This is a good example of why surveyors shouldn't keep there work secret. I could see these situations leading to confusion for the next surveyors if they don't?ÿ have?ÿ records of your work.?ÿ
I was inspecting a project that had been contracted out. One monument's stamped information wasn't oriented to the North. The guy with me bent down and twisted it North. We were both shocked how easy it rotated. The Contractor had cut the monument down to 6 inches and set it in dirt.
When I was a young party chief got sent to drill dimples in well monuments (set by contractor).?ÿ Found them spinning and off-center so could drill but could be easily rotated off.?ÿ Went back to office, tell contractor to affix the caps properly.?ÿ Got chewed out instead, just drill 'em and leave.?ÿ That's the subdivision business.
Finished up a job recently in a subdivision where one lot corner fell on the lid to a sewer manhole (or whatever some dumbbass Gubmit minion believes they should be called).?ÿ Nowhere near being dead center of course.?ÿ About four inches from the nearest portion of the rim.?ÿ We set reference bars on the boundaries two feet from the true corner.?ÿ I thought about breaking out a big magic marker, putting a one-inch dot and then drawing four or five marks on the rim.?ÿ Rotate the lid and the mark could move quite a distance.
@holy-cow a fair amount of centerline intersections within the city of Los Angeles have very similar monumentation (sewer manhole monuments, or SMHM).?ÿ
There??s 4 punches on the rim (where each centerline passes through the rim), and 4 hooks installed inside the walls of the manhole (same configuration, so you can pop the lid and string the true intersection).?ÿ
You nailed a very common problem on the head, though when people set a temporary point on the lid... But there??s also problems when there??s a lift or grind/overlay given that there??s a fair chance that the rim??s been rotated during the paving process. ?ÿYou have to pop the lid and check the punches versus the hooks.?ÿ
Sometimes hooks aren??t installed, and that creates a minor league pain when the rim appears to be have been spun. Fun fact, though: SMHM hooks are among the most stable monuments in California (read as: Earthquake Land).
Sorry for the useless info, just thought someone would appreciate it. They??re actually pretty neat monuments when you get used to them.?ÿ
The title of this thread sounds like an episode of the old Perry Mason TV show.?ÿ They all started with: The Case of the......................
This raises the question when do the boundaries stop moving with the monuments?
We all accept that everything moves with the tectonic plates. There are cases where boundaries cross the tectonic plate boundaries but that is not common in most of the United States.
All movement is relative to something and may be readily detectable or not detectable depending on how stable the control is. The case of the fence post is straight forward but what about an entire neighborhood moving at a steady, imperceptible rate? I've seen an entire block of lots sliding downhill towards the Pacific Ocean.
I don't recall a case dealing with this issue, perhaps in previous centuries measurement methods weren't sufficiently precise to detect the movement and attribute it to geological causes rather than inaccuracy present in record measurements.
Exactly!!
This is why I titled the post the moving corners instead of moving monuments. The 1/4 is straightforward, because of the evidence it is my opinion that it has been disturbed and no longer occupies the corner position.?ÿ
My other area with the entire ridge structure moving is more unclear. The monuments are perfectly upright and plumb, they are undisturbed locally and in place, even though they are not close together (+-500' apart) they are moving more or less in sync, do you accept the movement of the land or try and continually shift the monuments.
I have only seen a few cases concerning this. The one that makes the rounds of land surveyor seminars was wrongly decided-IMHO.?ÿ
It was a 1/4 corner set on a N-S line in an the original government survey#1, retraced by government survey#2 showing it well east of line and re-monumented there. Then a private surveyor came in and set a prorate on line between section corners, government survey#3 retraced and found the government monument now well east of government survey #2 and disputed the prorate by the private surveyor which was on-line and west of #2's position. The conclusion was to hold government #2's position.?ÿ
To me the movement and time between the 3 government surveys showed the monument moving since the original survey and the prorate was the correct position not #2.?ÿ
But that survey was in an area of well defined local movement from a water course, ditch and a draw, the land is sliding downhill and evident. Not the same as large land movement.?ÿ
I have heard people suggest that descriptions should be prepared using state plane coordinates as the corners.?ÿ That would not work, would it.
Very few surveyors can put the same state plane coordinate on an existing point repeatedly?ÿ
I agree fully.?ÿ However, we now have surveyors who won't dig up monuments from earlier work because they assume each monument is still there and at the exact same set of coordinates.
The trick is to retire and/or die before you live long enough for your monuments to move on you.?ÿ ????ÿ