Superseded Bench Mark Sheet for 8724099, MISSOURI-LITTLE DUCK CHANNEL FL

Present Epoch

Printable version

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

                                                   PUBLICATION DATE:  03/06/1986
Station ID: 8724099                                SUPERCEDED DATE:   04/21/2003
Name:       MISSOURI-LITTLE DUCK CHANNEL, STRAITS OF FLORIDA  
            FLORIDA
NOAA Chart: 11449                                  Latitude:         24° 40.8' N
USGS Quad:  SEVENMILE BRIDGE                       Longitude:        81° 14.1' W


To reach the tidal bench marks from the Post Office at Marathron, proceed 10.1
miles (16.3 km) SW on U.S. Highway 1 to the east end of the bridge between
Missouri Key and Little Duck Key.  The bench marks are located on the concrete
wingwalls and curbs of the old highway bridge (bridge #19), now used as a
fishing pier, and the new bridge.  The tide gage and staff were located at the
east end of the old bridge on the SE wingwall.


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


                 PRIMARY BENCH MARK STAMPING:  NO 2 1975

MONUMENTATION:           Survey Disk                               VM#:     6343
AGENCY:                                                            PID#:  AA0956
SETTING CLASSIFICATION:  Concrete Wingwall


The bench mark is located at the east end of the old bridge, set flush in the
top of the SE concrete wingwall, 31.5 feet (9.6 m) north of Bench Mark NO 1
1975, 15.0 feet (4.6 m) SE of the centerline of the bridge, 4.5 feet (1.4 m) SE
of the NE abutment, and 3 feet (1 m) below bridge level.



                         BENCH MARK STAMPING:  NO 1 1975

MONUMENTATION:           Survey Disk                               VM#:     6342
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Wingwall


The bench mark is located at the east end of the old bridge, set flush in the
top of the SE concrete wingwall, 54 feet (16 m) south of Bench Mark NO 3 1975,
36 feet (11 m) SE of the bridge abutment, and 31.5 feet (9.6 m) south of Bench
Mark NO 2 1975.

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

                                                   PUBLICATION DATE:  03/06/1986
Station ID: 8724099                                SUPERCEDED DATE:   04/21/2003
Name:       MISSOURI-LITTLE DUCK CHANNEL, STRAITS OF FLORIDA  
            FLORIDA
NOAA Chart: 11449                                  Latitude:         24° 40.8' N
USGS Quad:  SEVENMILE BRIDGE                       Longitude:        81° 14.1' W


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


                         BENCH MARK STAMPING:  NO 3 1975

MONUMENTATION:           Survey Disk                               VM#:     6344
AGENCY:                                                            PID#:  AA0957
SETTING CLASSIFICATION:  Concrete Curb


The bench mark is located at the east end of the old bridge, set flush in the
top of the NE concrete curb of the bridge, 18.0 feet (5.5 m) NE of the south end
of the NE concrete wingwall, 11 feet (3 m) NW of the centerline of the  bridge,
and 0.5 foot (0.2 m) above bridge level.



                         BENCH MARK STAMPING:  4099 D 1982

MONUMENTATION:           Survey Disk                               VM#:     6345
AGENCY:                                                            PID#:  AA0955
SETTING CLASSIFICATION:  Concrete Guardrail


The bench mark is located at the east end of the new bridge, set in the top of
the concrete guardrail at the NE end of the bridge, 23.4 feet (7.1 m) NW of the
centerline of the highway, 10.5 feet (3.2 m) SW of the NE end of the guardrail,
0.5 foot (0.2 m) NE of the abutment, and 3 feet (1 m) above highway level.



                         BENCH MARK STAMPING:  4099 E 1982

MONUMENTATION:           Survey Disk                               VM#:     6346
AGENCY:                                                            PID#:  AA0954
SETTING CLASSIFICATION:  Concrete Guardrail


The bench mark is located at the west end of the new bridge, set in the top of
the concrete guard rail at the SW end at the bridge, 23.3 feet (7.1 m) SE of the
centerline of the highway, 10.5 feet (3.2 m) NE of the SW end of the guardrail,
0.6 foot (0.2 m) SW of the abutment, and 3 feet (1 m) above highway level.

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

                                                   PUBLICATION DATE:  03/06/1986
Station ID: 8724099                                SUPERCEDED DATE:   04/21/2003
Name:       MISSOURI-LITTLE DUCK CHANNEL, STRAITS OF FLORIDA  
            FLORIDA
NOAA Chart: 11449                                  Latitude:         24° 40.8' N
USGS Quad:  SEVENMILE BRIDGE                       Longitude:        81° 14.1' W


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


                         BENCH MARK STAMPING:  4099 F 1982

MONUMENTATION:           Survey Disk                               VM#:     6347
AGENCY:                                                            PID#:  AA0953
SETTING CLASSIFICATION:  Concrete Cheekwall


The bench mark is located at the west end of the new bridge, set in the concrete
bridge cheekwall at the SW end of the bridge, 41.4 feet (12.6 m) SW of a metal
guard for an aquaduct, 25.5 feet (7.8 m) NW of the centerline of the highway,
2.8 feet (0.9 m) SE of the NW edge of the cheekwall, and at highway level.

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

                                                   PUBLICATION DATE:  03/06/1986
Station ID: 8724099                                SUPERCEDED DATE:   04/21/2003
Name:       MISSOURI-LITTLE DUCK CHANNEL, STRAITS OF FLORIDA  
            FLORIDA
NOAA Chart: 11449                                  Latitude:         24° 40.8' N
USGS Quad:  SEVENMILE BRIDGE                       Longitude:        81° 14.1' W


                            T I D A L   D A T U M S 


Tidal datums at MISSOURI-LITTLE DUCK CHANNEL, STRAITS OF FLORIDA based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           FEBRUARY 1975
     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 (02/23/1975)         =   1.74
     MEAN HIGHER HIGH WATER                     MHHW   =   1.28
     MEAN HIGH WATER                            MHW    =   1.09
     MEAN TIDE LEVEL                            MTL    =   0.60
     MEAN LOW WATER                             MLW    =   0.11
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (01/24/1975)         =  -0.48

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     NO 2 1975                                  10.47      9.38
     NO 1 1975                                   5.02      3.93
     NO 3 1975                                  12.99     11.90
     4099 D 1982                                18.28     17.19
     4099 E 1982                                18.28     17.19
     4099 F 1982                                15.58     14.49


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

                                                   PUBLICATION DATE:  03/06/1986
Station ID: 8724099                                SUPERCEDED DATE:   04/21/2003
Name:       MISSOURI-LITTLE DUCK CHANNEL, STRAITS OF FLORIDA  
            FLORIDA
NOAA Chart: 11449                                  Latitude:         24° 40.8' N
USGS Quad:  SEVENMILE BRIDGE                       Longitude:        81° 14.1' 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.

Return to Top
Products available at 8724099 MISSOURI-LITTLE DUCK CHANNEL, FL