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Details for Benchmark: OQ1093

N 43° 36.533 W 096° 28.417 (NAD 83)

Altitude: 1396.56

Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)

Location:
In MINNEHAHA county, SD View Original Datasheet
Designation:
I90 411.5
Marker Type:
NGS Benchmark
Setting:
setting not listed - see description
Stability:
Most reliable and expected to hold position/elevation well.

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Documented History (by the NGS)

Unknown by SDDT (MONUMENTED)
05/26/1991 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1991 17.6 KM (10.9 MI) EASTERLY ALONG INTERSTATE HIGHWAY 90 FROM THE JUNCTION OF INTERSTATE HIGHWAY 229 AT THE NORTHEAST EDGE OF SIOUX FALLS, A STAINLESS STEEL BALL EPOXIED TO A PIPE CAP THAT IS ATTACHED TO A 1 1/2-INCH GALVANIZED STEEL PIPE, 158.6 M (520.3 FT) EAST OF THE NORTHEAST CORNER OF HIGHWAY BRIDGE NUMBER 50-328-166 SPANNING LONE ROCK CREEK, 106.5 M (349.4 FT) WEST OF THE EXTENDED CENTER OF A GRAVELED ROAD LEADING NORTH, 32.1 M (105.3 FT) NORTH OF THE CENTERLINE OF THE WESTBOUND LANES OF THE HIGHWAY, 0.6 M (2.0 FT) SOUTH OF A FENCE, 0.6 M (2.0 FT) BELOW THE LEVEL OF THE HIGHWAY, AND 0.4 M (1.3 FT) SOUTH OF A WITNESS POST. NOTE--ACCESS TO THE DATUM POINT IS THROUGH A 5-INCH LOGO CAP AND THEN THROUGH A 4-INCH PVC SCREW CAP.

Control Text

  • The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in September 1993.
  • The geoid height was determined by GEOID99.
  • The dynamic height is computed by dividing the NAVD 88 geopotential number by the normal gravity value computed on the Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 degrees latitude (g = 980.6199 gals.).
  • The modeled gravity was interpolated from observed gravity values.

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