Details for Benchmark: HS3493
N 37° 40.900 W 121° 42.333 (NAD 83)
Coordinates may not be exact. Altitude is VERTCON and location is SCALED. (more info)
- In ALAMEDA county, CA View Original Datasheet
- C 738
- Marker Type:
- bench mark disk
- set into the top of a round concrete monument
- May hold, but of type commonly subject to surface motion.
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||KKCGeo found HS3493
Approx. 58 feet from original coordinates. None of the original descriptions apply to todays landscape. I will take a photo if I can get authorization.
Note: I only found this after I figured out what the footprint of the "control tower" was. A helpful site for this is: http://www.elivermore.com/photos/Hist_lvr_naval_air2.htm
[This entry was edited by KKCGeo on Friday, February 03, 2006 at 3:04:54 PM.]
Documented History (by the NGS)
|01/01/1944 by CGS (MONUMENTED)
|01/01/1958 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1958
AT LIVERMORE AECL. AT LIVERMORE ATOMIC ENERGY COMMISSION LABORATORY, ABOUT 0.15 MILE NORTH OF THE MAIN GATE, 147 FEET NORTHEAST OF THE GUARD GATE TO BUILDING 157, 36 FEET NORTH OF THE NORTH EDGE OF AN ASPHALT DRIVE LEADING EAST TO A PARKING LOT, 26.5 FEET SOUTHEAST OF THE NORTHEAST CORNER OF A CONCRETE FOUNDATION FOR A FORMER CONTROL TOWER, 3 FEET NORTH OF THE NORTHEAST CORNER OF THE CONCRETE FOUNDATION OF A FORMER PORCH, 0.4 FOOT EAST OF THE EAST EDGE OF A CONCRETE SLAB (FORMERLY A RAMP), ABOUT LEVEL WITH THE CONCRETE SLAB, AND SET IN THE TOP OF A CONCRETE POST FLUSH WITH THE ASPHALT.
|01/01/1960 by NGS (GOOD)
|RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1960
RECOVERED IN GOOD CONDITION.
- 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- The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) The vertical order pertains to the superseded datum.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.