I'll go on record, no one is really getting that kind of accuracy, and for almost all projects, it really isn't needed.
Storm sewer, sanitary sewer, culvert??ÿ Might as well record to the hundredth--the next best option is a tenth.
In some sewer projects I've done as well as concrete slabs/gutters, showing inverts to a tenth would jeopardize passing inspection (not to mention flow). 1/2% for 25' is 0.125 (0.13) but rounding that to a tenth blows it.
With the rod tilted, and sometimes guessing what you're resting on, broken pipe, covered with crap, etc, it's tough to pretend to get that kind of accuracy.?ÿ
I've seen guys spending time, trying to compensate for tilt, and record numbers that show flow running opposite from reality, and you can clearly see that one pipe is lower than the other, but their notes say otherwise.?ÿ Oh, well
In the grand scheme of things; if you think all of your measurements are within a hundredth, you're kidding yourself...
If you're using the right tools, to get inverts, you will get pretty close.
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It said "recorded to" not "guaranteed accurate to".
Looser than hundredth would not have to be tenth. It could say 0.02 or 0.05 or other I crement.
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It always amazes me how they calculate the slope of a pipe run between manholes with only two pieces of data, disregarding the 200 to 300 feet in between. Theoretically that may be fine for a design.
The only way to "as-built" a pipe run is to make measurements as it is built. Making observations at the top of the pipe, and subtracting the thickness and diameter will give you the invert, alignment, and actual proof of how the pipe was constructed.
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Any of you old farts remember Lamping and/or Mooning a sewer line installation? ?????ÿ
It said "recorded to" not "guaranteed accurate to".
Looser than hundredth would not have to be tenth. It could say 0.02 or 0.05 or other I crement.
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Well yeah, no kidding.?ÿ You get the pedantic point award.
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Makes just as much sense as reporting a property boundary to the 0.01' (which is none).
This is one of the fallacies promoted by our profession.?ÿ We consistently claim to be perfect measurers as that is what most clients believe us to be.?ÿ They don't understand all the mumbo jumbo speak we use and translate that involves title, physical evidence, parol evidence, perpetuation, and a host of other terms they assume attorneys are the only ones that understand.
The flattest sewer and storm I??ve commonly staked is in the most mountainous state I??ve lived in. If you are surveying for design err on the side of low on the outlet and high on the inlet. Better they design it a little bit to flat than a little bit to steep. ?ÿEvery measurement has error. ?ÿYou??ll still get your full moon. A good construction surveyor is going to verify both.
Looser than hundredth would not have to be tenth. It could say 0.02 or 0.05 or other increment.
I record to the nearest 0.01', but I annotate to the nearest 0.05'.?ÿ Even with the Chrisnik Pipe Mic (which I only use if I'm opening a bunch of MHs), I don't think I get any better than 0.05' accuracy.?ÿ The leg flexes a bit, and plumbing the rod bubble while reading the rod (manhole hook laid across the rim) introduces additional error.?ÿ But in 40+ years of dipping manholes, I have yet to have an engineer complain that my inverts aren't accurate enough.
