "you found where the disc used to be..."

 

For gc.com you must be able to read the disc.

 

For NGS the disc would make life a lot easier since the station is in a monument cover and buried in a lot of dirt. It really decreases the accuracy, even at third order to try turning angles with this station...

 

Just my.02

 

Rob

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I tried to read most of this but may have missed some.

 

Do not assume to mark to be dead center in the box. Things could have shifted.  I know from experience, we placed a similar box over a BM disk in a concrete headwall of a culvert along US-41.  The property owner wanted to fill in the ditch with a pipe for a parking lot.  I know for a fact we had the disk center in the box as I checked it after the paving was done, 2 ft below the blacktop lot.  Jump ahead about 15 yrs and we are back in the area looking for a BM. So we go to this one and cannot use it.  The box is now shifted and most of the disk is so close to the edge of the box we cannot plump a rod on the disk anymore.  The surface is what likely shifted..

As Mike said about the shifting. In some municipalities they pave over the monument covers and then come back later, Jackhammer the new Pavement, raise the Monument cover to the level of the new surface and patch around it. This way things stay centered.

 

In other municipalities the leave the cover standing above the surface and try to get over it with the paving machine. Often the screed on the paver hits the cover anyway and moves it in the direction they paved the road, thus causing the surface shift Mike described.

 

Mike and I concur that if you cannot center an instrument over it, exactly, it is of little use. and sometimes you can't. We can debate this point of course, but it isn't going to keep most Surveyors from moving on to a better one. This one just won't meet the standards we have to keep.

 

As to Trusting Deb's judgment, well, we can go with it, but to reset this using RM's is not doable. The Backsight has to be a lot further away than an RM to even say we are accurate here while we are here. You have to go long before you can go short, or you have no accuracy. In order to reset to Geodetic Quality, a monument would need to be re set and then 4 surveys must be closed on this location, minimum, and a least squares adjustment done just to get back to third order quality. NGS is really only accepting A or B order quality for new stations these days, so this would need to be re measured with an RTK GPS setup to get there form here if the site is suitable for GPS at the Geodetic quality level.

 

It would be poor if you can find the stem hole and I have not read where eyes were actually laid on a stem hole. It would be pretty poor... at the bottom of a dark monument casing. Try looking though an optical plummet at the bottom of a monument casing full of wet Muddy dirt sometime! :-)

 

Rob

Edited by evenfall
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...But if I had to guess, I'd say it's about 8 inches diameter.  Given a "standard disk" (say 4 inches for the big ones from Berntsen) as mentioned in the description, that would leave 2 inches around the disk if centered in the pipe.  That seems like it'd be enough to chisel.  But yeah.  It'd be a lot of work.

Yes, I saw the note about the pipe placed over the 12" x 12" monument by the Ocean Shores engineers.

 

Your quoted note confirms, to me, the possibility of it being dislodged by a misguided individual. The prybar I'm talking about is a long heavy bar that can lift a house off its foundation if the bolts have been removed.

 

I own and use this type of bar to bust out house footings where a deck post should go or other concrete busting tasks. I'd say the disk probably was hit several times in the process because it is hard to control the bar in a confined space, especially after you tire a bit.

 

EDIT: This is still an assumption on my part. There could be other reasons why the disk is not visible. I don't think that ground shifting or soil creep has caused the road and pipe to move off center. I don't think Ocean Shores has the geological conditions necessary for that type of movement.

 

But, of course, I'm writing all this from my computer desk 500 miles from the source.

 

Thanks RC for the stimulating benchmark mystery

Edited by Team Sagefox
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For gc.com you must be able to read the disc.

Thanks, I hadn't seen this in the benchmark guidelines prior to your note. I think this suggestion is general in nature and intended to discourage people from logging RM's for the station. I'm not sure it is appropriate in all situations.

 

For me, finding the exact location, and being certain that a preponderance of the evidence supports my assumption, is as satisfying as finding a marker. Actually, it offers an extra bit of sluthing and a memorable experience though clouded with the disappointment that the marker is no longer useful for its intended purpose.

 

I am comfortable with anyone loging this example on gc.com as Found - Damaged, or Poor because the station was, in fact, found. I have found only 3 to 5 monuments in this condition in 350 finds so the numbers aren't skewed by any means. My log for these clearly describe the site condition so no one will be mislead by the Found log. I also have no problem with anyone logging it as Not Found. It is a personal choice.

Edited by Team Sagefox
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Hypothetical question: The box score for this mark includes several nearby reference points with distances to millimeter resolution. I've omitted RM2 & 3 noted as gone, and the more distant lights. There is no mention elsewhere of the SUB STATION marks, so they may not still exist.

 

SD0457 BROWN RM 4 8.398 METERS 01544

SD0457 BROWN SUB STATION 2 99.700 METERS 01802

SD0457 BROWN RM 1 19.199 METERS 15308

SD0457 BROWN SUB STATION 1 62.500 METERS 28552

 

Assuming that RM1, RM4, and SUB STATION 1 (which have well spread angles) WERE all found in good condition, I'm sure the main station could be reset to pretty good accuracy relative to them using their distances. Having 3 distances gives a check. What accuracy would you think would be achievable relative to them (considering that they may not check perfectly), and what accuracy would this most likely result in relative to the original disk's position?

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It is the Hierarchy of the survey type involved, Bill.

 

First order stations were surveyed from the longest lines of sight possible. this is why there were so many of them done from towers. First order stations were usually on the highest ground, and chosen to be in locations that would help complete a line of triangulation of adequate lengths. z15 has some maps scanned in that show these triangulated lines. They were trying to form triangles here. the longer the line of sight the higher the accuracy. Then the standards which were set were such that first order accuracy was derived from no less than 12 and usually more than 16 separate survey observations , all performed on other 1st order stations to create a new first order station. All these triangulated observations had to close tight.

 

Second order stations required no less than 8 separate observations and Thirds had to have a minimum of four. These all had to be turned angles based on other survey markers of higher order, not RM's. Reference markers are not set to geodetic quality as a rule. They are for a "to find" to the actual survey marker.

 

It is good surveying practice for me to set up my backsight at least equal to, if not slightly further away than the distances I intend to survey as a form of foresight. This will insure a higher accuracy. If I do not observe this practice and start going long on my foresight, in reference to my backsight shot, I am asking to compound my margin for error. Control is only as good as the practices you use to maintain it.

 

I could plop in a new marker, sure, but it would have to be resurveyed to find out what the accuracy is, and it will most likely not be in the very same place, not exactly. Then the least squares adjustment has to be re-performed. Remember these particular survey markers were for measuring the shape and size of the earth and this particular marker is vintage NAD 27 so it was part of the equations that used the Clarke Ellipsoid of 1866 and the Meades Ranch reset Marker which was the main geodetic starting point for the country until superseded by NAD83 in 1986.

 

What I am trying to remind us all is that this is not just important as a single point. It has to relate to it's other local points. These were what measured the shape of the earth in the US.

 

Perhaps DaveD can chime in on how the first second and third order stations were derived and interrelated back in the day. Today it would be reset via GPS most likely, as it is much cheaper to do.

 

In the mean time, here is a rather lengthy article, which will serve as a nice primer that describes all the things a Surveyor has to keep in mind while we are surveying from these survey markers. It sort of lays out the standards I need to work to meet, all the time. enjoy!

 

http://www.state.nj.us/transportation/eng/...ey/Chapter3.htm

 

Rob

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R_C, It may be easier to ask NGS type questions over in the NGS Forum in the future.

 

. . .

 

Again as I said, If I cannot find a disc, I cannot survey from it. It is not Poor, It is not there and that = not found. Just my take.

Yeah, I thought of that after I had already posted it here, but I'm not yet accustomed to thinking in terms of the two forums (fora? fori? Why doesn't that ever look right?). I hope to do better sorting in the future.

 

And as I said above, I agree that it better fits "Not Found" than "Poor/Disturbed", but it HAS been fun discussing it! :unsure:

 

R_C

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