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Details for Benchmark: AA8640

N 38° 36.680 W 090° 21.542 (NAD 83)

Altitude: 455

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

Location:
In ST LOUIS county, MO View Original Datasheet
Designation:
SL-12-2
Marker Type:
survey disk
Setting:
set into the top of a round concrete monument
Stability:
May hold, but of type commonly subject to surface motion.

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Found as described, disk and setting in good condition.
In front of Forest Products Supply Co.

[Photos:]
photoSL-12-2 AA8640 St. Louis Co., MO
closeup of disk
photoSL-12-2 AA8640 St. Louis Co., MO
the setting

Nifty little find on a day of geocaching. Right where it was supposed to be.

Easy to find next to one of my favorite places to have a drink and watch the Rams

Found benchmark and even found azimuth mark -- with help of rogbarn's notes. His photos look like mine so will not post mine. My GPS was right on for this benchmark today!

[last edit: 12/2/2002 1:22:36 PM PST]

Found survey disk and azimuth disk. I pass the azimuth disk almost every day and never knew it was there. They have even spray painted the designation on the sidewalk! (see picture)

[Photos:]
photoAA8640 (SL-12-2), Rock Hill, MO
Located in front of Rock Hill Lumber on Manchester Rd.
photoAA8640 azimuth mark (SL-12A), Rock Hill, MO
AA8640 azimuth mark (SL-12A) at Manchester and Rock Hill Rds.
photoAA8640 azimuth mark and sidewalk designation

Documented History (by the NGS)

01/01/1991 by MODNR (MONUMENTED)
DESCRIBED BY MO DEPT OF NAT RES 1991 STATION, AZIMUTH MARKS AND REFERENCE TIES STATION SL-12, 1990 HAS BEEN DESTROYED. PRIOR TO ITS DESTRUCTION, SL-12-2, 1991 WAS SET. STATION SL-12-2, 1991 IS IN FRONT OF THE ROCK HILL LUMBER COMPANY AT 9267 MANCHESTER ROAD (MO HWY 100). IT IS IN THE GRASSY AREA FORMED BY THE HIGHWAY AND THE LUMBER COMPANY PARKING LOT, AND FLUSH WITH THE GROUND. IT IS 95.0 FT (29.0 M) SOUTH AND 16 FT (4.9 M) EAST OF THE SE CORNER OF THE LUMBER COMPANY BUILDING, 122 FT (37.2 M) SW OF THE CENTER OF THE ABANDONED RAILROAD BED, AND 127 FT (38.7 M) EAST FROM A SIDE STREET ON THE WEST SIDE OF THE LUMBER COMPANY BUILDING. THE AZIMUTH MARK IS ABOUT 1/4 MILE SOUTHWESTERLY IN THE SE ANGLE OF THE TRAFFIC LIGHT INTERSECTION OF MANCHESTER ROAD IN ROCK HILL ROAD. IT IS 1.39 FT (0.42 M) ESE OF THE EDGE OF A SIDEWALK, 5.67 FT (1.73 M) ESE OF BACK OF CURB, 5.48 FT (1.67 M) SE OF AN ALUMINUM NAIL AND SHINER IN THE NE SIDE OF A POWER POLE, 24.93 FT (7.60 M) SSW OF THE WEST CORNER OF A TRAFFIC SIGNAL CONTROL BOX, 26.48 FT (8.07 M) NORTH OF THE CENTER OF A GAS VALVE BOX IN THE SIDEWALK, 17.30 FT (5.27 M) WEST OF THE SOUTH POST OF A DEPARTMENT OF REVENUE SIGN, AND 2 FT (0.6 M) SW OF A CARSONITE WITNESS POST STATION AND AZIMUTH MARK TO REACH TO REACH THE AZIMUTH MARK FROM THE CENTER OF I-44 EXIT 280 (ELM AVENUE) GO NORTH ON ELM FOR 0.85 MILES (1.37 KM) TO LOCKWOOD AVE, TURN LEFT AND GO WEST ON LOCKWOOD FOR 0.4 MILES (0.6 KM) TO ROCK HILL ROAD, TURN RIGHT AND GO NORTH ON ROCK HILL FOR 1.1 MILES (1.8 KM) TO AZIMUTH MARK ON RIGHT IN THE SE QUADRANT OF THE TRAFFIC LIGHT INTERSECTION WITH MANCHESTER ROAD (MO HWY 100) AS DESCRIBED. TO REACH THE STATION FROM THE AZIMUTH MARK, GO NORTHEASTERLY ON MANCHESTER ROAD FOR 0.25 MILE (0.40 KM) TO THE STATION SITE ON THE LEFT (NORTH) SIDE OF THE ROAD IN FRONT OF THE ROCK HILL LUMBER COMPANY AT 9267 MANCHESTER ROAD AS DESCRIBED. DATE OF REPORT 06-06-1995

Control Text

  • The horizontal coordinates were established by GPS observations and adjusted by the National Geodetic Survey in February 2000.
  • The orthometric height was determined by GPS observations and a high-resolution geoid model.
  • The X, Y, and Z were computed from the position and the ellipsoidal ht.
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The ellipsoidal height was determined by GPS observations and is referenced to NAD 83.
  • The geoid height was determined by GEOID99.

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