Access To The Datum Pnt Through A 5 Inch Logo Cap

[+piper28]

Ok, I was looking for this benchmark the other day, and in the description it says "Access to the datum point is through a 5 inch logo cap." Any idea what that means? Looking back at the marker info, I also suspect that I didn't know exactly what I was looking for when I was there. The marker is listed as a Flange-encased rod, and the setting a stainless steel rod w/o sleeve.

 

Found the witness post without any trouble, never did find the marker though .

[Bill93]

You are looking for a 5-inch diameter cast bronze or aluminum circle which is a hinged lid or cap over the marked point and has the designation of the mark stamped on it. It is the type of benchmark they set now instead of the disk in concrete post of the old days.

 

This was very near surface level at the time it was set, but might be sticking out or covered up a little after a few years. Does the description tell how far and in which direction from the post? If it is covered a cheap metal detector is handy. You can also gently probe down a few inches to see if you hit it. Be very alert to buried utilities in the area before you try this.

 

The position mark itself is probably a dimple in the end of a rod under that hinged lid. The rod is driven to great depth or until it hits bedrock. It is in a greased sleeve for a few feet down so that frost can't get hold of it and heave it out of position.

[+mihiker]

The rod is driven to great depth or until it hits bedrock. It is in a greased sleeve for a few feet down so that frost can't get hold of it and heave it out of position.

Hmm.

Thanks for that info.

I was wondering how deep they went.

[Z15]

fyi

 

Edited May 10, 2005 by Z15

[evenfall]

The term we use is driven to refusal, It is everything like Bill said and looks like the pic Mike posted.

 

An electrical pavement breaker with special attachments as such is used and the stainless steel rod, of which can have many sections added to it, to whatever length is needed is driven, and driven until it stops going in the ground.

 

Here, this link will give you the basic idea.

 

http://www.holtwood.co.uk/Berntsen-Install.htm

 

Enjoy,

 

Rob

[ArtMan]

You are looking for a 5-inch diameter cast bronze or aluminum circle which is a hinged lid or cap over the marked point and has the designation of the mark stamped on it. 

Just to be clear, the stamping of the station designation (name) is on the rim, not the hinged cover itself.

 

In the top-view illustration posted by Z15, the stamping would be in the white area at around two o'clock.

 

-ArtMan-

[+Black Dog Trackers]

Here are a couple pictures of a logo cap and rod inside (and someone put a spark plug in there too).

[+piper28]

Thanks folks, now that I have a better idea I'll have to go back and take another look. As I recall, the description said it was only supposed to be about a foot and a half from the witness post, which is one reason it was so frustrating. Bill93 and Z15, your posts espeically were pretty helpful.

[Z15]

Here is a link to one I found.........AA8048

[+BuckBrooke]

The Logo caps are wide enough that when they're covered with an inch or so of dirt here in New Mexico they're hard to find unless you probe with something. They they're very easy to find.

[evenfall]

I came across what I was looking for as an addition to this thread. All you likely want to know about the survey marker.

 

These will be downloads in .pdf format. Be prepared to expect this. Open with Acrobat Reader.

 

ftp://ftp.ngs.noaa.gov/pub/uddf/info/Attach_7_9.pdf 288k

 

ftp://ftp.ngs.noaa.gov/pub/uddf/info/Attach_10.pdf 3.4MB But worth it.

 

Enjoy,

 

Rob

Edited May 19, 2005 by evenfall