Details for Benchmark: HT1860
N 37° 47.383 W 122° 10.850 (NAD 83)
Coordinates may not be exact. Altitude is VERTCON and location is SCALED. (more info)
- In ALAMEDA county, CA View Original Datasheet
- S 1253
- Marker Type:
- bench mark disk
- copper-clad steel rod
- Probably hold position/elevation well.
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Documented History (by the NGS)
|01/01/1974 by NGS (MONUMENTED)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1974
0.8 KM (0.50 MI) NORTH FROM OAKLAND. 0.5 MILES NORTH ALONG STATE HIGHWAY 13 FROM THE JUNCTION OF INTERSTATE HIGHWAY 580 IN OAKLAND, 0.45 MILES NORTH OF THE KUHNLE AVENUE OVERPASS, 0.15 MILES SOUTH OF THE LEONA HEIGHTS PEDESTRIAN CROSSING, 60 FEET WEST-NORTHWEST OF THE NORTHWEST CORNER OF A METAL GRATE FOR A CATCH BASIN, 8.7 FEET NORTH-NORTHEAST OF THE CENTER OF A 36-INCH MANHOLE COVER, 2.0 FEET NORTHEAST OF THE NORTH END OF A GATE, 1.2 FEET EAST OF A FENCE, 2.2 FEET SOUTHEAST OF A METAL WITNESS POST, A DISK ON TOP OF A 5/8-INCH COPPER COATED STEEL ROD DRIVEN TO GRADUAL REFUSAL AT A DEPTH OF 13 FEET, THE UPPER PORTION OF THE ROD IS ENCASED IN CONCRETE AROUND A 4-INCH PLASTIC PIPE THAT PROJECTS 0.1 FOOT ABOVE THE GROUND, THE DISK IS 0.2 FOOT UNDERGROUND, 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- The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) The vertical order pertains to the superseded datum.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.