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Details for Benchmark: HV1825

N 38° 55.626 W 077° 06.523 (NAD 83)

Altitude: 135.8

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:
GALENA
Marker Type:
survey disk
Setting:
set into the top of a metal pipe driven into the ground
Stability:
Mark of questionable or unknown stability.

Reference Points

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Documented History (by the NGS)

01/01/1925 by USE (MONUMENTED)
DESCRIBED BY US ENGINEERS 1925 (GLB) STATION IS SITUATED ON THE W END OF GALENA PLACE AT STREET INTERSECTION AT TOP OF BLUFF OVERLOOKING RIVER. BOTH CHAIN BRIDGE AND THE RAILROAD BRIDGE ARE VISIBLE. STATION MARKED BY A U.S. ENGINEERS MARK IS SET IN A 12-INCH TILE FILLED WITH CONCRETE AND SET BIG END DOWN, PROJECTING ABOUT 3 INCHES ABOVE SURFACE OF GROUND. REFERENCE MARK NO. 1 IS THE CENTER OF THE TOP NUT IN A FIRE HYDRANT. REFERENCE MARK NO. 2 IS THE CENTER OF THE CROSS CUT IN THE TOP OF A STONE PROPERTY MONUMENT ON THE NE CORNER OF THE STREET INTERSECTION. WITNESS MARK NO. 1 IS THE NORTHERNMOST OF TWO TREES ABOUT 6 INCHES IN DIAMETER ABOUT 12 FEET APART AND ON THE SE CORNER OF THE STREET INTERSECTION.
01/01/1925 by CGS (GOOD)
RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1925 AT WASHINGTON. AT WASHINGTON, AT THE JUNCTION OF GALENA PLACE AND POTOMAC AVENUE NORTHWEST, 53.2 FEET EAST OF THE CENTERLINE OF POTOMAC AVENUE, 28.6 FEET NORTH OF THE CENTERLINE OF GALENA PLACE, 20.7 FEET NORTHEAST OF A FIRE HYDRANT (R.M. 1), AND 16.6 FEET SOUTHEAST OF A STONE PROPERTY MONUMENT (R.M. 2) AT THE NORTHEAST CORNER OF THE INTERSECTION. A CORPS OF ENGINEERS, U.S. ARMY, STANDARD DISK, SET IN THE TOP OF A CONCRETE-FILLED 12-INCH TILE PIPE.
01/01/1947 by CGS (GOOD)
RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1947 (RMB) STATION WAS RECOVERED. R.M. 2 WAS SEARCHED FOR AND NOT FOUND. WITNESS MARK HAS BEEN REMOVED. THE DISTANCE TO REFERENCE MARK 1 WAS CHECKED AND FOUND TO BE 20.7 FEET (6.31 METERS). THE STATION IS AT THE TOE OF A 3-FOOT TERRACE UNDER A CLUSTER OF ROSE BUSHES.
01/01/1947 by CGS (GOOD)
RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1947 RECOVERED IN GOOD CONDITION.

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 vertical order pertains to the superseded datum.
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The geoid height was determined by GEOID99.

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