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Details for Benchmark: OA0790

N 42° 44.337 W 124° 29.954 (NAD 83)

Altitude: 19.27

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

Location:
In CURRY county, OR View Original Datasheet
Designation:
943 1647 TIDAL LEAD
Marker Type:
survey disk
Setting:
in rock outcrop
Stability:
Most reliable and expected to hold position/elevation well.

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Found early morning. Several of the benchmarks in this area have been covered over by the construction of the new dock in the early 2000's. I was able to locate 4 using the descriptions. Marks are scaled rather than adjusted so the coordinates are off a bit.

This marks description matched the actual location better than the others.

[Photos:]
photoOA0790 - Lead
photoLooking West
photoLooking South
photoLooking East
photoLooking North
photoTaken while benchmarking.

Documented History (by the NGS)

01/01/1964 by USE (MONUMENTED)
01/01/1988 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1988 0.7 KM (0.45 MI) SW FROM PORT ORFORD. 0.7 KM (0.45 MI) SOUTHWESTERLY ALONG HARBOR DRIVE FROM THE JUNCTION OF U.S. HIGHWAY 101 IN PORT ORFORD, IN A LARGE AREA OF OUTCROPPING BEDROCK ALONG THE WEST EDGE OF FISHERMAN WHARF, 31.6 M (103.7 FT) NORTHEAST OF BENCH MARK 1647 K TIDAL, 28.6 M (93.8 FT) SOUTH OF THE NORTHWEST CORNER OF THE WHARF, 10.8 M (35.4 FT) EAST OF BENCH MARK 1647 J TIDAL, AND 6.0 M (19.7 FT) WEST OF THE EXTENDED CENTER OF THE DRIVE.
05/23/1998 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1998 (CLS) NOTE--THE -A- IN THE STAMPING RESEMBLES A TRIANGLE. THE STATION IS LOCATED ABOUT 0.7 KM (0.45 MI) SOUTHWEST OF PORT ORFORD, IN A LARGE AREA OF OUTCROPPING BEDROCK, AT THE SOUTHWEST CORNER OF THE PORT ORFORD WHARF. OWNERSHIP--OREGON STATE COASTAL ZONE MANAGEMENT. TO REACH THE STATION FROM U.S. HIGHWAY 101 (6TH STREET) AND HARBOR DRIVE IN PORT ORFORD, GO SOUTH THEN WEST ON HARBOR DRIVE FOR 0.7 KM (0.45 MI) TO SOUTHERN END OF ASPHALT PARKING AREA AT FISHERMAN WHARF AND THE STATION DUE SOUTH TOWARDS OCEAN. THE STATION IS A U.S. ARMY CORPS OF ENGINEERS SURVEY MARK DISK CEMENTED IN A DRILL HOLE IN MASSIVE OUTCROP ABOUT 60 CM LOWER THAN THE PARKING AREA. IT IS 31.4 M (103.0 FT) EAST-SOUTHEAST FROM TIDAL BM 1647 K 1978, 30.45 M (99.90 FT) WEST-NORTHWEST FROM A METAL PIPE SUPPORTING WARNING SIGN AT NORTHWEST END OF STONE JETTY, 23.3 M (76.4 FT) SOUTHEAST FROM THE SOUTHWEST CONCRETE CURB FOR THE PARKING AREA, 21.3 M (69.9 FT) SOUTH FROM THE SOUTHEAST CONCRETE CURB OF PARKING AREA, AND 10.7 M (35.1 FT) EAST-NORTHEAST OF TIDAL BM 1647 J 1978.

Control Text

  • The horizontal coordinates were established by GPS observations and adjusted by the National Geodetic Survey in April 2000. This is a SPECIAL STATUS position. See SPECIAL STATUS under the DATUM ITEM on the data sheet items page. The horizontal coordinates are valid at the epoch date displayed above. The epoch date for horizontal control is a decimal equivalence of Year/Month/Day.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in June 1991.
  • This Tidal Bench Mark is designated as VM 1044 by the Center for Operational Oceanographic Products and Services.
  • 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.
  • 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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