Details for Benchmark: AL6483
N 28° 03.967 W 082° 26.917 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In HILLSBOROUGH county, FL View Original Datasheet
- K 257
- Marker Type:
- bench mark disk
- set into the top of a round concrete monument
- May hold, but of type commonly subject to surface motion.
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Documented History (by the NGS)
|01/01/1965 by CGS (MONUMENTED)
|01/01/1966 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1966
2.6 MI N FROM TAMPA. ABOUT 2.55 MILES NORTH ALONG THE SEABOARD AIR LINE RAILROAD FROM THE SULPHUR SPRINGS STATION AT TAMPA, NEAR THE CROSSING OF 131ST AVENUE, 47.1 FEET WEST OF THE WEST RAIL OF THE MAIN TRACK, 33.5 FEET NORTH OF THE CENTER LINE OF THE AVENUE, 2 FEET NORTH OF POWER POLE NO. 926, 4 1/2 FEET WEST OF A TELEPHONE POLE, 3 FEET SOUTH OF THE SOUTHEAST CORNER OF A STEEL FENCE AROUND HALLS GENERAL STORAGE, 1.2 FEET SOUTH OF A METAL WITNESS POST, ABOUT 0.5 FOOT BELOW THE LEVEL OF THE TRACK AND SET IN THE TOP OF A CONCRETE POST PROJECTING 0.3 FOOT.
- 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.