Superseded Bench Mark Sheet for 8724557, KEY WEST, WHITE STREET PIER FL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:  02/06/1992
Station ID: 8724557                                SUPERCEDED DATE:   04/21/2003
Name:       KEY WEST, HAWK CHANNEL                            
            FLORIDA
NOAA Chart: 11447                                  Latitude:         24° 32.7' N
USGS Quad:  KEY WEST                               Longitude:        81° 47.0' W


To reach the tidal bench marks from the intersection of Truman Avenue and White
Street in Key West, proceed SE on White Street for 0.75 mile (1.21 km) to the
pier at the foot of White Street.  The bench marks are on the L shaped pier. 
The tide gage and staff were near the SE end of the pier.


                         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#:     9622
AGENCY:                                                            PID#:  AA0919
SETTING CLASSIFICATION:  Concrete Walkway


The primary bench mark is set flush in a concrete walkway on the west side of
the pier at the L junction, 1 foot (0.3 m) north of the east/west sidewalk, 1
foot (0.3 m) west of the north/south sidewalk, and 1 foot (0.3 m) above the
road.



                         BENCH MARK STAMPING:  NO 2 1974

MONUMENTATION:           Survey Disk                               VM#:     9623
AGENCY:                                                            PID#:  AA0918
SETTING CLASSIFICATION:  Concrete Walkway


The bench mark is set flush in a concrete walkway on the east side of the pier,
259 feet (79 m) north of Bench Mark NO 1 1974, 7 feet (2 m) east of the second
light pole on the east side of the pier, 1 foot (0.3 m) east of the north/south
sidewalk, and 1 foot (0.3 m) above the road.

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

                                                   PUBLICATION DATE:  02/06/1992
Station ID: 8724557                                SUPERCEDED DATE:   04/21/2003
Name:       KEY WEST, HAWK CHANNEL                            
            FLORIDA
NOAA Chart: 11447                                  Latitude:         24° 32.7' N
USGS Quad:  KEY WEST                               Longitude:        81° 47.0' 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#:     9624
AGENCY:                                                            PID#:  AA0915
SETTING CLASSIFICATION:  Concrete Walkway


The bench mark is set flush in a concrete walkway on the east side of the pier,
185 feet (56 m) NE of Bench Mark NO 4 1974, 0.6 foot (0.2 m) south of the north
end of the walkway and the pier, and 1 foot (0.3 m) above the road.



                         BENCH MARK STAMPING:  NO 4 1974

MONUMENTATION:           Survey Disk                               VM#:     9625
AGENCY:                                                            PID#:  AA0916
SETTING CLASSIFICATION:  Concrete Walkway


The bench mark is set flush in a concrete walkway on the west side of the pier,
278 feet (85 m) NNW of Bench Mark NO 5 1974, 0.7 foot (0.2 m) north of the edge
of the pier wingwall, and 1 foot (0.3 m) above the road.



                         BENCH MARK STAMPING:  NO 5 1974

MONUMENTATION:           Survey Disk                               VM#:     9626
AGENCY:                                                            PID#:  AA0917
SETTING CLASSIFICATION:  Concrete Walkway


The bench mark is set flush in a concrete walkway on the west side of the pier,
176 feet (54 m) west of Bench Mark NO 2 1974, 8 feet (2 m) west of the first
light pole on the west side of the pier, 1 foot (0.3 m) west of the north/south
sidewalk, and 1 foot (0.3 m) above the road.

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

                                                   PUBLICATION DATE:  02/06/1992
Station ID: 8724557                                SUPERCEDED DATE:   04/21/2003
Name:       KEY WEST, HAWK CHANNEL                            
            FLORIDA
NOAA Chart: 11447                                  Latitude:         24° 32.7' N
USGS Quad:  KEY WEST                               Longitude:        81° 47.0' W


                            T I D A L   D A T U M S 


Tidal datums at KEY WEST, HAWK CHANNEL based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           SEPTEMBER 1974
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8724580 KEY WEST


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

     HIGHEST OBSERVED WATER LEVEL (09/18/1974)         =   2.96
     MEAN HIGHER HIGH WATER                     MHHW   =   1.96
     MEAN HIGH WATER                            MHW    =   1.66
     MEAN TIDE LEVEL                            MTL    =   0.94
     MEAN LOW WATER                             MLW    =   0.22
     MEAN LOWER LOW WATER                       MLLW   =   0.00

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1974                                   4.70      3.04
     NO 2 1974                                   4.68      3.02
     NO 3 1974                                   4.70      3.04
     NO 4 1974                                   4.76      3.10
     NO 5 1974                                   4.71      3.05


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

                                                   PUBLICATION DATE:  02/06/1992
Station ID: 8724557                                SUPERCEDED DATE:   04/21/2003
Name:       KEY WEST, HAWK CHANNEL                            
            FLORIDA
NOAA Chart: 11447                                  Latitude:         24° 32.7' N
USGS Quad:  KEY WEST                               Longitude:        81° 47.0' 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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