Details for Benchmark: HS4128
N 37° 42.150 W 121° 45.550 (NAD 83)
Coordinates may not be exact. Altitude is VERTCON and location is SCALED. (more info)
- In ALAMEDA county, CA View Original Datasheet
- D 1259
- Marker Type:
- bench mark disk
- pavements (street, sidewalk, curb, apron, etc.)
- Mark of questionable or unknown stability.
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Documented History (by the NGS)
|01/01/1974 by NGS (MONUMENTED)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1974
1.7 KM (1.05 MI) WEST FROM LIVERMORE. 1.05 MILES WEST ALONG INTERSTATE HIGHWAY 580 FROM THE STATE HIGHWAY 84 (FIRST STREET) OVERPASS IN LIVERMORE, AT THE EAST BOUND LANES BRIDGE OVER ARROYO LAS POSITAS, 20 FEET SOUTH OF THE SOUTH MOST CENTERLINE OF THE EAST BOUND HIGHWAY LANES, IN THE TOP OF THE SOUTHWEST CORNER OF THE BRIDGE FLOOR, 14.8 FEET WEST OF THE EAST END OF THE SOUTH CONCRETE GUARDRAIL, 1.4 FEET NORTH OF THE SOUTH CONCRETE GUARDRAIL, AND ABOUT LEVEL WITH THE HIGHWAY.
- 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- The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) The vertical order pertains to the superseded datum.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.