Superseded Bench Mark Sheet for 8723350, RAGGED KEY #3 FL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:  07/01/1986
Station ID: 8723350                                SUPERCEDED DATE:   04/21/2003
Name:       RAGGED KEY NO 3, BISCAYNE BAY                     
            FLORIDA
NOAA Chart: 11462                                  Latitude:         25° 32.0' N
USGS Quad:  SOLDIER KEY                            Longitude:        80° 10.3' W


To reach the tidal bench marks from Elliott Key Harbor, proceed by boat 4.7
miles (7.6 km) north to red day beacon 2, then 1.6 miles (2.6 km) NE passing on
the north side of green day beacon 5 to Ragged Key No. 3.  The bench marks are
located on or within a circular seawall.  The tide gage and staff were located
on the SSW side of the seawall.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1971

MONUMENTATION:           Survey Disk                               VM#:     5812
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Seawall


The bench mark is set flush on top of a concrete seawall which encircles a
two-story house and several small storage buildings, 162.0 feet (49.4 m) north
of the SE corner of the seawall, 75.9 feet (23.1 m) ESE of the SE corner of the
house, 69 feet (21 m) west of the east edge of the water line, and 15.9 feet
(4.8 m) NE of a small cement storage building.



                         BENCH MARK STAMPING:  NO 2 1971

MONUMENTATION:           Survey Disk                               VM#:     5813
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Seawall


The bench mark is set flush in the concrete seawall, 71.2 feet (21.7 m) WNW of
the NW corner of the two-story house, 53.0 feet (16.2 m) south of the NW corner
of the seawall, and 47.0 feet (14.3 m) west of the SW corner of a small
generator building.

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

                                                   PUBLICATION DATE:  07/01/1986
Station ID: 8723350                                SUPERCEDED DATE:   04/21/2003
Name:       RAGGED KEY NO 3, BISCAYNE BAY                     
            FLORIDA
NOAA Chart: 11462                                  Latitude:         25° 32.0' N
USGS Quad:  SOLDIER KEY                            Longitude:        80° 10.3' W


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


                         BENCH MARK STAMPING:  NO 3 1971

MONUMENTATION:           Survey Disk                               VM#:     5814
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Flagpole Base


The bench mark is set flush in the fourth step of the concrete flagpole base,
80.4 feet (24.5 m) south of the south wall of the two-story house, 46.0 feet
(14.0 m) north of a V in the seawall, and 22.4 feet (6.8 m) west of the west
edge of the boat slip.



                         BENCH MARK STAMPING:  NO 4 1974

MONUMENTATION:           Survey Disk                               VM#:     5815
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Seawall


The bench mark is set flush in the SE corner of the concrete seawall, 155 feet
(47 m) south of Bench Mark NO 1 1971, 99.5 feet (30.3 m) east of a boat slip,
and 5.3 feet (1.6 m) north of the SE corner of the seawall.



                         BENCH MARK STAMPING:  NO STAMPING 1

MONUMENTATION:           Compass Rose                              VM#:     5816
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Patio


The bench mark is set flush in a concrete patio, 63.9 feet (19.5 m) SSW of Bench
Mark NO 2 1971, 20.3 feet (6.2 m) SW of the corner of the two-story house, 19.6
feet (6.0 m) WSW of the west corner of the caretakers house, 18.3 feet (5.6 m)
SW of the south corner of the generator building, and 17.3 feet (5.3 m) west of
the cistern steps.

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

                                                   PUBLICATION DATE:  07/01/1986
Station ID: 8723350                                SUPERCEDED DATE:   04/21/2003
Name:       RAGGED KEY NO 3, BISCAYNE BAY                     
            FLORIDA
NOAA Chart: 11462                                  Latitude:         25° 32.0' N
USGS Quad:  SOLDIER KEY                            Longitude:        80° 10.3' W


                            T I D A L   D A T U M S 


Tidal datums at RAGGED KEY NO 3, BISCAYNE BAY based on:

     LENGTH OF SERIES:      12 MONTHS
     TIME PERIOD:           JANUARY-DECEMBER 1975
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8723170 MIAMI


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

     HIGHEST OBSERVED WATER LEVEL (10/06/1974)         =   3.75
     MEAN HIGHER HIGH WATER                     MHHW   =   1.83
     MEAN HIGH WATER                            MHW    =   1.78
     MEAN TIDE LEVEL                            MTL    =   0.95
     MEAN LOW WATER                             MLW    =   0.13
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (04/05/1977)         =  -0.98



Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1971                                   5.36      3.58
     NO 2 1971                                   5.12      3.34
     NO 3 1971                                   6.62      4.84
     NO 4 1974                                   5.36      3.58
     NO STAMPING 1                               4.97      3.19


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

                                                   PUBLICATION DATE:  07/01/1986
Station ID: 8723350                                SUPERCEDED DATE:   04/21/2003
Name:       RAGGED KEY NO 3, BISCAYNE BAY                     
            FLORIDA
NOAA Chart: 11462                                  Latitude:         25° 32.0' N
USGS Quad:  SOLDIER KEY                            Longitude:        80° 10.3' 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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