Superseded Bench Mark Sheet for 8724529, RIVERIA CANAL, KEY WEST FL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:  05/02/1986
Station ID: 8724529                                SUPERCEDED DATE:   04/21/2003
Name:       KEY WEST, RIVIERA CANAL                           
            FLORIDA
NOAA Chart: 11441                                  Latitude:         24° 33.8' N
USGS Quad:  KEY WEST                               Longitude:        81° 45.1' W


To reach the tidal bench marks from the intersection of U.S. Highway 1 and State
Highway A1A on the east side of Key West, proceed SE on State Highway A1A for
0.35 mile (0.56 km) to the bridge over the Riviera Canal.  The bench marks are
located along State Highway A1A in the vicinity of the bridge.  The tide gage
and staff were located on a private dock SW of the NW corner of the bridge.


                         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#:    10985
AGENCY:                                                            PID#:  AA1004
SETTING CLASSIFICATION:  Concrete Sidewalk


The bench mark is set flush in the concrete sidewalk at the NE corner of the
State Highway A1A bridge over Riviera Canal, 332 feet (101 m) SSE of Bench Mark
P 121 1945, 33 feet (10 m) NNW of the SE corner of the bridge bannister, and 31
feet (9 m) ENE of the centerline of the highway.



                         BENCH MARK STAMPING:  NO 2 1974

MONUMENTATION:           Survey Disk                               VM#:    10986
AGENCY:                                                            PID#:  AA1003
SETTING CLASSIFICATION:  Concrete Wingwall


The bench mark is set flush in the SE concrete wingwall of the State Highway A1A
bridge over Riviera Canal, 184 feet (56 m) SSE of Bench Mark NO 1 1974, 149 feet
(45 m) NNW of the south end of the east bannister, 140 feet (43 m) NNE of Bench
Mark B 271 1966, 35 feet (11 m) ENE of the centerline of the highway, and 1 foot
(0.3 m) below the highway.

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

                                                   PUBLICATION DATE:  05/02/1986
Station ID: 8724529                                SUPERCEDED DATE:   04/21/2003
Name:       KEY WEST, RIVIERA CANAL                           
            FLORIDA
NOAA Chart: 11441                                  Latitude:         24° 33.8' N
USGS Quad:  KEY WEST                               Longitude:        81° 45.1' 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#:    10987
AGENCY:                                                            PID#:  AA1002
SETTING CLASSIFICATION:  Concrete Wingwall


The bench mark is set flush in the SW concrete wingwall of the State Highway A1A
over Riviera Canal, 40 feet (12 m) WSW of the centerline of the highway, 1 foot
(0.3 m) east of the NW corner of the wingwall, and 3 feet (1 m) below the
highway.



                         BENCH MARK STAMPING:  B 271 1966

MONUMENTATION:           Survey Disk                               VM#:    10988
AGENCY:                                                            PID#:  AA0051
SETTING CLASSIFICATION:  Concrete Bannister


The bench mark is set on top of the SE concrete bannister of the State Highway
A1A bridge over Riviera Canal, 9.0 feet (2.7 m) NW of the SE end of the
bannister, 6.9 feet (2.1 m) NE of the NE curb of the highway, and 3.5 feet (1.1
m) above sidewalk level.



                         BENCH MARK STAMPING:  P 121 1945

MONUMENTATION:           Survey Disk                               VM#:    10989
AGENCY:                                                            PID#:  AA0052
SETTING CLASSIFICATION:  Concrete Seawall


The bench mark is set on top of a concrete seawall at the intersection of
Flagler Avenue and Roosevelt Boulevard (State Highway A1A) near the south corner
of the U.S. Naval Hospital, 45 feet (14 m) SE of the extended centerline of
Flagler Avenue, 41 feet (12 m) NW of the NW end of the NE concrete bannister of
the bridge over Riviera Canal, 9.5 feet (2.9 m) NE of the NE curb of State
Highway A1A, 1.1 feet (0.3 m) SW of a steel fence around the hospital grounds,
and 1.5 feet (0.5 m) above sidewalk level. Note: mark is severely rusted.

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

                                                   PUBLICATION DATE:  05/02/1986
Station ID: 8724529                                SUPERCEDED DATE:   04/21/2003
Name:       KEY WEST, RIVIERA CANAL                           
            FLORIDA
NOAA Chart: 11441                                  Latitude:         24° 33.8' N
USGS Quad:  KEY WEST                               Longitude:        81° 45.1' W


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


                         BENCH MARK STAMPING:  4529 F 1982

MONUMENTATION:           Survey Disk                               VM#:    10990
AGENCY:                                                            PID#:  AA1005
SETTING CLASSIFICATION:  Concrete Guard Rail Base


The bench mark is set in the concrete guard rail base at the north end of the
east bannister of the State Highway A1A bridge over Riviera Canal, 285.6 feet
(87.1 m) NNW of the north abutment of the bridge, 33.4 feet (10.2 m) ENE of the
centerline of the highway, 4.5 feet (1.4 m) SSE of the north end of the
bannister, and 1 foot (0.3 m) above highway level.

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

                                                   PUBLICATION DATE:  05/02/1986
Station ID: 8724529                                SUPERCEDED DATE:   04/21/2003
Name:       KEY WEST, RIVIERA CANAL                           
            FLORIDA
NOAA Chart: 11441                                  Latitude:         24° 33.8' N
USGS Quad:  KEY WEST                               Longitude:        81° 45.1' W


                            T I D A L   D A T U M S 


Tidal datums at KEY WEST, RIVIERA CANAL based on:

     LENGTH OF SERIES:      2 MONTHS
     TIME PERIOD:           NOVEMBER-DECEMBER 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 (10/16/1974)         =   2.26
     MEAN HIGHER HIGH WATER                     MHHW   =   1.29
     MEAN HIGH WATER                            MHW    =   1.02
     MEAN TIDE LEVEL                            MTL    =   0.59
   * NATIONAL GEODETIC VERTICAL DATUM           NGVD29 =   0.23
     MEAN LOW WATER                             MLW    =   0.15
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (12/27/1974)         =  -0.46

   * NGVD reference based on adjustment of 1971 and NOS levels of 1982. 
North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1974                                  12.37     11.35
     NO 2 1974                                  10.80      9.78
     NO 3 1974                                   7.23      6.21
     B 271 1966                                 10.58      9.56
     P 121 1945                                  5.33      4.31
     4529 F 1982                                 5.35      4.33


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

                                                   PUBLICATION DATE:  05/02/1986
Station ID: 8724529                                SUPERCEDED DATE:   04/21/2003
Name:       KEY WEST, RIVIERA CANAL                           
            FLORIDA
NOAA Chart: 11441                                  Latitude:         24° 33.8' N
USGS Quad:  KEY WEST                               Longitude:        81° 45.1' 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.

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