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Details for Benchmark: AA8581

N 38° 42.232 W 090° 13.364 (NAD 83)

Altitude: 430

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

Location:
In C OF ST LOUIS county, MO View Original Datasheet
Designation:
CSL-21
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 this one in fair condition.

[Photos:]
photoCSL-21

Found the main mark. There is no description for the main mark but it is very apparent -- it protrudes above ground level. My Gps got me in the vicinity. The CSL-21 is hard to read -- the disk has some scratches. See the photo. It is near Hall street pavement and in the vicinity of the SW corner of the St. Louis Medium Security Institution. I did not find the azimuth mark. I found a witness post for the azimuth mark. I guess that the disk is probably covered up by dirt.

[last edit: 2/20/2003 4:39:04 PM PST]

[Photos:]
photoAA8581 (CSL-21)
Hard to read the 21 in the photo.
photoview to NorthWest from AA8581
photoview to the South East from AA8581
photoWitness post for the azimuth mark
photowitness post for azimuth mark & RR crossing
Hall street crossing RR

Documented History (by the NGS)

01/01/1990 by MODNR (MONUMENTED)
DESCRIBED BY MO DEPT OF NAT RES 1990 STATION, AZIMUTH MARKS AND REFERENCE TIES THE AZIMUTH MARK IS ABOUT 0.3 MILES (0.5 KM) NW ON THE SE SIDE OF HALL STREET (APPROXIMATELY 250 FT SOUTH OF BLAZE AVENUE) AND 43.2 FT (13.2 M) SE OF TH SOUTH RAIL OF A RR X-ING. IT IS 9.29 FT (2.83 M) SE OF THE CORNER POST OF A CHAIN LINK FENCE, 7.28 FEET (2.22 M) FROM A CUT (X) 0.2 FT (6.1 CM) EAST OF SW EDGE OF HALL STREET PAVEMENT, 4.59 FT (1.40 M) SW OF EDGE OF PAVEMENT, 6.62 FT (2.02 M) NNW OF A CUT (X) 0.2 FT (6.1 CM) FROM SW EDGE OF PAVEMENT, 13.88 FT (4.23 M) FROM A BRACED POST IN THE CHAIN LINK FENCE, AND 4.3 FT (1.3 M) NE OF A CARSONITE WITNESS POST STATION AND AZIMUTH MARK TO REACH TO REACH THE STATION FROM THE CENTER OF I-70 EXIT 246B (ADELAIDE AVENUE), GO NE ON ADELAIDE AVENUE FOR 0.45 MILES (0.72 KM) TO TRAFFIC LIGHT INTERSECTION WITH HALL STREET. TURN LEFT AND GO NW ON HALL STREET FOR 1.75 MILES (2.82 KM) TO STATION SITE ON RIGHT (NE) SIDE OF STREET AS DESCRIBED. TO REACH THE AZIMUTH MARK FROM THE STATION CONTINUE NORTHWESTERLY ON HALL STREET FOR 0.3 MILES (0.5 KM) TO AZIMUTH MARK SITE ON LEFT (SW) SIDE JUST BEFORE REACHING THE RAILROAD CROSSING 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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