Superseded Bench Mark Sheet for 8724327, TARPON CREEK (OUTSIDE) FL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:  03/19/1986
Station ID: 8724327                                SUPERCEDED DATE:   04/21/2003
Name:       TARPON CREEK OUTSIDE, CUDJOE BAY                  
            FLORIDA
NOAA Chart: 11442                                  Latitude:         24° 37.7' N
USGS Quad:  SUGARLOAF KEY                          Longitude:        81° 30.6' W


To reach the tidal bench marks by boat from the State Highway S-939 bridge over
Tarpon Creek, proceed in an easterly heading out the dredged canal and into
Cudjoe Bay, go south to channel marker #9, from marker #9 run on a heading of
300  to the mangrove shoreline.  The bench marks are located along the east side
of Sugarloaf Key, midway between Tarpon Creek and Tarpon Creek Canal.  The tide
gage and staff were located on a platform in Tarpon Creek.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1974

MONUMENTATION:           Survey Disk                               VM#:     6944
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is 90 feet (27 m) west of the outer edge of mangroves and 1.0
foot (0.3 m) north of a witness sign and wood post.  The bench mark is crimped
to the top of a copper-clad steel rod driven to refusal, encased in a PVC pipe
and concrete kickblock, and 0.7 foot (0.2 m) above ground level.



                         BENCH MARK STAMPING:  NO 2 1974

MONUMENTATION:           Survey Disk                               VM#:     6945
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is 135 feet (41 m) west of the outer edge of mangroves, 44.3 feet
(13.5 m) WNW of Bench Mark NO 1 1974, 3.5 feet (1.1 m) NE of a witness sign
nailed to a tree.  The bench mark is crimped to the top of a copper-clad steel
rod driven to refusal, encased in a PVC pipe and concrete kickblock, and 0.7
foot (0.2 m) above ground level.

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

                                                   PUBLICATION DATE:  03/19/1986
Station ID: 8724327                                SUPERCEDED DATE:   04/21/2003
Name:       TARPON CREEK OUTSIDE, CUDJOE BAY                  
            FLORIDA
NOAA Chart: 11442                                  Latitude:         24° 37.7' N
USGS Quad:  SUGARLOAF KEY                          Longitude:        81° 30.6' W


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


                         BENCH MARK STAMPING:  NO 3 1974

MONUMENTATION:           Survey Disk                               VM#:     6946
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is 215 feet (66 m) west of the outer edge of mangroves, 79.4 feet
(24.2 m) WNW of Bench Mark NO 2 1974, and SW of a witness sign and wood post. 
The bench mark is crimped to the top of a copper-clad steel rod driven to
refusal, encased in a PVC pipe and concrete kickblock, and 0.7 foot (0.2 m)
above ground level.



                         BENCH MARK STAMPING:  NO 4 1974

MONUMENTATION:           Survey Disk                               VM#:     6947
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is 295 feet (90 m) west of the outer edge of mangroves and 82.0
feet (25.0 m) west of Bench Mark NO 3 1974.  The bench mark is crimped to the
top of a copper-clad steel rod driven to refusal, encased in a PVC pipe and
concrete kickblock, and 0.7 foot (0.2 m) above ground level.



                         BENCH MARK STAMPING:  NO 5 1974

MONUMENTATION:           Survey Disk                               VM#:     6948
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is set in a cut line through the mangroves, 375 feet (114 m) west
of the outer edge of mangroves, 79.6 feet (24.3 m) west of Bench Mark NO 4 1974,
and 2.2 feet (0.7 m) NE of a witness sign and wood post.  The bench mark is
crimped to the top of a copper-clad steel rod driven to refusal, encased in a
PVC pipe and concrete kickblock, and 0.7 foot (0.2 m) above ground level.

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

                                                   PUBLICATION DATE:  03/19/1986
Station ID: 8724327                                SUPERCEDED DATE:   04/21/2003
Name:       TARPON CREEK OUTSIDE, CUDJOE BAY                  
            FLORIDA
NOAA Chart: 11442                                  Latitude:         24° 37.7' N
USGS Quad:  SUGARLOAF KEY                          Longitude:        81° 30.6' W


                            T I D A L   D A T U M S 


Tidal datums at TARPON CREEK OUTSIDE, CUDJOE BAY based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           MAY 1974
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8724138 BAHIA HONDA KEY


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

     HIGHEST OBSERVED WATER LEVEL (05/23/1974)         =   2.32
     MEAN HIGHER HIGH WATER                     MHHW   =   1.64
     MEAN HIGH WATER                            MHW    =   1.38
     MEAN TIDE LEVEL                            MTL    =   0.76
     MEAN LOW WATER                             MLW    =   0.14
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (05/07/1974)         =  -0.09



Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1974                                   1.56      0.18
     NO 2 1974                                   1.72      0.34
     NO 3 1974                                   1.96      0.58
     NO 4 1974                                   2.03      0.65
     NO 5 1974                                   2.05      0.67


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

                                                   PUBLICATION DATE:  03/19/1986
Station ID: 8724327                                SUPERCEDED DATE:   04/21/2003
Name:       TARPON CREEK OUTSIDE, CUDJOE BAY                  
            FLORIDA
NOAA Chart: 11442                                  Latitude:         24° 37.7' N
USGS Quad:  SUGARLOAF KEY                          Longitude:        81° 30.6' 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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