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Details for Benchmark: MH0702

N 41° 14.897 W 093° 07.788 (NAD 83)

Altitude: 946.5

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

Location:
In MARION county, IA View Original Datasheet
Designation:
ET 14 JHB
Marker Type:
traverse station 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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Good condition.
Area is now a mowed lawn and there is no fence or pole. Disk is 118 ft (36.0 m) SE of the corner of a steel building, 71.5 ft ( 21.8 m) NW of the center line of Hwy 14, 50 ft (15.2 m) North of the projected center of Quaker Drive, 30.5 ft (9.3 m) Northeast of a leaning concrete Right Of Way post, 1.2 ft (0.4 m) Southeast of a witness post. and projecting 1 inch (3 cm).

A 1-hour OPUS-RS session found NAD83(2011) N 41 15 15.53278 W 093 7 14.54452, Ellip Ht 256.579 m (841.79 ft) and using Geoid12B ortho 288.433 m (946.30 ft). Sky is open.

Found where Bill93 said it was, although the disk is stamped "14 JHB ET 1964".

[Photos:]
photoMH0702 #1
photoMH0702 #2

Disk '14 JHB ET 1964' found in good condition consistent with description except pole is gone. Located about 50 ft north of projected center of straight portion of Quaker Drive, and 1.2 foot southeast of witness post, handheld coordinates N41.25433 W093.12071 (N41 15.260 W093 07.242) (N41 15' 15.59" W093 07' 14.56"), sky visibility good.

Values originally published as ADJUSTED coordinates for MH0702 do not match the disk by 0.6 mile. Geodetic azimuth from published coordinates to courthouse (calculated by plane trig only) 199 19.5', and from measured coordinates 195 30' much better agreement. Published values are 0.6 mile southwesterly from mark along highway, at next east-west road crossing, found by handheld GPS to be 96 feet east of the center of the crossing, and 8 feet south of the center line of the gravel road.

2006 Jun 7 The NGS determined that the wrong USGS station name and disk description had been entered for MH0702. They kept the coordinates for MH0702 but changed its designation to 'STA 50 CH 1837' and made it unpublished. It is the station 0.6 mile south. There may be no permanent monument at the coordinates. USGS sometimes used rebar for stations not monumented with a disk. 2006 Nov 6 a search with ferrous metal detector found no re-rod near the coordinates.

The station at the disk described on the old MH0702 sheet is actually MH0753 ET 14 JHB, very near the handheld coordinates I posted, and they have listed my recovery notes at MH0753 (which is not in the GC snapshot of the data).

The re-rods in concrete found on at least 3 corners of the southern intersection and many other intersections are not USGS or NGS stations, but are commonly used by the highway department as right-of-way markers.

2016 June 25 Fence is gone and new construction to the west of the mark. Marked stake indicates disk was used with elevation 946.00, which must have been measured because it doesn't match scaled elevation.

[Photos:]
photoMH0753_20041125_A.jpg
.
photoMH0753_20041125_C.jpg
.

Bummer! I'm not having much luck with this benchmark business so far, except for the easy ones like water towers and such. I need to visit one that's already been found so I know what I'm looking for.

I found this square concrete thing with rerod sticking out of it where the marker should have been. Don't know whether this was it or not. It looks at though it's been hit with the mower at least once. See picture.

James

[last edit: 1/16/2004 12:47:07 PM PST]

[Photos:]
photoMH0702???

Documented History (by the NGS)

1/1/1964 by USGS (MONUMENTED)
DESCRIBED BY US GEOLOGICAL SURVEY 1964 KNOXVILLE, APPROX. 5.0 MI S. OF ALONG STATE HWY. 14, T. 75 N., R. 20 W., APPROX. QUARTER CORNER BETWEEN SECS. 35 AND 36 AT Y-RD. W., 15 FT N. AND 66 FT W. OF POINT OF TANGENT OF Y-RD. AND HWY., 7 FT SW. OF A POLE AND 1.5 FT SE. OF FENCE, STANDARD TABLET STAMPED--- 14 JHB ET 1964--- AZIMUTH TO KNOXVILLE COURT HOUSE 195 32 40.

Control Text

  • The horizontal coordinates were established by classical geodetic methods and adjusted by the National Geodetic Survey in May 1999.
  • 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 Laplace correction was computed from DEFLEC99 derived deflections.
  • The geoid height was determined by GEOID99.

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