Extra Stamping Not Accounted For in Data Sheet

[GH55]

Searching for NH1526 the directions and description from the current datasheet were adequate. There are three orange witness osts surrounding the surface monument.

 

There are two troubling things about this staion:

 

First, the disc is set in a concrete post that surrounded by a piece of black plastic field tile that may have been used to form it, though there could be a possibility that the palsitc could have been added later as some sort of protection.

 

Second, according to my notes, the disc is stamped "VOGHT 1935 1992". Nothing on the datasheet would explain the "1992" in the stamping, such as a recovery or a reset.

 

From the previous, I would guess that the surface mark was reset or repaired in 1992 but was not logged at that time. However, the only activity I find in Stephenson County on any NGS datasheets is a recovery of a chiseled cross and setting of a disc in Winslow, Illinois, which is only a few miles away.

 

There is no activity on any datasheet in surrounding counties in Illinois:Jo Daviess, Whiteside, Ogle and Winnebago and Lafayette County, Wisconsin.

 

In adjoining Green County Wisconsin, there were two stations monumented in 1992: DF9436 and DF9437.

 

It is a mystery to me. I am thinking this over awhile before submitting recovery. Thanks for any help.

 

Added: NH1527 (VOGHT 1935 RM 2) was searched for and not found.

Edited August 29, 2009 by GH55

[andylphoto]

I can't give you a definitive answer about this particular station, but the stamping you found would be typical in my understanding for a triangulation station that was reset in 1992. See my recovery photos for Loretta Reset. Z15, a member here and retired M-DOT survey tech was involved in resetting this particular one and offered some insights on it in a thread on triangulation station resets.

 

I wouldn't connect the other 1992 settings--it looks like they were set by the Wisconsin DOT, and it would seem unlikely that they would be resetting a triangulation station in IL. It does seem likely that the station was properly reset by someone--either the NGS or the IL DOT, but the update never made it to the data sheet.

 

Also see my thread on QK0775. It's a similar case--found the station, but it's not what is described in the data sheet. There is also a post from Mike, Z15 with some thoughts on why the change never made it into the data sheet.

[GH55]

I can't give you a definitive answer about this particular station, but the stamping you found would be typical in my understanding for a triangulation station that was reset in 1992. See my recovery photos for Loretta Reset. Z15, a member here and retired M-DOT survey tech was involved in resetting this particular one and offered some insights on it in a thread on triangulation station resets.

 

I wouldn't connect the other 1992 settings--it looks like they were set by the Wisconsin DOT, and it would seem unlikely that they would be resetting a triangulation station in IL. It does seem likely that the station was properly reset by someone--either the NGS or the IL DOT, but the update never made it to the data sheet.

 

Also see my thread on QK0775. It's a similar case--found the station, but it's not what is described in the data sheet. There is also a post from Mike, Z15 with some thoughts on why the change never made it into the data sheet.

 

Thanks for the reply. This got me to thinking some more about the possible tie in to the WIDT settings in 1992. DF9437 is set as both a vertical and a horizontal control station. After studying its datasheet more closely, this struck me:

 

"---NOTE---THE STATION IS NORTH, SOUTH, AND WEST OF

DF9437'THREE ORANGE 4X4 PLASTIC WITNESS POSTS."

 

I found the disc in question here with three orange witness posts set around it.

 

Investigation of nearby horizontal control points set by the WI DT indicate that setting three orange plastic witness posts is a common practice, and may even be a standard. For instance, see ADAMS E GPS

, DECATUR GPS and MOUNT PLEASANT W GPS chosen at random from the horizontal control points in Green County, WI. See also the horizontal control monumented by WIDT in Rock County, Wi.

 

So, although at first I did not think of linking WIDT to this station, now it seems reasonable to infer that WIDT at least visited the station in 1992 and placed the orange witness posts. It would also be a reasonable conjecture to say that perhaps the WIDT crew repaired the station and stamped the 1992 stamp at that time, but that such activity did not make it into the data sheet for whatever reason, such as simply not reporting a recovery.

 

I think I am going to ask the Illinois and Wisconsin state advisors about this.