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Details for Benchmark: AA3905

N 41° 26.017 W 091° 32.467 (NAD 83)

Altitude: 651.3

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

Location:
In KEOKUK county, IA View Original Datasheet
Designation:
5 RESET
Marker Type:
vertical control disk
Setting:
setting not listed - see description
Stability:
Mark of questionable or unknown stability.

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Found NGS and State Survey aluminum disk with raised center stamped NO. 5 RESET 1975 in good condition at handheld coordinates N41 10.581 W092 21.460, 2.6 miles west of Main St in Hedrick, due south of southeast corner of a house at rural address 12801, 76.5 feet south of center of highway, 12 feet south and 1.5 foot east of highway station post 150, 30 feet south southeast of an orange post at the end of a culvert, 9.4 feet east southeast of a power pole, 1 foot west of a witness post, and 2 inches below the surface.

Handheld GPS elevation 814 feet (NAD83), above road elevation by a few feet. Topo map shows elevations between 800 and 850 feet in the general vicinity.

The listed coordinates are for MG0461 Designation 5 in Washington county and the listed elevation may be associated with that mark as it is unreasonable for this location. I cannot find a listing for the (destroyed) PID of the one in Keokuk county it replaced.

NGS has changed the SCALED coordinates to my handheld values (rounded).

[This entry was edited by Bill93 on Tuesday, January 22, 2008 at 3:31:29 PM.]

[Photos:]
photoAA3905_20040916_A.jpg
photoAA3905_20040916_C.jpg

Documented History (by the NGS)

01/01/1975 by NGS (MONUMENTED)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1975 (CLN) 2.6 MILES (4.2 KM) WEST ALONG STATE HIGHWAY 149 FROM THE RAILROAD CROSSING AND STATION IN HEDRICK, 130.80 FEET (39.87 M) AND ON A LINE ABOUT 10 DEGREES SOUTHWEST FROM THE ORIGINAL MARK, 3.2 FEET (1.0 M) EAST OF A POWER POLE, 1 FOOT (0.3 M) WEST OF A METAL WITNESS POST, ON THE SOUTH RIGHT-OF-WAY OF HIGHWAY 149 AND DUE SOUTH OF THE SOUTHEAST CORNER OF A FARM HOUSE OWNED BY MR F B DINNITT, SET FLUSH WITH THE GROUND SURFACE.

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  • The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) The vertical order pertains to the superseded datum.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