What am I missing?
Perspective. The guy just misspoke. R-E-L-A-X.
In my area the network of NGVD29 monuments was reobserved and re-adjusted in the 1940's. To this day the City of Vancouver, WA and the Port of Vancouver continue to use the pre-1947 version, while the local counties and cities that use NGVD29 (which is still most of them, except Portland itself, which has its own datum) use the 1947 adjustment. The difference is a couple of tenths.?ÿ ?ÿ ?ÿ?ÿ
FEMA has all the old FIRM maps archived. The benchmarks are described on them.?ÿ
We have a sweet spot where NAVD88 and NGVD29 are the same.?ÿ within 2mm
Everyone head for Clutier
NK0094 *********************************************************************** NK0094 DESIGNATION - S 82 NK0094 PID - NK0094 NK0094 STATE/COUNTY- IA/TAMA NK0094 COUNTRY - US NK0094 USGS QUAD - CLUTIER (2018) NK0094 NK0094 *CURRENT SURVEY CONTROL NK0094 ______________________________________________________________________ NK0094* NAD 83(1986) POSITION- 42 03 25. (N) 092 22 36. (W) SCALED NK0094* NAVD 88 ORTHO HEIGHT - 253.461 (meters) 831.56 (feet) ADJUSTED NK0094 ______________________________________________________________________ NK0094 GEOID HEIGHT - -31.543 (meters) GEOID18 NK0094 DYNAMIC HEIGHT - 253.371 (meters) 831.27 (feet) COMP NK0094 MODELED GRAVITY - 980,264.4 (mgal) NAVD 88 NK0094 NK0094 VERT ORDER - SECOND CLASS 0 NK0094 NK0094.The horizontal coordinates were scaled from a map and have NK0094.an estimated accuracy of +/- 6 seconds. NK0094. NK0094.The orthometric height was determined by differential leveling and NK0094.adjusted by the NATIONAL GEODETIC SURVEY NK0094.in June 1991. NK0094 NK0094.Significant digits in the geoid height do not necessarily reflect accuracy. NK0094.GEOID18 height accuracy estimate available here. NK0094 NK0094.Click photographs - Photos may exist for this station. NK0094 NK0094.The dynamic height is computed by dividing the NAVD 88 NK0094.geopotential number by the normal gravity value computed on the NK0094.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 NK0094.degrees latitude (g = 980.6199 gals.). NK0094 NK0094.The modeled gravity was interpolated from observed gravity values. NK0094 NK0094; North East Units Estimated Accuracy NK0094;SPC IA N - 1,062,480. 1,592,980. MT (+/- 180 meters Scaled) NK0094 NK0094_U.S. NATIONAL GRID SPATIAL ADDRESS: 15TWG515562(NAD 83) NK0094 NK0094 SUPERSEDED SURVEY CONTROL NK0094 NK0094 NGVD 29 (??/??/92) 253.459 (m) 831.56 (f) ADJ UNCH 2 0
@norm?ÿ
Not the case in the new datum??
BTW, this point was indicated to be ??not found? in 2018. Is it in fact recoverable?
Looking at the associated data for the point, I see that it was leveled to in 1934 during level project L4367. There are no other projects associated with the point. See: https://beta.ngs.noaa.gov/datasheets/leveling-projects/index.html?ÿ
@norm?ÿ
Pthis point was indicated to be ??not found? in 2018. Is it in fact recoverable?
The 2018 report is mine. He didn't quote the text. The facts seemed pretty conclusive to me.
STATION RECOVERY (2018)
NK0094
NK0094'RECOVERY NOTE BY INDIVIDUAL CONTRIBUTORS 2018 (BDH)
NK0094'TWO METAL TUBE CULVERTS HAVE REPLACED THE CONCRETE PIPE AT A FIELD
NK0094'DRIVE WHICH IS THE OLD RAILROAD BED. DESCRIBED LOCATION FALLS NEAR
NK0094'ROAD DITCH THAT LOOKS REGRADED. NO EVIDENCE OF THE POST OR DISK WAS
NK0094'FOUND IN A BRIEF METAL DETECTOR SEARCH.
Re-reading the to-reach, I think I may have misunderstood the concrete to have been under the RR when it makes more sense with the distances to be under the road.?ÿ But in either case, I walked the edge of the field along the ditch with the treasure hunter and didn't find any evidence.
I've never searched?ÿ for it. I just found the same heights in two datum for one mark interesting. We wont be so lucky in the new datum - probably a good thing.?ÿ
Many of the Bench Marks will not appear on the NGS search site. Having the old printed datasheets and level runs is priceless for the area you work in. Possibly they are still available somewhere, I used to call the Denver office to get mine.?ÿ
