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Details for Benchmark: HV4521

N 38° 53.385 W 077° 02.067 (NAD 83)

Altitude: 35

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:
WMG 1981
Marker Type:
survey disk
Setting:
setting not listed - see description
Stability:
Mark of questionable or unknown stability.

Reference Points

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Nothing now at coords

No sign of any asphalt pad here.. plastic caps all around the area - apparently sprinkler heads.

Could not find this disk. Found a plastic cap at nearly the exact coords, but there was no disk there.

Documented History (by the NGS)

01/01/1981 by CANDA (MONUMENTED)
DESCRIBED BY CERVANTES AND ASSOCIATES 1981 (GCC) THE SURVEY POINT IS A PUNCH HOLE LOCATED IN THE OPENING OF THE LETTER C IN A 3-1/2 INCH DIAMETER BRASS DISK. STATION IS LOCATED ON THE NORTH SIDE OF AN ASPHALT SIDEWALK LEADING TO THE WASHINGTON MONUMENT FROM 15TH STREET N.W. STATION IS 21.18 FT. NORTH OF PK AND CAP IN 4 FT X 4 FT ASPHALT PAD. STATION IS 49.35 FT NORTHWEST OF LIGHT POLE BASE.

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  • The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.)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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