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Details for Benchmark: MF0418

N 41° 18.900 W 088° 36.583 (NAD 83)

Altitude: 511.15

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

Location:
In LA SALLE county, IL View Original Datasheet
Designation:
N 141
Marker Type:
bench mark disk
Setting:
massive structures
Stability:
Probably hold position/elevation well.

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Still there and in good condition.

[Photos:]
photoMF0418

Found it yesterday (1/26). Good thing...I used it for elevation work I was doing. (civil engineering/land surveying work).

N 41° 18.907 W 088° 36.594

Found at the above coords; will upload pics soon. Mark is in good shape and so is the historical Hogan Grain Elevator nearby. Nice town, Seneca is.

[Photos:]
photoMF0418
photoMF0418 setting, looking north

found

[Photos:]
photoseneca im.jpg
photosenecaim.jpg

Documented History (by the NGS)

1/1/1947 by CGS (MONUMENTED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1947 AT SENECA. AT SENECA, SET IN THE TOP OF THE SOUTHEAST CONCRETE WING WALL OF THE STATE HIGHWAY 170 BRIDGE OVER THE ILLINOIS AND MICHIGAN CANAL, ABOUT 85 YARDS SOUTH OF THE POST OFFICE, 32 FEET EAST OF AND ABOUT 1/2 FOOT ABOVE THE CENTER LINE OF THE HIGHWAY.
1/1/1989 by USPSQD (GOOD)
RECOVERY NOTE BY US POWER SQUADRON 1989 (IB) RECOVERED IN GOOD CONDITION.
8/15/1997 by USPSQD (GOOD)
RECOVERY NOTE BY US POWER SQUADRON 1997 RECOVERED IN GOOD CONDITION.

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 June 1991.
  • 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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