Details for Benchmark: JV3975
N 39° 00.383 W 077° 15.267 (NAD 83)
Coordinates may not be exact. Altitude is VERTCON and location is SCALED. (more info)
- In FAIRFAX county, VA View Original Datasheet
- V 157=DAM
- Marker Type:
- survey disk
- in rock outcrop
- Most reliable and expected to hold position/elevation well.
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Documented History (by the NGS)
|Unknown by PBPP (MONUMENTED)
|01/01/1931 by (GOOD)
6.4 MI W FROM LANGLEY. 6.4 MILES WEST ALONG STATE HIGHWAY 193 FROM THE METHODIST CHURCH AT LANGLEY, FAIRFAX COUNTY, THENCE ABOUT 1 MILE NORTH ALONG SECONDARY STATE HIGHWAY 738 (ON THE OLD WASHINGTON AND OLD DOMINION RAILROAD GRADE) TO GREAT FALLS PARK, AND THENCE ABOUT 1 MILE NORTH ALONG A TRAIL FOLLOWING THE WEST BANK OF POTOMAC RIVER, 50 YARDS SOUTH OF THE WASHINGTON WATER-SUPPLY DAM, AND IN THE TOP OF A ROCK OUTCROP. A PUBLIC BUILDINGS AND PUBLIC PARKS STANDARD DISK.
|01/01/1959 by USGS (MARK NOT FOUND)
|RECOVERY NOTE BY US GEOLOGICAL SURVEY 1959
MARK NOT FOUND.
- The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
- The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) The vertical order pertains to the superseded datum.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 geoid height was determined by GEOID99.