USCGS triangulation stations sub-surface marks

[+LSUFan]

I found where the surface setting for DL1328 Triangulation station DONAGHEY has been basically uprooted and the disk is missing from the concrete setting.

 

I recall sometimes reading on the datasheet where it describes the sub-surface mark, but didn't see on this datasheet, any mention of a sub-surface mark.

 

I constantly read NGS Surveyors excellent pinned topic on triangulation stations, and see where it says these stations "may" have a sub-surface mark, but that may just be me interpreting it wrong.

 

Can ya please share your wisdom, and educate me as to 'if all USCGS triangulations stations are supposed to have a sub-surface mark'.

 

I wrote up a geocaching report assuming there is one, but was wanting to be more sure of myself before submitting a recovery report to NGS.

 

http://www.geocaching.com/mark/details.aspx?PID=DL1328

 

As always, thanks so much for any advice you care to give.

 

Bobby/LSUFan

Edited April 12, 2010 by LSUFan

[Bill93]

I'd tend to expect an underground disk, but I am not very familiar with practice in 1952 in y our area. Do you find mention of UG disks on other tri stations in the area?

 

We found an UG disk where a 1928 surface mark was taken out at LE0530. If you can find the RMs, it is just a matter of measuring and digging.

[AZcachemeister]

If an underground mark was set, I would expect a statement to that effect in the datasheet.

[Z15]

If the mark was a concrete post then a ug disk was required. If the mark is set in bedrock then obviously that was not possible.

 

One thing I found over the years in recovering a few of them is this; they are not always as deep as they say or as required due to laziness on the part of the hole diggers I assume.

 

They are not always a survey disk. I found copper a bolt once and once we found the disk had sunk into the small concrete mass so as to be almost totally unnoticeable.

 

So you have to be extremely careful uncovering it. We found where the USFS had inadvertently dug up the ug mark looking for it. We found an odd shape piece of concrete piled around the new mark, one of the guys picked it up and tossed it aside and it broke in 1/2 and revealed the disk covered over with thin film of concrete.

 

RL1102

RL1102 STATION RECOVERY (1995)

RL1102

RL1102'RECOVERY NOTE BY MICHIGAN DEPARTMENT OF TRANSPORTATION 1995 (BRT)

RL1102'MARK WAS FOUND REPLACED WITH AN IRON PIPE FROM REFERENCE MONUMENTS BY

RL1102'RICHARD L. DRAHN, US FOREST SERVICE, UNDERGROUND MARK WAS FOUND PILED

RL1102'IN STONES SURROUNDING FOREST SERVICE PIPE. PER INSTRUCTIONS FROM NGS

RL1102'STATE GEODETIC ADVISOR THE USFS MARK WAS REMOVED AND A NEW STATION WAS

RL1102'ESTABLISHED. FOR FURTHER INFORMATION CONTACT STATE GEODETIC ADVISOR.

Edited April 13, 2010 by Z15

[+LSUFan]

If the mark was a concrete post then a ug disk was required.

 

Yes, it was set in concrete, as the picture below shows. The datasheet made no mention of an underground mark, but I have found several other triangulation stations that do state it....which is what got my curiousity up on if all of these types had underground marks. It looks like I am going to have to make another trip back and do a full, all-out, take no prisoner, type of search now.....if there is an underground mark even though the datasheet doesn't declare it.

 

Edited April 13, 2010 by LSUFan

[NGS Surveyor]

Underground marks were specified by the USC&GS as early as 1905. By 1959 the specifications were published in USC&GS Special Pub. #247, “Manual of Geodetic Triangulation” (http://docs.lib.noaa.gov/rescue/cgs_specpubs/QB275U35no247rev1959.pdf)

 

From page 14 of SP#247:

“14. Marks.-Detailed specifications for marking stations are given on pages 84 to 95.

Each station will be permanently marked. Surface and underground marks are to be

used where local conditions permit.”

 

From page 88:

“5. Station mark.-Each station center should be marked with a standard triangulation mark of the type illustrated in figure 48. The mark should be set in the manner described in section 10. An underground station mark should also be set under the surface mark wherever conditions permit. Marks of other organizations may be used as described in section 9. The upper station mark may also be set underground when necessary, as when the station is in a cultivated field.”

 

See also Section 10 on page 90, diagram on page 92, photo on page 93, Section 10(d) on page 93, and “notes” for Underground Marks on page 121.

 

GeorgeL

NGS

[+LSUFan]

Underground marks were specified by the USC&GS as early as 1905. By 1959 the specifications were published in USC&GS Special Pub. #247, “Manual of Geodetic Triangulation” (http://docs.lib.noaa.gov/rescue/cgs_specpubs/QB275U35no247rev1959.pdf)

 

From page 14 of SP#247:

“14. Marks.-Detailed specifications for marking stations are given on pages 84 to 95.

Each station will be permanently marked. Surface and underground marks are to be

used where local conditions permit.”

 

From page 88:

“5. Station mark.-Each station center should be marked with a standard triangulation mark of the type illustrated in figure 48. The mark should be set in the manner described in section 10. An underground station mark should also be set under the surface mark wherever conditions permit. Marks of other organizations may be used as described in section 9. The upper station mark may also be set underground when necessary, as when the station is in a cultivated field.”

 

See also Section 10 on page 90, diagram on page 92, photo on page 93, Section 10(d) on page 93, and “notes” for Underground Marks on page 121.

 

GeorgeL

NGS

 

Many Thanks George, and everyone else who posted. My benchmark education has been furthered some more.