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Details for Benchmark: HV4243

N 38° 53.549 W 077° 01.968 (NAD 83)

Altitude: 125

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

Location:
In DISTRICT OF COLUMBIA county, DC View Original Datasheet
Designation:
COMMERCE 1934
Marker Type:
triangulation station disk
Setting:
setting not listed - see description
Stability:
Mark of questionable or unknown stability.

Reference Points

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Documented History (by the NGS)

01/01/1934 by CGS (MONUMENTED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1934 THE STATION CONSISTS OF A STANDARD MARK STAMPED C. AND G.S. OFFICE, SET IN THE CENTER OF A CONCRETE SHAFT THAT IS BUILT ON BEDROCK AND EXTENDS UP THROUGH THE COMMERCE BUILDING TO THE TOP. IT IS IN NO WAY CONNECTED WITH THE BUILDING. THEREFORE IS NOT EFFECTED BY MOVEMENTS OF THE LATTER. THIS SHAFT IS AT THE S END OF THE BUILDING, AND IS REACHED FROM THE 8TH FLOOR THROUGH A TRAP-DOOR. A TRAP-DOOR ALSO OPENS IN THE ROOF JUST OVER THE MARK, SO THAT THE STATION MAY BE OCCUPIED BY ERECTING A STAND ON THE ROOF. THE TRAP-DOOR IS LOCATED ABOUT THE CENTER OF THE S END OF THE BUILDING, AND IS THE CENTER ONE OF THREE. NO REFERENCE MARKS OR AZIMUTH MARKS WERE ESTABLISHED. NOTE--THIS DESCRIPTION IS IN ERROR IN STATING THAT STATION IS ON AN INDEPENDENT SHAFT EXTENDING UP THROUGH BUILDING. IT IS ON SHORT SHAFT FLOATED ON AN UPPER FLOOR.
01/01/1960 by MADHOP (GOOD)
RECOVERY NOTE BY MADDOX AND HOPKINS SURVEYORS 1960 (CJM) THIS STATION WAS RECOVERED AS DESCRIBED.

Control Text

  • The horizontal coordinates were established by classical geodetic methods and adjusted by the National Geodetic Survey in November 1994.
  • The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.)
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The geoid height was determined by GEOID99.

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