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Details for Benchmark: DX3486

N 33° 55.683 W 117° 56.867 (NAD 83)

Altitude: 278.73

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

Location:
In ORANGE county, CA View Original Datasheet
Designation:
S 1329
Marker Type:
bench mark disk
Setting:
galvanized steel rod
Stability:
Probably hold position/elevation well.

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Found it this time! OK, I assumed that the old, almost falling down utility pole was the one described (no number on it). The other directions / landmarks fit reasonably well. Had to move some pieces of railroad ties (luckily not whole ones!), and there it was! The described "...4-INCH PLASTIC SCREW PLUG..." has been destroyed.

[Photos:]
photoDX3486 Disc in La Habra CA
photoDX3486 Disc Maxi closeup
photoDX3486 Area in La Habra CA

Didn't find the access plug. Metal detector would help. Maybe I'll try it again with one.

Documented History (by the NGS)

01/01/1978 by NGS (MONUMENTED)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1978 LA HARBRA. AT LA HARBRA, AT THE CROSSING OF THE UNION PACIFIC RAIL ROAD AND EUCILID STREET, 21 FT. NORTH OF THE NORTH RAIL, 1 FOOT EAST OF TELEPHONE POLE NO. DFC 640, 54 FT. SOUTH OF THE FENCE AROUND TENNIS COURT, 78 FT. NORTHWEST OF A 24-INCH CULVERT, THE DISK IS FLUSH WITH THE SURFACE OF THE GROUND, ACCESS TO WHICH IS HAD THROUGH A 4-INCH PLASTIC SCREW PLUG.

Control Text

  • The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in February 1993. * This is a READJUSTED BENCH MARK height. Code A indicates a distribution rate of 0.0 thru 1.0 mm/km. The height was derived from older observations constrained to new heights in a crustal motion area. The height is approximate in relation to other heights in its vicinity.
  • The geoid height was determined by GEOID99.
  • The dynamic height is computed by dividing the NAVD 88 geopotential number by the normal gravity value computed on the Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 degrees latitude (G = 980.6199 gals.).
  • The modeled gravity was interpolated from observed gravity values.

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