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Superseded Bench Mark Sheet for 8724094, EAST BAHIA HONDA KEY FL

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  4

                                                   PUBLICATION DATE:  10/16/1986
Station ID: 8724094                                SUPERCEDED DATE:   04/21/2003
Name:       EAST BAHIA HONDA KEY, FLORIDA BAY                 
            FLORIDA
NOAA Chart: 11449                                  Latitude:         24° 46.5' N
USGS Quad:  EAST BAHIA HONDA KEY                   Longitude:        81° 13.6' W


To reach the tidal bench marks from the west end of Seven Mile Bridge on Little
Duck Key, proceed by boat 6.9 statute miles (11.1 km) 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

MONUMENTATION:           Survey Disk                               VM#:     6332
AGENCY:                                                            PID#:  AA1453
SETTING CLASSIFICATION:  Concrete


The bench mark is set in concrete on the SE end of East Bahia Honda Key, 295
feet (90 m) from the extreme southern tip, and 59 feet (18 m) from the south
shore on a narrow sand ridge behind a fringe of mangrove in a small open area.



                         BENCH MARK STAMPING:  TRADE NO 1 1935

MONUMENTATION:           Survey Disk                               VM#:     6333
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete


The bench mark is 45.8 feet (14.0 m) NW of the station, and 1.0 foot (0.3 m) SE
of a witness post.



                         BENCH MARK STAMPING:  TRADE NO 2 1935

MONUMENTATION:           Survey Disk                               VM#:     6334
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete


The bench mark is set in concrete 36.6 feet (11.2 m) SE of Bench Mark TRADE 1935
on the same ridge, and 0.4 foot (0.1 m) SE of a witness post.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  4

                                                   PUBLICATION DATE:  10/16/1986
Station ID: 8724094                                SUPERCEDED DATE:   04/21/2003
Name:       EAST BAHIA HONDA KEY, FLORIDA BAY                 
            FLORIDA
NOAA Chart: 11449                                  Latitude:         24° 46.5' N
USGS Quad:  EAST BAHIA HONDA KEY                   Longitude:        81° 13.6' W


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


                         BENCH MARK STAMPING:  DON 1974

MONUMENTATION:           Survey Disk                               VM#:     6335
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete/Rod Monument


The bench mark is set 85.3 feet (26.0 m) SE of Bench Mark CAL 1974, 11.0 feet
(3.4 m) south of the north side of the sand berm, 0.8 foot (0.2 m) NW of a
witness post,and is set atop a copper-clad steel rod driven to refusal in
concrete on a narrow sand berm on the south side of the key.



                         BENCH MARK STAMPING:  CAL 1974

MONUMENTATION:           Survey Disk                               VM#:     6336
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete/Rod Monument


The bench mark is set 85.3 feet (26.0 m) NW of Bench Mark DON 1974, 58.1 feet
(17.7 m) east of Bench Mark TRADE NO 2 1935, 0.7 foot (0.2 m) west of a witness
post, and is set atop a copper-clad steel rod driven to refusal on a narrow sand
berm behind a fringe of mangrove trees.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  4

                                                   PUBLICATION DATE:  10/16/1986
Station ID: 8724094                                SUPERCEDED DATE:   04/21/2003
Name:       EAST BAHIA HONDA KEY, FLORIDA BAY                 
            FLORIDA
NOAA Chart: 11449                                  Latitude:         24° 46.5' N
USGS Quad:  EAST BAHIA HONDA KEY                   Longitude:        81° 13.6' W


                            T I D A L   D A T U M S 


Tidal datums at EAST BAHIA HONDA KEY, FLORIDA BAY based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           JUNE 1974
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8724211 BIG PINE KEY VIADUCT


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

     HIGHEST OBSERVED WATER LEVEL (06/22/1974)         =   2.22
     MEAN HIGHER HIGH WATER                     MHHW   =   1.42
     MEAN HIGH WATER                            MHW    =   1.22
     MEAN TIDE LEVEL                            MTL    =   0.77
     MEAN LOW WATER                             MLW    =   0.32
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (06/03/1974)         =  -0.08

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     TRADE 1935                                  2.36      1.14
     TRADE NO 1 1935                             2.33      1.11
     TRADE NO 2 1935                             2.32      1.10
     DON 1974                                    2.32      1.10
     CAL 1974                                    2.56      1.34


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

                                                   PUBLICATION DATE:  10/16/1986
Station ID: 8724094                                SUPERCEDED DATE:   04/21/2003
Name:       EAST BAHIA HONDA KEY, FLORIDA BAY                 
            FLORIDA
NOAA Chart: 11449                                  Latitude:         24° 46.5' N
USGS Quad:  EAST BAHIA HONDA KEY                   Longitude:        81° 13.6' W


                             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 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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Revised: 08/08/2018
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