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Details for Benchmark: HT0171

N 37° 49.783 W 122° 09.933 (NAD 83)

Altitude: 624.5

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

Location:
In CONTRA COSTA county, CA View Original Datasheet
Designation:
T 571 EBMUD
Marker Type:
survey disk
Setting:
set into the top of a round concrete monument
Stability:
May hold, but of type commonly subject to surface motion.

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Documented History (by the NGS)

01/01/1939 by EBMUD (MONUMENTED)
01/01/1962 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1962 3.4 MI W FROM MORAGA. 1.9 MILES SOUTHWEST ALONG CANYON ROAD FROM THE POST OFFICE AT MORAGA, THENCE 1.5 MILES NORTHWEST ALONG PINEHURST ROAD, 105 FEET SOUTHWEST OF AND ACROSS THE ROAD FROM THE CANYON STORE, 22.0 FEET SOUTHWEST OF THE CENTERLINE OF THE ROAD, 1.5 FEET SOUTHWEST OF A FENCE LINE, 1.0 FOOT WEST OF THE WEST END OF A STONE RETAINING WALL OF A CULVERT, AND SET IN THE TOP OF A CONCRETE POST 0.4 FOOT BELOW THE SURFACE OF THE GROUND.
01/01/1987 by USPSQD (MARK NOT FOUND)
RECOVERY NOTE BY US POWER SQUADRON 1987 (CAP) MARK NOT FOUND.

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  • The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) The vertical order pertains to the superseded datum.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