Details for Benchmark: LC0421
N 40° 28.783 W 088° 59.617 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In MCLEAN county, IL View Original Datasheet
- Marker Type:
- bench mark disk
- massive structures with deep foundations
- Most reliable and expected to hold position/elevation well.
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Documented History (by the NGS)
|Unknown by USGS (MONUMENTED)
|01/01/1969 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1969
AT BLOOMINGTON. AT BLOOMINGTON, SET VERTICALLY IN THE EAST FACE AND 2.4 FEET NORTH OF THE SOUTHEAST CORNER OF THE EAST WING OF THE MCLEAN COUNTY COURTHOUSE, 32 FEET NORTH OF THE SOUTHEAST CORNER OF THE MAIN PART OF THE COURTHOUSE, 92 1/2 FEET WEST OF THE CENTER LINE OF N. MAIN STREET, 38 FEET SOUTH OF THE CENTER OF THE MAIN ENTRANCE TO THE COURTHOUSE, 2.2 FEET ABOVE THE LEVEL OF THE GROUND, AND ABOUT 8 FEET ABOVE THE LEVEL OF N. MAIN STREET.
|01/01/1986 by NGS (GOOD)
|RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1986
RECOVERED IN GOOD CONDITION. A NEW DESCRIPTION FOLLOWS. IN BLOOMINGTON, AT THE INTERSECTION OF NORTH MAIN AND WEST WASHINGTON STREETS, SET VERTICALLY IN THE EAST FACE NEAR THE SOUTHEAST CORNER OF THE CONCRETE FOUNDATION WALL OF THE EAST WING OF THE COUNTY COURTHOUSE, 38.5 M (126.3 FT) NORTH OF THE CENTERLINE OF WEST WASHINGTON STREET, 28.5 M (93.5 FT) WEST OF THE CENTERLINE OF NORTH MAIN STREET, 11.6 M (38.1 FT) SOUTH OF THE CENTER OF THE EAST ENTRANCE TO THE COURTHOUSE, AND 0.7 M (2.3 FT) NORTH OF THE SOUTHEAST CORNER OF THE EAST WING OF THE COURTHOUSE. THE MARK IS 0.7 M ABOVE THE GROUND.
- 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 June 1991. WARNING-Repeat measurements at this control monument indicate possible vertical movement.
- 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.