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Bench Mark Sheet for 8724094, EAST BAHIA HONDA KEY FL

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 8724094                         PUBLICATION DATE:  12/12/2003
Name:       EAST BAHIA HONDA KEY                              
            FL
NOAA Chart: 11449                           Latitude:   24° 46.5' N (  24.77500)
USGS Quad:  EAST BAHIA HONDA KEY            Longitude:  81° 13.6' W ( -81.22670)


To reach the tidal bench marks from the west end of Seven Mile Bridge on Little
Duck Key, proceed by boat 11.1 km (6.0 nm) north to the SE end of East Bahia
Honda Key.  The bench marks are located along the mangrove shoreline.  The tide
gage and staff were located on a small temporary offshore platform.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  TRADE 1935
                         DESIGNATION:          872 4094 TRADE

MONUMENTATION:           Triangulation Station disk            VM#:         6332
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AA1453
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   24° 46.5' N (  24.77500)          LONGITUDE:  81° 13.7' W ( -81.22830)


The primary bench mark is a disk set in the top of a concrete monument located
on the SE end of East Bahia Honda Key, 90 m (295 ft) from the extreme southern
tip, 18 m (59 ft) from the south shore, on a narrow sand ridge behind a fringe
of mangrove in a small open area, and 0.06 m (0.2 ft) above ground level.



                         BENCH MARK STAMPING:  TRADE NO 1 1935
                         DESIGNATION:          872 4094 TRADE 1

MONUMENTATION:           Reference Mark disk                   VM#:         6333
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   24° 46.5' N (  24.77500)          LONGITUDE:  81° 13.6' W ( -81.22670)


The bench mark is a disk set in the top of a concrete monument, 13.96 m (45.8
ft) NW of triangulation station TRADE 1935, 0.3 m (1 ft) SE of a witness post,
and 0.09 m (0.3 ft) above ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 8724094                         PUBLICATION DATE:  12/12/2003
Name:       EAST BAHIA HONDA KEY                              
            FL
NOAA Chart: 11449                           Latitude:   24° 46.5' N (  24.77500)
USGS Quad:  EAST BAHIA HONDA KEY            Longitude:  81° 13.6' W ( -81.22670)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  TRADE NO 2 1935
                         DESIGNATION:          872 4094 TRADE 2

MONUMENTATION:           Reference Mark disk                   VM#:         6334
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   24° 46.5' N (  24.77500)          LONGITUDE:  81° 13.6' W ( -81.22670)


The bench mark is a disk set in the top of a concrete monument, 11.16 m (36.6
ft) SE of triangulation station TRADE 1935 on the same ridge, 0.12 m (0.4 ft) SE
of a witness post, and 0.06 m (0.2 ft) above ground level.



                         BENCH MARK STAMPING:  DON 1974
                         DESIGNATION:          872 4094 DON

MONUMENTATION:           Tidal Station disk                    VM#:         6335
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   24° 46.5' N (  24.77500)          LONGITUDE:  81° 13.6' W ( -81.22670)


The bench mark is a disk located on a narrow sand berm on the south side of the
key, 26.00 m (85.3 ft) SE of bench mark CAL 1974, 3.35 m (11.0 ft) south of the
north side of the sand berm, and 0.24 m (0.8 ft) NW of a witness post.  The
bench mark is set 3 cm (0.1 ft) above the ground, crimped to a copper-clad steel
rod driven to refusal and encased in concrete.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 8724094                         PUBLICATION DATE:  12/12/2003
Name:       EAST BAHIA HONDA KEY                              
            FL
NOAA Chart: 11449                           Latitude:   24° 46.5' N (  24.77500)
USGS Quad:  EAST BAHIA HONDA KEY            Longitude:  81° 13.6' W ( -81.22670)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  CAL 1974
                         DESIGNATION:          872 4094 CAL

MONUMENTATION:           Tidal Station disk                    VM#:         6336
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   24° 46.5' N (  24.77500)          LONGITUDE:  81° 13.6' W ( -81.22670)


The bench mark is a disk located  on a narrow sand berm behind a fringe of
mangrove trees, 26.00 m (85.3 ft) NW of bench mark DON 1974, 17.71 m (58.1 ft)
east of reference mark TRADE NO 2 1935, and 0.21 m (0.7 ft) west of a witness
post.  The bench mark is set 6 cm (0.2 ft) above ground, crimped to a
copper-clad steel rod driven to refusal and encased in concrete.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 8724094                         PUBLICATION DATE:  12/12/2003
Name:       EAST BAHIA HONDA KEY                              
            FL
NOAA Chart: 11449                           Latitude:   24° 46.5' N (  24.77500)
USGS Quad:  EAST BAHIA HONDA KEY            Longitude:  81° 13.6' W ( -81.22670)


                            T I D A L   D A T U M S 


Tidal datums at EAST BAHIA HONDA KEY based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           June 1974 - June 1974
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8724211 BIG PINE KEY VIADUCT


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     MEAN HIGHER HIGH WATER                     MHHW   =  0.422
     MEAN HIGH WATER                            MHW    =  0.362
     MEAN TIDE LEVEL                            MTL    =  0.227
     MEAN SEA LEVEL                             MSL    =  0.208
     MEAN LOW WATER                             MLW    =  0.092
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     TRADE 1935                                  0.649    0.287
     TRADE NO 1 1935                             0.640    0.278
     TRADE NO 2 1935                             0.636    0.274
     DON 1974                                    0.635    0.273
     CAL 1974                                    0.711    0.349


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 8724094                         PUBLICATION DATE:  12/12/2003
Name:       EAST BAHIA HONDA KEY                              
            FL
NOAA Chart: 11449                           Latitude:   24° 46.5' N (  24.77500)
USGS Quad:  EAST BAHIA HONDA KEY            Longitude:  81° 13.6' W ( -81.22670)


                             D E F I N I T I O N S


Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal
Datum Epoch.  It pertains to local mean sea level and should not be confused
with the fixed datums of North American Vertical Datum of 1988 (NAVD88).

NAVD88 is a fixed datum derived from a simultaneous, least squares, minimum
constraint adjustment of Canadian/Mexican/United States leveling observations.
Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as
the single initial constraint.  NAVD88 replaces NGVD29 as the national
standard geodetic reference for heights.  Bench mark elevations relative to
NAVD88 are available from NGS through the World Wide Web at 
National Geodetic Survey.

NGVD29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded.  NGVD29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads.  NGVD29 was originally derived from a general
adjustment of the first-order leveling networks of the U.S. and Canada after
holding mean sea level observed at 26 long term tide stations as fixed.
Numerous local and wide-spread adjustments have been made since establishment in
1929.  Bench mark elevations relative to NGVD29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at 
National Geodetic Survey.

NAVD88 and NGVD29 are fixed geodetic datums whose elevation relationships to
local MSL and other tidal datums may not be consistent from one location to
another.

The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique
identifiers for bench marks in the tidal and geodetic databases, respectively.
Each bench mark in either database has a single, unique VM# and/or PID# assigned.
Where both VM# and PID# are indicated, both tidal and geodetic elevations are
available for the bench mark listed. The NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.

The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD88 elevations.
The NAVD88 elevation relationship shown in the table is derived from an average
of several bench mark elevations relative to tide station datum.  As a result of
this averaging, NAVD88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD88 elevations listed for
each bench mark in the NGS database.

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Products available at 8724094 EAST BAHIA HONDA KEY, FL

Revised: 10/15/2013
NOAA / National Ocean Service
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