I am studying the Surveyor Reference Manual (7th edition), and there is a practice problem that says "State whether single proportionate measure (S), single proportionate measure on a latitudinal (curved east-west) line (SC), or double proportionate measure (D) is used in restoring the following corners (assume none of the township boundaries are standard parallels).
1) northeast corner of sec 10
2) northeast corner of sec 12
3) south quarter-section corner of sec 12
4) southeast corner of sec 36
5) southwest corner of sec 36
Given answers: 1) D 2) S 3) S 4) D 5) SC
Am I thinking about this wrong or are a few of these answers incorrect?
They are all incorrect, you put them at the fence corner.
But I figure that's not what they want, it's difficult to read a test maker and I will guess your answers are correct, with the caveat that technically 3 should be SC, yet practically it's normally done as S. I was recently at a seminar and the presenter said S for #3, there wasn't any pushback. If I find a monument prorated at 3 either way I will accept it.
If I'm remembering right you only do the latitudinal proportion on standard parallels and since, according to the description, none of the township boundaries are on a standard parallel you won't use SC at all.
I'm mostly an urban surveyor, so I don't get a lot of practice in this area..... I have found that textbooks are all over the place with some of these things.
- northeast corner of sec 10 - any section corner interior to the township is going to be double proportioned
- northeast corner of sec 12 - that's going to be on the range line, so it gets single proportioned
- south quarter-section corner of sec 12 - any quarter corner will be a single proportion
- southeast corner of sec 36 - that's the SE township corner. I'd be examining the specific field notes to determine whether to single or double proportion. This is the one I'm least certain of.
- southwest corner of sec 36 - that's on the township line so I'm thinking single proportion, but could be latitudinal if the found monuments were distant.
Just find the monument and you won't have to worry about these things.
@mightymoe I remember some question like that in school in Colorado. This was mid 90’s and what I can recall is the answer is only use single or double proportion as a last resort. A fence line some evidence somewhere I hold more weight than the math. So yes at the fence corner. I am writing this one down as I study for my next exam seems like a good question.
Any township line is treated as a line of constant bearing. Inside the township the curvature is normally ignored, but technically all lines are lines of constant bearing meaning curved east-west lines. Doing this creates 1/4 corners 2" south of a line of sight between two section corners (near my usual latitude), 1/2" south for a 1/16th corner.
However, its mostly ignored by retracing surveyors.
But a township line, nope, for sure a curved line.
It's always, always, always important to know what imperial entanglements you're dealing with when doing a sectional survey.
That's why MT and OG plats are so useful.
The PLSS is based on one overriding principle........monuments hold over everything else (some exceptions).
This was an ancient principle when the PLSS was created, it's even laid out in the Bible.
So, proration is a very last resort. My advice is try everything else before stepping into the dark arts of prorating.
Always think of the four classes of monuments Existing, Existent, Obliterated, and Lost.
If you rate them on your body Existing is on top of your head, Existent is at your eyes, Obliterated might be mid chest and Lost is ten feet under your feet.
I hate, hate prorating, but, sometimes it's necessary.
As far as the test answers I would say the OP is spot on except I would need to get a feel for the test givers on 3.
excellent summary mightymoe
myself I try All of the prorating methods... and use those positions to narrow the search area.
I hate, hate prorating, but, sometimes it's necessary.
Such as when answering academic textbook questions. Otherwise rare.
In urban surveying we do have to restore destroyed PLSS monuments from time to time. But there are always adjacent property monuments, of record, to use as references. So they aren't lost, just obliterated.
When I was in OK, nearly every section line had a road of some sort running down it. So the road itself was a reference. The PLSS corners had to fall in the (dirt) roads, somewhere pretty close to the perceived centerline. If proration said otherwise, proration was wrong.
The number of obliterated corners grow as time passes.
There was a court case over placement of an oil well that hinged on lost vs. obliterated corners. The surveyor that prorated part of a township lost his argument since there was evidence available to show the original positions even though the original monuments were long gone.
The court case was probably the main reason the BLM executed the great Powder River Basin resurveys.
@sonicwave123 Which answers do you think are incorrect?
The 2009 manual is available for free as a download from the BLM website and the answers you seek are contained within.
Reference chapters 2-14, 7-10, 7-12, 7-16, 7-17, 7-20 & 7-35.
I found researching the answers to questions I had, and still have, created the base of my knowledge and at the same time expanded it, due to some of the research tangents I followed.
Once out in the field and recovering monuments well the game does deviate from the academic process.