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Details for Benchmark: HV8669

N 38° 47.528 W 077° 06.783 (NAD 83)

Altitude: 247

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

Location:
In FAIRFAX county, VA View Original Datasheet
Designation:
TWAIN
Marker Type:
survey disk
Setting:
surrounded by a mass of concrete
Stability:
Mark of questionable or unknown stability.

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Found with Nemo Consequentia while on a Bench Marking and cache run through Arlington, Alexandria and Fairfax County. Still quite visible after almost two years.

[Photos:]
photoHV8669

Observed with seadog129, photo with his log.

Found as described behind Twain Middle School. Mark was near the top of the stairs and on the school side of the sidewalk between the 8th and 9th sidewalk slabs (OK, it is all one slab but is separated by lines). Soccer was not a problem today but cricket was in in full swing.

N 38° 47.528 W 077° 06.783

This was an easy find--just need to watch for soccer balls and be ready to do a header.

Well-exposed disk toward the rear of the Mark Twain Middle School property and near the top of concrete steps leading down to Kerrybrook Drive (correcting street name in 1975 description). That description also mentions reference marks on eastern and western handrails. These could not be found, but the concrete steps, which currently have a central metal handrail, bear evidence of having previously flanked on each side by metal railings (stubs sheared off at the surface of the concrete), so possibly these reference marks have been destroyed.

[Photos:]
photoCloseup of 'Twain,' Fairfax County, VA
photo'Twain' in foreground (arrow), with steps down to Kerrybrook Dr in distance, Fairfax Co., VA

The mark was found. The lone shrub is gone. The nearby access is Kerrybrook Drive, not Kerrybrook Lane.

[Photos:]
photoStation TWAIN in Alexandria, Virginia
Worn but still there.
photoAt station TWAIN in Alexandria, Virginia
Station near sidewalk to steps down to Kerrybrook Drive.

Documented History (by the NGS)

01/01/1975 by VA-059 (MONUMENTED)
DESCRIBED BY FAIRFAX COUNTY VIRGINIA 1975 (EYB) THE STATION IS LOCATED ABOUT 5.7 MILES NORTH OF MT VERNON, 4 MILES EAST OF SPRINGFIELD, 1.7 MILES WEST OF PENN DAW, IN THE NORTHEAST CORNER OF THE MARK TWAIN ELEMENTARY SCHOOL PROPERTY JUST OFF THE CONCRETE SIDEWALK TO THE STEPS THAT LEAD TO KERRYBROOKE LANE. SEE FAIRFAX COUNTY TAX MAP 82-1. TO REACH THE STATION FROM THE JUNCTION OF ROUTE 611, TELEGRAPH ROAD, AND ROUTE 644, FRANCONIA ROAD, GO WEST ON ROUTE 644 FOR 1.7 MILES TO THE MARK TWAIN SCHOOL ON THE RIGHT. TURN RIGHT AND GO NORTH TO THE ASPHALT COURTS AT THE REAR OF THE SCHOOL. FOLLOW THE CONCRETE SIDEWWLK THAT BEGINS AT THE NORTHEAST CORNER OF THE ASPHALT AREA NORTH TO THE CONCRETE STEPS THAT LEAD DOWN INTO THE HOUSING AREA AND THE STATION ON THE LEFT IN THE GRASS PRIOR TO THE STEPS. THE STATION IS A FAIRFAX COUNTY BRASS SURVEY DISC STAMPED---TWAIN 1975--- SET INTO THE TOP OF AN IRREGULAR MASS OF CONCRETE FLUSH WITH GROUND LOCATED 5 FEET SW FROM THE EDGE OF THE CONCRETE SIDEWALK AND 40 FEET S FROM THE LONE SHRUB BESIDE THE CONCRETE STEPS. REFERENCE MARK NO. 01 IS A CHISELED X IN THE TOP OF THE EASTERN METAL HANDRAIL. LOCATED 150 FEET W FROM THE EDGE OF WOODS EAST. REFERENCE MARK NO. 02 IS A CHISELED X IN THE TOP OF THE WESTERN METAL HANDRAIL. LOCATED 210 FEET SE FROM THE EDGE OF WOODS WEST.

Control Text

  • The horizontal coordinates were established by classical geodetic methods and adjusted by the National Geodetic Survey in November 1994.
  • The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.)
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The geoid height was determined by GEOID99.

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