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Bill93

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Posts posted by Bill93

    Benchmark area looks to be paved over soon.

    in Benchmarking

    Posted

    This happens all the time and nobody does anything about it. NGS doesn't have funds to send crews out for this stuff. The "right" way is for a local surveyor to go through the NGS official RESET process to preserve a related elevation on a nearby new mark. That takes time $$ and knowledge that isn't going to happen very often.

     

    NGS officially says you should send in a destroyed disk, but that doesn't happen often either. Lots of people have souvenirs. We just hope they don't end up on eBay to encourage people to grab ones that weren't already destroyed.

     

    And then there is the upcoming redefinition of elevation NATRF2022 that should be released by 2025, after which all new work should use that, with GPS corrected for gravity variations, instead of physical disks. So the old disks will only be of use for finishing work in progress or checking historical work.

     

    Don't think your past recovery reports have been in vain. Many of the old disks were used to check whether the new datum was coming out consistent, via the GPSonBM program, so knowing which markers were still there helped guide the collection of the check data.

     

    • Upvote 1

    EB1257 recovery question

    in Benchmarking

    Posted

    Report what you see. The marker type is Disk, and Designation is TT 32 H, which is what is stamped on the disk. I'd say disk in good condition. You could also say Drill mark mentioned in 1993 also present.

     

    I have no idea why South Carolina Geodetic Survey would mention the drill hole in a report for this PID, and suspect a misinterpretation of the field notes by someone in the office who submitted the report.  Maybe there was an older drill mark before the disk was set in 1934? How old is the building?

     

    I question whether a mark so near a building would be suitable for satellite observation.

    • Helpful 1

    When did those orange carsonite posts start getting used?

    in Benchmarking

    Posted

    The coordinates are not always that good, but it's a place to start when nothing is obvious.

    I jumped in here without rereading the thread, so some advice may be irrelevant.

    The coords for the older marks were read from a USGS topo map in the 1960's after someone plotted the description.

    Sometimes changes in the surroundings caused large errors in figuring out where to plot it. Rerouted highway numbers are a major source of these errors. Ive found a mark at a creek culvert a quarter mile from the coords because that creek wasn't on the map and they plotted it where a creek did show.

    But a witness post is nearly always within a few feet of its mark, and it's unlikely to get moved far.

    Numeric Conversion Help Needed

    in Benchmarking

    Posted · Edited by Bill93

    Take the seconds of latitude or longitude, such as the 25.37653 in the latitude given, divide by 60 seconds/minute, and tack that decimal on the minutes, rounded if you are limited to 3 decimals.

    Here I get   38 21.423  081 36.299

     

    Most handhelds and many software tools will let you set the display format, so you can enter it one way, change format selection, and see it another way.

    Groundspeak is removing Benchmarking and the logs/photos

    in Benchmarking

    Posted · Edited by Bill93

    Those who want to be helpful, are careful about identification, and take the trouble to emulate the NGS style of report can log recoveries at the official NGS site.

     

    You can input updated To Reach, HH2 handheld coordinates DDD MM SS.S format (if it only had SCALED), and photos. You can use the category L GEOCAC group code and your initials as Chief of Party.

     

    There is a helpful guide on their site.

    https://geodesy.noaa.gov/datasheets/SurveyMarks_FAQ.shtml#RECOVERY

    https://geodesy.noaa.gov/surveys/mark-recovery/index.shtml

     

    It will ask if the mark is suitable for GPS. You can say UNKNOWN if you aren't sure. Suitable generally means most of the sky clear except for perhaps poles or isolated tree not too close. Hold your hand outstretched with little finger at the horizon and see what is higher than your thumb.

     

    Generally they want reports if it has been 5-10 years or more since last recovery OR condition has changed. Don't log it unless you have useful information to add. They don't need a dozen "me too" logs.

     

    At this point only marks with ADJUSTED or GPS elevations on the data sheet are of high interest. I think they still accept  Triangulation stations, but do not want Intersection stations (towers, etc).

     

    Condition means how well the mark has held position and not cosmetic condition.

     

    So you don't have to give up the hunt.

     

    • Upvote 1
    • Helpful 2

    Possible unlisted benchmark in Stockbridge, MA

    in Benchmarking

    Posted

    It is possible it is a bench mark not submitted to NGS, but much more likely that it is not and is a property corner set by that company. 

    Most property corners in the US are simply a pipe or rebar, often with a plastic cap identifying the surveyor or their company, but in some areas and for some clients a metal cap my be more common. I would have expected a license number, though.

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