[time-nuts] National Geodetic Survey Bench Mark

Michael Baker mpb45 at clanbaker.org
Wed Sep 14 23:10:26 UTC 2011


Hello, TimeNutters--

Majdi asked about details on the USGS benchmark located
about 1/2 mile from my house out here in the boonies.

Below is what I have in my file on it.

Some of this means nothing to me-- my only interest in the
benchmark was knowing (roughly) how accurately it is located
for comparing to my GPS and GPSDO receivers.

Mike Baker
-----------------------------------

N  29d     32m     31.00741s    (which is 31s plus 0.75ft)

W 082d   21m     04.77943s    (which is 04s plus 68.84ft)

Parked truck immediately beside the (apparent) marker location
and got the following readings:

N 29d    32.519m  (translates to:  32m  31.14s or 31s plus 14.12ft)
W 82d    21.078m  (translates to:  21m  04.92s or 04s plus 60.06ft)

At this location, each sec north = 100.83ft     each sec west = 88.33ft


Look for a cap and nail (small disk) on the centerline of the road,
or some sort of marker post by the southwest side of the road.

If you find the marker post, the benchmark is 7.5 feet south of it,
and pretty much next to the cap and nail in the road centerline.

  It will be between the driveways for 1926 SE Wacahoota Road and
2010 SE Wacahoota Road.

THE STATION IS A STANDARD AC GIS DISK STAMPED---STATION A107---,

SET IN THE GROUND 15 FT TO REFUSAL (6 IN PVC SLEEVE) 9.83 METERS
(32.24 FT) SOUTHWEST FROM A NAIL & CAP (NO 3765) SET
IN CENTERLINE OF ACR 18,

51.17 METERS (167.87 FT) NORTHWEST FROM A NAIL & CAP (NO 3765)
SET IN POWER POLE,

  2.3 METERS (7.5 FT) SOUTH OF CARSONITE POST SET,

31.82 METERS (104.40 FT) SOUTHEAST FROM A NAIL & CAP (NO 3765)
SET IN A POWER POLE,

7.96 METERS (26.13 FT) NORTHEAST FROM A REBAR & CAP (NO 3765) SET.
-------------------------------------------------------------------------------------------------------------------

AZIMUTH MARK NO. 1 IS A STANDARD AC GIS DISK STAMPED---AZIMUTH A108---,
SET INTO GROUND 10.5 FT TO REFUSAL (6 IN PVC SLEEVE)
5.95 METERS (19.52 FT) NORTHWEST FROM A NAIL & CAP (NO 3765) SET
IN POWER POLE,

9.58 METERS (31.43 FT) SOUTH FROM A NAIL & CAP (NO 3765) SET IN
CENTERLINE OF ACR 18.

TO REACH THE AZIMUTH FROM THE STATION, GO NORTHWEST FOR
0.5 KM (0.3 MI) ON ACR 18 TO AZIMUTH MARK ON THE SOUTH SIDE OF ROAD.


                          STATION RECOVERY (2002)

RECOVERY NOTE BY FL DEPT OF ENV PRO 2002 (BPJ)
THE MARK IS ABOUT 4.6 MI NORTHWEST OF MICANOPY, IN SECTION 18,
TOWNSHIP 11 SOUTH, RANGE 20 EAST.

A DISC & METAL ROD COMBINATION RECESSED 0.3 FT BELOW THE LEVEL
OF THE GROUND AND LEVEL WITH SOUTHEAST WACAHOOTA ROAD.

LOCATED 122.0 FT EAST-SOUTHEAST OF THE EXTENDED APPROXIMATE
CENTERLINE OF A DIRT DRIVEWAY AT 2010 SOUTHEAST WACAHOOTA
ROAD, 108.0 FT WEST-NORTHWEST OF THE EXTENDED APPROXIMATE
CENTERLINE OF A DIRT DRIVEWAY AT 1926 SOUTHEAST WACAHOOTA
ROAD, 32.3 FT SOUTH-SOUTHWEST OF THE APPROXIMATE CENTERLINE
OF SOUTHEAST WACAHOOTA ROAD, 7.8 FT SOUTH-SOUTHWEST OF A
BARB WIRE FENCE & 7.7 FT SOUTH-SOUTHWEST OF A CARSONITE
WITNESS POST.

NOTE A BAR MAGNET WAS EMBEDDED IN THE MONUMENT.

NOTE 6-INCH PVC SLEEVE AROUND THE DISC IS DAMAGED
BUT DISC IS IN GOOD CONDITION.
--------------------------------------------------------------------------------------------------------------------------------

The NGS Data Sheet
See file  dsdata.txt for more information about the datasheet.
DATABASE =  ,PROGRAM = datasheet, VERSION = 7.61
1        National Geodetic Survey,   Retrieval Date = SEPTEMBER  4, 2008
  AR1764
***********************************************************************
  AR1764  DESIGNATION -  A 107
  AR1764  PID         -  AR1764
  AR1764  STATE/COUNTY-  FL/ALACHUA
  AR1764  USGS QUAD   -  MICANOPY (1988)
  AR1764
  AR1764                         *CURRENT SURVEY CONTROL
  AR1764  
___________________________________________________________________
  AR1764* NAD 83(2007)-  29 32 31.00741(N)    082 21 04.77943(W)     
ADJUSTED
  AR1764* NAVD 88     -        29.117  (meters)      95.53   (feet)  
ADJUSTED
  AR1764  
___________________________________________________________________
  AR1764  EPOCH DATE  -        2002.00
  AR1764  X           -     739,157.689 (meters)                     COMP
  AR1764  Y           -  -5,504,058.842 (meters)                     COMP
  AR1764  Z           -   3,126,301.264 (meters)                     COMP
  AR1764  LAPLACE CORR-          -0.46  (seconds)                    
DEFLEC99
  AR1764  ELLIP HEIGHT-           1.257 (meters)          (02/10/07) 
ADJUSTED
  AR1764  GEOID HEIGHT-         -27.78  (meters)                     GEOID03
  AR1764  DYNAMIC HT  -          29.077 (meters)      95.40  (feet)  COMP
  AR1764
  AR1764  ------- Accuracy Estimates (at 95% Confidence Level in cm) 
--------
  AR1764  Type    PID    Designation                      North   East  
Ellip
  AR1764  
-------------------------------------------------------------------
  AR1764  NETWORK AR1764 A 107                             2.12   1.43   
4.21
  AR1764  
-------------------------------------------------------------------
  AR1764  MODELED GRAV-     979,275.5   (mgal)                       NAVD 88
  AR1764
  AR1764  VERT ORDER  -  SECOND    CLASS I
  AR1764
  AR1764.The horizontal coordinates were established by GPS observations
  AR1764.and adjusted by the National Geodetic Survey in February 2007.
  AR1764
  AR1764.The datum tag of NAD 83(2007) is equivalent to NAD 83(NSRS2007).
  AR1764.See National Readjustment for more information.
  AR1764.The horizontal coordinates are valid at the epoch date displayed
above.
  AR1764.The epoch date for horizontal control is a decimal equivalence
  AR1764.of Year/Month/Day.
  AR1764
  AR1764.The orthometric height was determined by differential leveling
  AR1764.and adjusted in May 2004.
  AR1764.No vertical observational check was made to the station.
  AR1764
  AR1764.The X, Y, and Z were computed from the position and the 
ellipsoidal
ht.
  AR1764
  AR1764.The Laplace correction was computed from DEFLEC99 derived 
deflections.
  AR1764
  AR1764.The ellipsoidal height was determined by GPS observations
  AR1764.and is referenced to NAD 83.
  AR1764
  AR1764.The geoid height was determined by GEOID03.
  AR1764
  AR1764.The dynamic height is computed by dividing the NAVD 88
  AR1764.geopotential number by the normal gravity value computed on the
  AR1764.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45
  AR1764.degrees latitude (g = 980.6199 gals.).
  AR1764
  AR1764.The modeled gravity was interpolated from observed gravity values.
  AR1764
  AR1764;                    North         East     Units Scale Factor 
Converg.
  AR1764;SPC FL N     -    62,036.260   808,252.110   MT  1.00000756   
+1 04
47.1
  AR1764;SPC FL N     -   203,530.63  2,651,740.46   sFT  1.00000756   
+1 04
47.1
  AR1764;UTM  17      - 3,268,792.469   369,066.923   MT  0.99981153   
-0 39
59.0
  AR1764
  AR1764!             -  Elev Factor  x  Scale Factor =   Combined Factor
  AR1764!SPC FL N     -   0.99999980  x   1.00000756  =   1.00000736
  AR1764!UTM  17      -   0.99999980  x   0.99981153  =   0.99981133
  AR1764
  AR1764                          SUPERSEDED SURVEY CONTROL
  AR1764
  AR1764  NAD 83(1999)-  29 32 31.00761(N)    082 21 04.77971(W) 
AD(       ) 2
  AR1764  ELLIP H (06/12/02)    1.228  (m)                       
GP(       ) 4
1
  AR1764  NAD 83(1990)-  29 32 31.00634(N)    082 21 04.77939(W) 
AD(       ) 2
  AR1764  ELLIP H (05/01/91)    1.267  (m)                       
GP(       ) 4
1
  AR1764  NAD 83(1986)-  29 32 31.01433(N)    082 21 04.78738(W) 
AD(       ) 2
  AR1764  NGVD 29 (11/17/89)   29.7    (m)           97.     (f) GPS OBS
  AR1764
  AR1764.Superseded values are not recommended for survey control.
  AR1764.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.
  AR1764.See file dsdata.txt to determine how the superseded data were 
derived.
  AR1764
  AR1764_U.S. NATIONAL GRID SPATIAL ADDRESS: 17RLN6906768792(NAD 83)
  AR1764_MARKER: DD = SURVEY DISK
  AR1764_SETTING: 2 = OBJECT DRIVEN INTO GROUND
  AR1764_SP_SET: OBJECT DRIVEN INTO GROUND
  AR1764_STAMPING: A107
  AR1764_MARK LOGO: FL-001
  AR1764_MAGNETIC: M = MARKER EQUIPPED WITH BAR MAGNET
  AR1764_STABILITY: D = MARK OF QUESTIONABLE OR UNKNOWN STABILITY
  AR1764_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR
  AR1764+SATELLITE: SATELLITE OBSERVATIONS - October 31, 2002
  AR1764
  AR1764  HISTORY     - Date     Condition        Report By
  AR1764  HISTORY     - 1988     MONUMENTED       PMC
  AR1764  HISTORY     - 20021031 GOOD             FLDEP




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