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Details for Benchmark: RD0797

N 45° 31.983 W 123° 09.167 (NAD 83)

Altitude: 197.12

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

Location:
In WASHINGTON county, OR View Original Datasheet
Designation:
N 163
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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Recovered. However, we wonder if the monument might have been bumped by recent work. The mark looks just slightly askew and one side of the concrete shows scrape marks. The occupants of the adjacent house said that the County recently performed cleaning work to improve drainage. The results of the ground scraping/clearing work are still clearly visible. Looking at the results, it seems possible that the mark could have been bumped.

It is unclear where the “farm road” is that the 1942 description made reference to.

The mark is 21.5 feet north of the painted centerline of the highway (as measured perpendicular to the alignment of the road).

The mark is 60 feet west from a utility pole as measured parallel to the highway. The utility pole is labeled as “VZ50255” and “VZ 508370”

The mark is 41 feet west from the approximate centerline of a driveway to a house.

The mark is 1.1 feet south of a galvanized metal post with no witness sign.

The mark is in a square concrete monument that protrudes 0.2 to 0.4 feet above the ground depending on which side is measured.

Our Nuvi 760 GPSr gave the coordinates of this mark as: N 45° 31.993 W 123° 09.195 (with “25 foot accuracy”).

[Photos:]
photoRD0797 - Disk - Forest Grove, Oregon.
photoRD0797 – Eye level - disk & post looking north.
photoRD0797 - Recent scrape of monument & earthwork.
Looking west at the monument and the earthwork that was done to improve drainage.
photoRD0797 - Looking west.
The post is on the right side of the photo. The concrete monument is just to the left of that.
photoRD0797 - Looking roughly east.
(Just for reference, RD0798 is located at the *very* upper right corner of this photo where you can see the road going uphill as it goes into Forest Grove).
photoRD0797 - Wide view, looking northwest.
Photo is taken while standing at the intersection of Sheeler road and Highway 8 and looking across Highway 8. The yellow arrow points to the location of the mark.

Documented History (by the NGS)

Unknown by DOD (MONUMENTED)
01/01/1942 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1942 2.5 MI NW FROM FOREST GROVE. 2.5 MILES NORTHWEST OF POST OFFICE ALONG HIGHWAY 6, 20 FEET WEST OF FARM ROAD, 25 FEET NORTH OF CENTER LINE OF HIGHWAY. WITNESS POST SET. NOTE-- ALONG STATE HIGHWAY 6 SHOULD BE CHANGED TO READ-- ALONG GALES CREEK ROAD.
01/01/1968 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1968 RECOVERED IN GOOD CONDITION.
01/01/1988 by USPSQD (GOOD)
RECOVERY NOTE BY US POWER SQUADRON 1988 (GL) RECOVERED IN GOOD CONDITION.
01/01/1988 by USPSQD (GOOD)
RECOVERY NOTE BY US POWER SQUADRON 1988 (WCC) RECOVERED IN GOOD CONDITION.
10/02/1994 by USPSQD (MARK NOT FOUND)
RECOVERY NOTE BY US POWER SQUADRON 1994 MARK NOT FOUND.

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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