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Details for Benchmark: HS3979

N 37° 41.833 W 121° 52.717 (NAD 83)

Altitude: 346.2

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

Location:
In ALAMEDA county, CA View Original Datasheet
Designation:
A 981
Marker Type:
bench mark disk
Setting:
copper-clad steel rod
Stability:
Probably hold position/elevation well.

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Documented History (by the NGS)

01/01/1964 by CGS (MONUMENTED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1964 2.4 MI N FROM PLEASANTON. 2.35 MILES NORTH ALONG SANTA RITA ROAD FROM THE AMADOR VALLEY HIGH SCHOOL AT PLEASANTON, 40 1/2 FEET WEST OF THE CENTER LINE OF THE ROAD, 4.8 FEET EAST OF A FENCE, 3 FEET SOUTH OF A POWER LINE POLE, 1.7 FEET NORTH OF A WITNESS POST, ABOUT 1 FOOT LOWER THAN THE ROAD, A DISK ON THE TOP OF A 5/8-INCH COPPER COATED ROD DRIVEN TO A DEPTH OF 90 FEET. THE UPPER PORTION OF THE ROD IS ENCASED IN A CONCRETE POST PROJECTING 0.2 FOOT ABOVE THE GROUND.
01/01/1965 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1965 RECOVERED IN GOOD CONDITION.
01/01/1974 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1974 RECOVERED IN GOOD CONDITION.

Control Text

  • The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
  • The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) The vertical order pertains to the superseded datum.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 geoid height was determined by GEOID99.

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